212-MM-LR-REV12.pdf

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111
REVISION ONLY
BHT-212-MM
NOTICE
This revision updates the front matter and Chapters 5, 32, 67, 71, 76, and 96.
Please incorporate these updates into the manual in accordance with the Log of
Pages attached.
Bell Helicopter Textron would like to thank its Customers for providing us with
Customer Feedback information. This information is very much appreciated and
allows us to improve the quality of our manuals with each revision.
7 JUNE 1993
REVISION 12  8 JUNE 2010
BHT-212-MM-1
 NOTICE
The instructions set forth in this manual, as supplemented or modified by Alert Service Bulletins (ASB) or
other directions issued by Bell Helicopter Textron Inc. and Airworthiness Directives (AD) issued by the
applicable regulatory agencies, shall be strictly followed.
7 JUNE 1993
REVISION 12  8 JUNE 2010
COPYRIGHT NOTICE
COPYRIGHT  
2010
BELL  HELICOPTER TEXTRON INC.
AND BELL HELICOPTER TEXTRON
CANADA LTD.
ALL RIGHTS RESERVED
MAINTENANCE MANUAL
VOLUME 1
GENERAL INFORMATION
BHT-212-MM-1
PN
Rev. 10 18 SEP 2009
Additional copies of this publication may be obtained by contacting:
Commercial Publication Distribution Center
Bell Helicopter Textron Inc.
P. O. Box 482
Fort Worth, Texas 76101-0482
PROPRIETARY RIGHTS NOTICE
These data are proprietary to Bell Helicopter Textron Inc. Disclosure,
reproduction, or use of these data for any purpose other than helicopter
operation or maintenance is forbidden without prior written authorization from
Bell Helicopter Textron Inc.
DESTINATION CONTROL STATEMENT
These commodities, technology, or software were exported from the United
States in accordance with the Export Administration Regulations (EAR).
Diversion contrary to U.S. law prohibited. The data contained in this manual are
classified as ECCN EAR99.
BHT-212-MM-1
8 JUN 2010 Rev. 12
Warning
WARNING
THIS MANUAL APPLIES ONLY TO HELICOPTERS AND COMPONENTS
MAINTAINED IN ACCORDANCE WITH BELL HELICOPTER TEXTRON
(BELL) APPROVED PROCEDURES USING BELL APPROVED PARTS.
ALL INSPECTION, REPAIR AND OVERHAUL PROCEDURES PUBLISHED
BY BELL, INCLUDING PART RETIREMENT LIFE, ARE BASED SOLELY ON
THE USE OF BELL PARTS THAT HAVE BEEN MAINTAINED USING BELL
APPROVED DATA. THE DATA PUBLISHED HEREIN OR OTHERWISE
SUPPLIED BY BELL IS NOT APPLICABLE TO NON-BELL PARTS OR
PARTS THAT HAVE BEEN REPAIRED USING DATA AND/OR PROCESSES
NOT APPROVED BY BELL.
BELL IS NOT RESPONSIBLE FOR ANY PART OTHER THAN THOSE THAT
IT HAS APPROVED.
BEFORE PERFORMING ANY PROCEDURE CONTAINED IN THIS MANUAL
YOU MUST INSPECT THE AFFECTED PARTS AND RECORDS FOR
EVIDENCE OF ANY MANUFACTURE, REPAIR, REWORK OR USE OF A
PROCESS NOT APPROVED BY BELL.
IF YOU IDENTIFY OR SUSPECT THE USE OF PARTS NOT AUTHORIZED
BY BELL, EITHER REMOVE THE AFFECTED ITEM FROM THE AIRCRAFT
OR OBTAIN INSTRUCTIONS FOR CONTINUED AIRWORTHINESS FROM
THE MANUFACTURER OR THE ORGANIZATION THAT APPROVED THE
REPAIR.
BHT-212-MM-1
CSS
Rev. 11 30 APR 2010
CUSTOMER SUPPORT AND SERVICES
Flying smart means that no matter where you are, or what time it is, you can make a call
and get additional information, clarification, or advice on a technical or operational issue
concerning your helicopter or information contained in our Technical Publications.
Product Support Engineering (PSE) is just a phone call away and may be contacted as
follows:
For additional information on Customer Support and Services as well as Product Support
Engineering (PSE) and your local Customer Service Representative (CSR) network,
please access http://www.bellhelicopter.com/en/support.
Model 206 or 407
Phone:
450-437-2862 or 800-243-6407 (U.S./Canada)
Fax:
450-433-0272
E-mail:
pselight@bellhelicopter.textron.com
Model 222, 230, 427, 429, or 430
Phone:
450-437-2077 or 800-463-3036 (U.S./Canada)
Fax:
450-433-0272
E-mail:
pseinter@bellhelicopter.textron.com
Model 204, 205, 212, or 412
Phone:
450-437-6201 or 800-363-8028 (U.S./Canada)
Fax:
450-433-0272
E-mail:
psemedium@bellhelicopter.textron.com
Model 214, 210, HUEY II and All Bell's Active and 
Surplus Military Medium Helicopter Models
Phone:
817-280-3548
Fax:
817-280-2635
E-mail:
mts-medium@bellhelicopter.textron.com
Model OH-58, TH-67, TH-57, Both Active and Surplus 
Military
Phone:
817-280-3548
Fax:
817-280-2635
E-mail:
mts-light@bellhelicopter.textron.com
BHT-212-MM-1
LOG OF REVISIONS
Insert latest revision pages and dispose of superseded ones.
On a revised page, the text and/or illustration affected by the latest revision is shown by a vertical line. A revised
page with only a vertical line next to the page number indicates that text has shifted or that non-technical
correction(s) were made on that page.
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Revision .......32 ......... 02 OCT 92
Revision .......33 ......... 15 DEC 92
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Revision .......1 ........... 14 OCT 94
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Revision .......4 ........... 01 MAY 96
Revision .......5 ........... 25 SEP 97
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Revision .......8 ...........02 AUG 04
Revision .......9 ...........08 AUG 08
Revision .......10 ......... 18 SEP 09
Revision .......11.......... 30 APR 10
Revision .......12 ..........08 JUN 10
VOLUME 1
Cover .........................................9
Title ..........................................12
PN ............................................10
Warning....................................12
CSS..........................................11
A  D ........................................12
E/F ...........................................12
Help..........................................12
Customer Feedback.................12
Helicopter Sale Notice .............10
Warranty...................................10
BR-1/2........................................5
i/ii................................................9
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INDEX
1  22 (Deleted)....................... 11
23/24 (Deleted)........................ 11
VOLUME 2
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10 .............................................11
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14 .............................................11
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15 .............................................. 5
16 .............................................11
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26 .............................................11
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30 .............................................11
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Chapter 62
1  46......................................... 9
Chapter 63
1  4......................................... 11
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Cover .......................................10
Title ..........................................10
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Chapter 64
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8 JUN 2010 Rev. 12
E/F
H ELP
E VALUATE
L OGISTICS
P UBLICATIONS
Have you found something wrong with this manual  an 
error, an inconsistency, unclear instructions, etc.? Although 
we strive for accuracy and clarity, we may make errors on 
occasion. If we do and you discover it, we would appreciate 
your telling us about it so that we can change whatever is 
incorrect or unclear. Please be as specific as possible. 
Your complaint or suggestion will be acknowledged and we 
will tell you what we intend to do. 
You may use the enclosed Customer Feedback form, as 
applicable, to inform us where we have erred. 
Your assistance is sincerely appreciated.

CUSTOMER FEEDBACK 
RETURN VIA FAX TO PRODUCT SUPPORT ENGINEERING (450) 433-0272
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PRODUCT SUPPORT ENGINEERING
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FOLD ON DOTTED LINES AND TAPE
BHT-212-MM-1
Chapter 4
4. Replace engine fire extinguisher container firing cartridges
in accordance with specified service life.
Chapter 28
FUEL SYSTEM
1.
Inspect all exposed fuel lines and connections for leakage,
damage, and security.
Every sixth 100 hour inspection (600 hours) or 12 months:
2. Remove four access doors, located just forward of the aft
crosstube, from the underside of the fuselage. Inspect fuel lines
for evidence of leakage, damage, and security.
Chapter 29
HYDRAULIC SYSTEMS
1.
Inspect all lines and hoses for security and general
condition.
Every sixth 100 hour (600 hours) inspection or 12 months:
NOTE
Hydraulic 
filter elements 205-076-034-003 are
non-cleanable. It is recommended they be replaced
every 600 hours or 12 months. Filter elements
205-076-034-007 are cleanable. The -003 and -007
elements are 
interchangeable; 
intermixing of
different element types is not permitted.
1. Remove and inspect hydraulic filter elements.
2. Discard or clean filter elements as applicable.
3.
Install hydraulic filter elements.
4.
Install 0 to 500 PSIG (0 to 3447 kPa) gauge in quick
disconnect at rotor brake caliper. Slowly pull rotor brake handle
through travel. Cylinder should generate 240 to 260 PSI (1655
to 1793 kPA) at any handle velocity and shall maintain 150 PSI
(1034 kPa) minimum in over center position for 3 minutes.
Adjust as necessary.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 AUG 2008 Rev. 9
Page 27
BHT-212-MM-1
5.
Inspect rotor brake linings for wear (minimum thickness
0.150 inch (3.81 mm)).
Chapter 32
LANDING GEAR SYSTEM
 General Visual Inspection
1.
If installed, emergency float reservoir pressure indicator for
proper charge indication.
2.
If installed, floats for proper stowage and condition.
3.
Landing gear crosstube assemblies, skid tubes, and skid
shoes, for condition and security of attachment. Inspect
crosstube retention cap (rubber bumper pads) for condition and
security of attachment.
4. Tail skid for deformation and security of attachment.
5. Fuselage supports for wear, damage, and security of
attachment.
6.
If installed, landing gear forward crosstube crew step
fittings for corrosion, damage, and security in area of
attachment.
 Restoration
1. Torque check crosstube to skid tube saddle bolts.
2. Torque check forward and aft crosstube support fittings "U"
bolts to 80 to 100 inch-pounds (9.0 to 11.3 Nm).
3. Torque check ground handling wheel attachment eyebolts
on skid tubes 40 to 58 foot-pounds (54 to 79 Nm). Eyebolts that
rotate prior to reaching 40 foot-pounds (54 Nm) shall be
removed and inspected for evidence of bending. No bending is
permitted.
Chapter 52
DOORS AND WINDOWS
1. Crew and passenger doors structure for corrosion,
damage, distortion, and positive locking mechanisms. Seals for
adherence, tears, separations, and deterioration.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 28
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
2. Crew doors emergency jettison mechanism for condition,
security, and operation.
NOTE
The following inspection (step a) is for helicopters
equipped with escape panels which may be identified
by a rotating handle installed below the passenger
door windows. The handle is labeled EMERGENCY
RELEASE PULL COVER TURN LEFT AND PUSH.
Every third 100 hour inspection (300 hours) or 12 months:
a. Inspect passenger door emergency egress panel pins
and mechanisms for wear, corrosion, operation, and security.
b. Perform operational check of passenger door escape
panels.
3. Passenger door window retainers and fillers (if applicable)
for damage.
4. Nose, electrical, and equipment compartment access
doors for corrosion, damage, distortion, and positive locking
mechanisms.
5. Baggage compartment door for corrosion, damage, and
positive locking.
6.
Inspect heated windshield, if installed, for condition and
proper operation.
Chapter 53
TAILBOOM
 General Visual Inspection
ASB 212-90-63 and 
TB 212-94-147
1.
Internal and external structure of tailboom for cracks,
distortion, corrosion, and security.
2.
Inspect tailboom attachment points for cracks and security.
3. Ensure all drain holes are open.
4. Torque check intermediate gearbox mounting bolts.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 JUN 2010 Rev. 12
Page 29
ECCN EAR99
BHT-212-MM-1
5. Torque check tail rotor gearbox attachment nuts.
ASB 212-00-110
6.
Inspect vertical fin spar caps for cracks and corrosion.
7.
Inspect vertical fin spar caps forward side and web from
upper tailboom skin to approximately 4 inches (101.6 mm)
below upper tailboom skin as follows:
Remove aft tailboom access door. Face aft and use bright light
and small mirror to inspect area for cracks, especially near rivet
holes.
NOTE
If necessary, clean area with cloth dampened with
MEK (C-309) or equivalent. Ventilate area to prevent
breathing fumes.
Every third 100 hour inspection (300 hours) or every 12 
months:
1.
Inspect tailboom joints, splices, longerons, attach fittings,
and attaching hardware for corrosion, damage, and cracks.
ASB 212-90-63
2. Remove plug button at BS 99.00.
NOTE
Paint fissures are common in the splice area, cracks
will be evident by black powder emanating from
cracked area, and corrosion will leave evidence of
white powder.
3. Using a borescope or suitable means, inspect inside of
longeron paying particular attention to cracking and/or corrosion
in area of splice.
4. Report any cracks to Product Support Engineering.
5.
Install plug button with sealant (C-308).
Chapter 53
FUSELAGE
1.
Inspect fuselage tailboom attachment points for security.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 30
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
2.
Inspect lift link and attachments for corrosion, damage, and
security. Check bearings for looseness.
3.
Inspect for evidence of oil leakage.
4. Check all transmission chip detectors for debris and then
clean.
5. Test all transmission chip detectors electrical circuits.
6. Every third 100 hour inspection (300 hours), check internal
oil filter or full flow oil monitor for debris and then clean.
7. Every third 100 hour inspection (300 hours), torque check
top case to ring gear case nuts, ring gear case to main case
nuts, and main case to support case nuts 230 to 250
inch-pounds (25.99 to 28.25 Nm). Retorque as required.
Chapter 63
MAIN ROTOR MAST
 Detailed Visual Inspection
1.
Inspect mast assembly for security, corrosion, and
mechanical damage. Pay particular attention to area contacted
by main rotor hub static stops, and damper assembly/adapter
set splines.
2.
Inspect for evidence of oil leaks at mast bearing cap.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 AUG 2008 Rev. 9
Page 35
BHT-212-MM-1
Chapter 64
TAIL ROTOR HUB AND BLADE ASSEMBLY
CAUTION
COUNTERWEIGHT BELLCRANK RETENTION
NUTS P/N MS14145L6 OR ITS EQUIVALENT
MS17826-6 ARE DESIGNATED AS ONE TIME USE
ONLY. IF MAINTENANCE ACTION REQUIRES
THAT IT BE REMOVED, THE COUNTERWEIGHT
BELLCRANK NUT IS TO BE DISCARDED AND
REPLACED WITH A NEW NUT. OVERTORQUING
OR INCORRECT APPLICATION OF THE NUT
COULD CAUSE MECHANICAL FAILURE
RESULTING IN EXCESSIVE VIBRATION OR
DAMAGE TO THE TAIL ROTOR BLADES.
1.
Inspect the tail rotor counterweight bellcrank (P/N
212-011-705-001) retention nuts for cracks, corrosion, and
security. Reapply corrosion preventive compound (C-101) if
nuts are not completely covered.
Every third 100 hour inspection (300 hours) or every 12 
months:
Chapter 18
1. Dynamically balance tail rotor.
2. Torque check nuts on tail rotor blade retention bolts.
3. Torque check tail rotor retaining nut.
Chapter 65
TAIL ROTOR GEARBOX
1.
Inspect chip detector for debris. If metallic particles are
found, determine and correct cause.
2. Clean chip detector.
3. Test chip detector electrical circuit.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 36
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
TAIL ROTOR FLIGHT CONTROL ACTUATOR
1. Tail rotor hydraulic actuator for leaks and security of
attachment, mechanical damage, corrosion, and bearings and
linkages for looseness.
Chapter 71
POWER PLANT
Every third 100 hour inspection (300 hours) or 12 months:
NOTE
If applicable, refer to BHT-212-SI-96 for installation of
adjustable seals or refer to Chapter 71 for seal
adjustment.
ASB 212-10-137
1.
Inspect the left-hand and right-hand engine air inlet
cowlings for gaps between the lower surface of the cowling
firewall and the mating horizontal engine firewall.
Chapter 71
LEFT POWER SECTION
NOTE
Refer to Pratt & Whitney PT6T-3/-3B Maintenance
Manual for engine inspection requirements.
Every third 100 hour inspection (300 hours) or 12 months:
 Detailed Visual Inspection
1.
Ignition leads for corrosion, chafing and security.
2. Chip detectors for debris.
 Restoration
1. Clean chip detectors.
 Functional Check
1. Test chip detectors electrical circuits.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 JUN 2010 Rev. 12
Page 41
ECCN EAR99
BHT-212-MM-1
RIGHT POWER SECTION
NOTE
Refer to Pratt & Whitney PT6T-3/-3B Maintenance
Manual for engine inspection requirements.
Every third 100 hour inspection (300 hours) or 12 months:
 Detailed Visual Inspection
1.
Ignition leads for corrosion, chafing and security.
2. Chip detectors for debris.
 Restoration
1. Clean chip detectors.
 Functional Check
1. Test chip detectors electrical circuits.
Chapter 76
ENGINE FUEL AND POWER CONTROLS
Every third 100 hour inspection (300 hours) or 12 months:
 Operational Check
1. Check controls for smooth movement through full travel
ranges.
Chapter 71
STARTER GENERATOR
Every third 100 hour inspection (300 hours) or 12 months.
 Detailed Visual Inspection
1.
Left power section starter generator cooling ducts for
obstruction, kinking, and security.
2. Right power section starter generator cooling ducts for
obstruction, kinking, and security.
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 42
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
3.
Left power section starter generator brushes for allowable
wear.
4. Right power section starter generator brushes for allowable
wear.
Chapter 76
ENGINE CONTROLS
1. Check controls for smooth movement through full range of
travel.
Every third 100 hour inspection (300 hours) or 12 months:
1. Engine fuel and power controls:
SCHEDULED INSPECTIONS
5-6.
100 HOURS/12 CALENDAR MONTHS  PART A (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 42A/42B
BHT-212-MM-1
i. Remove bolts attaching actuator to lower supports.
Check cylinder alignment to lower support. Rod end bearing
side loads are not permitted. Install bolts.
j. Clean exposed area of actuator piston with hydraulic
fluid and a clean lint-free cloth.
BHT-ALL-SPM
k. Upper cylinder housing mounting bracket cavity for
corrosion. Cavity drain hole for obstruction. Reapply corrosion
preventive compound (C-104) as required. Dust boot for
condition.
Chapter 67
7. Cyclic control tubes:
a. Control tubes between cyclic jackshaft and cyclic
control actuator pilot valve input lever for corrosion, wear, and
damage.
b. Control tube bellcranks, mixing levers, supports, and
attaching hardware for corrosion, wear, and damage.
Chapter 63
8. Transmission:
a. All transmission chip detectors for debris.
b. Clean all transmission chip detectors.
c. Test all transmission chip detector electrical circuits.
d. Transmission internal oil filter or full flow debris monitor
for debris.
e. Clean transmission internal oil filter or full flow debris
monitor.
f. Mounts for damage and security.
g. Lift link and attachments for corrosion, damage, and
security. Bearings for looseness.
BHT-212-CR&O
h. Torque check  top case to ring gear case nuts, ring
gear case to main case nuts and main case to support case
nuts 230 to 250 inch-pounds (25.99 to 28.25 Nm). Retorque as
required.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 AUG 2008 Rev. 9
Page 77
BHT-212-MM-1
Chapter 71
POWER PLANT
NOTE
If applicable, refer to BHT-212-SI-96 for installation of
adjustable seals or refer to Chapter 71 for seal
adjustment.
ASB 212-10-137
1.
Inspect the left-hand and right-hand engine air inlet
cowlings for gaps between the lower surface of the cowling
firewall and the mating horizontal engine firewall.
LEFT POWER SECTION
Chapter 71
NOTE
Refer to Pratt & Whitney PT6T-3/-3B Maintenance
Manual for engine inspection requirements.
 Detailed Visual Inspection
1. Chip detectors for debris.
 Restoration
1. Clean chip detector.
 Functional Check
1. Test chip detector electrical circuits.
RIGHT POWER SECTION
NOTE
Refer to Pratt & Whitney PT6T-3/-3B Maintenance
Manual for engine inspection requirements.
 Detailed Visual Inspection
1. Chip detectors for debris.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 78
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
 Restoration
1. Clean chip detector.
 Functional Check
1. Test chip detector electrical circuits.
Chapter 71
ENGINE ELECTRICAL CONNECTIONS
 Detailed Visual Inspection
1.
Left power section ignition leads for corrosion, chafing, and
security.
2. Right power section ignition leads for corrosion, chafing,
and security.
Chapter 71
COMBINING (REDUCTION) GEARBOX
NOTE
Refer to Pratt & Whitney PT6T-3/-3B Maintenance
Manual for engine inspection requirements.
 Detailed Visual Inspection
1. Chip detectors for debris.
 Restoration
1. Clean chip detector.
 Functional Check
1. Test chip detector electrical circuits
Chapter 71
STARTER GENERATOR
 Detailed Visual Inspection
1.
Left power section starter generator brushes for allowable
wear.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 JUN 2010 Rev. 12
Page 79
ECCN EAR99
BHT-212-MM-1
2. Right power section starter generator brushes for allowable
wear.
3.
Left power section starter generator cooling ducts for
obstruction, kinking, and security.
4. Right power section starter generator cooling ducts for
obstruction, kinking, and security.
Chapter 76
ENGINE FUEL AND POWER CONTROLS
 Detailed Visual Inspection
1. Engine control linkages for looseness, lost motion, chafing,
damage, and security of attachment.
2. Bellcranks, mounts, and jackshafts.
 Operational Check
1. Check controls for smooth movement through full travel
ranges.
Chapter 96
POWER DIODES
Perform functional check of power diodes.
Chapter 32
LANDING GEAR SYSTEM
 Detailed Visual Inspection
1.
Landing gear skid shoes for excessive wear, cracks,
damage, corrosion, and security of attachment.
 Restoration
1. Torque check crosstube to skid tube saddle bolts.
2. Torque check forward and aft crosstube support fittings "U"
bolts 80 to 100 inch-pounds (9.0 to 11.3 Nm).
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 80
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
3. Torque check ground handling wheel attachment eyebolts
on skid tubes 40 to 58 foot-pounds (54 to 79 Nm). Eyebolts that
rotate prior to reaching 40 foot-pounds (54 Nm) shall be
removed and inspected for evidence of bending. No bending is
permitted.
Chapter 26
FIRE DETECTION SYSTEM
 General Visual Inspection
1. Engine fire detection elements for condition and security.
TAILBOOM
Chapter 53
1. Tailboom structure:
a. Tailboom exterior structure for corrosion and damage.
b. Tailboom interior structure for corrosion and damage.
c. Inspect tailboom joints, splices, longerons, attach
fittings, and attaching hardware for corrosion, damage, and
cracks.
ASB 212-90-63
d. Remove plug button at BS 99.00.
NOTE
Paint fissures are common in the splice area, cracks
will be evident by black powder emanating from
cracked area, and corrosion will leave evidence of
white powder.
e. Using a borescope or suitable means, inspect inside of
longeron paying particular attention to cracking and/or corrosion
in area of splice.
f. Report any cracks to Product Support Engineering.
g. Install plug button with sealant (C-308).
h. Ensure all drain holes are open.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 JUN 2010 Rev. 12
Page 81
ECCN EAR99
BHT-212-MM-1
i. Vertical fin spar caps forward side and web from upper
tailboom skin to approximately 4 inches (101.6 mm) below
upper tailboom skin as follows: remove aft tailboom access
door. Face aft and use bright light and small mirror to inspect
area for cracks, especially near rivet holes.
BHT-ALL-SPM
NOTE
If necessary, clean area with cloth dampened with
MEK (C-309) or equivalent. Ventilate area to prevent
breathing fumes.
Chapter 67
2. Antitorque controls:
a. Tail rotor control tubes between tail rotor pedals and tail
rotor gearbox for corrosion, wear, and damage.
b. Control 
tube bellcrank, supports, and attaching
hardware for corrosion, security, wear, and damage.
c. Tail rotor hydraulic actuator for leaks and security of
attachment, damage, corrosion, and bearings and linkages for
looseness.
Chapter 67
3. Elevator:
 Detailed Visual Inspection
a. Check synchronized elevator push-pull tubes for
chafing, corrosion, wear, and damage.
b. Check elevator and horn assembly for security, cracks,
wear, damage, and corrosion.
c. Check left and right elevator assemblies for excessive
axial and radial play using a dial indicator mounted on the
tailboom, with stylus touching inboard edge of elevator near
attachment bolt for axial measurement, and touching upper
surface near attachment bolt for radial measurement. Applying
light force to move elevator in required direction, check that
radial movement does not exceed 0.010 inch (0.254 mm), and
that axial movement is within 0.005 to 0.030 inch (0.127 to
0.762 mm). Adjust shims as required.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 82
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
d. Elevator rigging for proper setting and travel.
Chapter 52
4. Baggage compartment door for corrosion, damage,
distortion, and positive locking mechanism.
Chapter 26
5. Baggage compartment smoke detector for condition and
security.
Chapter 96
6.
Inspect wire bundles and clamping for chafing, condition,
and security.
Chapter 65
7. Tail rotor driveshaft:
a. Hanger assemblies for cracks at mounting ears,
corrosion, and security of attachment.
b. Hanger supports 
for condition and security of
attachment.
c. Driveshaft sections and attaching hardware 
for
condition and security.
d. Coupling clamps for cracks in or near bolt lugs. Clamps
for proper position.
Chapter 65
8.
Intermediate gearbox:
a. Chip detector for debris.
b. Clean chip detector.
c. Functionally test chip detector electrical circuit.
Chapter 12
d. Service gearbox as required.
Chapter 65
9. Tail rotor gearbox:
a. Chip detector for debris.
b. Clean chip detector.
c. Functionally test chip detector electrical circuit.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
8 JUN 2010 Rev. 12
Page 83
ECCN EAR99
BHT-212-MM-1
Chapter 12
d. Service gearbox as required.
Chapter 64
10. Tail rotor hub and blade assembly:
a. Torque check nuts on tail rotor blade retention bolts.
b. Torque check tail rotor hub retaining nut.
Chapter 18
c. Dynamically balance tail rotor.
Chapter 62
MAIN ROTOR BLADE INSPECTION SYSTEM (BIS) (IF 
INSTALLED)
 Inspect
BHT-212-CR&O and 
Chapter 96
1. Test detector unit.
2. Perform continuity check on blade conductor circuits.
3. Remove BIS battery.
4. Perform battery condition check on replacement battery.
Install replacement battery.
Chapter 52 and 
Chapter 53
CABIN ROOF
1. Cabin roof structure:
a. Cabin roof structure, cowlings and fairings for damage,
delamination, and general condition.
b. Cabin roof and cowling/fairing mounted antennas for
condition and security.
SCHEDULED INSPECTIONS
5-10.
300 HOURS  PART B (CONT)
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
5-00-00
Page 84
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-1
SPECIAL INSPECTIONS
5-20.
EACH 7 DAY IN A CORROSIVE ENVIRONMENT AND EACH 30 DAYS IN A
NONCORROSIVE ENVIRONMENT
DATA REFERENCE
INSPECTION TASK DESCRIPTION
INITIAL
MECH     OTHER
DATE: __________________W.O. _____________________
FACILITY: _________________________________________
HELICOPTER S/N: __________________________________
REGISTRY NO.: ____________________________________
TOTAL TIME:_______________________________________
SIGNATURE:_______________________________________
NOTE
Accomplish each 7 days in a corrosive environment
and each 30 days in a noncorrosive environment.
Chapter 62
MAIN ROTOR BLADES 204-012-001, 212-010-750, AND 
212-015-501
 Clean
1. Wash upper and lower surfaces with a solution of cleaning
compound (C-318) and water. Rinse thoroughly and wipe dry.
2.
Inspect surfaces for condition.
3. Apply a light coat of preservative oil (C-125) to surfaces of
blade, including areas between main rotor hub grip tangs.
5-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 119/120
BHT-212-MM-5
 NOTICE
The instructions set forth in this manual, as supplemented or modified by Alert Service Bulletins (ASB) or
other directions issued by Bell Helicopter Textron Inc. and Airworthiness Directives (AD) issued by the
applicable regulatory agencies, shall be strictly followed.
COPYRIGHT NOTICE
COPYRIGHT  
2010
BELL  HELICOPTER TEXTRON INC.
AND BELL HELICOPTER TEXTRON
CANADA LTD.
ALL RIGHTS RESERVED
MAINTENANCE MANUAL
VOLUME 5
AIRFRAME
7 JUNE 1993
REVISION 12  8 JUNE 2010
BHT-212-MM-5
PN
Rev. 10 18 SEP 2009
Additional copies of this publication may be obtained by contacting:
Commercial Publication Distribution Center
Bell Helicopter Textron Inc.
P. O. Box 482
Fort Worth, Texas 76101-0482
PROPRIETARY RIGHTS NOTICE
These data are proprietary to Bell Helicopter Textron Inc. Disclosure,
reproduction, or use of these data for any purpose other than helicopter
operation or maintenance is forbidden without prior written authorization from
Bell Helicopter Textron Inc.
DESTINATION CONTROL STATEMENT
These commodities, technology, or software were exported from the United
States in accordance with the Export Administration Regulations (EAR).
Diversion contrary to U.S. law prohibited. The data contained in this manual are
classified as ECCN EAR99.
BHT-212-MM-5
LANDING GEAR ASSEMBLY
32-2.
LANDING GEAR ASSEMBLY
The landing gear is fabricated from aluminum alloy
tubes. The gear consists of two skids attached on the
ends of two arched crosstubes, which are secured to
the helicopter structure with four padded caps. Each
skid tube is fitted with a forward end step, a tow ring
fitting, two saddles with sockets for crosstubes, a
two-piece shoe along bottom end cap, and two
eyebolts for mounting of ground handling wheel
assemblies. Crosstubes are fitted with supports at
mounting points.
CAUTION
A HOIST WITH SUFFICIENT CAPACITY
TO LIFT ENTIRE HELICOPTER SHALL
BE USED TO RAISE HELICOPTER
CLEAR OF LANDING GEAR WHEN
REMOVING OR INSTALLING LANDING
GEAR AS AN ASSEMBLY.
NOTE
The landing gear can be removed as a
complete 
assembly 
or 
individual
components may be removed separately.
32-3.
LANDING GEAR ASSEMBLY 
REMOVAL
1.
If applicable, disconnect powered passenger step
electrical connector (17, Figure 32-1) at bottom of
fuselage.
NOTE
Superficial damage to cap fittings (12 and
18) is acceptable without repair. Loose,
missing, and/or deteriorated rubber pads
on cap fittings are cause for replacement of
cap fittings.
2. Support the weight of the helicopter until it is light
on the skids and remove bolts (9, 10, and 11, or 7 and
8). Remove forward cap fitting (18).
3. Remove other forward cap fitting (18) in the same
manner outlined in step 2.
4. Remove bolts (9, 10 and 11, or 7 and 8). Remove
aft cap fitting (12).
5. Remove other aft cap fitting (12) in the same
manner outlined in step 4.
6. Raise the helicopter slowly while monitoring the
forward and aft crosstubes coming out of the front and
aft airframe tunnels, to prevent damage.
7. Raise the helicopter until it is clear of skid landing
gear and remove landing gear (1).
8.
If necessary, remove the skid tubes (19) and the
associated hardware from the crosstubes (paragraph
32-8).
32-4.
LANDING GEAR ASSEMBLY 
INSPECTION
NOTE
Superficial damage is mechanical damage
that does not exceed 0.03 inch (0.7 mm)
depth or 1.25 inches (31.7 mm) length.
Superficial damage is acceptable where
noted.
No cracks in any landing gear parts or
attaching parts are acceptable.
Inspection procedure for high landing gear
is the same as for standard gear, except for
crosstube deflection limits.
1.
Inspect landing gear supports (paragraph 32-37).
2.
Inspect rubber bumpers on landing gear cap
fittings (12 and 18, Figure 32-1) for voids or unbonded
areas. No one void shall exceed 0.025 square inch
(16.13 mm2). The rubber bumper is not repairable.
32-00-00
8 JUN 2010 Rev. 12
Page 7
ECCN EAR99
BHT-212-MM-5
Figure 32-1.   Landing Gear (Standard) (Sheet 1 of 2)
212_MM_32_0001a+
D
D
F
1
19
30
E
E
S
1
7
2
12
12
6
5
5
2
7
4
3
3
5
or
5
or
5
or
5
or
2
2
8
9
10
11
9
10
11
18
18
8
13
2
2
3
3
14
15
15
32
16
16
17
27
A
C
B
DETAIL A
DETAIL B
VIEW C
31
32-00-00
Page 8
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-5
Figure 32-1.   Landing Gear (Standard) (Sheet 2 of 2)
19
28
25
26
22
23
1
2
23
24
23
22
24
23
212_MM_32_0001b+
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Landing gear
Aluminum washer
Nut
Aft crosstube support structure
Aluminum washer
Aft crosstube
Bolt
Bolt
Bolt
Bolt
Bolt
Aft cap fitting
Forward crosstube support structure
Forward crosstube
Forward support
Aft support
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
Power step electrical connector
Forward cap fitting
Skid tube
Bolt
Washer
Bolt
Washer
Bolt
Grommet
Cable assembly
Tow ring
Aft Saddle
Forward saddle
Passenger step
Step
Skid shoe
160 TO 190 IN-LBS
(18.08 TO 21.47 Nm)
T
50 TO 70 IN-LBS
(5.65 TO 7.91 Nm)
T
T
S
1
2
T
S
1
T
S
2
S
1
S
2
1
2
T 2
S
1
2
2
T
S
19
29
20
21
1
1
22
23
21
20
6
14
23
22
T
S
1
2
T
S
1
2
T
S
1
1
T
S
SEALANT (C-392)
SEALANT (C-308)
1
If TB 212-99-183 is incorporated,             applies.
NOTE
1
1
SECTION D-D
VIEW F
SECTION E-E
32-00-00
8 JUN 2010 Rev. 12
Page 9
ECCN EAR99
BHT-212-MM-5
3.
If required, 
inspect 
landing gear crosstube
deflection (Figure 32-2).
4.
Inspect skid tubes (19, Figure 32-1) for security of
attachment 
to 
crosstubes 
and 
for 
damage
(Figure 32-2).
32-5.
LANDING GEAR ASSEMBLY  REPAIR
1. Repair damaged skid tubes (19, Figure 32-1)
(paragraph 32-10 or paragraph 32-11).
2. Repair damaged skid shoes (32) (paragraph
32-17).
3. Repair damaged passenger step (30) (paragraph
32-47).
4. Replace components that are damaged in excess
of repairable limits.
32-6.
LANDING GEAR ASSEMBLY 
INSTALLATION
1. Position landing gear (1, Figure 32-1) under
helicopter.
2. Slowly lower the helicopter on each crosstube (6
and 14) to prevent damage.
3. Make sure that forward crosstube support
structure (13) properly engages forward supports (15).
4. Position one forward cap fitting (18) on forward
crosstube support structure (13).
5.
Install bolts (7, or 9 and 10) and aluminum
washers (2 or 5).
6.
Install bolts (8 or 11), aluminum washers (2 or 5),
and nuts (3).
7.
Install other forward cap fitting (18) in same
manner outlined in step 4 through step 6.
8. Position aft cap fitting (12) on landing gear
support structure (4).
9.
Install bolts (7, or 9 and 10) and aluminum
washers (2 or 5).
10.
Install bolts (8 or 11), aluminum washers (2 or 5),
and nuts (3).
11.
Install other aft cap fitting (12) in same manner
outlined in step 8 through step 10.
12.
If applicable, connect powered passenger step
electrical connector (17) at bottom of fuselage.
32-7.
SKID TUBES
The landing gear skid tubes are mounted on ends of
two arched crosstubes, which are secured to the
fuselage structure. Each skid tube is fitted with forward
end step, tow ring, two saddles with sockets for
crosstubes, rear end cap, two eyebolt fittings for
mounting ground handling wheels, and fore and aft
skid shoes to absorb wear that would otherwise be
inflicted to bottom of skid tubes during takeoff and
landing.
NOTE
Maintenance procedures for skid tubes
installed on high landing gear and standard
gear are the same.
Maintenance procedures for left and right
skid tubes are the same.
32-8.
SKID TUBES  REMOVAL
1. Remove landing gear (paragraph 32-3).
2.
If electrically powered passenger step (30,
Figure 32-1) is installed, disconnect passenger power
step electrical 
connector 
(17) 
from 
forward
crosstube (14).
3. Remove bolt (9, Figure 32-3) and thin aluminum
washer (8).
4. Remove bolt (5) and steel washer (4).
5. Cut sealant at intersection of skid tube forward
and aft saddles (2 and 6) and forward and aft
crosstubes (3 and 7) with a sharp plastic scraper.
6. Remove skid tube (1) from forward and aft
crosstubes (3 and 7). Use a rubber mallet to tap skid
tubes and forward and aft saddles (2 and 6) off
crosstubes, working both ends equally.
32-00-00
Page 10
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-5
32-9.
SKID TUBES  INSPECTION
NOTE
Superficial mechanical damage to skid
tubes (19, Figure 32-1) 
is acceptable
without repair. Sharp corners and gouges
should be repaired within allowable limits
(Figure 32-2). Distortion (deflection) 
in
excess of limits shown (Figure 32-2) is
cause 
for 
replacement. 
For 
BHT
205-050-400 and 412-050-023 skid tubes,
dents and/or holes in skid tubes up to
4 inches (101.6 mm) in diameter in the area
indicated in Figure 32-4 are acceptable, if
repaired as described in paragraph 32-10.
For BHT 412-050-030/-034 and AAI
412-320-119/-120/-123/-124 skid 
tubes,
dents and/or holes in skid tubes up to
3 inches (76.2 mm) in diameter in the area
indicated in Figure 32-5 or Figure 32-6 are
acceptable, if repaired as described in
paragraph 32-10. No repairs (patches) are
allowed under skid shoes.
1.
Inspect skid tubes (19, Figure 32-1), including
skid shoes (32) and saddles (28 and 29) for dents,
holes, cracks, scratches, scuffs, and corrosion
(Figure 32-2).
NOTE
Superficial mechanical damage on tow
rings (27, Figure 32-1) 
is acceptable
without repair. Distorted and/or loose fitting
tow rings are cause to replace tow rings
and, if attaching holes in skid tubes (19) are
elongated, replace skid tube(s).
2.
Inspect tow rings (27) for condition, damage, and
security of attachment.
3.
Inspect skid 
tubes 
(19, Figure 32-1) 
for
deformation and out-of-round condition.
4.
Inspect for missing paint, primer, and nonslip
compound (C-223). Restore as required.
5. Apply electrical power to passenger step (30) and
raise away from skid tube (19). Inspect actuator,
support levers, step, and attaching hardware for
condition.
32-10. SKID TUBES  PATCH REPAIR
NOTE
Repair to skid tube is limited to patching top
of skid 
tube 
in areas 
indicated 
in
Figure 32-2, and Figure 32-4, Figure 32-5,
or Figure 32-6 and to repairing skid shoes
(Figure 32-7) (paragraph 32-17).
1.
If dents are present in authorized repair area
shown in Figure 32-2, polish out raised areas that
would interfere with application of patch.
2.
If holes are present in authorized repair area
shown in Figure 32-2, smooth rough edges of holes to
remove sharp edges and raised areas that would
interfere with application of patch.
3. For 
skid 
tubes 
BHT 205-050-400 
and
412-050-023, fabricate a patch to cover dent or hole
from 2024 aluminum alloy tube, WW-T-700/2,T3 or
2024 aluminum sheet, per QQ-A-250/4, T73 with
0.095 inch (2.41 mm) wall thickness and 4.0 inches
(101.6 mm) inside diameter. See Figure 32-4 for
required patch size.
4. For skid 
tubes BHT 412-050-030/-034 and
AAI 412-320-119/-120/-123/-124, fabricate a patch to
cover dent or hole from 2024 aluminum alloy tube,
WW-T-700/7,T3 or 2024 aluminum sheet, per
QQ-A-250/4, T73 with 0.125 inch (3.17 mm) wall
thickness and 3.0 inches (76.2 mm) inside diameter.
See Figure 32-5 or Figure 32-6 for required patch size.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-100
Chemical Film Material
C-204
Epoxy Polyamide 
Primer
C-223
Nonslip Compound
C-308
Sealant
32-00-00
30 APR 2010 Rev. 11
Page 21
ECCN EAR99
BHT-212-MM-5
Figure 32-4.   Skid Tube (BHT 205-050-400 and 412-050-023) Patch Repair
212_MM_32_0004_c01
0.38 IN.
0.38 IN.
0.38 IN.
4.0 IN.
0.50 IN.
0.50 IN.
MINIMUM OF 4 ROWS OF M7885/6-6-3 RIVETS 
SPACED 0.72 IN. (18.288 mm) APART EACH 
SIDE OF DAMAGE
32-00-00
Page 22
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-5
32-00-00
8 JUN 2010 Rev. 12
Page 37
ECCN EAR99
32-30. LANDING GEAR CROSSTUBE
ASSEMBLIES  INSTALLATION
1.
Install aft crosstube (6, Figure 32-1) on left skid
tube (19) as follows:
NOTE
Install all fasteners and grommets with
sealant (C-392).
a. Insert aft crosstube (6) into aft saddle (28) of
skid tube (19), and secure with bolts (22 and 24) and
washers (23).
b. Torque bolts
.
2.
If applicable, install the powered step cable
assembly (26) as follows:
a. Route the wires for the powered step through
the crosstube.
b. Install the grommet (25) on the wires and
install the grommet in the crosstube or skid tubes, as
applicable.
c. Remove the tags and connect the wires to the
step disconnect connector and the left and right step
actuators, as shown in Figure 32-11.
CAUTION
USE CARE TO AVOID  CHAFING,
CUTT ING,  OR BREAKING CABLE
ASSEMBLY WHEN PERFORMING NEXT
STEP.
3.
Insert forward crosstube (14, Figure 32-1) into
forward saddle (29) of left skid tube (19). Secure
crosstube and saddle with bolts (20 and 22) and
washers (21 and 23). Torque bolts
.
4. Apply a bead of sealant (C-392) around joint of
saddles (28 and 29) and crosstubes (6 and 14).
5.
Install aft and forward crosstubes (6 and 14) to
right skid tube (19) same as left skid tube.
6.
If applicable, apply sealant (C-308) to the
grommet (25) and cable assembly (26).
32-31. CROSSTUBE SUPPORTS
NOTE
The Aeronautical Accessories Inc. (AAI)
forward crosstube assemblies 212-320-103
(standard) and 212-321-103 (high) are
similar to the Bell Helicopter Textron (BHT)
crosstube assemblies 205-050-400-013/
-039/-055 (standard) and 205-050-403-003/
-007/-023/-031 (high), however, different
material (black nylon coating) is used on
faying surfaces of the AAI crosstube
supports.
The 
BHT 
standard 
aft 
crosstube
assemblies 
205-050-400-007/-029/-035/
-705 have a limited life cycle (Chapter 4).
The BHT high aft crosstube assemblies
205-050-403-005/-009/-025/-033/-103/-111
and 212-050-224-101, and the AAI aft
crosstube assemblies 212-321-304 have a
limited life cycle (ASB 212-99-104).
32-32. BHT CROSSTUBE SUPPORTS
There are three BHT designs for the forward and aft
crosstube supports.
The 
forward 
crosstubes 
205-050-400-013/-039
(standard) and 205-050-403-003/-007/-023 (high) are
fitted with a single upper support that is riveted to the
crosstube.
The 
aft 
crosstubes 
205-050-400-007/-029/-035
(standard) and 205-050-403-005/-009/-025 (high) are
fitted with a single upper support that is riveted to the
crosstube.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-308
Sealant
C-392
Sealant
T
T
BHT-212-MM-5
32-00-00
Page 38
Rev. 12 8 JUN 2010
ECCN EAR99
The forward crosstubes 205-050-400-055 (standard)
and 205-050-403-031 (high) are fitted with an upper
and lower support that are bonded to the crosstube.
The aft crosstubes 205-050-400-053/-063 (standard)
and 205-050-403-033/-103/-111 (high) are fitted with
an upper and lower support that are bonded to the
crosstube.
The forward crosstubes 412-050-040-101 (standard)
and 412-050-046-101 (high) are fitted with a single
upper support that is riveted to the crosstube. An
abrasion strip is bonded to the lower surface. The
holes in the crosstube that accept the rivets are cold
worked.
The aft crosstubes 212-050-222-101 (standard) and
212-050-224-101 (high) are fitted with a single upper
support that is riveted to the crosstube. An abrasion
strip is bonded to the lower surface. The holes in the
crosstube that accept the rivets are cold worked.
32-33. BHT 
One-piece 
Riveted 
Supports
(Crosstubes 205-050-400/-403)  Removal
NOTE
This procedure is the same for the forward
and aft supports.
1. Remove landing gear (paragraph 32-3).
2. Using caution, remove rivets (3, Figure 32-12)
(BHT-ALL-SRM).
3. Remove support (2).
32-34. BHT Two-piece Support With U-bolts 
Removal
NOTE
This procedure is the same for the forward
and aft supports.
1. Remove landing gear (paragraph 32-3).
2. Remove 
nuts 
(6, 
Figure 32-13), 
steel
washers (5), and U-bolts (4).
3. Remove upper and lower supports (2 and 3).
32-35. BHT 
One-piece 
Riveted 
Supports
(Crosstubes 
212-050-222/-224 
and
412-050-040/-046)  Removal
CAUTION
ONE-PIECE CROSSTUBE/SUPPORT
FASTENER HOLES ARE COLD WORKED
(FIGURE 32-14). REPLACEMENT OF THE
SUPPORTS MUST ONLY 
BE
ACCOMPLISHED USING THE SAME
SIZE FASTENERS. IF DAMAGE HAS
OCCURRED TO THE COLD-WORKED
HOLE(S), DAMAGE UP TO 0.005 INCH
(0.12 MM) DEEP MAY BE REPAIRED BY
REAMING THE HOLE TO 0.205 TO
0.209 INCH (5.21 TO 5.30 MM) AND
INSTALLING A CR4652CW-6 FASTENER
OF THE CORRECT LENGTH. CONTACT
PRODUCT SUPPORT ENGINEERING
FOR DAMAGE GREATER THAN
0.005 INCH (0.12 MM) DEEP.
NOTE
This procedure is the same for the forward
and aft supports.
1. Remove landing gear (paragraph 32-3).
2. Using caution, remove rivets (3, Figure 32-15)
(BHT-ALL-SRM).
3. Remove forward support (2).
BHT-212-MM-8
 NOTICE
The instructions set forth in this manual, as supplemented or modified by Alert Service Bulletins (ASB) or
other directions issued by Bell Helicopter Textron Inc. and Airworthiness Directives (AD) issued by the
applicable regulatory agencies, shall be strictly followed.
7 JUNE 1993
REVISION 12  8 JUNE 2010
COPYRIGHT NOTICE
COPYRIGHT  
2010
BELL  HELICOPTER TEXTRON INC.
AND BELL HELICOPTER TEXTRON
CANADA LTD.
ALL RIGHTS RESERVED
MAINTENANCE MANUAL
VOLUME 8
FLIGHT CONTROLS
BHT-212-MM-8
PN
Rev. 11 30 APR 2010
Additional copies of this publication may be obtained by contacting:
Commercial Publication Distribution Center
Bell Helicopter Textron Inc.
P. O. Box 482
Fort Worth, Texas 76101-0482
PROPRIETARY RIGHTS NOTICE
These data are proprietary to Bell Helicopter Textron Inc. Disclosure,
reproduction, or use of these data for any purpose other than helicopter
operation or maintenance is forbidden without prior written authorization from
Bell Helicopter Textron Inc.
DESTINATION CONTROL STATEMENT
These commodities, technology, or software were exported from the United
States in accordance with the Export Administration Regulations (EAR).
Diversion contrary to U.S. law prohibited. The data contained in this manual are
classified as ECCN EAR99.
BHT-212-MM-8
67-00-00
8 JUN 2010 Rev. 12
Page 13
ECCN EAR99
Figure 67-3.   Cyclic Controls (Sheet 2 of 2)
212_MM_67_0003b_c01
DETAIL B
BEARING INSTALLATION
DETAIL C
(SOME PARTS OMITTED FOR CLARITY)
DETAIL A
43
44
37
44
46
38
39
40
23
23
36
45
42
37
23
41
AIRFRAME
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Bolt
Spring
Extension tube
Boot
Universal
Cylinder support
Hydraulic cylinder
Bellcrank
Control tube (2)
Extension tube
Boot
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Universal
Support
Hydraulic cylinder
Bellcrank
Control tube
Magnetic brake
Force gradient
Control tube
Magnetic brake
Force gradient
Control tube
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
Bellcrank
Control tube
Pilot cyclic stick
Cyclic jackshaft
Control tube
Mixing lever
Control tube
Valve arm
Stop bolt
Stop bolt
Bolt
Plate
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
SpringBellcrank
Transducer
Support assembly
Bolt
Washer
Nut
Sleeve
Bearing
Bolt
Washer
Nut
Cotter pin
39
BHT-212-MM-8
67-00-00
Page 14
Rev. 11 30 APR 2010
ECCN EAR99
NOTE
Alternate procedure for centering cyclic
stick with copilot cyclic stick installed. Install
cyclic stick fixture (T101330) on copilot
cyclic stick.
11. Set swashplate as per dimensions of Figure 67-4.
12. Position valve arm (30, Figure 67-3) to center.
13. Adjust each extension tube to correct length and
attach to swashplate with bolt, washer, nut, and cotter
pin. Torque jam nuts on control tubes 1500 to
1800 inch-pounds (169.47 to 203.36 Nm) and secure
with lockwire (C-405) (Figure 67-1, Detail D). Apply
sealant (C-308) around nut, lock, and threads on
clevis.
NOTE
If rigging system with hydraulic cylinder is
not completely bled of air, bottom valve arm
(30, Figure 67-3) at top of travel. Adjust
extension tube (3 and 10) to fit swashplate;
shorten one full 
turn and attach as
described in step 13.
14.
Install extension tubes (3 and 10) on swashplate
horns with bolts and nuts. Secure with cotter pins.
NOTE
When rigging with fluid in bled hydraulic
system, the hydraulic cylinder valve arms
should be centered and no change in
extension tubes (3 and 10) adjustment is
required.
15. Position output arm of longitudinal and lateral
magnetic brakes (17 and 20) at center of travel
(Views B and C).
16. Place pilot cyclic stick (25) against extreme
forward stop. Place output arm of 
longitudinal
magnetic brake (17) against aft stop. Adjust force
gradient (18) to fit. Extend clevis on force gradient two
turns and install. For initial installation, install spring
(35) in fourth hole in plate (34).
NOTE
With hydraulic boost on or at ground
run-up, adjust spring tension to position
pilot cyclic stick (25) (longitudinal cyclic
only) perpendicular to deck within 2.
17. Position pilot cyclic stick (25) perpendicular to
deck within 0.5. Set output arm of lateral magnetic
brake (20) at center of travel (View C). Adjust force
gradient (21) to fit and install with bolt and washer.
Secure bolt head with lockwire (C-405).
NOTE
Check clearances between force gradient
(21) and structure at extreme positions of
magnetic brake arm. If required, re-index
arm relative to shaft by one serration for
clearance. Repeat step 17.
18. Connect spring (2) to bracket on right forward
horn of swashplate.
19. Check complete system for secure installation
and unobstructed full travel.
NOTE
Adjust swashplate lateral pretilt within
dimension of Figure 67-4, for satisfactory
flight.
67-8.
ANTITORQUE CONTROLS
(HELICOPTERS PRIOR TO S/N 31175)
NOTE
Refer to paragraph 67-4 prior to beginning
rigging.
1. Ensure linkage is complete, with the following
adjustable links and control tubes disconnected:
a. Pitch change links (3, Figure 67-5) from tail
rotor blades.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-405
Lockwire
BHT-212-MM-8
67-39. MISCELLANEOUS CONTROL
COMPONENTS
Cyclic control components include push-pull tubes,
bellcranks, jackshaft, mixing lever, and supports.
NOTE
For maintenance practices on cyclic
controls dual control kit, refer to appropriate
Service Instruction.
67-40. Miscellaneous Control Components 
Removal
NOTE
Parts of control system can be removed
separately as need occurs, or completely in
any practical sequence. Take precautions
against damage by accidental movement of
linkage while disconnected.
1. Remove access covers on cabin floor, front of
pylon island, and lower skin of fuselage, as required.
2. Disconnect the control tubes (22 and 24,
Figure 67-3) from the pilot cyclic stick (25).
3. To remove the bellcrank assembly (23), proceed
as follows:
a. Disconnect the control tubes (22 and 27),
force gradient (21), and transducer (36).
b. Remove the cotter pin (46), bolt (43), washers
(44), and nut (45) from the bellcrank assembly (23).
Discard the cotter pin.
c. Remove the bellcrank assembly (23) from the
support assembly (37).
4. To remove the support assembly (37), remove
the bolts (38), washers (39), and nuts (40).
5. When removal of cyclic jackshaft (26) is required,
remove bolts and tapered bushings to separate
jackshaft tubes from each side of control lever.
Remove each jackshaft by removing four bolts
attaching bearing housing to beam, withdrawing
assembly through access opening inside of cabin
lower skin.
6. Disconnect control tubes from mixing lever (28)
bellcranks (8 and 15).
7. Remove bellcranks from or with supports as
required.
8. Remove either hydraulic cylinder (7 or 14).
9. Remove cylinder support (6) and support (13).
10. Remove cyclic mixing levers (Figure 67-15).
67-41. Miscellaneous Control Components 
Inspection
1.
Inspect cyclic control 
jackshaft components
(BHT-212-CR&O).
2.
Inspect bearings of cyclic control 
jackshaft
components for secure installation and serviceability
(BHT-ALL-SPM).
3.
Inspect cyclic control bellcranks, mixing lever,
supports, and control tubes (BHT-212-CR&O).
4. Check balance spring (2, Figure 67-3) for
security, distortion, and excessive length. Spring
should be approximately 9.41 inches (239.01 mm)
long, with a spring rate of 20 pounds (89.0 N) per inch
(25.4 mm).
5. On helicopters S/N 30850 and subsequent, check
spring (35, Figure 67-3) for security, distortion, and
excessive length. Spring should be approximately
7.6 inches (193.04 mm) long, with a spring rate of 2.3
pounds (10.2 N) per inch (25.4 mm).
6. The maximum allowable lateral movement on
cyclic 
jackshaft (26) 
is 0.20 
inch (5.08 mm)
(Figure 67-16).
67-42. Miscellaneous Control Components 
Repair
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-423
Abrasive Paper
67-00-00
30 APR 2010 Rev. 11
Page 39
ECCN EAR99
BHT-212-MM-8
NOTE
Check rigging and proper operation of
system after removal and installation of any
parts.
1. Polish out mechanical damage to cyclic control
jackshaft components with 400 grit or finer abrasive
paper (C-423) to obtain a smooth, scratch-free
surface. Refinish component 
to original 
finish
(BHT-ALL-SPM).
2. Remove corrosion from cyclic control jackshaft
components (BHT-ALL-SPM) and refinish component
to original finish.
3. Replace unserviceable bearings of cyclic control
jackshaft components (BHT-ALL-SPM).
4. Repair cyclic control bellcranks, mixing lever,
supports, and control tubes (BHT-212-CR&O).
67-43. Miscellaneous Control Components 
Installation
NOTE
If a support assembly (37, Figure 67-3) is
being replaced, the upper bearing (42) will
not be installed or supplied with the new
support.
This is to make sure the bearing inner race
touches the bellcrank bushing after ring
staking the sleeve. If the support assembly
is replaced, do the following step.
1. Temporarily put the bellcrank assembly (23) into
the support assembly (37) and put the new upper
bearing (42) in position on the support assembly.
2. Ring stake the sleeve (41) to secure the upper
bearing (42) in place (BHT-ALL-SPM, Chapter 9).
3.
Install the support assembly (37) on the airframe
with the bolts (38), washers (39), and nuts (40). Torque
the nuts.
4.
Install the bellcrank (23), bolt (43), washers (44),
nut (45), and new cotter pin (46) on the support
assembly (37).
5. Connect the control tubes (22 and 27), force
gradient (21), and transducer (36) on the bellcrank
assembly (23).
6. Connect the control tubes (22 and 24) on the pilot
cyclic stick (25).
7.
Install bellcranks (8 and 15) 
if 
removed.
Assemble and 
install mixing 
lever assembly
(Figure 67-15).
8.
Install cyclic jackshaft (26, Figure 67-3), if
removed.
9.
Insert right and left tube assemblies, with
bearings and supports in place, through access
openings at sides of cabin lower skin. Slip ends of
tubes on stub shafts of control arm. Align bolt holes
with center arm pointing up and end arms down, and
install bolts and tapered bushings.
10. Secure right and left bearing supports to each
beam by installing four bolts with nuts and washers.
Check for free operation.
11.
Install and attach all fixed-length control tubes. If
adjustable control tubes are not correct length to be
attached, leave one end free until controls are rigged.
12.
Install supports (6) and support (13).
13.
Install hydraulic cylinders (7 and 14).
14. Complete connection of linkage while rigging
control system (paragraph 67-6 or paragraph 67-7).
67-00-00
Page 40
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-9
 NOTICE
The instructions set forth in this manual, as supplemented or modified by Alert Service Bulletins (ASB) or
other directions issued by Bell Helicopter Textron Inc. and Airworthiness Directives (AD) issued by the
applicable regulatory agencies, shall be strictly followed.
7 JUNE 1993
REVISION 12  8 JUNE 2010
COPYRIGHT NOTICE
COPYRIGHT  
2010
BELL  HELICOPTER TEXTRON INC.
AND BELL HELICOPTER TEXTRON
CANADA LTD.
ALL RIGHTS RESERVED
MAINTENANCE MANUAL
VOLUME 9
POWER PLANT
BHT-212-MM-9
PN
Rev. 11 30 APR 2010
Additional copies of this publication may be obtained by contacting:
Commercial Publication Distribution Center
Bell Helicopter Textron Inc.
P. O. Box 482
Fort Worth, Texas 76101-0482
PROPRIETARY RIGHTS NOTICE
These data are proprietary to Bell Helicopter Textron Inc. Disclosure,
reproduction, or use of these data for any purpose other than helicopter
operation or maintenance is forbidden without prior written authorization from
Bell Helicopter Textron Inc.
DESTINATION CONTROL STATEMENT
These commodities, technology, or software were exported from the United
States in accordance with the Export Administration Regulations (EAR).
Diversion contrary to U.S. law prohibited. The data contained in this manual are
classified as ECCN EAR99.
BHT-212-MM-9
TABLE OF CONTENTS
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
CHAPTER  71  POWER PLANT
71-1
Power Plant (Engine) .....................................................................
71-00-00
5
71-2
Power Plant Maintenance.........................................................
71-00-00
5
71-3
Priming Power Plant Lubrication System..........................
71-00-00
5
71-4
Preoil  Combining Gearbox ...........................................
71-00-00
5
71-5
Priming Engine Fuel System.............................................
71-00-00
5
71-6
Wet Motoring Run  Power Plant ....................................
71-00-00
5
71-7
Alignment  Engine to Transmission...............................
71-00-00
6
71-8
Compressor Wash ............................................................
71-00-00
10
71-9
Troubleshooting ................................................................
71-00-00
10
71-10
Operational Check ............................................................
71-00-00
10
ENGINE ASSEMBLY
71-11
Engine Assembly ...........................................................................
71-00-00
13
71-12
Maintenance .............................................................................
71-00-00
13
71-13
Removal............................................................................
71-00-00
13
71-14
Installation.........................................................................
71-00-00
26
71-15
Engine Power Section ..............................................................
71-00-00
29
71-16
Removal............................................................................
71-00-00
29
71-17
Installation.........................................................................
71-00-00
32
71-18
Combining (Reduction) Gearbox ..............................................
71-00-00
34
71-19
Removal............................................................................
71-00-00
35
71-20
Installation.........................................................................
71-00-00
36
COWLING
71-21
Cowling ..........................................................................................
71-00-00
39
71-22
Forward Transmission and Engine Air Inlet Cowling ................
71-00-00
39
71-23
Forward Transmission and Engine Air Inlet Cowling 
Removal............................................................................
71-00-00
39
71-24
Forward Transmission and Engine Air Inlet Cowling 
Inspection and repair ........................................................
71-00-00
39
71-24A
Engine Air Inlet Cowlings  Gap Inspection ....................
71-00-00
42A
71-25
Forward Transmission and Engine Air Inlet Cowling
 Installation ....................................................................
71-00-00
42A
71-25A
Engine Air Inlet Cowlings  Adjustable Seal
Replacement.....................................................................
71-00-00
42D
71-25B
Engine Air Inlet Cowlings  Adjustable Seal Adjustment
71-00-00
42D
71-26
Engine Cowling.........................................................................
71-00-00
43
71-27
Engine Cowling  Removal .............................................
71-00-00
43
71-28
Engine Cowling  Inspection and Repair ........................
71-00-00
43
71-29
Engine Cowling  Installation ..........................................
71-00-00
43
71-30
Reduction Gearbox Cowling .....................................................
71-00-00
43
71-31
Reduction Gearbox Cowling  Removal .........................
71-00-00
43
71-32
Reduction Gearbox Cowling  Inspection and Repair.....
71-00-00
46
71-33
Reduction Gearbox Cowling  Installation ......................
71-00-00
46
71-00-00
8 JUN 2010 Rev. 12
Page 1
ECCN EAR99
BHT-212-MM-9
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
71-34
Oil Cooler Airscoop Cowling .....................................................
71-00-00
46
71-35
Oil Cooler Airscoop Cowling  Removal .........................
71-00-00
46
71-36
Oil Cooler Airscoop Cowling  Inspection and Repair.....
71-00-00
46
71-37
Oil Cooler Airscoop Cowling  Installation ......................
71-00-00
46
ENGINE MOUNTS
71-38
Engine Mounts ...............................................................................
71-00-00
47
71-39
Forward Mount..........................................................................
71-00-00
47
71-40
Removal............................................................................
71-00-00
47
71-41
Inspection and Repair .......................................................
71-00-00
47
71-42
Installation.........................................................................
71-00-00
47
71-43
Forward Mount Fittings .............................................................
71-00-00
50
71-44
Removal............................................................................
71-00-00
50
71-45
Inspection and Repair .......................................................
71-00-00
50
71-46
Installation.........................................................................
71-00-00
50
71-47
Forward Mount Deck Fittings....................................................
71-00-00
50
71-48
Inspection and Repair .......................................................
71-00-00
51
71-49
Installation.........................................................................
71-00-00
52
71-50
Aft Left Mount Tripod ................................................................
71-00-00
52
71-51
Removal............................................................................
71-00-00
52
71-52
Inspection and Repair .......................................................
71-00-00
53
71-53
Installation.........................................................................
71-00-00
53
71-54
Aft Left Mount Tripod Deck Fittings ..........................................
71-00-00
53
71-55
Inspection and Repair .......................................................
71-00-00
53
71-56
Installation.........................................................................
71-00-00
53
71-57
Aft Left and Right Engine Mount Bearings................................
71-00-00
56
71-58
Removal............................................................................
71-00-00
56
71-59
Inspection and Repair .......................................................
71-00-00
56
71-60
Installation.........................................................................
71-00-00
56
71-61
Aft Right Mount Bipod...............................................................
71-00-00
56
71-62
Removal............................................................................
71-00-00
56
71-63
Inspection and Repair .......................................................
71-00-00
56
71-64
Installation.........................................................................
71-00-00
58
71-65
Aft Right Mount Bipod Deck Fittings .........................................
71-00-00
58
71-66
Inspection and Repair .......................................................
71-00-00
58
71-67
Installation.........................................................................
71-00-00
58
ENGINE ACCESSORIES
71-68
Engine Accessories .......................................................................
71-00-00
61
71-69
Gas Producer (N1) Tachometer Generator ..............................
71-00-00
61
71-70
Removal............................................................................
71-00-00
61
71-71
Installation.........................................................................
71-00-00
61
71-72
Power Turbine (N2) Tachometer Generator .............................
71-00-00
61
71-73
Removal............................................................................
71-00-00
66
71-74
Installation.........................................................................
71-00-00
66
71-75
Differential Pressure Indicator ..................................................
71-00-00
66
71-00-00
Page 2
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-9
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
71-76
Removal............................................................................
71-00-00
66
71-77
Installation.........................................................................
71-00-00
66
71-78
Power Section Oil Pressure Switch ..........................................
71-00-00
66
71-79
Removal............................................................................
71-00-00
69
71-80
Installation.........................................................................
71-00-00
69
71-81
Reduction (Combining) Gearbox Oil Pressure Switch..............
71-00-00
69
71-82
Power Section Oil Temperature Bulb .......................................
71-00-00
69
71-83
Removal............................................................................
71-00-00
69
71-84
Installation.........................................................................
71-00-00
71
71-85
Reduction (Combining) Gearbox Oil Temperature Bulb ...........
71-00-00
71
71-86
Removal............................................................................
71-00-00
71
71-87
Installation.........................................................................
71-00-00
71
71-88
Torque Pressure Transmitters ..................................................
71-00-00
71
71-89
Removal............................................................................
71-00-00
71
71-90
Installation.........................................................................
71-00-00
72
71-91
Reduction (Combining) Gearbox Oil Pressure Transmitter ......
71-00-00
75
71-92
Reduction (Combining) Gearbox Oil Pressure
Transmitter  Removal ....................................................
71-00-00
75
71-93
Reduction (Combining) Gearbox Oil Pressure
Transmitter  Installation .................................................
71-00-00
75
71-94
Power Section Oil Pressure Transmitter...................................
71-00-00
75
71-95
Power Section Oil Pressure Transmitter  Removal .......
71-00-00
75
71-96
Power Section Oil Pressure Transmitter  Installation ....
71-00-00
75
71-97
Starter Generator......................................................................
71-00-00
78
71-98
Starter Generator  Removal ..........................................
71-00-00
78
71-98A
Starter Generator  Repair ..............................................
71-00-00
78
71-98B
Starter Generator  Inspection ........................................
71-00-00
78
71-98C
Starter Generator  Cleaning ..........................................
71-00-00
80A
71-99
Starter Generator  Installation .......................................
71-00-00
80C
ENGINE AIR MANAGEMENT SYSTEM
71-100
Engine Air Management System ...................................................
71-00-00
81
71-101
Ejectors.....................................................................................
71-00-00
81
71-102
Ejectors  Removal .........................................................
71-00-00
81
71-103
Repair ...............................................................................
71-00-00
85
71-104
Ejectors  Installation ......................................................
71-00-00
98
71-105
Transition Ducts........................................................................
71-00-00
99
71-106
Transition Ducts  Removal ............................................
71-00-00
99
71-107
Transition Ducts  Inspection ..........................................
71-00-00
99
71-108
Transition Ducts  Repair................................................
71-00-00
99
71-109
Transition Ducts  Installation .........................................
71-00-00
104
71-110
Valve Assembly ........................................................................
71-00-00
104
71-111
Valve Assembly  Removal.............................................
71-00-00
104
71-112
Valve Assembly  Inspection ..........................................
71-00-00
104
71-113
Valve Assembly  Repair ................................................
71-00-00
104
71-114
Installation.........................................................................
71-00-00
106
71-115
Forward Ducts ..........................................................................
71-00-00
108
71-00-00
8 JUN 2010 Rev. 12
Page 3
ECCN EAR99
BHT-212-MM-9
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
71-116
Forward Ducts  Removal...............................................
71-00-00
108
71-117
Forward Ducts  Inspection.............................................
71-00-00
108
71-118
Forward Ducts  Installation............................................
71-00-00
108
71-119
Induction Baffles .......................................................................
71-00-00
108
71-120
Induction Baffles  Removal............................................
71-00-00
108
71-121
Induction Baffles  Installation.........................................
71-00-00
108A
71-122
Exhaust Ducts...........................................................................
71-00-00
108A
71-123
Exhaust Ducts  Removal ...............................................
71-00-00
108A
71-124
Inspection..........................................................................
71-00-00
111
71-125
Repair ...............................................................................
71-00-00
111
71-126
Installation.........................................................................
71-00-00
113
FIGURES
   Figure
Page
  Number
Title
Number
71-1
Tool Application  Transmission Leveling Jacks (T101440),
Engine-to-transmission Alignment ......................................................................
8
71-2
Tool Application  Engine-to-transmission Alignment (T101579) .....................
9
71-3
Compressor Wash Fitting ...................................................................................
11
71-4
Cowling ...............................................................................................................
14
71-5
Power Section (Engine) ......................................................................................
15
71-6
Exhaust Ejectors .................................................................................................
17
71-7
Centerline Firewall ..............................................................................................
19
71-8
Upper Induction Baffle and Middle Firewall and Attached Ducts ........................
20
71-9
Engine Assembly ................................................................................................
21
71-10
Engine Connections at Rear of Combining Gearbox ..........................................
24
71-11
Engine Sling SWE 13833 and Rail System Handling Stand...............................
25
71-12
Engine Mounts ....................................................................................................
27
71-13
Accessory Gearbox Lines ...................................................................................
31
71-14
Transmission and Engine Cowling......................................................................
40
71-15
Forward Transmission Cowling...........................................................................
41
71-16
Engine Air Inlet Cowling......................................................................................
42
71-16A
Horizontal Engine Firewall  Straightness Check .............................................
42B
71-16B
Engine Air Inlet Cowlings  Adjustable Seals....................................................
42C
71-17
Lower Engine Cowling ........................................................................................
44
71-18
Oil Cooler Air Scoop Cowling..............................................................................
45
71-19
Engine Mounts ....................................................................................................
48
71-20
Forward Mount Tube...........................................................................................
49
71-21
Forward Engine Mount Fitting.............................................................................
51
71-22
Forward Mount Deck Fitting................................................................................
52
71-23
Aft Left Mount Tripod ..........................................................................................
54
71-24
Aft Left Mount Tripod Deck Fitting ......................................................................
55
71-25
Aft Left and Right Mount Engine Bearings..........................................................
57
71-26
Aft Right Mount Bipod.........................................................................................
59
71-27
Aft Right Mount Bipod Deck Fitting .....................................................................
60
71-00-00
Page 4
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-9
FIGURES (CONT)
   Figure
Page
  Number
Title
Number
71-28
Engine Accessories ............................................................................................
62
71-29
Gas Producer (N1) Tachometer Generator ........................................................
65
71-30
Power Turbine (N2) Tachometer Generator .......................................................
67
71-31
Differential Pressure Indicator.............................................................................
68
71-32
Power Section Oil Pressure Switch ....................................................................
70
71-33
Power Section Oil Temperature Bulb..................................................................
72
71-34
Reduction (Combining) Gearbox Oil Temperature Bulb .....................................
73
71-35
Reduction Gearbox Data Plate ...........................................................................
74
71-36
Reduction (Combining) Gearbox Oil Pressure Transmitter ................................
76
71-37
Power Section Oil Pressure Transmitter.............................................................
77
71-38
Starter Generator ................................................................................................
79
71-39
Starter Generator Electrical ................................................................................
80
71-39A
Starter Generator Brush  Installation...............................................................
80B
71-40
Engine Air Management System Schematic.......................................................
82
71-41
Engine Air Management System ........................................................................
83
71-42
Engine Air Management System Ejector Repair.................................................
86
71-43
Engine Air Management System Ducts ..............................................................
100
71-44
Engine Air Management System Transition Duct Removal/Installation..............
101
71-45
Engine Air Management System Transition Duct Repair....................................
102
71-46
Engine Air Management System Valve ..............................................................
105
71-47
Engine Air Management System Valve Assembly Repair ..................................
107
71-48
Engine Air Management System Forward Duct..................................................
109
71-49
Engine Air Management System Exhaust Duct ..................................................
110
71-50
Engine Air Management System Exhaust Duct Repair ......................................
112
71-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 4A/4B
BHT-212-MM-9
COWLING
71-21. COWLING
Cowling is utilized to protect and provide easy access
to engine, combining gearbox, air intake, exhaust
ejectors, and top of transmission.
The forward section of transmission cowling (1,
Figure 71-14) is secured by two latches and two hinge
assemblies. The engine air inlet cowlings (2) are
secured by a latch and screws. The lower engine
cowling (9) is secured by two latches and a brace
assembly that serves as a hinge. The upper engine
cowling (10) is secured by two latches and hinges.
The upper engine cowling is held open by a brace.
The following cowlings are secured by screws: engine
top (3), combining gearbox (4), oil cooler (5), engine
oil cooler support (6), oil cooler air scoop (7), and
combining gearbox side cowling (8). The combining
gearbox side cowling has an inspection door in the
front half.
71-22. FORWARD TRANSMISSION AND ENGINE
AIR INLET COWLING
71-23. Forward Transmission and Engine Air
Inlet Cowling  Removal
1. Remove 
forward 
transmission cowling 
(1,
Figure 71-15) as follows:
a. Press 
latch (2) and open transmission
cowling.
b. Connect hold open brace (7) to fitting.
c. Remove bolts (4) from hinge (6) and hinge
fitting (5). 
d. Disconnect hold open brace (7) and remove
transmission cowling (1).
2. Remove the left-hand or right-hand engine air
inlet cowling (1, Figure 71-16) as follows:
a. Open lower and upper engine cowling (9 and
10, Figure 71-14).
b. Remove bolts (7, Figure 71-16) and washers
(8) from the forward duct (6) and forward transition
duct (3).
CAUTION
DO NOT CONTACT THE COLLECTIVE
EXTENSION TUBE WHEN REMOVING
OR INSTALLING THE TRANSMISSION
COWLING AND ENGINE AIR INLET
COWLINGS. OTHERWISE, DAMAGE
CAN OCCUR TO THE COLLECTIVE
EXTENSION TUBE.
c. Press cowling latch (10), and lift forward end
of engine air inlet cowling (1) to clear dowel pin (12).
Pull forward and remove cowling.
71-24. Forward Transmission and Engine Air
Inlet Cowling  Inspection and Repair
NOTE
The following inspection and repair criteria
are also applicable to all other cowlings
called out in this section.
1.
Inspect hinges, latches, and fittings for wear,
damage, and serviceability.
2.
Inspect seals for proper fit against mating
surfaces as well as for cracks, tears, deterioration, and
security of bonding.
3. Replace 
latches, 
fittings, 
and 
seals 
if
unserviceable.
4.
Inspect cowling, duct, firewall, and fairing for
dents, cracks, and damage. Repair using maintenance
practices in accordance with FAA Publication AC
43.13.1B, Aircraft Inspection and Repair Manual.
71-00-00
8 JUN 2010 Rev. 12
Page 39
ECCN EAR99
BHT-212-MM-9
Figure 71-14.   Transmission and Engine Cowling
212_MM_71_0014
71-00-00
Page 40
Rev. 11 30 APR 2010
ECCN EAR99
BHT-212-MM-9
71-24A. Engine Air 
Inlet Cowlings  Gap
Inspection
NOTE
This inspection will determine if gaps exist
between the lower surface of the engine air
inlet cowlings (2, Figure 71-14) and the
associated mating 
surfaces 
of 
the
horizontal 
engine 
firewall 
(2,
Figure 71-16A). 
1. Remove the forward transmission cowling (1,
Figure 71-14) (paragraph 71-23).
2. Open the upper and lower engine cowlings (10
and 9) on the left-hand and right-hand sides of the
helicopter.
NOTE
Although a depiction of the engine air inlet
cowlings with adjustable seals installed is
shown in Figure 71-16B, this figure is also
provided to identify the areas to be
inspected on engine air inlet cowlings
without adjustable seals. Regardless of the
seal configuration of the engine air inlet
cowlings, inspect for gaps in the areas
identified by adjustable seals (2, 3, and 4).  
3. Using a bright light and a mirror, inspect for gaps
between the lower seal surfaces of the left-hand and
right-hand engine air inlet cowlings (1) and the
associated mating surfaces of the horizontal engine
firewall (2, Figure 71-16A). Regardless of the seal
configuration of the engine air inlet cowlings, inspect
for gaps in the areas identified by adjustable seals (2,
3, and 4, Figure 71-16B). 
4.
If a gap does not exist, proceed as follows;
a. Close the upper and lower engine cowlings
(10 and 9, Figure 71-14) on the left-hand and
right-hand sides of the helicopter.
b. Install the forward transmission cowling (1)
(paragraph 71-25).
5.
If a gap exists, remove the left-hand and
right-hand engine air inlet cowlings (2) (paragraph
71-23) and inspect the horizontal engine firewall (2,
Figure 71-16A) as follows:
a. Using a straight edge, inspect the forward
portion of the horizontal engine firewall (2) on the
left-hand and right-hand sides at W.L. 80.0 and
F.S. 154.46 between B.L. 4.0 and B.L. 14.31 along the
retainer (1). The surface of the retainer must be flat to
within 0.063 inch (1.6 mm) over 10.0 inches (254 mm).
b. If the retainer (1) of the horizontal engine
firewall (2) is not flat, investigate and repair to obtain
the required flatness of 0.063 inch (1.6 mm) over 10.0
inches (254 mm). If required, contact Product Support
Engineering for an approved repair.
c. If the retainer (1) of the horizontal engine
firewall (2) was repaired to obtain the required flatness
of 0.063 inch (1.6 mm) over 10.0 inches (254 mm),
install the left-hand and right-hand engine air inlet
cowlings (2, Figure 71-14) (paragraph 71-25) and
inspect for gaps (step 3). 
d. If a gap exists, carry out Part 
II of
ASB 212-10-137 or adjust/replace the engine air inlet
cowling adjustable  seals (2, 3, and 4, Figure 71-16B)
(Post BHT-212-SI-96), as applicable (paragraph
71-25B and paragraph 71-25A).
71-25. Forward Transmission and Engine Air
Inlet Cowling  Installation
1.
Install the left-hand and right-hand engine air inlet
cowling (1, Figure 71-16) as follows:
CAUTION
DO NOT CONTACT THE COLLECTIVE
EXTENSION TUBE WHEN REMOVING
OR INSTALLING THE TRANSMISSION
COWLING AND ENGINE AIR INLET
COWLINGS. OTHERWISE, DAMAGE CAN
OCCUR TO THE COLLECTIVE
EXTENSION TUBE.
a. Place cowling into position with forward end
raised to clear dowel pin (12).
b. Align and engage dowel pins (2 and 9), and
lower onto dowel pin (12).
71-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 42A
BHT-212-MM-9
Figure 71-16A.   Horizontal Engine Firewall  Straightness Check
NO OBJECT BEYOND THIS POINT
212_MM_71_0064
212 MODEL
S/N 30501 THROUGH 30999,
31101 THROUGH 31311,
32101 THROUGH 32143,
35001 THROUGH 35040,
35046 THROUGH 35051 AND 35102
212 MODEL
35041 THROUGH 35045, 35052 THROUGH 35101,
AND 35103
LBL 14.31
WL 80.0
LBL 4.0
WL 80.0
RBL 4.0
WL 80.0
RBL 14.31
WL 80.0
FS 154.46
WL 80.0
FS 160.80
WL 80.0
VIEW
VIEW B
MEASURE FOR GAP
ALONG THIS SURFACE
A
B
A
1
1
1
2
2
1.
2.
Retainer
Horizontal engine firewall
71-00-00
ECCN EAR99
Page 42B
Rev. 12 8 JUN 2010
BHT-212-MM-9
Figure 71-16B.   Engine Air Inlet Cowlings  Adjustable Seals
212_MM_71_0017
VIEW A
VIEW A
(ALTERNATE)
Engine air inlet cowling
Adjustable seal
Adjustable seal
Adjustable seal
Screw
Fixed seal
Nutplate channel
1.
2.
3.
4.
5.
6.
7.
ADHESIVE (C-314)
1
2
3
4
7
6
5
5
5
1
3
2
6
6
A
5
5
1
Applicable when adjustable seals have been installed on the
engine aiar inlet cowling (Post BHT-212-SI-96).
NOTE
1
1
1
71-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 42C
BHT-212-MM-9
c. Install bolts (7) and washers (8) to attach the
forward transition duct (3) to the forward duct (6).
d. Hook cowling latch (10) to cowling latch fitting
(11).
2.
Install 
forward 
transmission 
cowling 
(1,
Figure 71-15) as follows:
a. Position cowling in hinge fitting (5).
b. Engage hold open brace (7) to fitting.
NOTE
Hinge shall work freely. Do not over torque
hinge bolts.
c. Align bolt hole in hinge (6) and hinge fitting (5)
and install bolts (4).
d. Disengage and stow hold open brace (7).
Close cowling.
e. Close upper and lower engine cowling (9 and
10, Figure 71-14).
71-25A. Engine Air Inlet Cowlings  Adjustable
Seal Replacement
NOTE
The following procedure is only applicable
when adjustable seals have been installed
on 
the 
engine 
air 
inlet 
cowling
(Post BHT-212-SI-96).
1. Remove the left or right engine air inlet cowlings
as applicable (paragraph 71-23). 
2. Cut and remove the adhesive from the ends of
the adjustable seals (2, 3, and 4, Figure 71-16B), as
applicable.
3.
Loosen the screws (5) until the adjustable seals
(2, 3, and 4) become loose.
4. Slide out the adjustable seals (2, 3, and 4) as
applicable.
5. Slide in the new adjustable seals (2, 3, and 4), as
applicable, and tighten screw (5).
6. Perform the adjustment of the adjustable seals
(paragraph 71-25B).
71-25B. Engine Air Inlet Cowlings  Adjustable
Seal Adjustment
NOTE
The following procedure is only applicable
when adjustable seals have been installed
on 
the 
engine 
air 
inlet 
cowling
(Post BHT-212-SI-96).
1. Remove the left-hand or right-hand engine air
inlet cowlings as applicable (paragraph 71-23). 
2. Cut and remove the adhesive from the ends of
the adjustable seals (2, 3, and 4, Figure 71-16B) as
applicable.
3.
Loosen the screws (5) until the adjustable seals
(2, 3, and 4) can move with finger pressure, but not too
loose that they can slide off the engine air inlet
cowling (1).
4. Extend out the adjustable seals (2, 3, and 4) prior
to installing the engine air inlet cowling (1).
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-314
Adhesive
71-00-00
ECCN EAR99
Page 42D
Rev. 12 8 JUN 2010
BHT-212-MM-9
1.5 inches (38.1 mm) (Figure 71-42, Dimension A,
Sheet 11) may be welded. Cracks up to 5.0 inches
(127.0 mm) long (Dimension A) may be repaired by
welding a 0.032 inch (0.813 mm) thick titanium (per
MIL-T-9046) patch over crack. Patch shall extend
0.50 inch (12.70 mm) beyond stop-drill holes and
completely cover cracked area. Fillet weld around
edges of patch.
b. When cracks extend into vertical flanges,
repair as shown in Figure 71-42, Sheet 9 using
0.025 inch (0.635 mm) thick titanium per MIL-T-9046.
When cracks extend to attachment flanges, repair as
shown in Figure 71-42, Sheet 10 using 0.025 inch
(0.635 mm) thick titanium per MIL-T-9046. Rivet
spacing where used shall be 0.75 inch minimum/1.0
inch maximum (19.05 mm minimum/12.4 mm
maximum). When crack extends through attachment
flanges, frame may have only one repair in an 18.0
inch (457.2 mm) length of frame and no closer than
8.0 inches (203.2 mm) to any airframe attachment
fitting.
c. Support clips may have cracks in vertical
flange weld repaired once. Subsequent repairs require
replacement of clip, which may be fabricated from
same thickness titanium per MIL-T-9046.
d. Repair attachment flange as follows:
(1) Replace all 
loose 
rivets attaching
nutplates using MS20427M3 monel rivets.
(2) Cracks originating from rivet or bolt holes
may be welded (one weld per nutplate). Cracks that
run from hole-to-hole within a nutplate pattern shall be
reinforced by welding a doubler of 0.025 inch
(0.635 mm) thick titanium (per MIL-T-9046) over hole
pattern and redrilling holes (Figure 71-42, Sheet 12).
(3) Cracks in attachment flange in between
attachment holes may be welded and weld plenished
smooth. When crack runs across both flanges, a
doubler 0.025 inch (0.635 mm) thick titanium (per
MIL-T-9046) shall be used. Crack in attachment is to
be welded and plenished smooth. Since other flange is
attached to ejector, weld as far as practical. Attach
doubler and weld. Repairs of this nature are restricted
to five per ejector and shall be no closer to other
repairs than length of doubler.
71-104. Ejectors  Installation
NOTE
If gaps are identified between the flange of
the exhaust ejector and the mating surface
of the aft firewall during installation, refer to
BHT-212-SI-97 
for 
inspection 
and
shimming procedures, as applicable.
1.
Install ejector as follows:
a. Helicopters S/N 30504 through 30553:
(1) Remove exhaust cover and insert ejector
(5, Figure 71-41) through firewall, over exhaust duct
(2) and into end of transition duct (1).
(2) Align each of links (4) to mounting
bracket on oil cooler support, and install bolt with
washers and nut. Attach ejector flange to firewall with
screws and washers. Connect drain line (3) to fitting
under ejector.
b. Helicopters S/N 30554 and subsequent:
(1)
Install accessory case vent fitting and
vent hose fitting in ejector assembly with thin steel
washers either side of ejector.
(2) Tighten nuts and lockwire (C-405) to
adjacent flange (View B).
(3)
Insert ejector (5) through firewall, over
exhaust duct(s), and into end of transition duct (1).
(4) Align each of links (4) to mounting
bracket of lower and outboard sides of ejector and to
mounting bracket on oil cooler support.
(5)
Install bolts with washers and nuts.
(6) Attach ejector flange to firewall with
screws and washers.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-405
Lockwire
71-00-00
Page 98
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-9
(7) Connect drain line (3) to fitting under
ejector (5).
2. Spread blanket, and slide forward around ejector.
3.
Lace both sides of blanket together with lockwire
(C-405), making two complete and separate lines.
4.
Install links (4) to oil cooler support, and to bottom
and outboard sides of ejectors.
5. On helicopters S/N 30554 and subsequent,
connect vent lines.
6.
Install side and top cowling.
71-105. TRANSITION DUCTS
71-106. Transition Ducts  Removal
NOTE
The removal and installation procedures for
right transition duct (10, Figure 71-43) are
given. The procedures for left transition
duct (2) are the same.
1. Remove upper and 
lower engine cowling
(paragraph 71-27).
2. Remove screws (3 and 7, Figure 71-44).
3. Remove transition duct (2).
71-107. Transition Ducts  Inspection
1.
Inspect transition duct (2, Figure 71-44) for
distortion, cracks, and holes.
2.
Inspect transition duct (2) for secure installation
of attaching screws.
3.
Inspect transition duct (2) for proper clearance
with exhaust duct (8). Clearance shall be 0.10 to 0.70
inch (2.6 to 17.7 mm).
4.
Inspect transition duct (2) for secure installation
with ejector (1).
71-108. Transition Ducts  Repair
1. Repair transition duct (2, Figure 71-44) as
follows:
a. Local dings, dents, or bumps not exceeding
0.25 inch (6.3 mm) in depth and 2.0 inches (50.8 mm)
in diameter may be ignored or worked out at
operator's discretion.
b. Dings, dents, and bumps exceeding 0.25 inch
(6.3 mm) in diameter shall be worked out to original
contour.
c. All dings, dents, and bumps that penetrate
surface shall be worked out to original contour and
treated as a crack.
d. All cracks up to 3.0 inches (76.2 mm) in length
shall be stop-drilled (0.094 inch (2.38 mm) diameter),
cracks cleaned out, and a patch applied to outside
surface (Figure 71-45, View A). Use sealant (C-308).
e. All holes up to 3.0 inches (76.2 mm) in
diameter shall be cleaned and a patch applied to
outside surface (View B). Use sealant (C-308).
f. Repair cracks in flanges per View C. Only one
repair on each side is permitted. Use sealant (C-308).
g. Repairs to seal retainer are limited to
stop-drilling cracks 0.094 inch (2.38 mm) diameter,
and adding a doubler (View D). Use sealant (C-308).
h. Repairs to duct requiring a patch shall have
patch applied to outside surface, except in area of seal
retainer (aft end of duct) where patch shall be applied
on inside surface.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-204
Epoxy Polyamide 
Primer
C-308
Sealant
71-00-00
8 JUN 2010 Rev. 12
Page 99
ECCN EAR99
BHT-212-MM-9
Figure 71-43.   Engine Air Management System Ducts
212_MM_71_0043
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Left ejector
Left transition duct
Left valve assembly
Left forward duct
Left forward transition duct
Right forward transition duct
Right forward duct
Right induction baffle
Right valve assembly
Right transition duct
Right ejector
Left induction baffle
Valve assembly door
Right exhaust duct
Exhaust flange
6
1
2
3
4
5
6
11
10
9
8
7
10
9
11
15
14
13
12
8
7
FW
D
71-00-00
Page 100
Rev. 11 30 APR 2010
ECCN EAR99
BHT-212-MM
1. Perform automatic fuel control idle speed check
per Paragraph 76-10 prior 
to accomplishing
acceleration and deceleration check.
2. Start both engines and let idle for 5 minutes.
3. With collective at flat pitch and both engines at
IDLE, increase N2 to maximum beep. Set N1 IDLE
speed to 61% on each power section, using throttles.
4. Check acceleration time from 61 to 90% N1 for
ENG 1 as follows:
CAUTION
MONITOR ENGINE TORQUE AND ITT
DURING THIS PROCEDURE.
NOTE
Measurement of acceleration time begins
when ENG throttle is snapped to FULL
OPEN and stops when N1 reaches 90%.
a. Set ENG 2 throttle to IDLE and apply friction to
hold it in position.
b. Snap open ENG 1 throttle to FULL OPEN.
Start timing.
c. When 90% N1 is reached, snap ENG 1 throttle
back to IDLE. Stop timing.
NOTE
Acceleration time from 61 to 90% N1
should 
be 
4 
seconds maximum.
Acceleration times less than 3 seconds are
acceptable if outside air temperature is
below 32F (0C), provided there is no
compressor surge.
Match both power sections acceleration
times as close as possible. The maximum
acceptable difference in acceleration time is
0.5 second.
d. If acceleration time is too slow or too fast
(compressor surge), adjust acceleration dome (3,
Figure 76-11) (refer to Pratt & Whitney Maintenance
Manual).
5. Repeat step 4 with ENG 2.
6. Check deceleration time from 90 to 61% N1 for
ENG 1 as follows:
NOTE
Measurement of deceleration time begins
when ENG throttle is snapped to IDLE and
stops when N1 reaches 61%.
a. Set ENG 2 throttle to IDLE and apply friction to
hold it in position.
b. Gradually open ENG 1 throttle to FULL OPEN.
c. Increase power to 90% N1 and stabilize, then
snap ENG 1 throttle back to IDLE.
d. Confirm deceleration time from 90 to 61% N1
of 5 seconds maximum below 6000 ft pressure
altitude, and smooth deceleration to a stabilized IDLE
of 61% N1.
7. Repeat step 6 with ENG 2.
76-12. AUTOMATIC MODE MAXIMUM GAS
PRODUCER SPEED CHECK AND AFCU
MAXIMUM N1 STOP ADJUSTMENT
76-13. PT6T-3 Engine
NOTE
Refer to Pratt & Whitney Aircraft of Canada
Ltd. PT6T-3 Series Maintenance Manual
No. 3017042 for detailed procedure.
This single power section check to be
performed with helicopter heavily loaded
and light on skids. However, pilot must be
prepared for the possibility helicopter may
become airborne.
1. Rotate in place and secure part power trim stop
(12, Figure 76-11).
2. Start both engines and let idle for 5 minutes.
76-00-00
02 AUG 2004 Rev. 8
Page 35
BHT-212-MM-9
3. With collective at flat pitch and both engines at
IDLE, increase ENG 1 throttle to FULL OPEN. Using
INCR/DECR switch increase ROTOR RPM (NR) to full
INCR.
NOTE
Maximum gas producer 
(N1) speed
(topping) is achieved when N1 ceases to
increase and N2/NR droops as collective is
further applied. Do not droop below 90%
N2. The observed reading at this point
should be 96.1 to 97.1% N1 with part power
trim stop and 92.4 to 92.9% N1 with slave
stop at temperatures below +25F (-4C). A
minimum value of 96.3 or 92.6% N1 (slave
stop) is required to assure in flight topping
at 100.0% N1.
4. Gradually increase collective until N1 topping is
achieved and note N1 value.
NOTE
If maximum stop screw is adjusted,
re-adjust the interconnect linkage for proper
AUTO/MANUAL gap and throttle cushions
per paragraph 76-3 and Pratt & Whitney
Aircraft of Canada Ltd. PT6T-3 Series
Maintenance Manual. This is accomplished
once maximum gas producer (N1) speed is
attained and part power trim stop is
retracted.
5.
If required, adjust the topping adjustment screw
and repeat step 4.
6. Repeat step 3, step 4, and step 5 with ENG 2.
76-14. PT6T-3 Engine AFCU Maximum N1 Stop
Adjustment, Alternate Procedure
CAUTION
DO NOT EXCEED TORQUE LIMIT OF
71.8% OR ITT LIMIT OF 810C.
MAXIMUM N1  TOPPING CHECKS
SHOULD ONLY BE PERFORMED AFTER
ENGINE CONTROL RIGGING IS
ADJUSTED OR WHEN ANY OF THE
FOLLOWING COMPONENTS ARE
REPLACED: (TWO POWER SECTIONS
AND REDUCTION GEARBOX), POWER
SECTION, AFCU, MFCU, AND FUEL
PUMP.
NOTE
Field experience, particularly 
in warm
climates, has revealed it is not possible to
operate both power sections at 100.0% N1
RPM at any altitude without exceeding
maximum ITT limit of 810C. This condition
does not prevent engine from achieving
required performance, but does present a
functional test problem.
This single power section check to be
performed in flight or with helicopter heavily
loaded and light on skids. However, pilot
must be prepared for 
the possibility
helicopter may become airborne.
1. Start both engines and let idle for 5 minutes.
2.
Increase both throttles to FULL OPEN one at a
time and adjust ENG N2 RPM to INCR with RPM
INCR/DECR switch.
3. Decrease throttle of one engine to flight IDLE
leaving the other at FULL OPEN with ENG N2 RPM to
full INCR.
4.
Increase power by raising the collective, drooping
ENG RPM to approximately 97% to obtain 100.0% N1
RPM.
NOTE
If maximum stop screw is adjusted,
re-adjust the interconnect linkage for proper
AUTO/MANUAL gap and throttle cushions
per paragraph 76-3 and Pratt & Whitney
Aircraft of Canada Ltd. PT6T-3 Series
Maintenance Manual. This is accomplished
once maximum gas producer (N1) speed is
attained and part power trim is retracted.
a. If ENG RPM droops below 97% prior to
obtaining 100.0% N1 RPM, increase topping. Turn
stop screw (14, Figure 76-11) counterclockwise to
increase.
76-00-00
Page 36
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-9
b. If 100.0% N1 rpm is reached without ENG
RPM droop, apply power to a maximum of 100.5% N1
RPM. If droop does not occur between 100.0% and
100.5% N1 RPM, decrease topping. Turn stop screw
(14) clockwise to decrease.
5.
If stop screw (14) was adjusted, tighten jam nuts
and lockwire.
76-15. PT6T-3B Engine
NOTE
Refer to Pratt & Whitney Aircraft of Canada
Ltd. PT6T-3 Series Maintenance Manual
No. 3017042 for detail procedure.
This single power section check to be
performed with helicopter heavily loaded
and light on skids. However, pilot must be
prepared for the possibility helicopter may
become airborne.
1. Rotate in place and secure part power trim stop
(12, Figure 76-11).
2. Start both engines and let idle for 5 minutes.
3. With collective at flat pitch and both engines at
IDLE, increase ENG 1 throttle to FULL OPEN. Using
INCR/DECR switch increase ROTOR RPM NR to full
INCR.
NOTE
Maximum gas producer 
(N1) speed
(topping) is achieved when N1 ceases to
increase and N2/NR droops as collective is
further applied. Do not droop below 90%
N2. The observed reading at this point
should be 99.8 to 100.8% N1 or 96.1 to
96.7 N1 with slave stop at temperatures
below +25F (-4C). A minimum value of
100.1 or 96.4% (slave stops) N1 is required
to assure in flight topping at 103.4% N1.
4. Gradually increase collective until N1 topping is
achieved and note N1 value.
NOTE
If maximum stop screw is adjusted,
re-adjust the interconnect linkage for proper
AUTO/MANUAL gap and throttle cushions
per paragraph 76-3 and Pratt & Whitney
Aircraft of Canada Ltd. PT6T-3 Series
Maintenance Manual. This is accomplished
once maximum gas generator (N1) speed is
attained and part power trim stop is
retracted.
5.
If required, adjust the topping adjustment screw
and repeat step 4.
6. Repeat  step 3,  step 4, and  step 5 with ENG 2.
76-16. PT6T-3B Engine AFCU Maximum N1 Stop
Adjustment, Alternate Procedure
CAUTION
DO NOT EXCCED TORQUE LIMIT OF
79.4% OR ITT LIMIT OF 850C.
MAXIMUM N1  TOPPING CHECKS
SHOULD ONLY BE PERFORMED AFTER
ENGINE CONTROL RIGGING IS
ADJUSTED OR WHEN ANY OF THE
FOLLOWING COMPONENTS ARE
REPLACED: (TWO POWER SECTIONS
AND REDUCTION GEARBOX), POWER
SECTION, AFCU, MFCU, AND FUEL
PUMP.
NOTE
Field experience, particularly 
in warm
climates, has revealed it is not possible to
operate both power sections at 102.4% N1
RPM with indicator 212-075-037-101/105 or
103.4% 
N1 
RPM 
with 
indicator
212-075-037-113 at any altitude without
exceeding maximum ITT limit of 850C.
This condition does not prevent engine from
achieving required performance, but does
present a functional test problem.
This single power section check to be
performed in flight or with helicopter heavily
loaded and light on skids. However, pilot
must be prepared for 
the possibility
helicopter may become airborne.
1. Start both engines and let idle for 5 minutes.
76-00-00
8 JUN 2010 Rev. 12
Page 37
ECCN EAR99
BHT-212-MM
2.
Increase both throttles to FULL OPEN one at a
time and adjust ENG N2 rpm to INCR with RPM
INCR/DECR switch.
3. Decrease throttle of one engine to flight IDLE
leaving the other at FULL OPEN with ENG N2 rpm to
full INCR.
NOTE
N1 values with indicator 212-075-037-101
installed is 102.4% and 103.4% for indicator
212-075-037-113. 
For 
maintenance
purposes only adjust maximum N1 to
103.4% for both indicators.
4.
Increase power by raising the collective, drooping
ENG rpm to approximately 97% to obtain 103.4% N1
rpm.
NOTE
If maximum stop screw is adjusted,
re-adjust the interconnect linkage for proper
AUTO/MANUAL gap and throttle cushions
per Paragraph 76-3 and Pratt & Whitney
Aircraft of Canada Ltd. PT6T-3 Series
Maintenance Manual. This is accomplished
once maximum gas producer (N1) speed is
attained and part power trim stop is
retracted.
a. If ENG rpm droops below 97% prior to
obtaining 103.4% N1 rpm, increase topping. Turn stop
screw (14, Figure 76-11) counterclockwise to increase.
b. If 103.4% N1 rpm is reached without ENG rpm
droop, apply power to a maximum of 103.6% N1 rpm.
If droop does not occur between 103.4% and 103.6%
N1 rpm, decrease topping. Turn stop screw (14)
clockwise to decrease.
5.
If stop screw (14) was adjusted, tighten jamnuts
and lockwire.
76-17. ENGINE IDLE SPEED ADJUSTMENT
1. Start both engines and let idle for 5 minutes.
2. With collective at flat pitch and both engines at
IDLE, set ENG 1 N1 at 61% using throttle.
3. Gradually increase ENG 1 throttle to FULL
OPEN, then retard throttle to IDLE.
4. Verify ENG 1 idle speed is 61  1% N1. If
required, adjust idle stop adjustment screw (9, Figure
76-4). If available adjustment of idle stop adjustment
screw (9) is not adequate (insufficient threads),
replace four NAS43DD3 spacers (5) under the idle
stop solenoid (7) with longer or short lengths as
required (refer to Paragraph 76-3).
5. Repeat steps 3 and 4 above with ENG 2.
76-18. MANUAL CHANGE-OVER CHECK
NOTE
The reference in engine manual to Fuel
Control Selector Switch refers to ENG 1
GOV and ENG 2 GOV switches in aircraft.
If operator flies below 5000 feet, refer to
Pratt & Whitney Aircraft of Canada Ltd.
PT6T-3 Series Maintenance Manual for
procedures.
If operator flies higher than 5000 feet,
accomplish check at 6000 feet altitude.
1. Fly helicopter to 6000 feet altitude.
2. Rotate ENG 1 throttle to IDLE. GAS PROD (N1)
rpm should be 61  1%. Record rpm indication.
NOTE
MANUAL GAS PROD (N1) rpm should be
recorded within approximately 2 to 3
seconds after selecting ENG GOV switch.
3. Position ENG 1 GOV switch to MANUAL. GAS
PROD rpm should be 61  5%. Record rpm indication.
4. Position ENG 1 GOV switch to AUTO. Record
rpm indication.
5. Repeat steps 2 through 4 for ENG 2.
6.
If either power section is out of acceptable limit 61
 5% adjust AUTO/MANUAL interconnect linkage
(refer to Paragraph 76-3 and Pratt & Whitney Aircraft
of Canada Ltd. PT6T-3 Series Maintenance Manual).
76-00-00
Page 38
Rev. 8 02 AUG 2004
BHT-212-MM-10
 NOTICE
The instructions set forth in this manual, as supplemented or modified by Alert Service Bulletins (ASB) or
other directions issued by Bell Helicopter Textron Inc. and Airworthiness Directives (AD) issued by the
applicable regulatory agencies, shall be strictly followed.
7 JUNE 1993
REVISION 12  8 JUNE 2010
COPYRIGHT NOTICE
COPYRIGHT  
2010
BELL  HELICOPTER TEXTRON INC.
AND BELL HELICOPTER TEXTRON
CANADA LTD.
ALL RIGHTS RESERVED
MAINTENANCE MANUAL
VOLUME 10
INSTRUMENTS/ELECTRICAL
BHT-212-MM-10
PN
Rev. 11 30 APR 2010
Additional copies of this publication may be obtained by contacting:
Commercial Publication Distribution Center
Bell Helicopter Textron Inc.
P. O. Box 482
Fort Worth, Texas 76101-0482
PROPRIETARY RIGHTS NOTICE
These data are proprietary to Bell Helicopter Textron Inc. Disclosure,
reproduction, or use of these data for any purpose other than helicopter
operation or maintenance is forbidden without prior written authorization from
Bell Helicopter Textron Inc.
DESTINATION CONTROL STATEMENT
These commodities, technology, or software were exported from the United
States in accordance with the Export Administration Regulations (EAR).
Diversion contrary to U.S. law prohibited. The data contained in this manual are
classified as ECCN EAR99.
BHT-212-MM-10
TABLE OF CONTENTS
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
CHAPTER  96  ELECTRICAL SYSTEM
ELECTRICAL SYSTEM
96-1
General Description .......................................................................
96-00-00
11
96-1A
Electrical Systems..........................................................................
96-00-00
11
96-2
Primary and Secondary Electrical Power Systems Analysis ....
96-00-00
11
96-2A
Electrical Power Source Component Data ...............................
96-00-00
12
96-2B
Summary of Electrical System Analysis ...................................
96-00-00
13
96-3
Emergency DC Power ..............................................................
96-00-00
13
96-4
Emergency AC Power ..............................................................
96-00-00
13
96-4A
Electrical Safety and Hazards...................................................
96-00-00
14
96-4B
Safety Practices  General..............................................
96-00-00
14
96-4C
Standard Practices  Electrical Maintenance or
Repairs..............................................................................
96-00-00
14
96-4D
Standard Practices  Electrical Work In Confined
Spaces ..............................................................................
96-00-00
15
96-4E
Standard Practices  After Electrical Maintenance or
Repairs..............................................................................
96-00-00
15
96-4F
Miscellaneous Electrical Tools..................................................
96-00-00
15
96-5
Operational Checks  Electrical Systems ...............................
96-00-00
15
96-6
Troubleshooting  Electrical Systems .....................................
96-00-00
16
96-7
Miscellaneous Electrical Components  Maintenance
Practices ...................................................................................
96-00-00
16
96-8
Miscellaneous Electrical Components  Removal ..........
96-00-00
16
96-8A
Miscellaneous Electrical Components  Cleaning ..........
96-00-00
17
96-9
Miscellaneous Electrical Components  Inspection ........
96-00-00
17
96-10
Miscellaneous Electrical Components  Repair ..............
96-00-00
19
96-11
Miscellaneous Electrical Components  Installation .......
96-00-00
19
96-12
Control Panels  Electrical ...........................................................
96-00-00
19
96-13
Control Panels  Removal...............................................
96-00-00
19
96-14
Control Panels  Inspection ............................................
96-00-00
19
96-15
Control Panels  Repair ..................................................
96-00-00
19
96-16
Control Panels  Installation............................................
96-00-00
19
96-17
Circuit Breakers ........................................................................
96-00-00
19
96-18
Circuit Breakers  Removal.............................................
96-00-00
19
96-19
Circuit Breakers  Inspection ..........................................
96-00-00
20
96-20
Circuit Breakers  Repair/Replacement ..........................
96-00-00
20
96-21
Circuit Breakers  Installation..........................................
96-00-00
20
96-22
Semiconductor Devices ............................................................
96-00-00
20
96-22A
Semiconductor Devices  Maintenance Practices ..........
96-00-00
20
96-23
Track Mounted Relays..............................................................
96-00-00
21
96-23A
Track Mounted Relays  Removal ..................................
96-00-00
21
96-23B
Track Mounted Relay  Cleaning ....................................
96-00-00
21
96-23C
Track Mounted Relay  Inspection..................................
96-00-00
21
96-23D
Track Mounted Relay  Installation .................................
96-00-00
21
96-23E
Electrical and Avionics Equipment  Reference Designator,
Nomenclature, and Location.....................................................
96-00-00
21
96-00-00
8 JUN 2010 Rev. 12
Page 1
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
DC POWER SYSTEMS
96-24
DC Power Systems........................................................................
96-00-00
65
96-25
Battery............................................................................................
96-00-00
65
96-26
Battery Servicing.......................................................................
96-00-00
65
96-27
Removal  Battery...................................................................
96-00-00
66
96-28
Inspection  Battery ................................................................
96-00-00
66
96-29
Installation  Battery................................................................
96-00-00
66
96-30
Operational Check  Battery System ......................................
96-00-00
67
96-31
External Power...............................................................................
96-00-00
68
96-32
Removal  External Power Receptacle...................................
96-00-00
68
96-33
Installation  External Power Receptacle................................
96-00-00
69
96-34
Operational Check  External Power .....................................
96-00-00
69
96-35
Generator.......................................................................................
96-00-00
69
96-36
Operational Check  Generator No. 1 System........................
96-00-00
70
96-37
Operational Check  Generator No. 2 System........................
96-00-00
72
96-38
Operational Check  Generator No. 1 and Generator
No. 2 System ............................................................................
96-00-00
73
96-39
Operational Check  Voltage Control Paralleling Adjustment.
96-00-00
74
96-40
Operational Check  Non-essential bus..................................
96-00-00
75
96-41
Power Diode Functional Checkout Procedures ........................
96-00-00
75
96-42
Starter and Igniter ..........................................................................
96-00-00
77
96-43
Operational Check  Starter and Igniter Systems...................
96-00-00
77
96-44
Starter No. 1 Circuitry .......................................................
96-00-00
77
96-45
Engine Ignition Unit No. 1 .................................................
96-00-00
77
96-46
Starter No. 2 Circuitry .......................................................
96-00-00
80
96-47
Engine Ignition Unit No. 2 .................................................
96-00-00
80
AC POWER SYSTEM
96-48
AC Power System..........................................................................
96-00-00
81
96-49
Inverter...........................................................................................
96-00-00
81
96-50
Inverters PS1, PS2, or PS7  Removal ..................................
96-00-00
81
96-51
Inspection  Inverters PS1, PS2, or PS7 ................................
96-00-00
82
96-52
Installation  Inverters PS1, PS2, or PS7 ...............................
96-00-00
82
96-53
Operational Check  Inverter System (S/N 30504
through 30553) .........................................................................
96-00-00
82
96-54
Inverters No. 1 and No. 2..................................................
96-00-00
82
96-55
Inverters No. 1 and No. 2..................................................
96-00-00
83
96-56
Operational Check  Inverter System (S/N 30554
and Subsequent) ......................................................................
96-00-00
83
96-57
Ac Power Tests.................................................................
96-00-00
83
96-58
Inverter No. 1 ....................................................................
96-00-00
83
96-59
Inverter No.  2 Circuitry .....................................................
96-00-00
83
96-60
Inverter No. 3 Circuitry ......................................................
96-00-00
84
96-61
Operational Check  Inverter Caution Lights ..........................
96-00-00
85
96-00-00
Page 2
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
AC INDICATOR SYSTEMS
96-62
AC Indicator Systems ....................................................................
96-00-00
87
96-63
Torque Indicator.............................................................................
96-00-00
87
96-64
Torque Indicator  Operational Check and Calibration ...........
96-00-00
87
96-65
Engine Oil Pressure Indicator ........................................................
96-00-00
87
96-66
Engine Oil Pressure Indicator  Operational Check................
96-00-00
87
96-67
Transmission Oil Pressure Indicator ..............................................
96-00-00
90
96-68
Transmission Oil Pressure Indicator  Operational Check .....
96-00-00
90
96-69
Hydraulic Pressure Indicator..........................................................
96-00-00
90
96-70
Hydraulic Pressure Indicator  Operational Check .................
96-00-00
90
96-71
Combining Gearbox Oil Pressure Indicator ...................................
96-00-00
91
96-72
Combining Gearbox Oil Pressure Indicator  Operational
Check........................................................................................
96-00-00
91
96-73
Fuel Pressure Indicator..................................................................
96-00-00
91
96-74
Fuel Pressure Indicator  Operational Check .........................
96-00-00
91
96-75
Attitude Indicator (Helicopters S/N 30504 through 30596) ............
96-00-00
92
96-76
Attitude Indicator System (VFR Helicopters)  Operational
Check........................................................................................
96-00-00
92
96-77
Attitude Indicator System (IFR Helicopters)  Operational
Check........................................................................................
96-00-00
92
96-78
Attitude Indicator (Helicopters S/N 30597 and Subsequent) .........
96-00-00
92
96-79
Attitude Indicator System  Operational Check ......................
96-00-00
92
96-80
Fuel Quantity Indicator...................................................................
96-00-00
93
96-81
Tank Unit and System Wiring Installation  Insulation
Resistance Test ........................................................................
96-00-00
93
96-82
Fuel Quantity Indicator System (Preferred Method 
No Fuel in Tank)  Calibration ................................................
96-00-00
93
96-83
Fuel Quantity Indicator System (Alternate Method 
Fuel in Cell)  Calibration........................................................
96-00-00
93
96-84
Triple Tachometer Indicator ...........................................................
96-00-00
93
96-85
Triple Tachometer Indicator System (Rotor RPM, Power
Turbine No. 1 RPM, Power Turbine No. 2 RPM)
 Operational Check ...............................................................
96-00-00
95
96-86
Gas Producer Tachometer Indicator..............................................
96-00-00
95
96-87
Gas Producer Tachometer Indicator  Operational Check .....
96-00-00
95
DC INDICATOR SYSTEMS
96-88
DC Indicator Systems ....................................................................
96-00-00
97
96-89
Engine Oil Temperature Indicator ..................................................
96-00-00
97
96-90
Engine Oil Temperature Indicator  Operational Check .........
96-00-00
97
96-91
Transmission Oil Temperature Indicator........................................
96-00-00
97
96-92
Transmission Oil Temperature Indicator  Operational Check
96-00-00
97
96-93
Combining Gearbox (C BOX) Oil Temperature Indicator...............
96-00-00
97
96-94
Combining Gearbox (C BOX) Oil Temperature Indicator
 Operational Check ...............................................................
96-00-00
97
96-00-00
8 JUN 2010 Rev. 12
Page 3
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
96-95
Engine Hourmeter..........................................................................
96-00-00
97
96-96
Engine Hourmeter  Operational Check .................................
96-00-00
97
96-97
Turn-and-slip Indicator ...................................................................
96-00-00
98
96-98
Turn-and-slip Indicator  Operational Check ..........................
96-00-00
98
96-98A
Interturbine Temperature Indicator (ITT) (Helicopters S/N 30504
through 30553)...............................................................................
96-00-00
98
96-98B
Interturbine Temperature Indicator (ITT) (Helicopters
S/N 30504 through 30553)  Operational Test .......................
96-00-00
98
96-99
Interturbine Temperature Indicator (ITT) (Helicopters S/N 30554
and Subsequent)............................................................................
96-00-00
100
96-100
Interturbine Temperature Indicator (ITT) (Helicopters
S/N 30554 and Subsequent)  Operational Test ....................
96-00-00
100
96-101
Hydraulic Oil Temperature Indicator ..............................................
96-00-00
101
96-102
Hydraulic Oil Temperature Indicator  Operational Check......
96-00-00
101
INTERIOR LIGHTING SYSTEM
96-103
Interior Lighting Systems ...............................................................
96-00-00
103
96-104
Cockpit Lights ................................................................................
96-00-00
103
96-105
Operational Check  Cockpit Lights........................................
96-00-00
103
96-106
Dome Lights...................................................................................
96-00-00
103
96-107
Operational Check  Dome Lights ..........................................
96-00-00
103
96-108
Pilot and Copilot Instrument Panel Lights ......................................
96-00-00
103
96-109
Operational Check  Pilot and Copilot Instrument
Panel Lights ..............................................................................
96-00-00
103
96-110
Engine Instrument Panel Lights .....................................................
96-00-00
104
96-111
Operational Check  Engine Instrument Panel Lights ............
96-00-00
104
96-112
Instrument Secondary Lights .........................................................
96-00-00
104
96-113
Operational Check  Instrument Secondary Lights.................
96-00-00
104
96-114
Pedestal Lights ..............................................................................
96-00-00
104
96-115
Operational Check  Pedestal Lights......................................
96-00-00
105
96-116
Overhead Console Lights ..............................................................
96-00-00
105
96-117
Operational Check  Overhead Console Lights......................
96-00-00
105
96-118
Baggage Compartment Lights .......................................................
96-00-00
105
96-119
Operational Check  Baggage Compartment Lights...............
96-00-00
105
CAUTION AND WARNING SYSTEM
96-120
Caution and Warning System ........................................................
96-00-00
107
96-121
Operation  Caution and Warning System..............................
96-00-00
107
96-122
Operational Test  Caution Panel Light ..................................
96-00-00
107
96-123
DC Generator Caution Light ..........................................................
96-00-00
109
96-124
Operational Check  DC Generator Caution Light..................
96-00-00
109
96-125
Engine Oil Pressure Caution Light.................................................
96-00-00
110
96-126
Operational Check  Engine Oil Pressure Caution Light ........
96-00-00
110
96-127
Particle Separator Caution Light ....................................................
96-00-00
111
96-128
Operational Check  Particle Separator Caution Light ...........
96-00-00
111
96-129
Fuel Boost Caution Light................................................................
96-00-00
111
96-00-00
Page 4
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
96-130
Operational Check  Fuel Boost Caution Light .......................
96-00-00
111
96-131
Fuel Filter Caution Light.................................................................
96-00-00
111
96-132
Operational Check  Fuel Filter Caution Light ........................
96-00-00
111
96-133
Fuel Low Caution Light ..................................................................
96-00-00
111
96-134
Operational Check  Fuel Low Caution Light Systems...........
96-00-00
111
96-135
Governor Manual Control Caution Light .......................................
96-00-00
112
96-136
Operational Check  Governor Manual Control Caution
Light Systems ...........................................................................
96-00-00
112
96-137
Engine Chip Detector Caution Light...............................................
96-00-00
112
96-138
Operational Check  Engine Chip Detector Caution
Light Systems ...........................................................................
96-00-00
112
96-139
Hydraulic Caution Light (S/N 30554 and Subsequent) ..................
96-00-00
113
96-140
Operational Check  Hydraulic Caution Light System ............
96-00-00
113
96-141
Transmission Oil Pressure Caution Light.......................................
96-00-00
113
96-142
Operational Check  Transmission Oil Pressure Caution
Light System .............................................................................
96-00-00
113
96-143
Combining Gearbox (C BOX) Chip Detector Caution Light ...........
96-00-00
113
96-144
Operational Check  Combining Gearbox Chip
Detector Caution Light System .................................................
96-00-00
113
96-145
Combining Gearbox (C BOX) Oil Pressure Caution Light .............
96-00-00
113
96-146
Operational Check  Combining Gearbox (C BOX) Oil
Pressure Caution Light System ................................................
96-00-00
113
96-147
Inverter No. 1 Caution Light ...........................................................
96-00-00
114
96-148
Operational Check  Inverter No. 1 Caution Light System .....
96-00-00
114
96-149
Inverter No. 2 Caution Light ...........................................................
96-00-00
114
96-150
Operational Check  Inverter No. 2 Caution Light System .....
96-00-00
114
96-151
Inverter No. 3  Caution Light ......................................................
96-00-00
114
96-152
Operational Check  Inverter No. 3 Caution Light System .....
96-00-00
114
96-153
Transmission Chip Detector Caution Light ....................................
96-00-00
114
96-154
Operational Check  Transmission Chip Detector Caution
Light System .............................................................................
96-00-00
114
96-155
Transmission Oil Temperature Caution Light ................................
96-00-00
115
96-156
Operational Check  Transmission Oil Temperature
Caution Light System................................................................
96-00-00
115
96-157
Intermediate (42C) Gearbox Chip Detector Caution Light............
96-00-00
115
96-158
Operational Check  Intermediate Gearbox Chip Detector
Caution Light System................................................................
96-00-00
115
96-159
Tail Rotor (90) Gearbox Chip Detector Caution Light...................
96-00-00
115
96-160
Operational Check  Tail Rotor Chip Detector Caution
Light System .............................................................................
96-00-00
115
96-161
Combining Gearbox (C BOX) Oil Termperature Caution Light ......
96-00-00
116
96-162
Operational Check  Combining Gearbox Termperature
Caution Light System................................................................
96-00-00
116
96-163
External Power Caution Light ........................................................
96-00-00
116
96-164
Operational Check  External Power Caution Light System...
96-00-00
116
96-165
Door Lock Caution Light ................................................................
96-00-00
116
96-166
Operational Check  Door Lock Caution Light System...........
96-00-00
116
96-167
Adjustment Procedure  Door Lock Caution Light System .....
96-00-00
116
96-00-00
8 JUN 2010 Rev. 12
Page 5
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
96-168
Battery Caution Light .....................................................................
96-00-00
116
96-169
Operational Check  Battery Caution Light System................
96-00-00
116
96-170
Heater Air Line Caution Light.........................................................
96-00-00
116
96-171
Operational Check  Heater Air Line Caution Light System ...
96-00-00
116
96-172
RPM Limit Warning (Light and Audio) (S/N 30597
and Subsequent)............................................................................
96-00-00
117
96-173
Operational Check  RPM Warning System ...........................
96-00-00
117
96-174
RPM Limit Warning System  On Helicopter Test ..................
96-00-00
118
96-175
Rotor Low RPM Warning Test ..........................................
96-00-00
118
96-176
Rotor High RPM Warning Test .........................................
96-00-00
118
96-177
Engine RPM Warning Test ...............................................
96-00-00
120
96-178
Fire Detection Warning  Power Plant .........................................
96-00-00
120
96-179
Fire Detection Warning System  Operational Check.............
96-00-00
120
96-180
Engine No. 1 Fire Detection Warning ...............................
96-00-00
120
96-181
Engine No. 2 Fire Detection Warning ...............................
96-00-00
120
96-182
Fire Detection Warning  Baggage Compartment .......................
96-00-00
120
96-183
Fire Detection Warning  Baggage Compartment
 Operational Check ...............................................................
96-00-00
121
96-184
Hydraulic Filter Clogged Warning ..................................................
96-00-00
121
96-185
Engine No. 1 and No. 2 Fuel Valve Caution Light .........................
96-00-00
121
96-186
Engine No. 1 and No. 2 Fuel Valve Caution Lights
 Operational Check ...............................................................
96-00-00
121
96-187
Generator 1 and 2 Overheat Caution Light....................................
96-00-00
121
96-188
Generator 1 and 2 Overheat Caution Light System
 Operational Check ...............................................................
96-00-00
121
96-189
Caution Panel Light........................................................................
96-00-00
122
96-190
Fuel Crossfeed Valve Caution Light ..............................................
96-00-00
122
96-191
Fuel Crossfeed Valve Caution Light System  Operational
Check........................................................................................
96-00-00
122
96-192
Battery Temperature Sensor Caution Light ...................................
96-00-00
123
96-193
Battery Temperature Sensor Caution Light System
 Operational Check ...............................................................
96-00-00
123
96-194
Battery Temperature Sensor  Test Procedure ......................
96-00-00
123
96-195
Navigation Command Caution Light ..............................................
96-00-00
123
EXTERIOR LIGHTING SYSTEMS
96-196
Exterior Lighting Systems ..............................................................
96-00-00
125
96-197
Utility Lights....................................................................................
96-00-00
125
96-198
Utility Light System  Operational Check................................
96-00-00
125
96-199
Position Lights................................................................................
96-00-00
125
96-200
Position Lights System  Operational Check ..........................
96-00-00
125
96-201
Anticollision Lights .........................................................................
96-00-00
125
96-202
Anticollision Light System  Operational Check......................
96-00-00
125
96-203
Searchlight .....................................................................................
96-00-00
125
96-204
Operational Check  Searchlight System ...............................
96-00-00
126
96-205
Landing Light .................................................................................
96-00-00
126
96-206
Operational Check  Landing Light System............................
96-00-00
126
96-00-00
Page 6
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
ENGINE CONTROLS AND ACCESSORIES SYSTEMS
96-207
Engine Controls and Accessories Systems ...................................
96-00-00
127
96-208
Fuel Control Heaters......................................................................
96-00-00
127
96-209
Operational Check  Fuel Control Heaters System ................
96-00-00
127
96-210
Fuel Boost Pumps..........................................................................
96-00-00
127
96-211
Operational Check  Fuel Boost Pumps System ....................
96-00-00
127
96-212
Fuel Shutoff Valves........................................................................
96-00-00
127
96-213
Operational Check  Fuel Shutoff Valves ...............................
96-00-00
128
96-214
Engine Fuel Control Valves ...........................................................
96-00-00
128
96-215
Operational Check  Fuel Control Valves ...............................
96-00-00
128
96-216
Fuel Interconnect Valves ...............................................................
96-00-00
129
96-217
Operational Check  Fuel Interconnect Valves.......................
96-00-00
129
96-218
Fuel Crossfeed Valve.....................................................................
96-00-00
129
96-219
Operational Check  Fuel Crossfeed Valve ............................
96-00-00
130
96-220
Governor RPM Actuators...............................................................
96-00-00
130
96-221
Operational Check  Governor RPM Actuator System ...........
96-00-00
130
96-222
Sump Drain Valves ........................................................................
96-00-00
131
96-223
Operational Check  Sump Drain Valves................................
96-00-00
131
96-224
Idle Stop Release Solenoids..........................................................
96-00-00
131
96-225
Operational Check  Idle Stop Release Solenoids .................
96-00-00
131
96-226
Engine Particle Separator ..............................................................
96-00-00
132
96-227
Operational Check  Engine Particle Separator .....................
96-00-00
132
FLIGHT CONTROL SYSTEMS
96-228
Flight Control System.....................................................................
96-00-00
135
96-229
Force Trim......................................................................................
96-00-00
135
96-230
Operational Check  Force Trim .............................................
96-00-00
135
96-231
Hydraulic Bypass ...........................................................................
96-00-00
135
96-232
Operational Check  Hydraulic Bypass...................................
96-00-00
135
HEATING SYSTEMS
96-233
Heating Systems............................................................................
96-00-00
137
96-234
Pitot Tube Heaters .........................................................................
96-00-00
137
96-235
Operational Check  Pitot Tube Heaters ................................
96-00-00
137
96-236
Static Port Heaters (IFR) (S/N 30597 and Subsequent) ................
96-00-00
137
96-237
Operational Check  Static Port Heaters (IFR) .......................
96-00-00
137
96-238
Cabin Heater..................................................................................
96-00-00
138
96-239
Operational Check  Cabin Heater .........................................
96-00-00
138
96-240
Cabin Temperature Control (S/N 30756 and Subsequent)............
96-00-00
140
96-241
Rigging  Cabin Temperature Control ...................................
96-00-00
140
96-242
Operational Check  Cabin Temperature Control ..................
96-00-00
140
96-243
Vent Blower....................................................................................
96-00-00
140
96-244
Operational Check  Vent Blower ...........................................
96-00-00
140
96-00-00
8 JUN 2010 Rev. 12
Page 7
ECCN EAR99
BHT-212-MM-10
TABLE OF CONTENTS (CONT)
Paragraph
                        Chapter/Section
Page
  Number
Title
                         Number
Number
MISCELLANEOUS ELECTRICAL SYSTEMS
96-245
Miscellaneous Electrical Systems..................................................
96-00-00
143
96-246
Windshield Wiper ...........................................................................
96-00-00
143
96-247
Windshield Wiper  Operational Check ..................................
96-00-00
143
96-248
Engine Fire Extinguisher Systems.................................................
96-00-00
143
96-249
Engine Fire Extinguishing Systems  Operational Check.......
96-00-00
144
96-250
Power Passenger Step ..................................................................
96-00-00
145
96-251
Power Passenger Step  Operational Check..........................
96-00-00
145
AUTOMATIC FLIGHT CONTROL SYSTEM
96-252
Automatic Flight Control System (AFCS) (S/N 30597 and
Subsequent)...................................................................................
96-00-00
147
96-253
Automatic Flight Control System  Operational Check ...........
96-00-00
148
VOICE/FLIGHT DATA RECORDER SYSTEMS
96-254
Voice/Flight Data Recorder............................................................
96-00-00
177
96-255
Flight Data Recorder (FDR) System ..............................................
96-00-00
177
96-256
Cockpit Voice Recorder (CVR) ......................................................
96-00-00
177
96-257
Operational Check  Cockpit Voice Recorder.........................
96-00-00
177
96-258
Ground Support Equipment Available for Voice/Flight
Data Recorder Systems............................................................
96-00-00
178
FIGURES
   Figure
Page
  Number
Title
Number
96-1
Track Mounted Relay  Removal/Installation (Typical) .....................................
22
96-1A
Fuselage Equipment Location ............................................................................
23
96-2
Nose Compartment Equipment Location  Electrical........................................
30
96-3
Engine Equipment Location  Electrical............................................................
34
96-4
Transmission Equipment Location  Electrical..................................................
38
96-5
Tailboom Equipment Location  Electrical ........................................................
39
96-5A
Instrument Panel (Typical) ..................................................................................
64E
96-5B
Overhead Console (Typical) ...............................................................................
64F
96-5C
Miscellaneous and Engine Control Panel ...........................................................
64G
96-6
Generator Control Box ........................................................................................
71
96-7
Voltage Control Paralleling Adjustment ..............................................................
78
96-8
Power Diode Electrical Bus Wiring Schematic (Helicopters S/N 30554 and
Subsequent)........................................................................................................
79
96-9
Deleted................................................................................................................
88
96-10
Pressure Tester ..................................................................................................
89
96-00-00
Page 8
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
FIGURES (CONT)
   Figure
Page
  Number
Title
Number
96-11
Test Setup for Fuel Quantity Indicator Calibration, Dry Cell ...............................
94
96-11A
RPM Limit Detector.............................................................................................
119
96-12
Test Harness for Battery Temperature Sensor (Helicopters S/N 30597
and Subsequent).................................................................................................
124
96-13
Cabin Temperature Control ................................................................................
142
96-14
Installation of Shorting Device ............................................................................
146
96-15
Simplified Block Diagram Voice/Flight Data Recorder System...........................
179
TABLES
    Table
Page
  Number
Title
Number
96-1
Electrical Power Source Component Data..........................................................
12
96-1A
Electrical System Excess Capacities ..................................................................
13
96-1B
Miscellaneous Electrical Component Inspections  Electrical Wire
Interconnection System (EWIS)..........................................................................
17
96-1C
Equipment Reference Designator, Nomenclature, and Location........................
40
96-2
Power Diode Functional Checkout Procedures (Helicopters S/N 30554
and Subsequent).................................................................................................
76
96-3
Deleted................................................................................................................
87
96-4
AFCS Operational Check (S/N 30597 and Subsequent) ....................................
149
96-5
Voltage and Resistance Tests (S/N 30597 and Subsequent).............................
173
96-00-00
ECCN EAR99
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ELECTRICAL SYSTEM
96-1.
GENERAL DESCRIPTION
This chapter provides 
the data necessary 
to
understand the operation of the electrical systems and
to perform the necessary maintenance actions. This
includes the data that follows:
 Electrical safety and hazard procedures
 Removal and installation procedures for the
electrical components

Inspection procedures 
for 
the electrical
components
 Operational checks for the electrical systems
and components
For specific electrical wiring maintenance information
and procedures, refer to the Bell Helicopter Electrical
Standard Practices Manual (BHT-ELEC-SPM). This
manual gives the data necessary to repair and replace
the wires, cables, or the electrical components to the
standards of performance and quality as specified by
the manufacturer.
96-1A. ELECTRICAL SYSTEMS
Maintenance 
of 
electrical 
circuitry, 
electrical
equipment, and electrical components installed on the
Model 212 helicopter is presented in the following text.
Control panels for AC and DC electrical systems are
located on the overhead console. All extended range
fuel system circuit breakers referred to in this chapter
are located in circuit breaker panels mounted on
overhead console. Control relays, power relays,
voltage regulators and other equipment required to
control, regulate, and effect power transfer and
malfunction monitoring are located in respective
compartments. For equipment locations, refer to
paragraph 96-23E. Refer to Chapter 98 for wiring
diagrams.
Perform operational checks to ensure no new
malfunctions have been introduced when equipment is
replaced and/or airframe wiring is repaired/replaced.
When performing operational checks, external power
should be utilized whenever possible. Using battery
power may deplete the battery. 
96-2.
PRIMARY AND SECONDARY
ELECTRICAL POWER SYSTEMS
ANALYSIS
On helicopters S/N 30504 through 30553, primary
28 VDC electrical power is supplied by two 30 volt,
200 amp starter generators (derated to 150 amps),
one mounted on each engine.
This power is distributed by two main fuses connected
together to permit parallel operation of generators.
Each main bus supplies power to an essential and a
non-essential bus. In event that one generator or one
engine 
fails, 
both 
non-essential 
buses 
are
automatically disconnected and all essential DC loads
are supplied by remaining starter generator. A bus
reset feature allows nonessential buses to be
manually reactivated at pilot discretion.
A backup source of emergency power, in event both
starter generators become inoperative, is provided by
24 volt, 34 amp-hour battery. Power for engine starting
is provided by battery or, an external 28 VDC power
source.
Secondary power is supplied by two 115/26 VAC,
400 Hz, single phase, 250 Va, solid state inverters,
one connected to each essential DC bus. AC power is
distributed by a dual bus arrangement such that each
inverter normally supplies its own buses independent
of the other inverters buses. In event of an inverter
failure, AC buses are automatically connected
together and all AC loads are supplied by remaining
inverter. Over and under voltage protection is disabled
when operating on one inverter only.
On helicopters S/N 30554 and subsequent, primary
28 VDC electrical power is supplied by two 30 volt,
200 amp starter-generators (derated to 150 amps),
one mounted on each engine.
Output voltage of each generator is monitored and
regulated by a DC control unit. DC control units control
paralleled 
generator 
operation 
and 
provide
overvoltage and reverse current protection. Each
generator provides power to an individual main DC
bus and a common nonessential DC bus. Each main
DC bus provides power to two common essential
buses through appropriate circuit breaker protection
and isolation circuitry. In event that one generator or
one engine should 
fail, non-essential bus 
is
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automatically disconnected and all essential DC loads
are supplied by remaining starter generator.
A 24 volt, 34 amp hour battery provides a backup
source of emergency DC power in event both
generators should fail. Power for engine starting is
provided by battery, or an external 28 VDC power
source.
Secondary power is supplied by three identical
250 Va, 115/26 VAC, 400 Hz, single phase, solid-state
inverters. One inverter is energized by each of two
essential DC buses. These two inverters provide
power to their respective 115 VAC and 26 VAC
essential AC buses and are completely independent of
each other. The third inverter can be energized from
either main DC bus and normally supplies power to
115 volt non-essential bus only. In event of failure of
one of the other inverters, non-essential AC bus is
disconnected and third inverter supplies power to the
essential AC bus in lieu of failed inverter.
Refer to Chapter 98, for wirings diagram.
96-2A. ELECTRICAL POWER SOURCE
COMPONENT DATA
Individual power system components and their
respective ratings are shown below (Table 96-1).
Table 96-1.   Electrical Power Source Component Data
ITEM
STARTER GENERATOR 
NO. 1 AND NO. 2
BATTERY
INVERTER NO. 1, NO. 2, 
AND NO. 3
No. Units
2
1
2 
3 
Rating
200 amps 
34 AH
250 Va
Voltage
30 VDC
24 VDC
115/26 VAC
Frequency


400 Hz
Power Factor


0.95 LEAD
0.75 LAG
Configuration


SINGLE PHASE
Manufacturer
Lear Siegler Inc.
Sonotone Inc. or 
Marathon
AMF Electrosystems or 
EMP Electronics Inc.
Part Number
209-060-221
24535-10
ID250 or ASH584-5
Voltage Regulator
3.6% Maximum

1.74% 
2.18%
DC Control Unit
(Qty 2) Lear Siegler 
51509-002R or 
51539-002N

1.0% 
 1.75% 
NOTES:
Helicopters S/N 30504 through 30553.
Helicopters S/N 30554 and subsequent.
Derated to 150 amps for this installation.
1
2
3
1
1
2
1
2
3
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96-2B. SUMMARY OF ELECTRICAL SYSTEM
ANALYSIS
The available excess capacities are as follows
(Table 96-1A):
NOTE
All available excess capacities are based
on most severe conditions disclosed by this
analysis over a 15-minute interval (takeoff,
basic helicopter).
96-3.
EMERGENCY DC POWER
In event of one generator or one engine failure, the
remaining starter generator can supply all essential
DC loads. The 24 volt, 34 amp-hour battery provides a
second source of emergency power in event both
starter generators fail. Assuming an 85% charged
condition, battery can supply essential loads for a
period of 23.5 minutes.
96-4.
EMERGENCY AC POWER
In event of one inverter failure, No. 3 inverter can
supply power to AC loads of failed inverter.
Table 96-1A.   Electrical System Excess
Capacities
SYSTEM
NOTE
AVAILABLE 
EXCESS 
CAPACITY
PRIMARY POWER  28 VDC
Parallel Starter 
Generator
178.7 amps
179.0 amps
88.7 amps
82.2 amps
13.1 amps
SECONDARY POWER  115 VAC
Inverter No. 1
156.8 Va
157.7 Va
51.9 Va
75.2 Va
45.5 Va
Inverter No. 2
173.0 Va
173.0 Va
144.9 Va
143.9 Va
141.9 Va
Inverter No. 3
Unloaded
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
2
Unloaded
Unloaded
Unloaded
EMERGENCY
28 VDC
49.2 amps
74.2 amps
47.9 amps
29.5 amps
24.4 amps
115 VAC
80.3 Va
157.7 Va
NOTES:
Helicopters S/N 30504 through 30553.
Helicopters S/N 30554 through 30596.
Helicopters S/N 30597 through 30679.
Helicopters S/N 30680 through 30849.
Helicopters S/N 30850 and subsequent.
Table 96-1A.   Electrical System Excess
Capacities (Cont)
SYSTEM
NOTE
AVAILABLE 
EXCESS 
CAPACITY
3
4
5
1
2
3
4
5
1
2
1
2
3
4
5
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96-4A. ELECTRICAL SAFETY AND HAZARDS
WARNING
OBEY ALL THE SAFETY PRECAUTIONS
WHEN YOU DO MAINTENANCE ON OR
NEAR ELECTRICAL/ELECTRONIC
EQUIPMENT.
High voltages in the electrical and electronic systems
are hazardous to personnel. Electrical shocks may
cause serious injuries. The generation of sparks in the
presence of flammable vapors may cause explosions.
Metallic objects that come in contact with the powered
electrical conductors or the components can cause
injuries to personnel and damage to the components.
96-4B. Safety Practices  General
WARNING
OBEY ALL THE SAFETY PRECAUTIONS
WHEN YOU DO MAINTENANCE ON OR
NEAR ELECTRICAL/ELECTRONIC
EQUIPMENT.
When you do any maintenance or repairs to an
electrical system, or to any system that requires
electrical power, follow these precautions:
 Personnel must be trained for the specific
task.
 Do not touch components that have electrical
power. Direct contact with a high voltage
circuit, or lower voltage circuit with a high
current capability can be fatal.
 Proper tools and safety equipment must be
available. Use them to ensure the safety of
personnel. Use them to make sure the given
task is done to the specified standards.
 Do not wear jewelry when you work on a
system that is powered.
 Use recommended test equipment or their
equivalents. Follow the equipment operation
instructions. Additional test equipment, lights,
etc., may be used as desired, provided the
purpose and intent of the specified test is not
compromised.
 The leads and the probes of the test
equipment must be serviceable. They must be
of a sufficient length to put the test equipment
at a proper location. The location of the test
equipment must give a full view of the
indicator. Make sure there is no tension on the
test leads or the probes.
 Give special attention to the WARNINGS,
CAUTIONS 
and 
NOTES 
before 
a
maintenance procedure is initiated. Some
maintenance procedures require the use of
toxic chemicals, extreme temperatures, and
flammable materials.
96-4C. Standard 
Practices 
 
Electrical
Maintenance or Repairs
WARNING
UNLESS POWER IS REQUIRED FOR A
MAINTENANCE 
PROCEDURE,
DISCONNECT THE BATTERY AND THE
EXTERNAL POWER. PUT A TAG ON THE
BATTERY SWITCH TO INFORM OTHER
PERSONNEL THAT WORK IS BEING
DONE.
WARNING
INFORM ALL OF THE PERSONNEL THAT
WORK ON THE HELICOPTER BEFORE
YOU SUPPLY POWER TO THE
ELECTRICAL SYSTEMS.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-136
Caps and/or plugs
C-156
Caps and/or plugs
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1. The procedure that follows will help to avoid
injuries to personnel and damage to equipment.
a. If an electrical connector 
is to be left
disconnected, install protective caps and/or plugs to
protect the contacts from shorts and prevent FOD
damage. Use either caps and/or plugs (C-136) for
Electrostatic Discharge Sensitive (ESDS) equipment,
or caps and/or plugs (C-156) for other non-ESDS
sensitive equipment.
b. If a circuit breaker must remain open until a
maintenance procedure is complete, install a clip or a
plastic cable strap under the circuit breaker button. Put
a tag on the circuit breaker to inform other personnel
not to set the circuit breaker to the closed position.
c. If a switch must remain open or closed until a
maintenance procedure is complete, put a tag on the
switch to inform other personnel not to touch the
switch.
d. Inform all of the personnel that work on the
helicopter before you supply power to the electrical
systems.
96-4D. Standard Practices  Electrical Work In
Confined Spaces
1. Some equipment installations are in confined
areas and access to the test points can be difficult.
When you do a test on a powered circuit in a confined
area, follow these precautions:
a. Have the applicable fire safety equipment
available when you do a maintenance procedure.
b. Before you start work in a confined area, look
at the wiring diagrams (Chapter 98) of the applicable
electrical systems and at the location of the equipment
you will test. Make a note of the location of the high
voltage areas near the equipment you will test.
c. Be careful around any control cable or
mechanism. Movement of engine or flight controls can
cause movement of control cables or rods.
d. For systems not tested, set the applicable
circuit breakers to the open position.
96-4E. Standard Practices  After Electrical
Maintenance or Repairs
1. After completing a task on any electrical system,
make sure you do the steps that follow before you
return the helicopter to the flight configuration:
a. Remove all protective caps from equipment or
electrical equipment.
b. Make sure all of the disconnected electrical
connectors are properly re-installed.
c. After troubleshooting any electrical system,
reinstall any removed control panels or electrical
components such as relays, terminal modules,
switches and other miscellaneous components.
d. Remove the tags or the cable straps from the
switches and the circuit breakers. Close the circuit
breakers.
NOTE
As applicable, refer to the engine shutdown
procedures (BHT-212-FM, Section 2) to
determine the switch and control positions.
e. Make sure all of the switches and the controls
are in the correct position. This prevents the accidental
system operation when the power is turned on.
f.
If applicable, connect the battery.
g. Do an operational check on the system or
systems that were repaired.
h. Install all applicable access panels and close
all doors (Chapter 52).
96-4F. MISCELLANEOUS ELECTRICAL TOOLS
The majority of tools required to perform basic
electrical maintenance and repair practices are listed
in 
the Electrical Standard Practices Manual
(BHT-ELEC-SPM).
96-5.
OPERATIONAL CHECKS  ELECTRICAL
SYSTEMS
Throughout this chapter, when performing operational
checks, external power should be utilized whenever
possible. Performing operational checks on battery
power may deplete the charge in the battery.
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Perform operational checks to ensure no new
malfunctions have been introduced when components
have been repaired or replaced, and/or airframe wiring
has been repaired or replaced.
Operational checks for each applicable system are
co-located with the system maintenance procedures.
Also, use system diagrams, wiring diagrams
(Chapter 98) in accomplishing operational checks.
96-6.
TROUBLESHOOTING  ELECTRICAL
SYSTEMS
The following troubleshooting procedures are general
in nature and may be used as a guide to find a
malfunction in an electrical system. Make sure the
system and component operation is understood prior
to doing any troubleshooting.
1. Make sure electrical power is applied to the
system being checked. Make sure ground connections
meet required bonding values and are tight and
properly installed. Refer to the Electrical Standard
Practices Manual (BHT-ELEC-SPM), Chapter 8 for
bonding information, and to Chapter 98 of this manual
for the applicable wiring diagrams.
2. Make sure the switches, relays, diodes, and other
electrical components are not defective.
3. Examine the wires, connectors and terminal
junctions. Make sure they are in good condition. Make
sure the connections are properly connected and
tightened.
4. Make sure that each component of a system
operates correctly.
96-7.
MISCELLANEOUS ELECTRICAL
COMPONENTS  MAINTENANCE
PRACTICES
The miscellaneous electrical components include but
are not limited to: relays, contactors, solenoids,
rheostats, 
switches, 
leads, 
connectors, wires,
receptacles, shock mounts, capacitors, diodes,
resistors and panel lights.
96-8.
Miscellaneous Electrical Components 
Removal
CAUTION
BEFORE ATTEMPTING TO REMOVE AN
ELECTRICAL/ELECTRONIC COMPONENT,
DISCONNECT ELECTRICAL POWER
SOURCE.
1. Disconnect the battery.
2. Make sure all of the other sources of DC power
are disconnected.
NOTE
To assist with 
reinstallation, 
it 
is
recommended that the wires be identified
for their installed location and orientation
prior to removal.
3.
Identify the connectors or wires connected to the
component.
4. Disconnect these electrical connectors or wires
from the component.
5.
Install caps and/or plugs (C-136) or caps and/or
plugs (C-156) on the connectors or apply tape on the
end of the wires.
6. Remove the attaching hardware. If the attaching
hardware is serviceable, keep it for reinstallation.
7. Remove the component.
8. Do a general visual inspection of the immediate
area where the component was removed. See
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-136
Caps and/or Plugs
C-156
Caps and/or Plugs
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Miscellaneous Electrical Components 
Inspection
(paragraph 96-9) for the inspection requirements.
96-8A. Miscellaneous Electrical Components 
Cleaning
1. Remove all loose debris with a brush or clean
cloth.
CAUTION
SOLVENTS CAN CAUSE DAMAGE TO
SOME MATERIALS. THEY CAN REMOVE
LUBRICANTS AND SOFTEN CERTAIN
MATERIALS. REFER TO THE STANDARD
PRACTICES MANUAL (BHT-ALL-SPM)
FOR THE APPROPRIATE SOLVENT FOR
THE MATERIAL YOU ARE CLEANING.
2. Remove grease or dirt with an approved solvent
depending on the material of 
the component
(BHT-ALL-SPM, Chapter 5).
3. Make sure the electrical component is totally dry
before installation.
96-9.
Miscellaneous Electrical Components 
Inspection
NOTE
It is also recommended to do a general
visual inspection in the immediate area
where the component was removed.
1. For the inspection requirements of miscellaneous
electrical components, see Table 96-1B.
2. Examine the attaching hardware for cracks, wear,
mechanical damage, and corrosion damage. Replace
as necessary.
Table 96-1B.   Miscellaneous Electrical Component Inspections  Electrical Wire
Interconnection System (EWIS)
ITEM
DEFECT, DAMAGE, FAILURE, OR IRREGULARITY
Wire/wire harnesses
Wire bundle/wire bundle or wire bundle/structure contact/chafing
Wire bundle sagging or improperly secured
Wires damaged (obvious damage due to mechanical impact, 
overheat, localized chafing, etc.)
Lacing tape and/or ties missing/incorrectly installed
Wiring protection sheath/conduit deformity or incorrectly installed
End of sheath rubbing on end attachment device
Grommet missing or damaged
Dust and lint accumulation
Surface contamination by metal shavings/swarf
Contamination by liquids
Deterioration of previous repairs (e.g., splices)
Deterioration of production splices
Inappropriate repairs (e.g., incorrect splice)
Inappropriate attachments to or separation from fluid lines
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Connectors
External corrosion on receptacles
Missing/loose or damaged dust cap
Backshell tail broken
Rubber pad or packing on backshell missing
No backshell wire securing device
Fool proofing chain broken
Missing or broken safety wire
Discoloration/evidence of overheating on terminal lugs/blocks
Torque stripe misalignment
Damaged or bent contacts
Switches/switch-lights and 
annunciators
Rear protection cap damaged
Corrosion
Weak detents
Ground points
Corrosion and looseness
Bonding braid/bonding jumper
Braid broken or disconnected
Multiple strands corroded or broken
Wiring clamps or brackets
Corroded
Broken/missing
Bent or twisted
Faulty attachment (bad attachment or fastener missing)
Debonded/detached
Protection/cushion damaged
Supports (rails or tubes/conduit)
Broken
Deformed
Fastener missing
Missing edge protection on rims of feed through holes
Racetrack cushion damaged
Obstructed drainage holes (in conduits)
Circuit breakers, contactors, relays, 
rheostats or fuses
Signs of overheating
Signs of arcing
Looseness
Corrosion
Table 96-1B.   Miscellaneous Electrical Component Inspections  Electrical Wire
Interconnection System (EWIS) (Cont)
ITEM
DEFECT, DAMAGE, FAILURE, OR IRREGULARITY
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96-10. Miscellaneous Electrical Components 
Repair
1. Tighten loose terminal connections, mountings,
and attachments of electrical components.
2. Replace miscellaneous electrical components
that fail to meet inspection requirements.
96-11. Miscellaneous Electrical Components 
Installation
1. Disconnect the battery.
2. Make sure all of the other sources of DC power
are disconnected.
3. Do a general visual inspection of the immediate
area where the component was removed. See
Miscellaneous Electrical Components 
Inspection
(paragraph 96-9) for the inspection requirements.
4. Use the correct attaching hardware and install the
component.
5. Remove the caps and/or plugs (C-136) or caps
and/or plugs (C-156) from the connectors and tape
from the ends of the wires. Use the applicable wiring
diagram in Chapter 98 and attach the connectors or
the wires to the proper location or terminals.
6. Do the applicable operational check of the
system.
7. Return the helicopter to the flight configuration
after electrical maintenance or repairs (paragraph
96-4E).
96-12. CONTROL PANELS  ELECTRICAL
Controls and control panels are mounted in the
overhead console, pedestal, and instrument panel
(Figure 96-5 through Figure 96-5C).
96-13. Control Panels  Removal
NOTE
Removal procedure for all panels 
is
relatively the same. A single removal
procedure may be used for any panel.
1. Remove all electrical power.
2. Disengage fasteners securing panel to mount.
3. Carefully lift panel from mount and disconnect
electrical connector.
96-14. Control Panels  Inspection
Visually inspect for scratched, chipped, or broken
edge and 
integrally 
lit panels, 
loose wiring
connections, damaged connector, corrosion, and
broken or missing mounting fasteners.
96-15. Control Panels  Repair
Replace 
items 
that 
fail 
to meet 
inspection
requirements.
96-16. Control Panels  Installation
1. Connect electrical connector.
2. Position panel in mount being careful not to
damage wiring.
3. Engage fasteners. 
96-17. CIRCUIT BREAKERS
There is one type of circuit breaker used on Model 212
helicopters, the fault clearing push-pull type. Circuit
breakers are mounted in the overhead console,
pedestal, nose compartment, and throughout the
helicopter.
Circuit breakers are electromagnetic devices that
protect the electrical circuits and equipment by
automatically opening the electrical circuit when the
current in the line exceeds a predetermined value.
96-18. Circuit Breakers  Removal
WARNING
BEFORE YOU REMOVE A CIRCUIT
BREAKER ON THE HELICOPTER,
REMOVE ALL ELECTRICAL POWER AND
DISCONNECT THE BATTERY. IF NOT
ACCOMPLISHED, YOU CAN CAUSE
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ELECTRICAL SHOCK TO PERSONS
AND/OR DAMAGE TO EQUIPMENT.
1. Remove all electrical power.
NOTE
To assist with 
reinstallation, 
it 
is
recommended that the wires and bus bars
be identified for their installed location and
orientation prior to removal. 
2. Gain access to circuit breaker wiring. 
3. Tag wires and disconnect. 
4. Protect wires. 
5. Remove screw securing circuit breaker to bus bar
(if required). 
6. Remove nut and washers securing circuit breaker
to panel. 
7. Remove circuit breaker from panel. 
96-19. Circuit Breakers  Inspection
Inspect circuit breakers 
for secure mounting,
corrosion, general condition, power on and off
actuation, and reset retention. 
96-20. Circuit Breakers  Repair/Replacement
Replace circuit breaker if inspection requirements can
not be met. 
96-21. Circuit Breakers  Installation
WARNING
BEFORE YOU INSTALL A CIRCUIT
BREAKER ON THE HELICOPTER,
REMOVE ALL ELECTRICAL POWER AND
DISCONNECT THE BATTERY. IF NOT
ACCOMPLISHED, YOU CAN CAUSE
ELECTRICAL SHOCK TO PERSONS
AND/OR DAMAGE TO EQUIPMENT.
1. Position circuit breaker on structure and secure
with hardware.
2.
Install screw securing circuit breaker to bus bar (if
required).
3. Remove tags and install wires.
4. Perform circuit operational check.
96-22. SEMICONDUCTOR DEVICES
The semiconductor devices used are as follows:
 Standard and zener diodes
 Transient suppression diode assemblies.
 Transistors
96-22A. Semiconductor Devices  Maintenance
Practices
1. Remove the semiconductor device (paragraph
96-8).
NOTE
Refer to the Electrical Standard Practices
Manual 
(BHT-ELEC-SPM) 
for detailed
information on testing and troubleshooting
semiconductor devices.
2.
Inspect the semiconductor device (paragraph
96-9).
NOTE
When you install a semiconductor device,
refer to the associated wiring diagram in
Chapter 98 to make sure of the correct
orientation and wiring attachment. 
3.
Install the semiconductor device (paragraph
96-11).
4. Return the helicopter to the flight configuration
after electrical maintenance or repairs (paragraph
96-4E).
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96-23. TRACK MOUNTED RELAYS
Track mounted relays are electromagnetic switches
that open and close under the control of other
components in the electrical circuit.
96-23A. Track Mounted Relays  Removal
1. Disconnect the battery and external power from
the helicopter.
2.
Loosen the screws (2, Figure 96-1).
3. Carefully pull the relay (1) out from the socket
base (3).
96-23B. Track Mounted Relay  Cleaning
1. Clean relay pins with isopropyl alcohol (C-385)
and if necessary to do a deep cleaning use butyl
acetate (C-552).
2. Dry pins and surfaces with a clean cloth (C-516).
Turn relay sockets down and let the solvent evaporate/
dry for 20 minutes.
96-23C. Track Mounted Relay  Inspection
1. For the inspection of the track mounted relay,
refer to paragraph 96-9.
96-23D. Track Mounted Relay  Installation
1. Correctly position the relay (1, Figure 96-1) on
the socket base (3) and apply finger pressure until it
latches into place.
2. Tighten the screws (2).
3. Connect the battery and the external power.
4. Do the applicable operational check of the
system.
96-23E. ELECTRICAL AND AVIONICS EQUIPMENT
 REFERENCE DESIGNATOR,
NOMENCLATURE, AND LOCATION
To identify the installed location of electrical and
avionics components, refer to Figure 96-1A through
Figure 96-5C.
To determine the nomenclature or general location of
reference designator items, refer to Table 96-1C.
Refer to BHT-ALL-SPM for specifications.
MATERIALS REQUIRED
NUMBER
NOMENCLATURE
C-385
Isopropyl Alcohol
C-516
Clean Cloth
C-552
Butyl Acetate
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Figure 96-1.   Track Mounted Relay  Removal/Installation (Typical)
Relay
Screw
Socket base
1.
2.
3.
3
1
2
(TYPICAL)
412_MM_96_0001+
96-00-00
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Figure 96-1A.   Fuselage Equipment Location (Sheet 1 of 7)
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Figure 96-1A.   Fuselage Equipment Location (Sheet 2 of 7)
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ECCN EAR99
BHT-212-MM-10
Figure 96-1A.   Fuselage Equipment Location (Sheet 3 of 7)
96-00-00
8 JUN 2010 Rev. 12
Page 25
ECCN EAR99
BHT-212-MM-10
Figure 96-1A.   Fuselage Equipment Location  Electrical (Sheet 4 of 7)
212_MM_96_0001d
BL
15.25
BL
15.25
WL
79.92
WL
79.92
J147
P147A P147B
CP4
P145A
P146A
J145
J146
J148
P148A P148B
VIEW G-G
VIEW LOOKING AFT, LEFT SIDE AT STA 159.50
VIEW ROTATED 90 CW
VIEW H-H
VIEW LOOKING AFT
 RIGHT SIDE AT STA 159.50
VIEW ROTATED 90 CW
VIEW J
TYPICAL INSTALLATION
OF TRANSISTOR Q4, Q5, AND Q6
VIEW I
I
CAP
CAP
COVER
WASHER
MICA WASHER
WASHER
LOCKWASHER
INSULATOR
TRANSISTOR
EMITTER
MICA WASHER
BL 30.00
E
EMITTER
BASE
B
COLLECTOR
C
COLLECTOR
BASE
CAP
INBD
INBD
INBD
96-00-00
Page 26
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-1A.   Fuselage Equipment Location  Electrical (Sheet 5 of 7)
212_MM_96_0001e
96-00-00
8 JUN 2010 Rev. 12
Page 27
ECCN EAR99
BHT-212-MM-10
Figure 96-1A.   Fuselage Equipment Location (Sheet 6 of 7)
96-00-00
Page 28
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-1A.   Fuselage Equipment Location (Sheet 7 of 7)
96-00-00
8 JUN 2010 Rev. 12
Page 29
ECCN EAR99
BHT-212-MM-10
Figure 96-2.   Nose Compartment Equipment Location  Electrical (Sheet 1 of 4)
96-00-00
Page 30
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-2.   Nose Compartment Equipment Location  Electrical (Sheet 2 of 4)
96-00-00
8 JUN 2010 Rev. 12
Page 31
ECCN EAR99
BHT-212-MM-10
Figure 96-2.   Nose Compartment Equipment Location  Electrical (Sheet 3 of 4)
96-00-00
Page 32
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-2.   Nose Compartment Equipment Location  Electrical (Sheet 4 of 4)
96-00-00
8 JUN 2010 Rev. 12
Page 33
ECCN EAR99
BHT-212-MM-10
Figure 96-3.   Engine Equipment Location  Electrical (Sheet 1 of 4)
212_MM_96_0003a
96-00-00
Page 34
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-3.   Engine Equipment Location  Electrical (Sheet 2 of 4)
96-00-00
8 JUN 2010 Rev. 12
Page 35
ECCN EAR99
BHT-212-MM-10
Figure 96-3.   Engine Equipment Location  Electrical (Sheet 3 of 4)
96-00-00
Page 36
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-3.   Engine Equipment Location  Electrical (Sheet 4 of 4)
96-00-00
8 JUN 2010 Rev. 12
Page 37
ECCN EAR99
BHT-212-MM-10
Figure 96-4.   Transmission Equipment Location  Electrical
212_MM_96_0004
FWD
1
2
NOTES
1
S28
1
Installed on 212-040-001-059 and subsequent transmissions and earlier model transmissions 
modified by TB 212-80-35.
Installed on helicopters S/N 31312 and subsequent, 35026 and subsequent, 212-040-001-131 and 
subsequent transmissions and earlier model transmissions modified by TB 212-91-131.
SEE DETAIL A
FOR CONTINUATION 
VIEW LOOKING INBOARD
RIGHT SIDE
DETAIL A
P36
S26
Z5
B7
P39
P37
P41
8E11
E1
MAGNETIC
PLUG
P35
G7
E17
E16
96-00-00
Page 38
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Figure 96-5.   Tailboom Equipment Location  Electrical
96-00-00
8 JUN 2010 Rev. 12
Page 39
ECCN EAR99
BHT-212-MM-10
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location
REF DES
NOMENCLATURE
LOCATION
A
A1
Panel
Overhead console, left
A2
Panel
Overhead console, right
A3
Panel, engine and fuel
Pedestal
A5
Panel, master caution
Pedestal or instrument panel
A7
Panel, circuit breaker
Overhead console, left
A8
Panel, circuit breaker
Overhead console, right
A9
Panel
Collective stick, pilot
A10
Panel, miscellaneous
Pedestal
A11
Panel
Collective stick, copilot
A13, A14
Panel, resistor
Cabin roof, forward
A15
Panel, engine instrument
Instrument panel
A18
Panel, compass identification
Instrument panel
A19
Panel
Cyclic stick, pilot
A20
Panel
Cyclic stick, copilot
A23
Panel, auxiliary circuit breaker
Overhead console
A24
Box, attitude
Nose compartment shelf
A25
Box, SCAS
Nose compartment shelf
A26
Panel, trim control
Pedestal
A27
Panel, autopilot control
Pedestal
B
B1
Transmitter, torque
Engine 1
B2
Transmitter, torque
Engine 2
B3
Transmitter, engine oil pressure
Engine 1
B4
Transmitter, engine oil pressure
Engine 2
B5
Transmitter, fuel pressure
Engine 1
96-00-00
Page 40
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
B6
Transmitter, fuel pressure
Engine 2
B7
Transmitter, transmission oil pressure
Transmission
B8
Motor, governor RPM actuator
Engine compartment, center
B9, B10
Motor, fuel shutoff valve
Fuselage, lower station 147
B11
Motor, fuel boost pump
Fuel cell, left
B12
Motor, fuel boost pump
Fuel cell, right
B13
Motor, windshield wiper copilot
Cabin roof, left forward
B14
Motor, windshield wiper pilot
Cabin roof, right forward
B15
Actuator, particle separator
Engine compartment, left
B16
Actuator, particle separator
Engine compartment, right
B17
Motor, fuel interconnect valve, forward
Fuel cells, lower forward of
B18
Motor, fuel interconnect valve, aft
Fuel cells, lower between
B19
Motor, fuel crossfeed
Fuel cell, aft forward and above
B20
Motor, vent blower
Nose compartment, upper right
B21
Motor, vent blower
Nose compartment, upper left
B22
Transmitter, combining gearbox oil 
pressure
Engine compartment, aft
B23
Transmitter, No. 2 hydraulic pressure
Pylon compartment
B24
Transmitter, No. 1 hydraulic pressure
Pylon compartment
B25
Actuator, left step
Skid, left
B26
Actuator, right step
Skid, right
B27
Motor, inverter blower
Nose compartment
B30
Motor, cabin temperature positioning
Cabin, lower station 180
BT1
Battery
Nose compartment, forward
C
CP1
Coupler, fuel quantity, unshielded
Cabin floor, station 63, center
CP2
Tee
Cabin floor, station 74, left
CP3, CP4
Tee
Cabin floor, station 159, left
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 41
ECCN EAR99
BHT-212-MM-10
CR3, CR4
Diode, crossfeed test
Pedestal, A3
CR9
Diode, external power relay
Nose compartment, lower right, K1
CR10, CR11, 
CR12, CR13
Diode, fuel crossfeed
Pedestal, A3
CR18
Diode, audio RPM
Pedestal, A10
CR19
Diode, particle separator relay
Pedestal, K27
CR20
Diode, particle separator relay
Pedestal, K26
CR21 through 
CR25
Diode, engine start
Collective stick, pilot
CR30, CR31, 
CR36, CR37
Diode, main DC bus No. 1
Overhead console, main bus 1
CR32, CR33, 
CR34, CR35
Diode, main DC bus No. 2
Overhead console, main bus 2
CR38
Diode, No. 2 non-essential relay
Cabin roof, station 74, right, K2
CR39
Diode, No. 1 non-essential relay
Cabin roof, station 74, left, K39
CR41
Diode, copilot turn-and-slip
Instrument panel, aft
CR42
Diode, pilot turn-and-slip
Instrument panel, aft
CR43
Diode, No. 1 idle stop relay
Cabin roof, station 147, left, K15
CR44
Diode, No. 2 idle stop relay
Cabin roof, station 147, right, K16
CR45
Diode, No. 1 idle stop solenoid
Engine compartment, left, L5
CR46
Diode, No. 2 idle stop solenoid
Engine compartment, right, L6
CR47
Diode, force trim
Pedestal, TB12
CR48
Diode, turn-and-slip caution light
Pedestal, TB33
CR49, CR50
Diode, caution light dim
Nose compartment shelf, TB50
CR51, CR52
Diode, caution light dim
Nose compartment shelf, TB51
CR63 through 
CR70
Diode, non-essential bus
Cabin roof, station 84, TB52
CR71
Diode, battery interlock
Nose compartment, lower right, K10
CR72
Diode, No. 1 start relay
Cabin rood, station 142, left, K5
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 42
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
CR73
Diode, No. 2 start relay
Cabin roof, station 142, right, K6
CR74
Diode, particle separator relay
Pedestal, forward, K26
CR75
Diode, hydraulic system No. 2
Pedestal, A10
CR76
Diode, hydraulic system No. 1
Pedestal, A10
CR77
Diode, heater system select switch
Overhead console, S189
CR78
Diode, cargo release
Pylon compartment, K17
CR79
Diode, No. 1 generator relay
Cabin roof, station 82, left, K3
CR80
Diode, No. 2 generator relay
Cabin roof, station 82, right, K4
CR82
Diode, cargo release relay
Pylon compartment, K17
CR85
Diode, No. 1 AC control relay
Cabin roof, station 68, left, K11
CR86
Diode, No. 2 AC control relay
Cabin roof, station 68, center, K12
CR87
Diode, No. 1 governor switch
Pedestal, A3-S13
CR88
Diode, No. 2 governor switch
Pedestal, A3-S14
CR89
Diode, No. 1 governor auto-manual 
switch
Pedestal, A3-S13
CR90
Diode, No. 2 governor auto-manual 
switch
Pedestal, A3-S14
CR91
Diode, No. 3 inverter
Nose compartment, TB53
CR92
Diode, RPM warning
Pedestal, forward, TB1
CR95, CR96
Diode, fuel valve caution light
Pedestal, A3
CR97, CR98, 
CR99
Diode, transmission chip
Pedestal, right, TB80
D
DS5
Light, cargo release arm
Instrument panel
DS7
Light, anticollision, lower
Fuselage or tailboom, underneath
DS8
Light, anticollision, upper
Pylon, top
DS9
Light, utility, copilot
Cabin roof, forward
DS10
Light, utility, pilot
Cabin roof, forward
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 43
ECCN EAR99
BHT-212-MM-10
DS11
Light, dome
Cabin roof, center and station 144, right and 
left
DS12
Light, search
Fuselage, forward, station 40, underneath
DS13
Light, landing
Fuselage, forward, station 8, underneath
DS14
Light, secondary
Instrument panel
DS15
Light, left position
Fuselage, station 104, top left
DS16
Light, right position
Fuselage, station 104, top right
DS17
Light, tail
Tail cone
DS18
Light, passenger warning
Cabin roof
DS20
Light, baggage
Baggage compartment
DS21
Light, baggage fire warning
Instrument panel
DS26
Light, heater outlet valve
Door post, right crew
DS28
Indicator, hydraulic filter clog
Nose compartment, forward, right
DS29
Light, left utility
Fuselage, station 102, lower left
DS30
Light, right utility
Fuselage, station 102, lower right
DS31
Light, ENG 1 OUT
Instrument panel
DS32
Light, ENG 2 OUT
Instrument panel
DS37
Light, MASTER CAUTION, copilot
Instrument panel
DS38
Light, MASTER CAUTION, pilot
Instrument panel
DS39
Light, RPM CAUTION, copilot
Instrument panel
DS40
Light, RPM CAUTION, pilot
Instrument panel
DS41
Light, outside air temperature indicator
Cabin overhead, forward, right
DS44
Light, pilot AFCS
Instrument panel
DS45
Light, copilot AFCS
Instrument panel
DS50
Indicator, transmission chip, sump
Pedestal, right
DS51
Indicator, transmission chip, planetary
Pedestal, right
DS52
Indicator, transmission chip, upper 
mast
Pedestal, right
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 44
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
E
E1
Detector, magnetic chip, transmission
Transmission
E2
Detector, magnetic chip, engine 
gearbox
Power plant
E3
Detector, magnetic chip, engine 1 
forward
Power plant
E4
Detector, magnetic chip, engine 2 
forward
Power plant
E5
Detector, magnetic chip, engine 1 aft
Power plant
E6
Detector, magnetic chip, engine 2 aft
Power plant
E7
Detector, magnetic chip, 42 gearbox
Gearbox, intermediate
E8
Detector, magnetic chip, 90 gearbox
Gearbox, tail rotor
E16
Detector, transmission chip, planetary
Transmission
E17
Detector, transmission chip, upper 
mast
Transmission
G
G1
Starter generator
Engine 1
G2
Starter generator
Engine 2
G3
Generator, tachometer, gas producer
Engine 1
G4
Generator, tachometer, gas producer
Engine 2
G5
Generator, tachometer, power turbine
Engine 1
G6
Generator, tachometer, power turbine
Engine 2
G7
Generator, tachometer, rotor
Transmission
H
HR1
Heater, pitot, pilot
Nose compartment, forward
HR2
Heater, pitot, copilot
Nose compartment, forward
HR3
Heater, static port, pilot, left
Fuselage, forward left
HR4
Heater, static port, pilot, right
Fuselage, forward right
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 45
ECCN EAR99
BHT-212-MM-10
HR5
Heater, static port, copilot, left
Fuselage, forward left
HR6
Heater, static port, copilot, right
Fuselage, forward right
J (Also See P For Additional Listing)
J3
Connector, external power
Nose compartment, forward
J56
Receptacle, 28 VDC auxiliary
Pedestal, left
K
K1
Relay, external power
Nose compartment, lower right
K2
Relay, non-essential 2
Cabin roof, station 74
K3
Relay, No. 1 starter generator
Cabin roof, station 84
K4
Relay, No. 2 starter generator
Cabin roof, station 84
K5
Relay, No. 1 starter
Cabin roof, station 146
K6
Relay, No. 2 starter
Cabin roof, station 146
K7
Relay, No. 1 starter control
Nose compartment, lower
K8
Relay, No. 2 starter control
Nose compartment, lower
K9
Relay, battery bus No. 1
Nose compartment, lower
K10
Relay, battery bus No. 2
Nose compartment, lower
K11
Relay, No. 1 AC bus control
Cabin roof, station 70
K12
Relay, No. 2 AC bus control
Cabin roof, station 70
K13
Relay, No. 1 AC voltage sense
Nose compartment, lower
K14
Relay, No. 2 AC voltage sense
Nose compartment, lower
K15
Relay, idle stop delay No. 1
Cabin roof
K16
Relay, idle stop delay No. 2
Cabin roof
K17
Relay, cargo hook release
Cabin roof
K18
Relay, heater
Cabin roof
K23
Relay, fuel crossfeed
Pedestal
K24, K25
Relay, light dim
Pedestal
K26, K27
Relay, particle separator
Pedestal
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 46
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
K30
Relay, hourmeter
Pedestal
K33, K34
Relay, non-essential bus
Nose compartment
K39
Relay, non-essential bus No. 1
Cabin roof, station 74, left
K46
Relay, duct overheat
Cabin roof
K47
Relay, air conditioning
Cabin roof
K50
Relay, No. 3 AC voltage sense
Nose compartment shelf
K51
Relay, navigation command light
Pedestal
K52
Relay, caution panel fail
Pedestal
K57
Relay, battery interlock
Nose compartment shelf
L
L1
Solenoid, fuel control valve No. 1
Engine compartment, left
L2
Solenoid, fuel control valve No. 2
Engine compartment, right
L3
Solenoid, hydraulic bypass No. 1
Pylon compartment
L4
Solenoid, hydraulic bypass No. 2
Pylon compartment
L5
Solenoid, idle stop No. 1
Engine compartment, left
L6
Solenoid, idle stop No. 2
Engine compartment, right
L7
Solenoid, variable mixing valve
Heater compartment
L8
Magnetic brake, anti-torque
Cabin floor, station 63 and 23
L9
Magnetic brake, fore and aft
Cabin floor, station 63 and 23
L10
Magnetic brake, lateral
Cabin floor, station 63 and 23
L11
Solenoid, door post
Door post, right
L12
Solenoid valve, right sump drain
Fuel cell, left
L13
Solenoid valve, left sump drain
Fuel cell, right
L14
Solenoid valve, bleed air No. 2
Engine compartment, right
L15
Solenoid valve, bleed air No. 1
Engine compartment, left
L16
Valve, aft outlet
Heater compartment
L19
Valve, winterization kit
Heater compartment
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 47
ECCN EAR99
BHT-212-MM-10
L22
Actuator, rotary (yaw)
Fuselage, lower
L23
Actuator, SCAS (roll)
Fuselage, lower
L24
Actuator, SCAS (pitch)
Fuselage, lower
L25
Actuator, rotary (pitch)
Fuselage, lower
L26
Actuator, rotary (roll)
Fuselage, lower
L27
Solenoid (roll)
Fuselage, lower
L28
Solenoid (pitch)
Fuselage, lower
L29
Actuator, SCAS (yaw)
Fuselage, aft, station 178
L30
Solenoid (yaw)
Fuselage, aft, station 178
M
M1
Indicator, copilot attitude
Instrument panel
M2
Indicator, pilot attitude
Instrument panel
M3
Indicator, fuel pressure No. 1
Instrument panel
M4
Indicator, fuel pressure No. 2
Instrument panel
M5
Indicator, engine oil temperature and 
pressure No. 1
Instrument panel
M6
Indicator, engine oil temperature and 
pressure No. 2
Instrument panel
M11
Indicator, copilot triple tachometer
Instrument panel
M12
Indicator, pilot triple tachometer
Instrument panel
M13
Indictor, dual ammeter
Instrument panel
M15
Indicator, combining gearbox oil 
pressure and temperature
Instrument panel
M16
Indicator, transmission oil pressure 
and temperature
Instrument panel
M17
Indicator, gas producer No. 1
Instrument panel
M18
Indicator, gas producer No. 2
Instrument panel
M19
Indicator, copilot dual torque
Instrument panel
M20
Indicator, pilot dual torque
Instrument panel
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 48
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
M21
Indicator, dual voltmeter No. 1
Instrument panel
M22
Indicator, dual voltmeter No. 2
Instrument panel
M23
Indicator, interturbine temperature 
No. 1
Instrument panel
M24
Indicator, interturbine temperature 
No. 2
Instrument panel
M25
Indicator, fuel quantity
Instrument panel
M26
Hourmeter
Pedestal, right
M28
Indicator, standby compass
Above windshield, right
M29
Clock
Instrument panel
M30
Indicator, pilot airspeed
Instrument panel
M31
Indicator, pilot vertical speed
Instrument panel
M32
Indicator, pilot altimeter
Instrument panel
M33
Indicator, copilot altimeter
Instrument panel
M34
Indicator, copilot vertical speed
Instrument panel
M35
Indicator, copilot airspeed
Instrument panel
M36
Indicator, No. 1 hydraulic
Instrument panel
M37
Indicator, No. 2 hydraulic
Instrument panel
M40
Indicator, copilot clock
Instrument panel
M41
Indicator, copilot standby compass
Above windshield, left
MT1
Transducer (pitch)
Fuselage, lower, station 40
MT2
Transducer (yaw)
Fuselage, lower, station 40
MT3
Transducer (roll)
Fuselage, lower, station 25
P
P and/or J
1
Connector, pitot heater, left
Nose compartment, HR1
2
Connector, pitot heater, right
Nose compartment, HR2
4
Connector, battery
Nose compartment, BT1
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 49
ECCN EAR99
BHT-212-MM-10
P and/or J
5
Connector, RPM warning
Nose compartment, Z1
6
Connector, displacement gyro
Nose compartment, Z2
7
Connector, rate switch gyro
Nose compartment, Z3
8
Connector, AC volt sense, No. 2
Nose compartment, lower, K14
9
Connector, AC volt sense, No. 1
Nose compartment, lower, K13
10
Connector, DC control panel, No. 2
Nose compartment, lower, Z22
11
Connector, DC control panel, No. 1
Nose compartment, lower, Z23
12
Connector, inverter, No. 1
Nose compartment, lower, PS2
13
Connector, inverter, No. 1
Nose compartment, lower, PS1
14
Connector, pilot attitude indicator
Instrument panel, M1
15
Connector, copilot attitude indicator
Instrument panel, M2
16
Connector, fuel pressure No. 2 
indicator
Instrument panel, M4
17
Connector, fuel pressure No. 1 
indicator
Instrument panel, M3
18
Connector, engine oil temperature and 
pressure indicator, No. 2
Instrument panel, M6
19
Connector, engine oil temperature and 
pressure indicator, No. 1
Instrument panel, M5
22
Connector, gas producer indicator, 
No. 2
Instrument panel, M18
23
Connector, gas producer indicator, 
No. 1
Instrument panel, M17
26
Connector, pilot triple tachometer 
indicator
Instrument panel, M12
27
Connector, copilot triple tachometer 
indicator
Instrument panel, M11
28
Connector, pilot dual torque indicator
Instrument panel, M20
29
Connector, copilot dual torque 
indicator
Instrument panel, M19
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 50
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
P and/or J
30
Connector, transmission oil pressure 
and temperature indicator
Instrument panel, M16
31
Connector, combining gearbox oil 
pressure and temperature indicator
Instrument panel, M15
32
Connector, fuel quantity indicator
Instrument panel, M25
33
Connector, instrument panel, left
Instrument panel, aft left
34
Connector, instrument panel, right
Instrument panel, aft right
35
Connector, rotor tachometer generator
Pylon compartment, G7
36
Connector, transmission oil pressure 
switch
Pylon compartment, S28
37
Connector, transmission oil 
temperature bulb
Pylon compartment, R26
38
Connector, miscellaneous panel
Pedestal, A10
39
Connector, transmission oil pressure 
transmitter
Transmission, B7
40
Connector, fuel quantity selector
Instrument panel or pedestal
41
Connector, transmission disconnect
Pylon compartment
42
Connector, caution panel, No. 2
Pedestal or instrument panel, A5
43
Connector, caution panel, No. 1
Pedestal or instrument panel, A5
44
Connector, engine and fuel panel, right
Pedestal, A3
45
Connector, engine and fuel panel, left
Pedestal, A3
46
Connector, pilot cyclic stick
Cyclic stick, pilot, A19
47
Connector, copilot cyclic stick
Cyclic stick, copilot, A20
48
Connector, pilot collective
Collective stick, pilot, A9
49
Connector, copilot collective
Collective stick, copilot, A11
50
Connector, anticollision light, lower
Fuselage or tailboom, underneath, DS7
51
Connector, copilot windshield wiper 
motor
Cabin roof, forward, left B13
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 51
ECCN EAR99
BHT-212-MM-10
P and/or J
52
Connector, pilot windshield wiper 
motor
Cabin roof, forward, right B14
53
Connector, fire detector amplifier, No. 1
Cabin roof, station 142-Z4
54
Connector, fire detector amplifier No. 2
Cabin roof, station 142-Z6
57
Connector, pylon disconnect, left
Pylon compartment, left
58
Connector, pylon disconnect, right
Pylon compartment, right
59
Connector, forward engine No. 1
Engine compartment, left
60
Connector, forward engine No. 2
Engine compartment, right
61
Connector, generator No. 1 roof 
disconnect
Cabin roof, station 148 left
62
Connector, generator No. 2 roof 
disconnect
Cabin roof, station 148 right
63
Connector, fire detector, firewall 
forward, left
Cabin roof, station 162 left
64
Connector, fire detector, firewall 
forward, right
Cabin roof, station 162 left
65
Connector, fire detector element, left
Engine compartment, left, Z17
66
Connector, fire detector element, right
Engine compartment, left, Z17
67
Connector, fire detector, firewall 
forward, left
Cabin roof, station 162 right
68
Connector, fire detector, firewall 
forward, right
Cabin roof, station 162 right
69
Connector, fire detector element, left
Engine compartment, right, Z18
70
Connector, fire detector element, right
Engine compartment, right, Z18
73
Connector, engine pressure switch, 
No. 1
Engine compartment, aft, S73
74
Connector, engine pressure switch, 
No. 2
Engine compartment, aft, S74
77
Connector, oil temperature bulb, No. 1
Engine compartment, forward, Z7
78
Connector, oil temperature bulb, No. 2
Engine compartment, forward, Z8
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 52
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
P and/or J
79
Connector, oil pressure transmitter, 
No. 1
Engine compartment, forward, B3
80
Connector, oil pressure transmitter, 
No. 2
Engine compartment, forward, B4
81
Connector, fuel pressure transmitter, 
No. 1
Engine compartment, forward, B5
82
Connector, fuel pressure transmitter, 
No. 2
Engine compartment, forward, B6
83
Connector, oil tank chip, forward, No. 1
Engine compartment, forward, E3
84
Connector, oil tank chip, forward, No. 2
Engine compartment, forward, E4
85
Connector, engine fuel control heater, 
No. 1
Engine compartment, forward, HR3
86
Connector, engine fuel control heater, 
No. 2
Engine compartment, forward HR4
87
Connector, engine fuel control manual, 
No. 1
Engine compartment, forward, L1
88
Connector, engine fuel control manual, 
No. 2
Engine compartment, forward, L2
89
Connector, gas producer tachometer, 
No. 1
Engine compartment, forward, G3
90
Connector, gas producer tachometer, 
No. 2
Engine compartment, forward G4
91
Connector, igniter, No. 1
Engine compartment, center, Z9
92
Connector, igniter, No. 2
Engine compartment, center Z10
93
Connector, particle separator actuator, 
No. 1
Engine compartment, forward, B15
94
Connector, particle separator actuator, 
No. 2
Engine compartment, forward, B16
95
Connector, engine disconnect, No. 1 
center
Engine compartment, center, left
96
Connector, engine disconnect, No. 2 
center
Engine compartment, center, right
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 53
ECCN EAR99
BHT-212-MM-10
P and/or J
97
Connector, fire disconnect, No. 1 aft
Engine compartment, aft, left
98
Connector, fire disconnect, No. 2 aft
Engine compartment, aft, right
99
Connector, engine disconnect, No. 1 
aft
Engine compartment, aft, left
100
Connector, engine disconnect, No. 2 
aft
Engine compartment, aft, right
101
Connector, fire detector element, No. 1 
left, aft
Engine compartment, aft, Z21
102
Connector, fire detector element, No. 1 
right, aft
Engine compartment, aft, Z21
103
Connector, fire detector element, No. 2 
left, aft
Engine compartment, aft, Z20
104
Connector, fire detector element, No. 2 
right, aft
Engine compartment, aft, Z20
105
Connector, No. 2 hydraulic 
temperature switch
Pylon compartment, S205
106
Connector, No. 1 Hydraulic 
temperature switch
Pylon compartment, S204
107
Connector, combining gearbox oil 
temperature bulb
Engine compartment, Z24
108
Connector, clock
Instrument panel, M29
109
Connector, torque transmitter, No. 1
Engine compartment, B1
110
Connector, torque transmitter, No. 2
Engine compartment, B2
111
Connector, power turbine tachometer, 
No. 1
Engine compartment, G5
112
Connector, power turbine tachometer, 
No. 2
Engine compartment, G6
113
Connector, chip detector, No. 1 aft
Engine compartment, E5
114
Connector, chip detector, No. 2 aft
Engine compartment, E6
115
Connector, chip detector, center
Engine compartment, E2
116
Connector, anticollision light, upper
Engine compartment, DS8
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 54
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
P and/or J
117
Connector, tailboom disconnect
Tailboom
118
Connector, smoke detector disconnect
Tailboom
119, 120
Connector, smoke detector amplifier
Nose compartment, upper, Z11
121
Connector, left firewall, fuel shut-off
Pylon compartment, B9
122
Connector, right firewall, fuel shut-off
Pylon compartment, B10
123
Connector, forward fuel interconnect
Fuel cells, lower, forward of, B17
124
Connector, aft fuel interconnect
Fuel cells, lower, between, B18
125
Connector, fuel crossover
Pylon compartment, B19
126
Connector, hydraulic bypass solenoid 
valve, No. 1
Pylon compartment, L4
128
Connector, cargo hook
Pylon compartment
129
Connector, cargo sling
Pylon compartment
130 through 133
Connector, fuel quantity coupler
Cabin floor, center, station 63, CP1
124A, B
Connector, fuel quantity tank unit, right
Fuel cell, Z14
135A, B
Connector, fuel quantity tank unit, right
Fuel cell, Z14
137A, B
Connector, fuel quantity tank unit, left
Fuel cell, Z13
138A, B
Connector, fuel quantity tank unit, left
Fuel cell, Z13
139A, B
Connector, fuel quantity tank unit, aft
Fuel cell, Z17
140A, B
Connector, fuel quantity tank unit, aft
Fuel cell, Z17
141, 142
Connector, fuel capacitance simulator, 
right
Cabin roof, station 166, Z16
143, 144
Connector, fuel capacitance simulator, 
left
Cabin roof, station 166, Z15
145A, B
Connector, fuel quantity inline
Cabin roof, station 160
146A, B
Connector, fuel quantity inline
Cabin roof, station 160
147A, B, C
Connector, fuel quantity, tee
Cabin roof, station 160, CP4
148A, B, C
Connector, fuel quantity, tee
Cabin roof, station 160, CP3
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 55
ECCN EAR99
BHT-212-MM-10
P and/or J
149A, B, C
Connector, fuel quantity, tee
Cabin roof, station 74, CP2
150
Connector, interturbine temperature, 
No. 1
Instrument panel, M23
151
Connector, interturbine temperature, 
No. 2
Instrument panel, M24
155
Connector, anti-torque magnetic brake
Fuselage, lower, station 60, L8
156
Connector, fore and aft magnetic brake
Fuselage, lower, station 60, L9
157
Connector, lateral magnetic brake
Fuselage, forward, station 23, L10
158
Connector, dual ammeter
Instrument panel, M13
160
Connector, dual voltmeter, No. 2
Instrument panel, M22
161
Connector, dual voltmeter, No. 1
Instrument panel, M21
162
Connector, combining gearbox oil 
pressure switch
Engine compartment, aft, S90
163, 164
Connector, pilot triple tachometer 
indicator
Instrument panel, M12
165, 166
Connector, copilot triple tachometer 
indicator
Instrument panel, M11
167
Connector, door post solenoid
Fuselage, forward, lower, L11
168
Connector, heater compartment
Heater compartment
169
Connector, heater mixing valve
Heater compartment, L7
171
Connector, No. 2 hydraulic pressure 
solenoid
Pylon compartment, L3
173
Connector, No. 2 hydraulic pressure 
switch
Pylon compartment, S95
174
Connector, No. 1 hydraulic pressure 
switch
Pylon compartment, S94
175
Connector, No. 1 idle stop delay relay
Cabin roof, aft, K15
176
Connector, No. 2 idle stop delay relay
Cabin roof, aft, K16
177
Connector, No. 1 bleed air pressure 
valve
Engine compartment, center, L15
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 56
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
P and/or J
178
Connector, No. 2 bleed air pressure 
valve
Engine compartment, center, L14
181
Connector, combining gearbox oil 
pressure transmitter
Engine compartment, aft, B22
182
Connector, No. 1 fuel differential 
pressure switch
Engine compartment, forward, S100
183
Connector, No. 2 fuel differential 
pressure switch
Engine compartment, aft, S101
184
Connector, combining gearbox oil 
temperature switch
Engine compartment, aft, S102
185
Connector, miscellaneous panel
Pedestal, A10
186
Connector, standby compass
Cabin roof, above windshield, M28
187
Connector, aft outlet actuator valve
Heater compartment, L16
188
Connector, pilot vertical speed 
indicator
Instrument panel, M31
189
Connector, copilot altimeter indicator
Instrument panel, M33
190
Connector, pilot altimeter indicator
Instrument panel, M32
191
Connector, pilot airspeed indicator
Instrument panel, M30
192
Connector, copilot airspeed indicator
Instrument panel, M35
193
Connector, copilot vertical speed 
indicator
Instrument panel, M34
195
Connector, passenger step actuator
Fuselage, lower, station 74, B25 and B26
196
Connector, copilot instrument 5V 
power supply
Nose compartment, PS3
197
Connector, engine instrument 5V 
power supply
Nose compartment, PS4
198
Connector, pilot instrument 5V power 
supply
Nose compartment, PS5
210
Connector, No. 1 hydraulic indicator
Instrument panel, M36
211
Connector, No. 2 hydraulic indicator
Instrument panel, M37
212
Connector, No. 1 hydraulic transmitter
Pylon compartment, B24
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 57
ECCN EAR99
BHT-212-MM-10
P and/or J
219
Connector, No. 2 hydraulic transmitter
Pylon compartment, B23
222
Connector, winterization kit control 
valve
Heater compartment, L19
223
Connector, heater control line
Heater compartment, S191
225
Connector, landing light
Fuselage, forward, station 84, underneath, 
DS13
226
Connector, anticollision light, lower
Fuselage or tailboom, underneath, DS7
229
Connector, No. 2 hydraulic 
temperature bulb
Pylon compartment, Z25
230
Connector, No. 1 hydraulic 
temperature bulb
Pylon compartment, Z26
237
Connector, pilot dual torque indicator, 
No. 2
Instrument panel, M20
238
Connector, copilot dual torque 
indicator, No. 2
Instrument panel, M19
239
Connector, heater relay
Cabin roof, station 68, left, K18
281
Connector, battery temperature sensor
Nose compartment, underneath battery, Z54
286, 287
Connector, interturbine temperature 
compensator, No. 1
Engine compartment, aft, Z27
288, 289
Connector, interturbine temperature, 
compensator, No. 2
Engine compartment, aft, Z28
290
Connector, pilot RPM caution light
Instrument panel, DS40
291
Connector, copilot RPM caution light
Instrument panel, DS37
292
Connector, pilot MASTER CAUTION 
light
Instrument panel, DS38
293
Connector, copilot MASTER CAUTION 
light
Instrument panel, DS39
294
Connector, engine instrument 5V 
power supply
Nose compartment, shelf, PS6
295
Connector, copilot clock
Instrument panel, M40
296
Connector, copilot standby compass
Above windshield, left, M41
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 58
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
P and/or J
297
Connector, No. 3 inverter
Nose compartment, PS7
298
Connector, No. 3 AC voltage sense 
relay
Nose compartment, shelf, K50
299
Connector, No. 2 hydraulic pressure 
switch
Pylon compartment, S207
300
Connector, No. 1 hydraulic pressure 
switch
Pylon compartment, S206
350
Connector, cabin temperature control
Cabin floor, station 66, Z65
351
Connector, cabin temperature motor
Heater compartment, station 180, B30
506
Connector, instrument panel 
disconnect
Instrument panel
3000
Connector, copilot three-axis sensor
Aft electrical compartment
3001
Connector, copilot rate gyro
Nose compartment, shelf, Z52
3002
Connector, pilot three-axis sensor
Aft electrical compartment
3003
Connector, pilot rate gyro
Nose compartment, shelf, Z52
3005
Connector, SCAS box (pitch)
Nose compartment, shelf, A25
3006
Connector, attitude box (pitch)
Nose compartment, shelf, A24
3007
Connector, SCAS box (roll)
Nose compartment, shelf, A25
3008
Connector, attitude box (roll)
Nose compartment, shelf, A24
3009
Connector, SCAS box (yaw)
NOse compartment, shelf, A25
3010
Connector, attitude box (heading)
Nose compartment, shelf, A24
3011
Connector, trim control
Pedestal, A26
3012
Connector, autopilot control
Pedestal, A27
3013
Connector, autopilot control
Pedestal, A27
3014
Connector, rotary actuator (yaw)
Fuselage, lower, station 178, L22
3015
Connector, SCAS actuator (roll)
Fuselage, lower, station 74, L23
3016
Connector, SCAS actuator (pitch)
Fuselage, lower, station 64, L24
3017
Connector, rotary actuator (pitch)
Fuselage, lower, station 55, L25
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 59
ECCN EAR99
BHT-212-MM-10
P and/or J
3018
Connector, transducer (pitch)
Fuselage, lower, station 40, MT1
3019
Connector, rotary actuator (roll)
Fuselage, lower, station 30, L26
3020
Connector, transducer (yaw)
Fuselage, lower, station 40, MT2
3021
Connector, solenoid (roll)
Fuselage, lower, station 78, L27
3022
Connector, transducer (roll)
Fuselage, lower, station 25, MT3
3023
Connector, solenoid (pitch)
Fuselage, lower, station 69, L28
3024
Connector, solenoid (yaw)
Fuselage, aft, station 178, L30
3025
Connector, SCAS actuator (yaw)
Fuselage, aft, station 178, L29
3031
Connector, AFCS power supply
Fuselage, lower, station 37, PS8
3032
Connector, AFCS switch disconnect
Fuselage, lower, station 37, S199
3033
Connector, AFCS switch disconnect
Fuselage, lower, station 52, S200
3034
Connector, AFCS switch disconnect
Fuselage, lower, station 55, S214
3407MP3P1
Connector, copilot three-axis sensor
Aft avionics compartment
PS
PS1
Inverter No. 1
Nose compartment, lower
PS2
Inverter No. 2
Nose compartment, lower
PS3
Copilot instrument power supply (5V)
Nose compartment, left
PS4
Engine instrument power supply (5V)
Nose compartment, right
PS5
Pilot instrument power supply (5V)
Nose compartment, right
PS6
Engine instrument power supply (5V)
Nose compartment, left
PS7
Inverter No. 3
Nose compartment
PS8
AFCS power supply (5V)
Fuselage, lower, station 37
Q
Q4
Transistor, secondary instrument lights
Cabin roof, station 116
Q5
Transistor, overhead console lights
Cabin roof, station 142, right
Q6
Transistor, pedestal lights
Cabin roof, station 92, left
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 60
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
Q7
Transistor, engine instrument lights
Cabin roof, station 92, right
R
R1
Rheostat, pilot instrument lights
Overhead console
R2
Rheostat, copilot instrument lights
Overhead console
R3
Rheostat, engine instrument lights
Overhead console
R4
Rheostat, secondary instrument lights
Overhead console
R5
Rheostat, overhead console lights
Overhead console
R6
Rheostat, pedestal lights
Overhead console
R7
Rheostat, aft dome lights
Overhead console
R9
Shunt, generator No. 1
Cabin roof, station 142, left
R10
Shunt, generator No. 2
Cabin roof, station 142, right
R13
Resistor, fire detector No. 1
Pedestal, forward, TB15
R14
Resistor, fire detector No. 2
Pedestal, forward, TB15
R15 through R17
Resistor, windshield wipers
Cabin roof, station 64, left, A13
R19 through R21
Resistor, windshield wipers
Cabin roof, station 64, right, A14
R28
Resistor, secondary instrument lights
Overhead console
R30
Resistor, pedestal lights
Overhead console
R32
Resistor, overhead console lights
Overhead console
R33, R34
Resistor, light dimming
Pedestal, forward, K25
R35, R36
Resistor, light dimming
Pedestal, forward, K24
R37
Resistor, overheat relay
Instrument panel
R42
Resistor, ECU temperature control
Overhead console
R43, R44, R47, 
R48, R52
Resistor, ECU temperature control
Nose compartment, shelf, TB50
R45, R46, R49, 
R50, R51
Resistor, ECU temperature control
Nose compartment, shelf, TB51
R53 through R56
Resistor, transformer
Cabin roof, T3 through T6 respectively
R57, R58
Resistor, transformer
Nose compartment, T1 and T2 respectively
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 61
ECCN EAR99
BHT-212-MM-10
R65, R66
Resistor, navigation command light 
relay
Pedestal, K51
S
S1
Switch, emergency fire handle No. 1
Instrument panel
S2
Switch, emergency fire handle No. 2
Instrument panel
S3
Switch, fire extinguisher, main and 
reserve
Instrument panel
S5
Switch, fire detector test
Instrument panel
S7
Switch, fuel quantity select
Instrument panel or pedestal
S9
Switch, hydraulic system No. 1
Pedestal, A10
S10
Switch, force trim
Pedestal, A10
S11
Switch, particle separator, No. 1
Pedestal, A3
S12
Switch, particle separator, No. 2
Pedestal, A3
S13
Switch, governor auto-manual, No. 1
Pedestal, A3
S14
Switch, governor auto-manual, No. 2
Pedestal, A3
S15
Switch, rotor RPM audio
Pedestal, A10
S16
Switch, fuel crossfeed
Pedestal, A3
S17
Switch, fuel No. 1
Pedestal, A3
S18
Switch, fuel No. 2
Pedestal, A3
S19
Switch, fuel interconnect
Pedestal, A3
S20
Switch, landing light, extend-retract
Collective stick, pilot, A9
S21
Switch, search light, on-stow
Collective stick, pilot, A9
S22
Switch, landing light, on-off
Collective stick, pilot, A9
S23
Switch, engine start
Collective stick, pilot, A9
S25
Switch, search light control
Collective stick, pilot, A9
S26
Switch, transmission oil temperature
Transmission
S27
Switch, governor RPM
Collective stick, pilot, A9
S28
Switch, transmission oil pressure
Pylon compartment
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 62
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
S29
Switch, idle stop
Collective stick, pilot, A9
S31
Switch, aft outlet (limit)
Pedestal, forward
S32
Switch, cargo release
Cyclic stick, pilot, A19
S33
Switch, AFCS release
Cyclic stick, pilot, A19
S34
Switch, force trim
Cyclic stick, pilot, A19
S36
Switch, cargo release
Cyclic stick, copilot, A20
S38
Switch, force trim
Cyclic stick, copilot, A20
S40
Switch, governor RPM
Collective stick, copilot, A11
S41
Switch, sump drain valve, No. 1
Fuselage, station 129, left
S42
Switch, sump drain valve, No. 2
Fuselage, station 129, right
S43
Switch, generator reset, No. 1
Overhead console
S44
Switch, generator reset, No. 2
Overhead console
S45
Switch, non-essential bus
Overhead console
S46
Switch, battery bus, No. 1
Overhead console
S47
Switch, radio, ICS
Cyclic stick, pilot, A19
S48
Switch, radio, ISC
Cyclic stick, copilot, A20
S53
Switch, inverter, No. 1
Overhead console
S56
Switch, inverter, No. 2
Overhead console
S59
Switch, position lights
Overhead console
S62
Switch, anticollision lights
Overhead console
S63
Switch, dome lights
Overhead console
S64
Switch, windshield wiper select
Overhead console
S65
Switch, windshield wiper speed
Overhead console
S67
Switch, cargo release arm
Overhead console
S68
Switch, heater aft outlet
Overhead console
S69
Switch, pilot heater
Overhead console
S71
Switch, lock
Passenger door, left
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
8 JUN 2010 Rev. 12
Page 63
ECCN EAR99
BHT-212-MM-10
S72
Switch, lock
Passenger door, right
S73
Switch, engine oil pressure, No. 1
Engine compartment, aft
S74
Switch, engine oil pressure, No. 2
Engine compartment, aft
S81
Switch, overheat
Heater compartment
S82
Switch, baggage compartment door
Baggage compartment door sill
S85
Switch, baggage compartment fire test
Instrument panel
S86, S88
Switch, fuel flow
Fuel cell, right
S87, S89
Switch, fuel flow
Fuel cell, left
S90
Switch, combining gearbox oil 
pressure
Engine compartment, aft
S91
Switch, fuel boost, No. 1
Pedestal, A3
S92
Switch, fuel boost, No. 2
Pedestal, A3
S94, S95
Switch, hydraulic filter
Pylon compartment, lower
S96
Switch, utility light
Overhead console
S100
Switch, fuel differential pressure, No. 1
Power plant
S101
Switch, fuel differential pressure, No. 2
Power plant
S102
Switch, combining gearbox oil 
temperature
Power plant
S105
Switch, external power
Nose compartment
S182
Switch, hydraulic system, No. 2
Pedestal, A10
S183
Switch, power step
Pedestal, A10
S185
Sensor, non-essential bus
Cabin roof, station 74
S186
Sensor, non-essential bus
Nose compartment, lower or cabin roof, 
station 80
S187
Switch, overheat
Heater compartment, station 178 and 211
S189
Switch, heater
Overhead console
S190
Switch, vent
Overhead console
S191
Switch, heater control line sensor
Heater compartment
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
Page 64
Rev. 12 8 JUN 2010
ECCN EAR99
BHT-212-MM-10
S198
Switch, inverter, No. 3
Overhead console
S199
Switch, AFCS roll
Fuselage, lower, station 39
S200
Switch, AFCS pitch
Fuselage, lower, station 52
S201
Switch, outside air temperature light
Overhead console
S202
Switch, battery bus, No. 2
Overhead console
S203
Switch, fuel crossfeed test
Pedestal, A3
S204
Switch, temperature
Hydraulic reservoir 1
S205
Switch, temperature
Hydraulic reservoir 2
S206
Switch, pressure
Hydraulic module 1
S207
Switch, pressure
Hydraulic module 2
S208
Switch, generator 2 overheat
Engine 2 compartment
S209
Switch, generator 1 overheat
Engine 1 compartment
S214
Switch, AFCS (yaw)
Fuselage, lower, station 55
S240
Switch, pilot gyro
Instrument panel
S241
Switch, copilot gyro erect
Instrument panel
SQ1
Squib, left
Engine compartment, No. 1
SQ2
Squib, right
Engine compartment, No. 1
SQ3
Squib, left
Engine compartment, No. 2
SQ4
Squib, right
Engine compartment, No. 2
T
T1, T2
Transformer
Nose compartment, lower
T3
Transformer
Cabin roof, left, station 142
T4
Transformer
Cabin roof, right, station 142
T5, T6
Transformer
Cabin roof, center, station 76
TB1
Terminal board, nose rack ground
Pedestal, forward
TB2, TB3
Terminal board
Overhead console
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 64A
BHT-212-MM-10
TB4
Terminal board, engine and fuel control 
panel
Pedestal, A3
TB6
Terminal board, cockpit lights, right
Cabin roof, forward
TB7
Terminal board, cockpit lights, left
Cabin roof, forward
TB9
Terminal board, aft roof lights
Cabin roof, right, station 92
TB10
Terminal board
Fuel cell, right
TB11
Terminal board
Fuel cell, left
TB12
Terminal board, ground
Pedestal
TB14
Terminal board, secondary instrument 
lights
Fuselage, right
TB15
Terminal board
Pedestal, forward
TB22
Terminal board, copilot headset
Cabin roof, copilot
TB23
Terminal board, pilot headset
Cabin roof, pilot
TB27
Terminal board, lighting, 5V
Nose compartment, bottom shelf
TB28
Terminal board, lighting, 5V ground
Nose compartment, bottom shelf
TB29
Terminal board, AC and DC ground
Pedestal, forward
TB33
Terminal board, RPM warning
Pedestal, forward
TB34
Terminal board
Collective stick, pilot, A9
TB50, TB51
Terminal board, attitude system
Nose compartment, shelf
TB52
Terminal board, non-essential bus
Cabin roof, center, station 84
TB53
Terminal board, inverter, No. 3
Nose compartment, lower
TB80
Terminal board, transmission chip 
detector
Pedestal, right
Z
Z1
Box, RPM limit warning
Nose compartment, upper
Z2
Gyro, displacement, pitch and roll
Nose compartment, shelf
Z4
Amplifier, fire detector, left
Cabin roof, left, station 146
Z5
Bulb, transmission temperature
Pylon compartment
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
ECCN EAR99
Page 64B
Rev. 12 8 JUN 2010
BHT-212-MM-10
Z6
Amplifier, fire detector, right
Cabin roof
Z7
Bulb, engine oil temperature, left
Engine compartment, forward
Z8
Bulb, engine oil temperature, right
Engine compartment, forward
Z9
Ignition unit, left
Engine compartment, center
Z10
Ignition unit, right
Engine compartment, center
Z11
Amplifier, smoke detector
Nose compartment, upper
Z12
Smoke detector
Baggage compartment
Z13
Fuel probe
Fuel cell, left
Z14
Fuel probe
Fuel cell, right
Z15
Fuel capacitance simulator, left
Cabin roof, station 166 (auxiliary fuel cell)
Z16
Fuel capacitance simulator, right
Cabin roof, station 166 (auxiliary fuel cell)
Z17
Fuel probe
Fuel cell, aft
Z18
Sensing element
Engine compartment, forward, right
Z19
Sensing element
Engine compartment, forward, left
Z20
Sensing element
Engine compartment, center, right
Z21
Sensing element
Engine compartment, center, left
Z22
DC control unit, No. 2
Nose compartment, lower
Z23
DC control unit, No. 1
Nose compartment, lower
Z24
Bulb, combining gearbox oil 
temperature
Engine compartment, aft
Z25
Bulb, hydraulic temperature, No. 2
Pylon compartment, right
Z26
Bulb, hydraulic temperature, No. 1
Pylon compartment, left
Z27
Compensator, interturbine 
temperature, No. 1
Engine compartment, aft
Z28
Compensator, interturbine 
temperature, No. 2
Engine compartment, aft
Z52
Gyro, pilot, rate-of-turn
Nose compartment, shelf
Z53
Gyro, copilot rate-of-turn
Nose compartment, shelf
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 64C
BHT-212-MM-10
Z54
Sensor, battery temperature
Nose compartment, under battery
Z55
Controller, servo, cabin temperature
Cabin, station 66
NUMERICAL
2337A1
Cockpit voice recorder
Nose compartment, shelf
2337S1
Impact (inertia) switch
Nose compartment, shelf
27A1
Flight data recorder
Nose compartment, shelf
27A2
Air data computer
Nose compartment, shelf
27AR1
Flight data acquisition unit
Nose compartment, shelf
27K1
Flight data recorder relay
Nose compartment, shelf
27MT1
Accelerometer
Pylon compartment
27TB1
Terminal junction block
Nose compartment, shelf
3400TB1
Terminal junction block
Nose compartment, shelf
3400TB2
Terminal junction block
Nose compartment, shelf
Table 96-1C.   Equipment Reference Designator, Nomenclature, and Location (Cont)
REF DES
NOMENCLATURE
LOCATION
96-00-00
ECCN EAR99
Page 64D
Rev. 12 8 JUN 2010
BHT-212-MM-10
96-00-00
R99
Figure 96-5A.   Instrument Panel (Typical)
212_MM_96_0007
8 JUN 2010 Rev. 12
Page 64E
ECCN EA

BHT-212-MM-10

96-00-00
Page 64F
Rev. 12 8 JUN 2010
ECCN EAR99
Figure 96-5B.   Overhead Consol (Typical)
212_MM_96_0008
BHT-212-MM-10
Figure 96-5C.   Miscellaneous and Engine Control Panel
212_MM_96_0009
S183
S15
S10
S9
S13
S17
S91
A3
S11
S182
S203
S14
S18
S12
S92
S19
S16
96-00-00
ECCN EAR99
8 JUN 2010 Rev. 12
Page 64G/64H