HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990)

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(b). Use 5X to 10X magnifying glass and

(3). Inspect all other surfaces of the drive

bright side light (45° or less; down

shaft (Ref. Main Rotor Drive Shaft

ward lighting may not define cracks).

Inspection).

(c). Pay particular attention to side of

NOTE: If surface corrosion or pitting of the

(each) tooth with larger wear pattern.

shaft surface is noted, perform field repair of

Hairline cracks appear crescent-

drive shaft (Ref. Main Rotor Drive Shaft -

shaped and at the center and bottom

Exterior Repair and Main rotor Drive Shaft

of tooth in the root area. Also, inspect

- Corrosion Removal).

neck (shaded area) of spline for

cracks.

(4). Remove protective cover and install

main rotor drive shaft (Ref. Main Rotor

NOTE:

Drive Shaft Installation).

D If cracking is suspected, perform magnet

ic particle inspection of shaft spline and

teeth.

D If cracking or damage is found, the shaft

is no longer airworthy. Discard drive shaft

and return it to MDHS Customer Service

Department.

D Inspect replacement drive shaft per steps

(a). thru (c). prior to installation of shaft

on helicopter.

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CSP-HMI-2

MAINTENANCE MANUAL

DRIVE SHAFTS / CLUTCHES / COUPLINGS

REPAIRS

1. Main Rotor Drive Shaft Exterior Repair

Exercise care when removing

CAUTION

pits to ensure that shot peening

(Ref. Figure 601) No repair of drive shaft is

is not completely penetrated. Remove only

permitted except for removal of light surface

minimum material necessary to remove

corrosion and polishing of minor nicks and

pits. Minimum wall thickness of 0.1775 inch

chips in noncritical spline areas indicated

(4.5085 mm) must be maintained.

below.

(d). Lightly abrade corroded surface with

crocus cloth (CM803) to remove pits.

If pit removal exceeds depth of

Consumable Materials

0.0012 inch (0.03048 mm) in Area 1

(Ref. Section 91−00−00)

or 0.0008 inch (0.02032 mm) in Area

Item

Nomenclature

2, shaft is unserviceable and must be

CM121

Preservation oil

replaced.

CM222

1,1,1-Trichloroethane

(e). Repeat steps (a). thru (c). above.

CM228

Surface cleaner

(f). Spray two coats of epoxy primer and

CM302

Epoxy primer / Catalyst reducer

catalyst reducer (CM302), mixed per

CM803

Crocus cloth

manufacturers instructions, on shaft

exterior. Do not prime spline teeth or

mounting surface.

(1). Remove corrosion as follows:

(2). Polish out minor nicks and chips on

(a). Degrease corroded area of drive shaft

shaft spline teeth as follows:

with clean cloth saturated with

(a). Using 320 - 400 grit abrasive stone,

trichloroethane (CM222).

carefully grind, blend and polish out

nicks and chips which are outside the

Surface cleaner, used in step

critical (active) spline tooth contact

WARNING

below, irritates hands on re

areas (Area 4 profile and end views

peated exposure. Rubber gloves should

for permissible repair areas).

be worn.

(b). If the repair (grind and polish)

(b). Swab shaft exterior with diluted

operation extends beyond limits

solution of surface cleaner (CM228).

shown, or if any tooth damage exists

(Mix one part surface cleaner with

within the critical tooth contact area,

four parts water.) Keep wet with

shaft is unserviceable and must be

solution for 10 minutes or until

replaced.

corrosion appears to be removed.

(c). Perform magnetic particle inspection

Wipe clean and inspect. Repeat as

according to Specification MIL-

necessary until there is no further

I-6868. No surface or subsurface

evidence of corrosion.

defects are permissible.

(c). Rinse with water and dry with

(3). Apply preservation oil (CM121) to

compressed air.

spline teeth.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(4). Immediately reinstall main rotor drive

Do not allow epoxy primer or

CAUTION

shaft.

epoxy enamel to contact drive

shaft splines or mounting surfaces.

2. Main Rotor Drive Shaft Corrosion

(7). Fill shaft with epoxy primer (CM302)

Removal

mixed according to manufacturer's

instructions. Drain primer from shaft.

(Ref. Figure 601)

Ensure that shaft ID is completely

coated. Allow primer to dry one hour at

Consumable Materials

room temperature.

(Ref. Section 91−00−00)

(8). Apply one coat of black epoxy enamel

Item

Nomenclature

(CM304) to driveshaft by filling and

CM222

1,1,1-Trichloroethane

draining shaft. Allow enamel to dry 48

CM228

Surface cleaner

hours at room temperature or let dry 30

CM302

Epoxy primer / Catalyst reducer

minutes at room temperature, then

CM303

Wash primer

cure for three hours in oven at 250° -

275°F (122° - 136°C).

CM304

Enamel, epoxy

CM425

Sealing compound

(9). Apply thin coat of sealing compound

(CM425), mixed according to container

instructions, to all cork plug surfaces;

(1). Degrease entire shaft inner diameter

press cork into drive shafts until top of

(ID), using 1, 1, 1, trichloroethane

cork is flush with top of drive shaft.

(CM222).

Allow sealing compound to cure

according to container instructions.

(2). Using a fine wire rotary brush or wire

Apply second coat of sealing compound

brush, remove corrosion and contami

to exposed surfaces of cork; allow to dry.

nants from drive shaft ID.

3. Main Transmission Drive Shaft Repair

Turco WO-1 will irritate the

(Bendix)

WARNING

skin; always use rubber

gloves when handling this material.

(Ref. Figure 402)

Wash skin exposed to Turco WO-1,

thoroughly with water.

Consumable Materials

(Ref. Section 91−00−00)

(3). Using swab and extension rod, swab ID

Item

Nomenclature

of driveshaft with Turco WO-1

CM318

Primer

(CM228), diluted one part to four parts

water.

CM801

Abrasive paper, silicon carbide

CM803

Crocus cloth

(4). Thoroughly rinse drive shaft ID with

clear water; dry with compressed air.

(1). Repair of drive shaft diaphragms

(5). Using suitable light or borescope,

(Bendix) is not permissible.

inspect shaft ID for corrosion pitting.

(2). Repair all damage that is no deeper

Remove pitting by honing locally. Shaft

than 0.003 inch (0.076 mm).

ID may not exceed 1.655 inches (4.2037

cm) after honing. Blend honed area

(a). Completely remove defect. Maintain

with existing surrounding area. If

smooth transition into surrounding

pitting removal causes or would cause

surface.

shaft ID to exceed 1.655 inches (4.2037

cm), replace shaft.

(b). Use grade 400 wet or dry abrasive

paper (CM801) for preliminary

(6). Apply one coat of wash primer (CM303)

finishing, and then polish with crocus

to shaft ID according to primer man

cloth (CM803). Restore surface until

ufacturer's instructions.

it equals original finish of shaft.

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(c). After rework, check shaft tube wall

Care should be taken when re

CAUTION

thickness in repair area. Wall thick

moving or installing nutplates

ness shall not be less than 0.025 inch

in Kamatic drive shafts. Damage to flex

(0.635 mm).

frames could cause drive shaft replacement.

(a). Carefully drill out rivets securing

(d). Apply primer coating (CM318) for

nutplate.

corrosion protection.

(b). Using two MS20605-MP3W3 rivets,

4. Main Transmission Drive Shaft Repair

install a new MS21075-L4 nutplate

(Kamatic)

in place.

5. Overrunning Clutch Repair/Overhaul

Consumable Materials

(Ref. Section 91−00−00)

Accomplish repair/overhaul of overrunning

Item

Nomenclature

clutch according to instructions in COM.

CM318

Primer

6. Overrunning Clutch−to−Firewall Seal

CM801

Abrasive paper, silicon carbide

Repair

CM803

Crocus cloth

Consumable Materials

(Ref. Section 91−00−00)

(1). Repairs of Kamatic drive shaft flexible

Item

Nomenclature

couplings are limited. Repairs to spring

area are not allowed. No cracks are

CM411

Adhesive, epoxy

allowed.

Replace engine firewall seal by bonding new

(2). Repair drive shaft tube area damage

seal to backing with adhesive (CM411).

that is no deeper than 0.005 inch (0.127

mm). Maximum depth after repair is

7. Main Transmission Drive Shaft Coupling

0.010 inch (0.254 mm). The maximum

Corrosion Removal

thickness of material removed shall not

be more than 10 percent of the original

material thickness.

Consumable Materials

(Ref. Section 91−00−00)

(a). Completely remove defect. Maintain

Item

Nomenclature

smooth transition into surrounding

CM801

Abrasive paper, silicon carbide

surface.

CM804

Emery cloth, fine

(b). Use grade 400 wet or dry abrasive

paper (CM801) for preliminary

(1). Prior to installing original drive shaft

finishing, then polish with crocus

coupling (369A5512 or 369H5560 only),

cloth (CM803). Restore surface until

inspect flange face of coupling for

it equals original finish of shaft.

corrosion. Evidence of corrosion may be

removed by hand lapping the affected

parts by using a sheet of #440 (or finer)

(c). After rework, check shaft tube wall

emery cloth (CM804) or wet or dry

thickness in repair area.

abrasive paper (CM801) placed on a

surface table with a figure eight motion,

(d). Apply primer coating (CM318) for

using care not to let the part rock.

corrosion protection.

NOTE: Couplings may be reused if flange is not

(3). Replace nutplates on Kamatics drive

less than 0.100 inch (2.540 mm) after clean

shafts as follows:

up. Recheck shimming.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

8. Bendix Coupling Repair

9. Kamatic Coupling Repair

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

Item

Nomenclature

CM202

Metal protector, aerosol

CM318

Primer

CM318

Primer

CM801

Abrasive paper, silicon carbide

CM801

Abrasive paper, silicon carbide

CM803

Crocus cloth

CM803

Crocus cloth

CM804

Emery cloth, fine

NOTE: If coupling is cleaned with solvent or de

(1). Repairs to coupling spring areas are not

tergent, spray a light coating of metal pro

allowed.

tector (CM202) on interior and exterior of

coupling diaphragm. Dip flange of coupling

(2). Repair damage to splined section and

in liquid or spray with aerosol metal protec

flange of coupling that is no deeper

tor. Wipe away excess liquid. Metal protec

than 0.005 inch (0.127 mm). Use

tor cures in eight hours at room tempera

abrasive paper grade 320 grit or finer

ture or 15 minutes at 150°F (66°C).

(CM801) and crocus cloth (CM803) to

completely remove and polish out

Metal protector

(CM202)

defect. Maximum depth after rework is

WARNING

must only be used in a well

0.007 inch (0.178 mm). Apply primer

ventilated area. Persons using the met

(CM318) to repaired area.

al protector must follow all safety pre

cautions normally used with a chlori

NOTE: Flange may be hand-lapped using a

nated solvent and all safety

sheet of #440 emery cloth (CM804), placed

precautions on the product label.

on a surface table. A figure ``8'' motion

should be used while lapping the coupling,

(1). Repairs to flexible web areas of dia

using care not to let part ``rock''.

phragms are not allowed.

(3). Minimum flange thickness after

(2). Repair damage to splined section and

cleanup is 0.100 inch (2.540 mm).

flange of coupling that is no deeper

than 0.005 inch (0.127 mm). Use

(4). Replace nutplates on Kamatics cou

abrasive paper (CM801) grade 400 -

plings as follows:

600 and crocus cloth (CM803) to

completely remove and polish out

Care should be taken when re

CAUTION

defect. Maximum depth after rework is

moving or installing nutplates

0.010 inch (0.254 mm). Apply primer

in Kamatic couplings. Damage to flex

(CM318) to repaired area.

frames could cause coupling replacement.

(3). Repair damage to outer welded portion

(a). Carefully drill out rivets securing

of diaphragm halves as in step (2).

nutplate.

above, except that maximum thickness

of material removed shall be not more

(b). Using two MS20605-MP3W3 rivets,

than 10 percent of original material

install a new MS21075-L4 nutplate

thickness.

in place.

Page 804

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TAIL ROTOR DRIVE SHAFT

REMOVAL/INSTALLATION

1. Tail Rotor Drive Shaft

washers, and remove drive shaft from

tail rotor transmission.

The tail rotor drive shaft connects the main

transmission and the tail rotor transmission.

B. Tail Rotor Drive Shaft Installation with

The total drive shaft length is approximately

Bendix Couplings

13 feet long for 369D/E and approximately 14

feet long for 369FF. Flanges at each end of the

shaft attach to flexible joint couplings on the

(Ref. Figure 401) Whenever main transmis

transmission shafts.

sion, tail rotor transmission, forward coupling

bolt and/or socket, transmission couplings or

2. Tail Rotor Drive Shaft Replacement

coupling shims, tail rotor drive shaft or

tailboom assembly have been replaced, start

A. Tail Rotor Drive Shaft Removal

installation with step (1). below. If none of

these components has been replaced, and only

(Ref. Figure 401, and Figure 402)

installation is involved, start with step (7).

below.

(1). Remove (or open) tail rotor drive shaft

access doors.

Consumable Materials

(2). Remove three bolts and washers that

(Ref. Section 91−00−00)

secure tail rotor drive shaft to output

Item

Nomenclature

shaft coupling on main transmission.

CM111

Grease, aircraft

(3). Disconnect chip detector wire from tail

CM112

Anti-seize compound high temperature

rotor transmission.

CM115

Grease, oscillating bearing

(4). Detach Sta. 284.00 bellcrank from tail

CM311

Coating, logo white / Thinner

rotor transmission.

CM318

Primer

(5). Remove nuts and washers that attach

tail rotor transmission to tailboom.

NOTE: If tail rotor drive shaft is replaced for

To prevent damage to transmis

CAUTION

torsional buckling, replace and discard

sion input shaft coupling during

transmission output gear shaft coupling bolt

and after shaft removal, provide level sup

and socket, and tail rotor gearbox coupling

port for both transmission and tail rotor, as

and coupling bolt.

weight of these items might buckle coupling

diaphragm.

(1). Remove existing shims. Coat coupling

(6). With assistance in guiding shaft

splines with grease (CM111) and

through damper, remove tail rotor, tail

coupling failsafe bolt threads with

rotor transmission and tail rotor drive

anti-seize compound (CM112) before

shaft as an assembly. Slowly and

assembly. Install coupling and tighten

carefully slide assembly aft until drive

failsafe coupling bolt to 250 - 300

shaft clears tailboom.

inch-pounds (28.25 - 33.90 Nm) plus

drag torque. (Check coupling bolt for

Do not carry or otherwise sup

CAUTION

drag torque serviceability of 25 inch-

port transmission by use of cou

pounds (2.82 Nm) minimum, 200

pling. Use care with removal tools to pre

inch-pounds (22.60 Nm) maximum.)

vent scratching of coupling diaphragms.

(7). Support assembly along its entire

(2). Determine shim thickness required at

length, remove three coupling bolts and

forward flexible coupling:

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

COUPLING

SHIMS

TAIL ROTOR DRIVE

SHAFT DAMPER

MAIN TRANSMISSION

SHAFT DAMPER

OUTPUT GEARSHAFT

SLEEVE

COUPLING

TAIL ROTOR

DRIVE SHAFT

FAILSAFE

COUPLING

BOLT

FAILSAFE

SOCKET

DRIVE SHAFT INSTALLATION

NOTES:

DO NOT LIFT TAIL ROTOR TRANSMISSION OR DRIVE SHAFT BY COUPLING. KEEP THE ASSEMBLY ALIGNED DURING REMOVAL.

SHIM AS REQUIRED.

ADD 0.005 IN. (0.127 MM) TO MEASURED GAP FOR MINIMUM SHIM THICKNESS.

HOLD COUPLING AT 1.370 IN. (34.798 MM) OD ONLY, TO BOTTOM COUPLING.

INSTALL BOLT WITH ANTI-SEIZE COMPOUND. MINIMUM DRAG TORQUE FOR COUPLING BOLT, 25 INCH-POUNDS (2.82 NM).

MINIMUM 0.010 IN. (0.254 MM) STEP BETWEEN AFT END OF OUTPUT SHAFT AND SHOULDER OF FORWARD COUPLING.

INSTALL WITH GAP EITHER SIDE OF FAILSAFE BOLT.

G63-1005-1B

Figure 401. Tail Rotor Drive Shaft Installation (369D/E/FF) (Sheet 1 of 3)

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CSP-HMI-2

MAINTENANCE MANUAL

LOCK RING

AND STUD

(4 PLCS)

TRANSMISSION

COUPLING (NOTE 1)

COUPLING SHIM

TAIL BOOM

(NOTE 2)

COUPLING

BOLT

FAILSAFE

SOCKET

FAILSAFE

COUPLING BOLT

INPUT

SHAFT

TAIL ROTOR TRANSMISSION

TRANSMISSION

COUPLING SHIM

COUPLING (NOTE 1)

(NOTE 2)

MEASURED GAP

0.010-0.020 IN.

THIN WASHER

ALIGNMENT

(0.254-0.508 MM)

(3 PLCS)

AFT

1.370 IN.

BOLT OR PIN

COUPLING TAIL ROTOR

(34.798 MM) OD

GEARSHAFT

(NOTE 4)

INPUT SHAFT

NOTE 3

SHIMS

MAIN TRANSMISSION

COUPLING BOLT

OUTPUT PINION

TAIL ROTOR

(NOTE 5)

DRIVE SHAFT

COUPLING BOLT

FORWARD KAMATIC COUPLING

AFT KAMATIC COUPLING

(NOTE 5)

0.010 IN. (0.254 MM)

MINIMUM STEP

(NOTE 6)

KAMATIC COUPLINGS

G63-1005-2A

Figure 401. Tail Rotor Drive Shaft Installation (369D/E/FF) (Sheet 2 of 3)

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

MEASURED GAP

0.010-0.020 IN.

(0.254-0.508 MM)

ALIGNMENT

THIN

BOLT OR PIN

WASHER

TAIL ROTOR GEARBOX

(3 PLCS)

MAIN TRANSMISSION

(3 PLCS)

OUTPUT SHAFT

OUTPUT PINION

FAILSAFE

TAIL ROTOR

BOLT

DRIVE SHAFT

AFT

NOTE 3

COUPLING

SHIMS

1.370 IN

SHIMS

(34.798 MM) OD

(NOTE 5)

FAILSAFE SOCKET

FAILSAFE BOLT

(NOTE 5)

AFT BENDIX COUPLING

FORWARD BENDIX COUPLING

COUPLING

0.010 IN. (0.254 MM)

MINIMUM STEP

FAILSAFE BOLT

FAILSAFE SOCKET

(NOTE 6)

(NOTE 7)

D-D FAILSAFE INSTALLATION

G63-1005-3D

Figure 401. Tail Rotor Drive Shaft Installation (369D/E/FF) (Sheet 3 of 3)

Page 404

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CSP-HMI-2

MAINTENANCE MANUAL

(a). Install minimum shim thickness on

CAUTION

main transmission output shaft.

D Ensure security of tail rotor gearbox

Bottom the flexible coupling by

CAUTION

mount studs. Maximum allowable side

holding at the

1.370 inch

play at end of stud is 0.004 inch (0.102

(3.4798 cm) OD of coupling. Do not bottom

mm), maximum allowable axial play is

coupling by pushing on drive shaft attach

0.005 inch

(0.127 mm)

(Ref. Sec.

flange; doing so may damage coupling.

63-25-10).

(b). Bottom forward coupling on main

D When installing tail rotor transmission

transmission output shaft.

and drive shaft, do not compress the for

ward or aft couplings as damage to the

(c). Measure step between aft end of

coupling could result.

output shaft and shoulder of flexible

coupling, by bottoming coupling

(7). With assistance, support transmission

against shims (refer to CAUTION

and shaft in line, for minimum deflec

above).

tion of coupling, and guide drive shaft

carefully through tailboom and damper

NOTE: Maintain minimum 0.010 inch (0.254

into position.

mm) step between aft end of output shaft

(8). Secure transmission to four tailboom

and coupling shoulder to prevent coupling

mounting studs (Ref. Sec. 63-25-10).

bolt from bottoming on output shaft.

Install four washers and nuts, torque

nuts to 75 - 95 inch-pounds (8.47 -

(d). Install additional shims to maintain

10.73 Nm) plus drag torque.

0.010 inch (0.254 mm) minimum step

as required.

(9). Align forward end of drive shaft with

coupling on main transmission output

(3).

Position failsafe socket on aft face of

gearshaft. Partially install two bolts as

forward coupling so that three of the

an alignment aid but do not tighten.

nine holes are indexed to the three

Align drive shaft inspection markings.

nutplates of the coupling in such a way

If any of four white stripes is indistinct

that maximum clearance is obtained

or does not exist, paint (CM311)

between the bolt key and socket.

replacement stripe:

Visually verify proper clearance before

installing tail rotor drive shaft.

(10). Obtain 0.010-0.020 inch (0.254-0.508

mm) gap between forward flange of tail

(4).

Repeat previous step to install failsafe

rotor drive shaft and aft end of socket,

socket on input coupling of tail rotor

using the following procedure:

transmission.

(a). Back off three attach bolts on for

(5).

Support entire length of tail rotor drive

ward flange of tail rotor drive shaft

shaft and position end stamped AFT to

assembly 0.050-0.100 inch

align with tail rotor transmission

(1.270-2.540 mm).

coupling.

(b). Pull and hold tail rotor output shaft

(6).

Install three bolts and washers to

of main rotor transmission aft (out of

connect tail rotor transmission coupling

transmission) to remove end play. If

to shaft; torque bolts to 80 - 100

rotor brake is installed, make certain

inch-pounds (9.04 - 11.30 Nm) plus

that brake pucks do not restrict axial

drag torque.

travel of tail rotor output shaft.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(c).

Remove end play in tail rotor trans

(12). With assistance, support transmission

mission by applying force to tail rotor

and shaft in line for minimum deflec

blades in opposite direction of

tion of coupling and guide drive shaft

operational rotation (while holding

carefully through tailboom and damper

forward coupling of tail rotor drive

into position.

shaft on main transmission output

shaft to prevent rotation). Do not

(13). Apply primer (CM318) to the four

push tail rotor drive shaft fore or aft.

gearbox mounting studs. Install nuts

and washers while the primer is still

(d).

Using feeler gage, measure gap

wet; torque evenly to 75 - 95 inch-

between socket and flange of tail

pounds (8.47 - 10.73 Nm) plus drag

rotor drive shaft. Socket flange must

torque.

be in full contact with flange of

flexible coupling.

Verify that a minimum of (1) one

CAUTION

thread protrudes through each

nut from the four tail rotor transmission

(e).

With assistance, remove tail rotor

mounting studs. If less than one thread is

transmission and driveshaft in line

showing, refer to CSP-DEF-6, Structural

for minimum deflection of coupling.

Repair Manual, to replace with a longer

MS1992A803-14 stud and insert.

(f).

Using measured gap from step (d).

above, add or remove required

(14).

Install three bolts and washers at

number of shims at tail rotor trans

forward end of tail rotor drive shaft to

mission input pinion shaft and

connect to forward coupling; torque

coupling to obtain specified gap of

bolts to 80 - 100 inch-pounds (9.04 -

0.010-0.020 inch (0.254-0.508 mm).

11.30 Nm) plus drag torque.

NOTE:

(15).

Connect electrical wire to tail rotor

transmission chip detector. Torque nut

D Maintain minimum 0.010 inch (0.254

to 12 - 15 inch-pounds (1.36 - 1.69

mm) step between coupling shoulder and

Nm).

output shaft (Ref. step (2).).

D If less than specified gap, 0.010-0.020

(16).

Coat pin of Sta. 284.00 bellcrank with

inch (0.254-0.508 mm) exists under mini

grease (CM111) and insert it into

mum shim requirements, install a maxi

bearing in tail rotor pitch control. Pivot

mum of one HS306-326 or HS306-326H

bellcrank to align with mating hole in

washer on each of the four tail rotor

tail rotor transmission and install bolt,

transmission mounting studs, between

washers, nut and cotter pin.

gearbox housing and boom fitting. Apply

primer (CM318) to both sides of washer at

(17).

Check transmission oil level and service

installation. After washer installation, re

peat step (10).

as required.

(18).

Slowly rotate drive shaft and visually

(11). Coat forward coupling splines with

check to ensure shaft is not bent and for

grease (CM111) and coupling bolt

not less than 0.250 inch (6.35 mm)

threads with antiseize compound (36)

clearance between shaft and fairing

before assembly. Install coupling and

tube at Sta. 137.5. In addition, check

torque failsafe bolt to 250 - 300

for minimum clearance of 0.190 inch

inch-pounds (28.25 - 33.90 Nm) plus

(4.83 mm) between shaft and cooling

drag torque. (Check coupling bolt for

blower scroll.

drag torque serviceability of 25 inch-

pounds minimum (2.82 Nm), 200

inch-pounds (22.60 Nm) maximum.)

(19).

Install all access doors and covers.

Page 406

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MD Helicopters, Inc.

MAINTENANCE MANUAL

C. Tail Rotor Drive Shaft Installation with

coupling onto main transmission;

Kamatic Couplings

torque coupling bolt to 250 - 300

inch-pounds (28.25 - 33.90 Nm) plus

(Ref. Figure 401 and Figure 402) Whenever

drag torque. (Check coupling bolt for

main transmission, tail rotor transmission,

drag torque serviceability of 25 inch-

transmission couplings, coupling shims, tail

pounds (2.82 Nm) minimum, 200

rotor drive shaft or tailboom assembly have

inch-pounds (22.60 Nm) maximum.)

been replaced, start installation with step (1).

below. If none of these components have been

(3). Support entire length of tail rotor drive

replaced, and only installation is involved,

shaft and position end marked AFT to

start with step (5). below.

align with tail rotor transmission

coupling.

Consumable Materials

(4). Install three bolts and washers to

(Ref. Section 91−00−00)

connect tail rotor gearbox coupling to

Item

Nomenclature

shaft; torque bolts to 80 - 100 inch-

CM111

Grease, aircraft

pounds (9.04 - 11.30 Nm) plus drag

torque.

CM112

Anti-seize compound high temperature

CM115

Grease, oscillating bearing

Ensure security of tail rotor

CAUTION

CM311

Coating, logo white / Thinner

gearbox mount studs. Maxi

CM318

Primer

mum allowable side play at end of stud is

0.004 inch (0.102 mm), maximum allowable

axial play is 0.005 inch (0.127 mm) (Ref. Sec.

NOTE:

63-25-10).

D Kamatic couplings do not require failsafe

(5). With assistance, support tail rotor

bolts or sockets.

transmission and shaft in line, for

D When installing 369D25501-3 Kamatic

minimum deflection of coupling, and

coupling, install SKCP2554-13 coupling

guide drive shaft carefully through

bolt supplied with the Kamatic coupling.

tailboom and damper into position.

D If tail rotor drive shaft is replaced for tor

(6). Secure transmission to four tailboom

sional buckling, replace and discard main

mounting studs with washers and nuts;

transmission output gear shaft coupling,

torque to 75 - 95 inch-pounds (8.47 -

tail rotor gearbox coupling and both cou

10.73 Nm) plus drag torque.

pling bolts.

(7). Align forward end of driveshaft with

(1). Coat coupling splines with grease

coupling on main transmission output

(CM111) and coupling bolt threads with

gearshaft. Partially install two bolts as

anti-seize compound (CM112) before

an alignment aid but do not tighten.

assembly. Install coupling onto tail

Align drive shaft inspection markings.

rotor gearbox and torque coupling bolt

If any of four white stripes is indistinct

to 250 - 300 inch-pounds (28.25 -

or does not exist, paint replacement

33.90 Nm) plus drag torque (Check

stripes.

coupling bolt for drag torque service

ability of 25 inch-pounds (2.82 Nm)

(8). Obtain 0.010-0.020 inch (0.254-0.508

minimum, 200 inch-pounds (22.60 Nm)

mm) gap between forward flange of tail

maximum.)

rotor drive shaft and flange of forward

coupling using the following procedure:

(2). Coat forward coupling splines with

grease (CM111) and coupling bolt

(a). Ensure alignment bolts in previous

threads with anti-seize compound

step are backed off between

(CM112) before assembly. Install

0.050-0.100 inch (1.270-2.540 mm).

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(b).

Pull and hold tail rotor output shaft

guide drive shaft carefully through

of main rotor transmission aft (out of

tailboom and damper into position.

transmission) to remove end play. If

(11).

Secure transmission to four tailboom

rotor brake is installed, ensure that

mounting studs with washers and nuts;

brake pucks do not restrict axial

torque to 75 - 95 inch-pounds (8.47 -

travel of tail rotor output shaft.

10.73 Nm) plus drag torque.

(c).

Remove end play in tail rotor trans

(12).

Install three bolts and washers at

mission by applying force to tail rotor

forward coupling; torque bolts to 80 -

blades in opposite direction of

100 inch-pounds (9.04 - 11.30 Nm)

operation (while holding forward

plus drag torque.

coupling of tail rotor drive shaft on

main transmission to prevent rota

(13).

Connect electrical wire to tail rotor

tion). Do not push tail rotor drive

transmission chip detector. Torque nut

shaft fore or aft.

to 12 - 15 inch-pounds (1.36 - 1.69

Nm).

(d).

Using feeler gage, measure gap

between forward coupling flange and

(14).

Coat pin of Sta. 284.00 bellcrank with

flange of tail rotor drive shaft. Record

grease (CM111) and insert into bearing

the gap.

in tail rotor pitch control. Pivot bell

crank to align with mating hole in tail

(e).

With assistance, remove tail rotor

rotor transmission and install bolt,

transmission and driveshaft in line

washers, nut and cotter pin.

for minimum deflection of coupling.

(15).

Check transmission oil level and service

as required (Ref. Sec. 12-10-00).

(f).

Using measured gap from step (d).

above, add or remove required

(16).

Slowly rotate driveshaft and check for

number of shims at tail rotor trans

not less than 0.25 inch (6.35 mm)

mission input pinion shaft and

clearance between shaft and fairing

coupling to obtain specified gap of

tube at Sta. 137.50. In addition, check

0.010-0.020 inch (0.254-0.508 mm).

for minimum clearance of 0.190 inch

(4.83 mm) between shaft and cooling

NOTE:

blower scroll.

D Maintain minimum 0.010 inch (0.254

(17).

Install all access doors and covers.

mm) step between coupling shoulder and

output shaft (Ref. Figure 401).

3. Tail Rotor Drive Shaft Damper

D If less than specified gap, 0.010-0.020

inch (0.254-0.508 mm) exists under mini

(Ref. Figure 603) The tail rotor drive shaft

mum shim requirements, install a maxi

damper is a graphite-filled teflon plate that

mum of one HS306-326 or HS306-326H

controls and limits deflection of the tail rotor

washer on each of the four tail rotor

drive shaft about its approximate mid-point.

transmission mounting studs, between

The damper is spring-loaded against a

gearbox housing and boom fitting. Apply

structural support bracket mounted on the aft

primer (CM318) to both sides of washer at

section tailboom fairing. On 369FF Model

installation. After washer installation, re

helicopters, a second damper is located at Sta.

peat step (10).

137.50 (Ref. Figure 602).

(9). Re-install coupling and torque coupling

4. Tail Rotor Drive Shaft Damper

bolt to 250 - 300 inch-pounds (28.25

Replacement

- 33.90 Nm) plus drag torque.

(Ref. Figure 602)

(10). With assistance, support tail rotor

(1). Remove boom-bolts access covers.

transmission and shaft in line for

minimum deflection of coupling and

(2). Remove tail rotor drive shaft.

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(3). Remove two bolts, washers, springs,

(6). Install tail rotor drive shaft.

thin washers, plate and spacers and

damper.

(7). Displace damper so that it touches tail

NOTE: The damper at Sta. 137.50 (369FF only)

rotor drive shaft.

has 369DSK152-13 bushings installed in

side the Teflon Graphite Damper in conjunc

tion with the spacers.

(8). Use wire gage to measure damper to

(4). Position new damper over mounting

shaft clearance 180° from contact point.

holes in support bracket. Install plate

Minimum acceptable clearance is 0.020

and spacers with bolts, washers,

inch (0.508 mm).

springs and spacer washers.

Ensure washers under bol

CAUTION

(9). Repeat steps (7). and (8). above at 90°

theads are seated against

intervals from initial check point.

spacer when tightened. Bolts wear rapidly if

clamp-up is not solid.

(5). Adjust damper friction.

(10). Install boom-bolts access covers.

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TAIL ROTOR DRIVE SHAFT

INSPECTION/CHECK

1. Tail Rotor Drive Shaft Inspection

straightness. When rotated between

centers, or with ends plugged and rolled

Inspect shaft as described below. Replace bent

over roller, runout of large diameter

shaft. Other damage (scratches, nicks, etc)

must not exceed 0.060 inch (1.524 mm)

that exceeds repairable limits also requires

(allowable dents excluded).

shaft replacement.

2. Tail Rotor Drive Shaft Twist Inspection

(1). Inspect for scratches in shaft section

that passes through plenum chamber

(Ref. Figure 601 and Figure 602) Following

fairing tube. Such scratches indicate

inspection determines if drive shaft has been

possible contact with tube edges at

torsionally strained to extent that permanent

bulkhead openings.

twist exists.

(2). Inspect for evidence of torsional

(1). Hand-turn main rotor until two white

buckling or shaft bending as result of

stripes (A, Figure 601) are aligned.

blade strike or hard ground contact by

lower stabilizer.

(2). Look inboard from tail rotor side of

helicopter and locate two white stripes

(3). Inspect for corrosion.

(B, Figure 601). Stripe on input shaft

bearing retainer flange of tail rotor

(4). Inspect for evidence of shaft damper

transmission is located at approximate

sleeve bond failure (sleeve shifting)

ly 2 o'clock, looking aft. Stripe on

from excessive heat or loads.

coupling should be at approximately 10

(5). If there is abnormal shaft vibrations,

o'clock, looking forward. Both stripes

check damper friction and shaft

should be aligned.

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3. Tail Rotor Drive Shaft Damper Inspection

NOTE: Tail rotor drive shaft must be removed

to perform following inspection.

(Ref. Figure 603)

(2). Inspect damper for correct drag friction

NOTE: If there is excessive drive shaft vibra

adjustment.

tion as shaft passes through first critical

rpm range, probable cause is defective or

(3). Inspect inside diameter of damper for

loose damper.

excessive wear. If diameter is more

than 3.035 inches (7.7089 cm), damper

(1). Inspect damper for shaft clearance as

must be replaced.

follows:

(4). Adjust friction damper as necessary to

(a). Remove boom-bolts access cover.

achieve the required drag as follows:

(b). Inspect tail rotor drive shaft damper

(a). Fabricate friction-checking tool.

and support structure for broken,

cracked or bent parts.

(b). Using 0-10 pound spring scale,

measure force required to move

(c). Displace damper so that it touches

damper radially on bulkhead. Fric

tail rotor drive shaft.

tion must be adjusted so that pull of

(d). Use wire gage to measure damper to

2 ±0.25 pounds (0.91 ±0.11 kg) is

shaft clearance 180° from contact

required to slide damper between

point. Minimum acceptable clearance

plate and support bracket.

is 0.020 inch (0.508 mm).

NOTE: Minimum of one washer must always

(e). Repeat steps (c). and (d). above at 90°

remain between each spring and plate.

intervals from initial check point.

(c). To increase friction, add thin washers

(f). Dampers not meeting minimum

between springs and plate. To

clearance of 0.020 inch (0.508 mm) at

decrease friction, remove washers.

four equidistant points are to be

(Add or remove same number of

replaced.

washers at each spring.)

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MAINTENANCE MANUAL

TAIL ROTOR DRIVE SHAFT

REPAIRS

1. Tail Rotor Drive Shaft Repair Procedure

depth of a dent is 0.040 inch (1.016

mm). Dents that raise material require

that shaft be replaced.

Consumable Materials

(Ref. Section 91−00−00)

2. Tail Rotor Drive Shaft Index Stripe

Item

Nomenclature

Application

CM206

Chemical coating

CM318

Primer

(Ref. Figure 601 and Figure 602)

CM801

Abrasive paper, silicon carbide

CM803

Crocus cloth

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

Nicks and scratches no deeper than 0.0015

CM311

Coating, logo white / Thinner

inch (0.0381 mm) are allowable without

rework but require finish protection with

chemical film (CM206). Other surface damage

If any of the four white index stripes used for

shall be evaluated and repaired according to

twist inspection of tail rotor drive shaft are

limits specified below. Use grade 400 abrasive

indistinct or do not exist, paint (CM311)

paper (CM801) to smooth out and blend repair

replacement aligning index stripes as follows:

area into surrounding material until damage

is completely removed; then polish with crocus

To prevent damage to gearbox

CAUTION

cloth (CM803) to equal original finish. Apply

coupling during and after shaft

finish protection with chemical film and two

removal, provide good level support for both

coats of primer (CM318).

tail rotor transmission and shaft, as the

weight of these items might buckle the cou

Any section of shaft that ap

pling.

CAUTION

pears to be scratched, nicked or

corroded in a previously reworked area

NOTE: Any time the associated tail rotor drive

must not be repaired a second time. Remove

shaft units are removed or replaced, an in

such shaft from further service. Replace any

dexing check and re-application of index

shaft that has damage in excess of following

marks is required.

limits.

(1). Remove tail rotor transmission and

(1). Scratches 0.007 inch (0.178 mm) deep

drive shaft as an assembly.

to maximum length of 1.00 inch (2.54

cm) at any random angle may be

(2). Inspect tail rotor drive shaft for

repaired.

evidence of torsional twist or buckling.

(2). Scratches 0.010 inch (0.254 mm) deep

(3). Remove any old index stripes.

to maximum length of 0.250 inch (6.35

(4). Apply white index stripe 0.120 inch

mm) at any random angle may be

(3.048 mm) wide and 0.250 inch (6.35

repaired.

mm) long onto tail rotor transmission

(3). Circumferential scratches 0.004 inch

input shaft bearing flange, at approxi

(0.102 mm) deep may be repaired.

mate 10 o'clock position (viewed looking

forward), so it can be seen when viewed

(4). Smoothly contoured dents are allowable

on left side of tailboom.

when ratio of dent diameter to dent

depth is at least 15:1; for example,

(5). Apply white index stripe 0.120 inch

when depth is 0.040 inch (1.016 mm)

(3.048 mm) wide and any length, on the

minimum acceptable diameter is 0.60

aft coupling in line with index stripe on

inch (15.24 mm). Maximum acceptable

tail rotor gearbox retainer.

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(6). Install tail rotor drive shaft.

mm) long on boom bulkhead doubler

(Sta. 137.50), at approximately 6 - 8

(7). Align index stripes on tail rotor gearbox

o'clock position looking forward.

bearing retainer and aft coupling.

(8). Remove tail rotor bellcrank access door

(10). Apply a corresponding joining index

at the forward left side of fuselage boom

stripe on the tail rotor drive shaft at

fairing and observe the area where tail

Sta. 137.50, approximately 0.120 inch

rotor drive shaft passes through the

(3.048 mm) wide and 0.50 inch (12.70

fairing forward bulkhead.

mm) long.

(9). Apply white index stripe 0.120 inch

(3.048 mm) wide and 0.50 inch (12.70

(11). Install all access doors and covers.

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NOTAR) ANTI−TORQUE SYSTEM DRIVE SHAFTS

MAINTENANCE PRACTICES

1. Anti−Torque System Drive Shafts

coupling and remove three bolts and

washers that secure fan gearbox drive

The Fan Gearbox Drive Shaft connects the

shaft to input shaft coupling on fan

main transmission and the fan gearbox. The

transmission gearbox. Support drive

total drive shaft length is approximately 14

shaft and output shaft coupling on

inches long. Flanges on each end of the shaft

main transmission.

attach to flexible (Kamatic) type joint coupling

on the main transmission output shaft and fan

(6). Remove fan gearbox (Ref. Sec.

gearbox input shaft.

63-25-30).

The Fan Inter-Connecting Drive Shaft is

(7). Remove fan gearbox drive shaft by

equipped with a kamatic flexible-type joint

removing three bolts and washers from

and mounting flange (coupling) at each end.

output shaft couping on main transmis

The shaft connects the fan gearbox to the fan

sion.

assembly by (two) couplings mounted on the

B. Fan Gearbox Drive Shaft Installation

output shaft of the fan gearbox and input shaft

of the fan assembly. The fan pitch control rod

(Ref. Figure 201) Whenever main transmis

is routed through the center of the inter-con

sion, fan gearbox, transmission couplings,

nect drive shaft.

coupling shims, fan gearbox drive shaft

assembly have been replaced, start installation

2. Fan Gearbox Drive Shaft Replacement

with step (1). below. If none of these compo

nents have been replaced, and only installa

A. Fan Gearbox Drive Shaft Removal

tion is involved, start with step (3). below.

(Ref. Figure 201)

Consumable Materials

(1). Remove fan gearbox drive shaft access

(Ref. Section 91−00−00)

doors and covers, upper aft section

Item

Nomenclature

fuselage and interior trim panels as

CM111

Grease, aircraft

required.

CM112

Anti-seize compound high temperature

(2). Remove tailboom fairing and tailboom

CM115

Grease, oscillating bearing

(Ref. Sec. 53-40-30).

CM318

Primer

(3). Remove fan pitch control rod (Ref. Sec.

67-20-30).

NOTE: Kamatic couplings do not require fail

safe bolts or sockets. When installing

(4). Remove fan inter-connecting drive

369D25501-9 Kamatic coupling, install

shaft (Ref. Fan Inter-Connect Drive

SKCP2554-15 coupling bolt supplied with

Shaft Replacement).

the Kamatic coupling or 369D25503-1 bolt.

If fan gearbox drive shaft is replaced for

WARNING

torsional buckling, replace and discard

main transmission output gear shaft

D To prevent damage to the engine in

coupling, fan gearbox coupling and both

stall F.O.D. cover over engine air in

coupling bolts.

let.

(1). Coat coupling splines with grease

D To prevent damage to shaft provide

(CM111) and coupling bolt threads with

level support for fan transmission

anti-seize compound (CM112) before

drive shaft during removal or instal

assembly. Install coupling onto fan

lation.

gearbox input shaft and torque coupling

(5). Gain access thru plenum chamber and

bolt to 250 - 300 inch-pounds (28.25

remove drive shaft access panel to aft

- 33.90 Nm) plus drag torque. Check

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coupling bolt for drag torque service

(b).

Pull and hold fan output pinion shaft

ability of 25 inch-pounds (2.82 Nm)

of main rotor transmission aft (out of

minimum, 200 inch-pounds (22.60 Nm)

transmission) to remove end play. If

maximum.

rotor brake is installed, ensure that

brake pucks do not restrict axial

travel of fan output shaft.

(2).

Coat forward coupling splines with

grease (CM111) and coupling bolt

(c).

Remove end play in fan transmission

threads with anti-seize compound

by applying force to the coupling in

(CM112) before assembly. Install

opposite direction of operation while

coupling onto main transmission output

still holding forward coupling of drive

shaft and torque coupling bolt to 250 -

shaft on main transmission. Do not

300 inch-pounds (28.25 - 33.90 Nm)

push fan drive shaft fwd or aft.

plus drag torque. Check coupling bolt

for drag torque serviceability of 25

(d).

Using feeler gage, measure gap

inch-pounds (2.82 Nm) minimum, 200

between forward coupling flange and

inch-pounds (22.60 Nm) maximum.

flange of fan drive shaft using

average of 3 readings. Record the

gap.

(3).

Support drive shaft and position to

align with fan transmission coupling on

(e).

Adjust the number of shims

main transmission.

(369A5516-3, -5, -7, or -9). Using

measured gap from step 4 above, add

or remove required number of shims

(4).

Install fan gearbox with four mounting

behind the coupling of main trans

bolts and torque to 70 - 90 inch

mission output pinion shaft or

pounds (7.90 - 10.17 Nm); torque-

between fan gearbox forward cou

stripe bolts.

pling to obtain specified gap of

0.010-0.020 inch (0.254-0.508 mm).

NOTE: If re-shimming is required, removal

and installation of the fan gearbox is neces

NOTE: All shims may be removed from forward

sary to obtain the specified gap between the

or aft coupling if required.

coupling flange and flange of drive shaft.

(f). Coat forward coupling splines with

grease (CM111) and coupling bolt

(5). Install three bolts and washers to

threads with anti-seize compound

connect fan gearbox coupling to drive

(CM112) before assembly. Install

shaft; torque bolts to 80 - 100 inch-

coupling and torque coupling bolt to

pounds (9.04 - 11.30 Nm) plus drag

250 - 300 inch-pounds (28.25 -

torque.

33.90 Nm) plus drag torque. Check

coupling bolt for drag torque service

ability of 25 inch-pounds (2.82 Nm)

(6). Align forward end of drive shaft with

minimum, 200 inch-pounds (22.60

coupling on main transmission output

Nm) maximum.

gearshaft. Partially install three bolts

as an alignment aid but do not tighten.

(8). Install three bolts and washers at

forward coupling; torque bolts to 80 -

(7). Obtain 0.010-0.020 inch (0.254-0.508

100 inch-pounds (9.04 - 11.30 Nm)

mm) gap between forward flange of the

plus drag torque.

fan gearbox drive shaft and flange of

(9). Slowly rotate drive shaft and check for

forward coupling using the following

not less than 0.25 inch (6.35 mm)

procedure:

clearance between shaft and fairing

tube at Sta. 137.50. In addition, check

(a). Ensure alignment bolts in previous

for minimum clearance of 0.190 inch

step are backed off between

(4.83 mm) between shaft and cooling

0.050-0.100 inch (1.270-2.540 mm).

blower scroll.

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(10). Install fan gearbox (Ref. Sec.

(1). Replace bent shaft. Other damage

63-25-30).

(scratches, nicks, etc.) that exceeds

repairable limits also requires shaft

(11). Install inter-connecting drive shaft

replacement.

(Ref. Fan Inter-Connect Drive Shaft

(2). Inspect for scratches in shaft section

Replacement)

that passes through plenum chamber

(12). Install fan pitch control; control rod

fairing tube. Such scratches indicate

(Ref. Sec. 67-20-30).

possible contact with tube edges at

bulkhead openings.

(13). Install tailboom and fairing (Ref. Sec.

(3). Inspect for evidence of torsional twist,

53-40-30).

buckling or shaft bending as result of

blade strike or hard ground contact.

(14). Check anti-torque flight control rigging

(Ref. Sec. 67-20-30).

(4). Inspect for corrosion.

(15). Install all access doors and covers, and

4. Fan Gearbox Drive Shaft Repair

interior trim panels.

Procedure

3. Fan Gearbox Drive Shaft Inspection

For information on repair procedures, refer to

Sec 63-15-10, Tail Rotor Drive Shafts Repair

Inspect shaft as described below.

Procedure.

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5. Fan Inter−Connect Drive Shaft

Do not exceed 0.100 inch (2.540

CAUTION

Replacement

mm) shim thickness in either of

the two flange locations. Shim thickness in

(Ref. Figure 201)

both locations to be within 0.020 inch (0.508

mm) of each other.

A. Fan Inter−Connect Drive Shaft Removal

(4). Adjust the shim thickness between the

forward flange and the aft flange of the

(1). Remove fan inlet screen and fan

inter-connect drive shaft and the two

transmission cover (Ref. Sec.

couplings.

53-30-30).

(5). Install shims to obtain the specified

(2). Remove tailboom fairing and tailboom

0.010-0.020 inch (0.254-0.508 mm)

(Ref. Sec. 53-40-30).

gap. Install inter-connect drive shaft

with eight mounting bolts and washers.

(3). Remove fan pitch control rod (Ref. Sec.

Torque forward and aft mounting bolts

67-20-30).

50 - 70 inch-pounds (5.65 - 7.91 Nm)

plus drag torque.

To prevent damage to the shaft

CAUTION

(6). Install fan pitch control; control rod

and couplings during and after

(Ref. Sec. 67-20 -30).

removal, provide level support for inter-

connecting drive shaft.

(7). Install tailboom and fairing (Ref. Sec.

53-40-30).

(4). Remove four mounting bolts and

washers (2 places) and remove shims at

(8). Check control rigging (Ref. Sec.

both ends of inter-connect drive shaft,

67-20-30).

remove inter-connect drive shaft.

(9). Install access panels and covers (Ref.

Retain shims for reinstallation.

Sec. 53-30-30).

B. Fan Inter−Connect Drive Shaft

6. Inter−Connect Drive Shaft Inspection

Installation

Install inter-connect drive shaft to obtain

Consumable Materials

0.010-0.020 inch (0.254-0.508 mm) gap

(Ref. Section 91−00−00)

between the forward flange of the inter-con

Item

Nomenclature

nect drive shaft and the coupling aft flange as

CM318

Primer

follows:

(1). Inspect drive shaft coupling for dents,

(1). Install inter-connect drive shaft, install

cracks, scratches, nicks, rust spots and

8 mounting bolts and washers except

evidence of joint separation from shaft

leave the 4 mounting bolts on the

or outside edges.

forward flange of the inter-connect

drive shaft backed off 0.050-0.100 inch

(2). Inspect drive shaft tube between

(1.270-2.540 mm) and torque the four

coupling for dents, scratches, cracks or

aft mounting bolts 50 - 70 inch-

corrosion pits.

pounds (5.65 - 7.91 Nm).

(a). Measure depth and diameter of

(2). Pull and hold the coupling on the fan

dents. Dents that blend smoothly into

gearbox Aft to remove end play.

surrounding surface area with no

sharp change in contour and do not

(3). With a feeler gage measure gap (aver

exceed 0.010 inch (0.254 mm) depth

age of 4 readings) between the flange of

are acceptable. Dents not within

the inter-connect drive shaft and the

these limits require removal of shaft

coupling.

from service.

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(b). Measure depth of cracks, nicks,

be more than 10 percent of original

corrosion pits or scratches; length

material thickness.

and direction are not limited. Maxi

(a). Completely remove defect. Maintain

mum depth allowed before rework is

smooth transition into surrounding

0.005 inch (0.127 mm).

surface.

(c). Check suspected cracks using dye

(b). Use grade 400 wet or dry abrasive

penetrant. If crack indication ap

paper (CM801) for preliminary

pears, remove coating from area.

finishing, and then polish with crocus

cloth (CM803).

(d). Re-inspect suspected area using

magnetic-particle or dye-penetrant

(c). After rework, check shaft tube wall

methods. If crack does not reappear,

thickness in repair area.

touch up cleaned area with primer

coating (CM318) and return part to

(d). Apply primer coating (CM318) for

service.

corrosion protection.

(3). Inspect all attaching hardware for

8. Transmission and Fan Coupling

serviceable condition. Discard and

Inspection

replace defective hardware.

The following procedures is for inspection of

fan gearbox and fan input coupling. For

NOTE: Perform inspection steps (4). and (5).

information on Kamatics coupling inspection,

below only if shaft damage is suspected.

refer to Sec. 63-10-00.

(4). Inspect shaft tube for out-of-round

(1). Inspect coupling splined section and

condition, which shall not exceed 0.060

flange for cracks, scratch, nicks, dent

inch (1.524 mm).

and corrosion pits. No cracks are

allowed. Maximum depth of other

(5). Inspect shaft for straightness. Shaft

defects allowed before rework is 0.005

shall be straight within 0.030 inch

inches.

(0.762 mm) at all locations relative to

centerlines of two flange mounting bolt

(2). Inspect coupling speedi-sleeve for wear,

patterns.

security of attachment to coupling.

7. Inter−Connect Drive Shaft Repair

9. Gearbox and Fan Coupling Repair

The following procedures is for repair of fan

Consumable Materials

gearbox and fan input coupling. For informa

(Ref. Section 91−00−00)

tion on Kamatic coupling repair, refer to Sec.

Item

Nomenclature

63-10-00.

CM318

Primer

Consumable Materials

CM801

Abrasive paper, silicon carbide

(Ref. Section 91−00−00)

CM803

Crocus cloth

Item

Nomenclature

CM318

Primer

(1). Repair of drive shaft Kamatic flexible

CM801

Abrasive paper, silicon carbide

type joint is limited. Repairs to spring

CM803

Crocus cloth

area are not allowed. No cracks are

allowed.

(1). Repair damage to splines section and

(2). Repair drive shaft tube area damage

flange of coupling that is no deeper

that is no deeper than 0.005 inch (0.127

than 0.005 inch (0.127 mm). Use

mm). Maximum depth after repair is

abrasive paper (CM801) grade 400 -

0.010 inch (0.254 mm). The maximum

600 and crocus cloth (CM803) to

thickness of material removed shall not

completely remove and polish out

Page 206

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

defect. Maximum depth after rework is

0.010 inch (0.254 mm). Apply primer

Special Tools

(CM318) to repaired area.

(Ref. Section 91−00−00)

Item

Nomenclature

(2). After rework, check coupling wall

ST604

Coupling socket

thickness in repair area. The maximum

thickness of material removed shall not

A. Transmission Coupling / Fan Coupling

be more than 10 percent of original

Removal

material thickness.

(1). Remove nut from shaft using coupling

socket (ST604) and coupling holding

10. Transmission Coupling / Fan Coupling

fixture tool; remove coupling.

Replacement

B. Transmission Coupling / Fan Coupling

(Ref. Figure 202)

Installation

(1). Slide coupling onto support shaft.

Consumable Materials

(2). Install nut using anti-seize compound

(Ref. Section 91−00−00)

(CM113) as required. Torque nut to 800

Item

Nomenclature

- 1000 inch-pounds (90.39 - 112.98

CM113

Anti-seize compound low temperature

Nm) plus drag torque using coupling

socket (ST604) and holding fixture.

G63-1023A

Figure 202. Fan Interconnect Drive Shaft Coupling Installation

Page 207

63-15-30

Revision 20

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

P/N 369D25100

369D25100 MAIN TRANSMISSION

MAINTENANCE PRACTICES

1. Main Transmission

(7). Drain oil from transmission.

The main transmission is secured to the

(8). Disconnect tail rotor output shaft seal

underside of the main rotor mast support

drain line, input shaft seal drain line

structure pan by four structure bolts, washers,

and two hoses that attach to lubrication

and nuts. The transmission is a two-stage

pump.

speed reduction unit. The first reduction stage

is for the tail rotor drive system and accessory

(9). With assistance, support transmission;

drive trains. The second stage is for further

then remove four nuts and washers

reducing rpm for the main rotor. The transmis

from mast support structure studs.

sion housing is magnesium alloy. The accesso

ry gear train drives a rotor tachometer

Lower transmission with ex

generator and the transmission oil pump that

CAUTION

treme care to prevent contact

are mounted on drive pads at the aft end of the

between tail rotor drive coupling and sur

transmission. The transmission is cooled by air

rounding structure. Any dents, nicks or

drawn through a cooling blower and routed

scratches on coupling diaphragm requires

through the transmission oil cooler. Access to

that coupling be scrapped. Use care to pro

the main transmission is attained by entrance

tect oil pressure sender and chip detector

into the passenger compartment.

terminal studs from damage during handl

ing or when placing transmission on any

2. Main Transmission Buildup and

surface.

Replacement

A. Main Transmission Removal

(10). With assistance, carefully lower

transmission from mounting studs.

(Ref. (Ref. Figure 201)

NOTE: Cover top opening of transmission to

(1). Remove sound insulation and transmis

prevent entry of foreign material. Residual

sion access covers (Ref. Sec. 52-40-00).

operating lubricant is an approved preser

vative for transmission shipment or storage.

(2). Remove main transmission drive shaft

(Ref. Sec. 63-10-00).

(11). Perform the following steps as applica

ble to strip main transmission.

(3). Remove cooling blower (Ref. Sec.

63-21-00).

(a). Remove tachometer generator.

(4). Remove anti-torque drive shaft (Ref.

Sec. 63-15).

(b). Remove coupling bolt, coupling and

shim from tail rotor output shaft.

NOTE: Removal of main rotor drive shaft (step

e. below) is optional. If help is not available

(12). Remove coupling bolt, coupling, shim,

to rotate rotor hub for spline alignment,

drive pulley and pulley guard from

shaft removal simplifies reinstallation of

main transmission input shaft.

transmission.

(a). Remove input shaft seal drain

(5). Remove main rotor drive shaft (Ref.

connector (Ref. Figure 202).

Sec. 63-10-00).

(6). Disconnect wires from tachometer

(b). Install suitable covers and plugs to

generator, two chip detectors and oil

protect all openings, including

pressure sender.

threaded holes.

Page 201

63-20-00

Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

P/N 369D25100

COUPLING BOLT

COUPLING (KAMATIC)

MAIN ROTOR

DRIVE SHAFT

TAIL ROTOR

MAST BASE

DRIVE SHAFT

FAILSAFE SOCKET

(NOTE 2)

COUPLING

(BENDIX)

FAILSAFE COUPLING

DEBRIS

BOLT

COVER

OUTPUT SHAFT

LAMINATED SHIM

OUTPUT SHAFT

COOLING BLOWER

FILLER

PLUG

COUPLING

O-RING

INPUT SHAFT PULLEY GUARD

(NOTE 1)

INTERNAL-

PULLEY

SEAL

WRENCHING

(NOTE 3)

BOLT

(NOTE 3)

LAMINATED SHIM

SAFETY WIRE

ÇÇÇÇ ÇÇÇÇ

Ç ÇÇ ÇÇ ÇÇ

ÇÇÇÇ ÇÇÇÇ

ÇÇÇ ÇÇÇ NOTES:

SEALANT

O-RING MUST BE CEMENTED IN PLACE BEFORE INSTALLING TRANSMISSION.

(NOTE 4)

NOT USED WITH KAMATIC COUPLING.

SEAL MUST BE CEMENTED IN PLACE BEFORE INSTALLING TRANSMISSION.

FILLER SEAL INSTALLATION

FILL CUT IN SEAL WITH SEALANT (CM430).

G63-2004B

Figure 201. 369D25100 Main Transmission Installation

Page 202

Revision 20

63-20-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

P/N 369D25100

B. Main Transmission Installation

especially area contacted by O-ring on

top of transmission.

(Ref. Figure 201)

Damage to main rotor drive

CAUTION

shaft or main transmission

Consumable Materials

splines can occur during installation. Care

(Ref. Section 91−00−00)

should be taken while meshing drive shaft

Item

Nomenclature

splines into transmission output splines to

CM111

Grease, aircraft

prevent damage.

CM112

Anti-seize compound high temperature

(3). With assistance, slowly and evenly lift

CM121

Preservation oil

and position transmission in place on

CM125

Oil

mounting studs.

CM126

Oil, turbine

(4). Install four washers and nuts; torque to

CM234

Solvent, dry-cleaning

60 - 80 inch-pounds (6.78 - 9.04

CM417

Cement

Nm).

CM425

Sealing compound

(5). If transmission is new, drain any

CM430

Sealant, solvent resistant

residual preservative oil. Service

transmission with lubricating oil

(CM125 or CM126) (Ref. Sec.

(1). Perform the following steps as applica

12-00-00).

ble to build up main transmission prior

to installation.

(6). Connect wiring to tachometer genera

tor, two chip detectors and oil pressure

(a).

Install one preliminary 0.010 inch

switch.

(0.250 mm) shim on tail rotor output

shaft to prevent coupling bolt from

(7). Install anti-torque drive shaft (Ref.

bottoming in shaft.

Sec. 63-15-10/30).

(b).

Coat coupling splines with grease

When reinstalling main rotor

CAUTION

(CM111) and coat bolt threads with

drive shaft, check that there is

anti-seize compound (CM112) before

no gap between shaft mounting flange and

assembly. Install shaft coupling and

rotor hub before tightening installation

temporarily tighten coupling bolt to

bolts. Gap indicates that shaft splines are

approximately 250 inch-pounds

not correctly meshed in transmission.

(28.25 Nm).

(8). If main rotor drive shaft has been

removed, apply coating of lubricating

(c).

Install tachometer generator. With

rotor brake installed, ensure electri

oil (CM121) on shaft before reinstalla

cal receptacle is at 11 o'clock position.

tion and install drive shaft (Ref. Sec.

63-10-00).

(d).

Install input shaft seal drain connec

(9). Connect tail rotor output shaft seal

tor, bonding it in place with sealing

drain line and input shaft seal drain

compound (CM425).

line and two hoses that attach to

(e).

Bond main rotor output shaft O-ring

lubrication pump.

in place with cement (CM417).

(10). Install cooling blower (Ref. Sec.

(f).

Bond filler seal to transmission with

63-21-00).

cement (CM417).

(11). Coat input drive coupling splines with

grease (CM111) and coat bolt threads

(g).

If filler is safetied to case bolt, cut a

with anti-seize compound (CM112)

small section from seal and bond in

before assembly. Install pulley guard,

place. After bonding, fill gap in seal

drive pulley, shim, coupling and

with sealant (CM430).

coupling bolt and temporarily tighten

(2). Use clean, absorbent cloth to clean pan

coupling bolt to approximately 250

beneath main rotor mast support,

inch-pounds (28.25 Nm).

Page 203

63-20-00

Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

P/N 369D25100

NOTE: Refer to Sec. 63-10-00, Main Transmis

4. Main Transmission Repair Procedure

sion Drive Shaft Installation for coupling

(Ref. Figure 201) Replace electrical compo

shimming, coupling torque and drive shaft

nents, breather-filler, filler screen, externally

installation.

accessible O-rings, lubrication pump, filter,

input shaft oil seal and tail rotor output shaft

oil seal if defective. Dents in outer surface of

(12). Install main transmission drive shaft

transmission housing deeper than 0.10 inch or

(Ref. Sec. 63-10-00).

covering more than 0.60 square inch (3.87 cm²)

area require replacement of transmission (for

repairs not covered in this section, Ref. COM).

(13). Ground run helicopter (refer to appro

This procedure is applicable to dents not

priate PFM) and check drive system for

exceeding specified limits.

excessive vibration and unusual noise.

Verify absence of oil over-temperature

and low pressure indications. Inspect

Consumable Materials

for oil leakage.

(Ref. Section 91−00−00)

Item

Nomenclature

CM234

Solvent, dry-cleaning

(14). Install access covers and sound insula

CM318

Primer

tion (Ref. Sec. 52-40-00).

CM411

Adhesive, epoxy

CM801

Abrasive paper, silicon carbide

3. Main Transmission Inspection Procedure

NOTE: Any evidence of lubricating oil leakage

(Ref. Figure 201) The following procedures provide

in a repair area requires replacement of

information for checking the main transmission

transmission.

for oil leakage and mechanical defect.

(1). Clean area with solvent (CM234) and

(1). Remove sound insulation and transmis

remove sharp edges with grade 320

sion access covers (Ref. Sec. 52-40-00).

abrasive paper (CM801).

(2). Apply coat of primer (CM318) on

repaired surface.

(2). Inspect transmission for oil leaks,

cracks, corrosion, secure electrical

(3). If dent is deeper than 0.030 inch (0.76

connections and correct oil level.

mm), fill depression with epoxy adhe

Evaluate oil leakage according to Fluid

sive (CM411) and blend to surrounding

Leak Analysis.

surfaces.

(4). Touch up re-worked area with paint

(Ref. Sec. 20-30).

Inspect all fluid lines for ade

CAUTION

quate clearance between struc

5. Input Drive Assembly − Oil Leakage

ture and components. Vibration may cause

Repair Procedure

chafing of lines and subsequent leaking.

(Ref. Figure 202) Use the following repair

procedure when oil leakage occurs between the

(3). Inspect four mounting flanges on main

main transmission housing and the pinion

transmission housing for corrosion and

bearing sleeve flange. Replace the

cracks. Check that transmission

369D25184-3 O-ring as follows.

mounting studs and nuts are secure.

This should be accomplished from

Consumable Materials

fuselage interior as well as exterior at

(Ref. Section 91−00−00)

main rotor mast base.

Item

Nomenclature

CM218

Alcohol, denatured

(4). Check that all safety wiring is intact.

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CSP-HMI-2

MAINTENANCE MANUAL

P/N 369D25100

(1). Remove the shaft interconnect, trans

(12). Remove alignment bolts and install

mission input coupling, drive pulley

assembly aid tool halves between

and guard, and cooling blower assembly

O-ring and input bearing sleeve flange.

(Ref. Sec. 63-21-00).

(Refer to Figure 203 for locally fabri

cated assembly aid tool.)

(2). Drain oil from input drive assembly

through the lower chip detector plug

(13). Install attaching hardware in blower

(Ref. Sec. 12-00-00).

mount, input pinion bearing sleeve, and

assembly aid tool.

(3). Remove attaching hardware securing

blower mount assembly (Ref. Sec.

(14). Tighten attaching hardware as follows:

63-21-00).

(a). Maintain an inward preload of the

(4). Install four alignment bolts in place of

assembly aid tool halves against the

attaching hardware for blower mount

input pinion bearing sleeve while

assembly. (Use any type of 2.00 inch

tightening the four attaching bolts

(5.08 cm) length x 1/4-28 diameter

equally.

bolt.)

(b). Tighten hardware until attaining a

(5). Install slide hammer tool on input drive

positive clamp-up between the main

assembly pinion.

housing, assembly aid tool halves,

and input pinion bearing sleeve

NOTE:

flange.

D It may be necessary to heat main housing

to move input drive assembly.

(15). Remove attaching hardware and slide

out the assembly aid tool halves.

D Any movement of more than 0.150 inch

(3.81 mm) may cause disengagement of

(16). Ensure the O-ring is seated in main

scavenge pump drive.

housing groove.

(6).

Gently tap input drive assembly away

(17). When O-ring is seated correctly,

from main housing no more than 0.150

reinstall input pattern shim between

inch (3.81 mm) to gain access to O-ring

main housing and input pinion bearing

between main housing and input

sleeve flange and reinstall hardware.

pattern shim.

(18). Tighten attaching hardware as follows:

(7).

Remove slide hammer tool from input

drive assembly pinion.

(a). Maintain an inward preload on input

pattern shim during the tightening

(8).

If required, cut defective O-ring for

sequence.

removal.

(9).

Clean and inspect pattern shim for

(b). Torque attaching hardware 65 - 75

distortion and ensure no overlap

inch-pounds (7.34 - 8.47 Nm).

condition exists at butt/split line of

shim.

(19). Inspect pattern shim to ensure no

overlap condition exists at butt/split

(10).

Clean area between main housing and

line.

input drive sleeve with alcohol (CM218)

to remove paint chips or other foreign

(20). Reinstall the shaft interconnect,

matter.

transmission input coupling, drive

pulley and guard, and cooling blower

(11).

Install new 369D25184-3 O-ring by

assembly (Ref. Sec. 63-21-00).

slipping over blower mount. Seat

O-ring in contact with the main

(21). Add oil to input drive assembly (Ref.

housing.

Sec. 12-00-00).

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63-20-00

Revision 36

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

P/N 369D25100

ASSEMBLY AID TOOL

COOLING BLOWER

MOUNTING BRACKET

SCAVENGE

PUMP DRIVE

(NOTE 1)

COOLING BLOWER

INPUT DRIVE

PULLEY SPACER

PINION

CHIP DETECTOR

INPUT SHAFT

SELF-CLOSING

DRAIN VALVE

INPUT SHAFT

NOTE 2

SEAL DRAIN

CONNECTOR

INPUT PATTERN

SHIM HALVES

NOTE 5

O-RINGS

CHANGE THIS

O-RING ONLY

NOTES:

MOVEMENT IN EXCESS OF

0.15 IN. (3.81 MM) MAY CAUSE

DISENGAGEMENT OF SCAVENGE

CLAMP-UP

PUMP DRIVE.

SHIM

INSTALL SLIDE HAMMER ON

INPUT DRIVE ASSEMBLY PINION.

INSTALL BETWEEN O-RING AND

ASSEMBLY AID

FLANGE ON INPUT PINION

TOOL HALVES

BEARING SLEEVE.

(NOTE 3)

USE SAME MOUNTING HOLES

FOR ALIGNMENT BOLTS.

MOUNT SHIM WITH SPLIT AT

INPUT PINION

3 AND 9 O'CLOCK POSITION.

BEARING SLEEVE

0.000-0.030 IN. (0.000-0.762 MM)

MAXIMUM GAP ALLOWED.

MOUNTING

O-RINGS

HARDWARE

(NOTE 4)

BLOWER MOUNT

ASSEMBLY

G63-2027A

Figure 202. Input Drive Assembly O−Ring Replacement

Page 206

Revision 20

63-20-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

P/N 369F5100

369F5100 MAIN TRANSMISSION

MAINTENANCE PRACTICES

1. Main Transmission

(8). Disconnect anti-torque output shaft

seal drain line, input shaft seal drain

The main transmission is secured to the

line and two hoses that attach to

underside of the main rotor mast support

lubrication pump.

structure pan by four structure bolts, washers,

and nuts. The transmission is a two-stage

NOTE: The following step will require an assis

speed reduction unit. The first reduction stage

tant to hold the transmission mount bolts

is for the tail rotor drive system and accessory

from the top of the helicopter and an assis

drive trains. The second stage is for further

tant to remove the nuts and washers.

reducing rpm for the main rotor. The transmis

sion housing is magnesium alloy. The accesso

(9). With assistance, support transmission;

ry gear train drives a rotor tachometer

then remove hardware securing

generator and the transmission oil pump that

transmission to mast support structure.

are mounted on drive pads at the aft end of the

transmission. The transmission is cooled by air

Lower transmission with ex

CAUTION

drawn through a cooling blower and routed

treme care to prevent contact

through the transmission oil cooler. Access to

between anti-torque drive coupling and sur

the main transmission is attained by entrance

rounding structure. Any dents, nicks or

into the passenger compartment.

scratches on coupling requires that coupling

be scrapped. Use care to protect oil pressure

2. Main Transmission Replacement

sender and chip detector terminal studs

from damage during handling or when plac

A. Main Transmission Removal

ing transmission on any surface.

(Ref. Figure 201)

(10). With assistance, carefully lower

transmission.

(1). Remove sound insulation and transmis

sion access covers.

NOTE: Cover top opening of transmission to

prevent entry of foreign material. Residual

(2). Remove main transmission drive shaft

operating lubricant is an approved preser

(Ref. Sec. 63-10-00).

vative for transmission shipment or storage.

(3). Remove cooling blower (Ref. Sec.

B. Main Transmission Installation

63-21-00).

(Ref. Figure 201)

(4). Remove anti-torque drive shaft (Ref.

Sec. 63-15-10/30).

Consumable Materials

(Ref. Section 91−00−00)

NOTE: Removal of main rotor drive shaft is op

Item

Nomenclature

tional. If help is not available to rotate rotor

hub for spline alignment, shaft removal sim

CM111

Grease, aircraft

plifies reinstallation of transmission.

CM112

Anti-seize compound high temperature

CM121

Preservation oil

(5). Remove main rotor drive shaft (Ref.

Sec. 63-10-00).

CM125

Oil

(6). Disconnect wires from tachometer

generator, two chip detectors and oil

(1). Use clean, absorbent cloth to clean pan

pressure sender.

beneath main rotor mast support,

especially area contacted by O-ring on

(7). Drain oil from transmission.

top of transmission.

Page 201

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Revision 20

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CSP-HMI-2

MAINTENANCE MANUAL

P/N 369F5100

Damage to main rotor drive

with anti-seize compound (CM112)

CAUTION

shaft or main transmission

before assembly.

splines can occur during installation. Care

When installing pulley and

should be taken while meshing drive shaft

CAUTION

guard, make sure the spring pin

splines into transmission output splines to

in pulley is fully engaged inside hole in

prevent damage.

pulley guard. If the spring pin does not align

NOTE: The following procedure will require

correctly with hole in pully guard, the

the assistance of another person.

torque will be incorrect.

(2). With assistance, slowly and evenly lift

(11). Install pulley guard, drive pulley, shim,

and position transmission in place.

coupling and coupling bolt and tempo

rarily tighten coupling bolt to approxi

(3). Install four washers and nuts; torque to

mately 250 inch-pounds (28.25 Nm).

900 - 1100 inch-pounds (101.69 -

124.28 Nm) plus drag torque.

NOTE: Refer to Sec. 63-10-00, Main Transmis

sion Drive Shaft Installation and for cou

(4). If transmission is new, drain any

pling shimming, coupling torque and drive

residual preservative oil. Service

shaft installation.

transmission with lubricating oil

(CM125) (Ref. Sec. 12-00-00).

(12). Install main transmission drive shaft

(Ref. Sec. 63-10-00).

(5). Connect wiring to tachometer genera

tor, two chip detectors and oil pressure

(13). Ground run helicopter (refer to appro

switch.

priate PFM) and check drive system for

excessive vibration and unusual noise.

(6). Install anti-torque drive shaft (Ref.

Verify absence of oil over-temperature

Sec. 63-15-10/30).

and low pressure indications. Inspect

When reinstalling main rotor

for oil leakage.

CAUTION

drive shaft, check that there is

(14). Install access covers and sound insula

no gap between shaft mounting flange and

tion.

rotor hub before tightening installation

bolts. Gap indicates that shaft splines are

3. Main Transmission Stripping

not correctly meshed in transmission.

(Ref. Figure 202)

(7). If main rotor drive shaft has been

removed, apply coating of preservative

(1). Remove tachometer generator.

oil (CM121) on shaft before reinstalla

tion and install drive shaft (Ref. Sec.

(2). Remove coupling bolt, coupling and

63-10-00).

shim from anti-torque output shaft.

(8). Connect anti-torque output shaft seal

(3). Remove coupling bolt, coupling, shim,

drain line and input shaft seal drain

drive pulley and pulley guard from

line and two hoses that attach to

main transmission input shaft.

lubrication pump.

(4). Remove input shaft seal drain connec

(9). Install cooling blower (Ref. Sec.

tor (Ref. Sec. 12-00-00).

63-21-00).

(5). Install suitable covers and plugs to

(10). Coat input drive coupling splines with

protect all openings, including threaded

grease (CM111) and coat bolt threads

holes.

Page 203

63-20-25

Revision 41

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

P/N 369F5100

4. Main Transmission Build−Up

(6). Using a new O-ring, install oil pressure

switch and safety with lockwire

(CM702).

(Ref. Figure 202)

(7). Bond main rotor output shaft O-ring in

place with cement (CM417).

Consumable Materials

(Ref. Section 91−00−00)

(8). Using two new O-rings, install exten

Item

Nomenclature

sion, screen and filler on transmission.

CM111

Grease, aircraft

Use 369A5169 shims to ensure filler is

angled no more than 30° from center

CM112

Anti-seize compound high temperature

facing forward.

CM417

Cement

CM425

Sealing compound

5. Main Transmission Inspection Procedure

CM702

Lockwire CRES

(Ref. Figure 201) The following procedures

provide information for checking the main

transmission for oil leakage and mechanical

(1).

Install one preliminary 0.010 inch

defect.

(0.254 mm) shim on anti-torque output

shaft to prevent coupling bolt from

(1). Remove sound insulation and transmis

bottoming in shaft.

sion access covers.

(2).

Coat coupling splines with grease

(2). Inspect transmission for oil leaks,

(CM111) and coat bolt threads with

cracks, corrosion, secure electrical

anti-seize compound (CM112) before

connections and correct oil level.

assembly. Install shaft coupling and

Evaluate oil leakage according to Fluid

temporarily tighten coupling bolt to

Leak Analysis.

approximately 250 inch-pounds

(28.25 Nm).

Inspect all fluid lines for ade

CAUTION

quate clearance between struc

(3).

Install tachometer generator. With

ture and components. Vibration may cause

rotor brake installed, ensure electrical

chafing of lines and subsequent leaking.

receptacle is at 11 o'clock position.

Torque nuts to 30 - 40 inch-pounds

(3). Inspect four mounting flanges on main

(3.39 - 4.52 Nm) plus drag torque.

transmission housing for corrosion and

cracks. Check that transmission

mounting nuts are secure.

(4).

Install input shaft seal drain connector,

bonding it in place with sealing com

(4). Check that all safety wiring is intact.

pound (CM425).

6. Main Transmission Repair Procedure

NOTE: On the 369F5100 transmission, the oil

pressure switch is mounted on the bottom,

(Ref. Figure 201) Replace electrical compo

right side, facing down.

nents, breather-filler, filler extension, filler

screen, externally accessible O-rings, scavenge

(5).

600N: Using a new O-ring, install

pump, lubrication pump, filter, input shaft oil

147D-2 snubber and torque to 155 -

seal and anti-torque output shaft oil seal if

165 inch-pounds (17.51 - 18.64 Nm).

defective. Dents in outer surface of transmis

369D/E/FF - 500N: Using a new

sion housing deeper than 0.10 inch (2.54 mm)

O-ring, install 369F5195-1 adapter

or covering more than 0.60 square inch (3.87

with teflon tape wrapped around

cm²) area require replacement of transmission

threads as required and torque to 155 -

(for repairs not covered in this section, Ref.

165 inch-pounds (17.51 - 18.64 Nm).

CSP-COM-5).

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MAINTENANCE MANUAL

P/N 369F5100

This procedure is applicable to dents not

(3). Remove attaching hardware securing

exceeding specified limits.

blower mount assembly.

(4). Using NAS603-64 jack screws at two

Consumable Materials

corners of the input quill, begin pulling

(Ref. Section 91−00−00)

the input quill from the transmission

Item

Nomenclature

housing. As required, operators may

CM234

Solvent, dry-cleaning

use 0.5-1.0 inch (12.70-25.40 mm) bar

stock or equivalent as spacers to put

CM318

Primer

under the jack screws to assist

CM411

Adhesive, epoxy

removing the input quill.

CM801

Abrasive paper, silicon carbide

NOTE: It may be necessary to heat main hous

ing to move input drive assembly.

NOTE: Any evidence of lubricating oil leakage

in a repair area requires replacement of

(5).

Gently screw input drive assembly

transmission.

away from main housing no more than

0.150 inch (3.81 mm) to gain access to

(1). Clean area with solvent (CM234) and

O-ring between main housing and

remove sharp edges with grade 320

input pattern shim.

abrasive paper (CM801).

(6).

Remove jack screws from input drive

(2). Apply coat of primer (CM318) on

assembly pinion.

repaired surface.

(7).

If required, cut defective O-ring for

(3). If dent is deeper than 0.030 inch (0.762

removal.

mm), fill depression with epoxy adhe

sive (CM411) and blend to surrounding

(8).

Clean and inspect pattern shim for

surfaces.

distortion and ensure no overlap

condition exists at butt/split line of

(4). Touch up re-worked area with paint

shim.

(Ref. Sec. 20-30-00).

(9).

Clean area between main housing and

7. Input Drive Assembly − Oil Leakage

input drive sleeve with alcohol (CM218)

Repair Procedure

to remove paint chips or other foreign

matter.

A. Input Pinion O−Ring Replacement

(10).

Install new O-ring by slipping over

(Ref. Figure 203) Use the following repair

blower mount. Seat O-ring in contact

procedure when oil leakage occurs between the

with the main housing.

main transmission housing and the pinion

(11).

Remove alignment bolts and install

bearing sleeve flange.

attaching hardware in blower mount

and input pinion bearing sleeve.

Consumable Materials

(Ref. Section 91−00−00)

(12).

Tighten attaching hardware as follows:

Item

Nomenclature

(a). Tightening the four attaching bolts

CM218

Alcohol, denatured

equally.

(b). Tighten hardware until attaining a

(1). Remove the shaft interconnect, trans

positive clamp-up between the main

mission input coupling, drive pulley

housing and input pinion bearing

and guard, and cooling blower assembly

sleeve flange.

(Ref. Sec. 63-21-00).

(13). Remove attaching hardware.

(2). Drain oil from input drive assembly

through the lower chip detector plug

(14). Ensure the O-ring is seated in main

(Ref. Sec. 12-00-00).

housing groove.

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MAINTENANCE MANUAL

P/N 369F5100

O-RING

SLEEVE

CRUSH SEAL

INPUT SEAL

O-RING

FAN MOUNT

BEARING RETAINER

BOLT

WASHER

BOLT

INPUT LABYRINTH SEAL

WASHER

INPUT PINION

LOCKNUT

INPUT

LOCKWASHER

NOSE BEARING

INPUT

BEARING

PULLEY SHIM

SHIM

SPACER

INPUT BEARING SHIM

O-RINGS

O-RING

INPUT SHAFT OUTER SLEEVE

INPUT BEARING

INPUT THRUST BEARING

O-RING

G63-2033B

Figure 203. Drive Assembly O−Ring Replacement

(15).

When O-ring is seated correctly,

(17). Inspect pattern shim to ensure no

reinstall input pattern shim between

overlap condition exists at butt/split

main housing and input pinion bearing

line.

sleeve flange and reinstall hardware.

(16).

Tighten attaching hardware as follows:

(18). Reinstall the shaft interconnect,

transmission input coupling, drive

(a). Maintain an inward preload on input

pulley and guard, and cooling blower

pattern shim during the tightening

assembly.

sequence.

(b). Torque attaching hardware 50 - 70

inch-pounds (5.65 - 7.91 Nm) plus

(19). Service the transmission (Ref. Sec.

drag torque.

12-00-00).

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MAINTENANCE MANUAL

P/N 369F5100

B. Input Pinion Seal Replacement

(c). Insert adapter and breaker bar into

socket.

(Ref. Figure 203) Use the following repair

procedure when oil leakage occurs at the input

(d). Turn locknut removal tee counter-

pinion seal.

clockwise, while holding spline socket

stationary, to remove nut.

NOTE:

(6). Using seal removal tool, remove seal

D If replacing a magnetic seal with a la

from input quill.

brynth seal, a speedi-sleeve must be

installed (Ref. COM, Sec. 63-20-25).

(7). Clean sealant from seal seating surface

in blower mount with denatured alcohol

D If installing a 369F5165-1 labrynth seal,

(CM218).

seal must be modified (Ref. COM, Sec.

63-20-25).

(8). Allow to air dry.

(9). Apply sealing compound (CM425) to

Consumable Materials

seal edge and mating surface in blower

(Ref. Section 91−00−00)

mount.

Item

Nomenclature

CM112

Anti-seize compound high temperature

(10). Insert seal into blower mount.

CM218

Alcohol, denatured

(11). Clean any excess sealant and allow

CM425

Sealing compound

sealant to cure per manufacturer's

instructions.

Special Tools

(12). Apply anti-seize compound (CM112) to

(Ref. Section 91−00−00)

non-serrated threads on pinion and

Item

Nomenclature

install locknut.

N/A

369F5100ATP-1 Locknut removal tool

NOTE: The following procedure requires two

people to accomplish.

(1).

Remove the main transmission drive

(a). Insert tee over locknut and put

shaft (Ref. Sec. 63-10-00, Main

cheater bar over one ear of tee.

Transmission Drive Shaft Replace

ment).

(b). Insert socket through center of tee to

engage splines on input shaft.

(2).

Remove nut from transmission input

coupling, drive pulley and guard (Ref.

(c). Insert adapter and breaker bar into

Sec. 63-10-00, Main Transmission

socket.

Drive Shaft Replacement), keep all

shims with coupling.

(d). Turn input shaft counter-clockwise,

while holding locknut stationary, to

(3).

Drain oil from input drive assembly

install nut.

through the lower chip detector plug

(e). Torque nut to 250 foot-pounds (339

(Ref. Sec. 12-00-00).

Nm). Loosen locknut and re-torque

(4).

Remove lockwasher.

to 183 - 225 foot-pounds (248 -

305 Nm).

(5).

Using locknut removal tool, remove

locknut.

(13). Install lockwasher.

NOTE: The following procedure requires two

(14). Reinstall input coupling with shims

people to accomplish.

previously removed (Ref. Sec.

63-10-00, Main Transmission Drive

(a). Insert tee over locknut and put

Shaft Replacement).

cheater bar over one ear of tee.

(15). Reinstall main transmission drive shaft

(b). Insert socket through center of tee to

(Ref. Sec. 63-10-00, Main Transmission

engage splines on input shaft.

Drive Shaft Replacement).

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MAINTENANCE MANUAL

P/N 369F5100

(16). Service transmission (Ref. Sec.

9. Main Transmission Run−In Procedure

12-00-00).

New (from the factory) transmissions must

have a run-in period to remove the corrosion

8. Main Transmission Filter Replacement

preventive coating from the coast-side of the

(Ref. Figure 202)

drive gears. If not done at installation, the

coating will come off, over time, and cause the

(1).

Remove interior trim and blower access

impending bypass button to pop.

door.

(1). Fly aircraft normally, monitoring the

(2).

Position container or cloth to catch

transmission chip detectors for metal

residual oil. Loosen and remove filter

particles, for the first 10 hours.

housing by turning counterclockwise.

NOTE: Ignore the impending bypass indicator

(3).

Remove filter element.

in the first 10 hours of flight.

(4).

Inspect filter element for metal par

(2). During the first 10 hours of flight time,

ticles. If metal particles are present,

perform at least three partial autorota

remove main transmission chip detec

tions (Ref. Pilots Flight Manual) to load

tors and inspect for other evidence of

the transmission on the coast side of

internal failure in gearbox.

the gears.

(5).

If filter is excessively clogged, flush

NOTE: Each autorotation should be at least 30

system and check filter bypass valve for

seconds in duration.

operation (Ref. COM).

(3). After 10 hours flight time has elapsed,

(6).

Install new filter element and new

replace filter element (Ref. Main

O-rings.

Transmission Filter Replacement).

(7).

Install housing and torque to 90 - 100

NOTE:

inch-pounds (10.17 - 11.30 Nm).

D Coating particles are black in color. Some

silver non-magnetic metallic particles

(8).

If necessary, replenish transmission oil

could be in the filter bowl, which are mag

supply.

nesium machining debris from manufac

turing.

(9).

Perform ground runup of helicopter and

check for oil leakage.

D Flushing transmission oil is preferred but

not necessary.

(10).

Reinstall, in order, blower access door

and interior trim.

(4). Reset the impending bypass indicator.

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MAINTENANCE MANUAL

MAIN TRANSMISSION LUBRICATION

AND COOLING SYSTEM

REMOVAL/INSTALLATION

1. Main Transmission Lubrication System

(4). Ground run helicopter (Ref. PFM) and

check pump interface for leaks per

The main transmission lubrication system

Fluid Leak Analysis (Ref. Sec. 63-20).

consists of a lubrication pump driven by the

Verify that pressure warning light is

transmission, an oil filter, oil cooler, oil cooler

not on at 55% N₂.

bypass valve, oil temperature sender, oil

pressure sender, liquid level plug, two chip

(5). Reinstall access covers and sound

detectors, a drain line from the tail rotor

insulation.

output shaft seal and a drain line from the

input shaft seal.

3. Main Transmission Lubrication Pump

Replacement (369F5100 Transmission)

2. Main Transmission Lubrication Pump

Replacement (369D25100 Transmission)

(Ref. Figure 402)

(Ref. Figure 401)

A. Main Transmission Lubrication Pump

Removal (369F5100 Transmission)

Removal (369D25100 Transmission)

(1). Remove sound insulation and transmis

sion access covers (Ref. Sec. 52-40).

sion access covers.

(2). Remove hardware that secure pump

housing to mounting pad.

(3). Remove pump and discard O-rings.

(3). Remove pump and discard three

O-rings.

B. Main Transmission Lubrication Pump

Installation (369F5100 Transmission)

Installation (369D25100 Transmission)

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

Item

Nomenclature

CM114

Petrolatum

CM114

Petrolatum

(1). Install new O-rings in ports and in

groove of pump sleeve. Apply light

coating of petrolatum (CM114) to both

O-rings and mating bores in transmis

sion to prevent damage to O-rings.

(2). Align square drive of pump with drive

shaft in transmission and carefully

press pump into place.

(3). Install attaching hardware; torque to

50 - 70 inch-pounds (5.65 - 7.91

40 - 50 inch-pounds (4.52 - 5.65 Nm)

Nm).

plus drag torque.

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MAINTENANCE MANUAL

(4). Ground run helicopter (Ref. PFM) and

tors and inspect for other evidence of

check pump interface for leaks per

internal failure in gearbox.

Fluid Leak Analysis (Ref. Sec. 63-20).

(5). If filter is excessively clogged, flush

Verify that pressure warning light is

system and check filter bypass valve for

not on at 55% N₂.

operation (Ref. COM).

(5). Reinstall access covers and sound

(6). Install new filter element and new

insulation (Ref. Sec. 52-40).

O-rings.

Main Transmission Filter Replacement

(7). Install and tighten housing.

(369D25100 Transmission)

(8). If necessary, replenish transmission oil

(1).

Remove interior trim and blower access

supply; then perform ground runup of

door.

helicopter and check split line for oil

(2).

Position container or cloth to catch

leakage.

residual oil. Loosen and remove filter

(9). Reinstall blower access door and

housing by turning counterclockwise.

interior trim.

(3).

Remove filter element.

6. Main Transmission Scavenge Pump

(4).

Inspect filter element for metal par

Replacement (369F5100 Transmission)

ticles. If metal particles are present,

remove main transmission chip detec

(Ref. Figure 402)

tors and inspect for other evidence of

A. Main Transmission Scavenge Pump

internal failure in gearbox.

Removal (369F5100 Transmission)

(5).

If filter is excessively clogged, flush

(1). Remove sound insulation and transmis

system and check filter bypass valve for

sion access covers (Ref. Sec. 52-40).

operation (Ref. COM).

(2). Remove hardware that secure pump

(6).

Install new filter element and new

housing to mounting pad.

O-rings.

(3). Remove pump and discard O-rings.

(7).

Install housing and torque to 70 - 100

inch-pounds (7.91 - 11.30 Nm).

B. Main Transmission Scavenge Pump

Installation (369F5100 Transmission)

(8).

If necessary, replenish transmission oil

supply; Then perform ground runup of

helicopter and check for oil leakage.

Consumable Materials

(Ref. Section 91−00−00)

(9).

Reinstall, in order, blower access door

Item

Nomenclature

and interior trim.

CM114

Petrolatum

Main Transmission Filter Replacement

(369F5100 Transmission)

(1). Install new O-rings in ports and in

groove of pump sleeve. Apply light

(1). Remove interior trim and blower access

coating of petrolatum (CM114) to both

door.

O-rings and mating bores in transmis

(2). Position container or cloth to catch

sion to prevent damage to O-rings.

residual oil. Loosen and remove filter

(2). Align square drive of pump with drive

housing by turning counterclockwise.

shaft in transmission and carefully

(3). Remove filter element.

press pump into place.

(4). Inspect filter element for metal par

(3). Install attaching hardware; torque to

ticles. If metal particles are present,

40 - 50 inch-pounds (4.52 - 5.65 Nm)

remove main transmission chip detec

plus drag torque.

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MAINTENANCE MANUAL

(4). Ground run helicopter (Ref. PFM) and

NOTE: MDHS Notice DN-72.1 provides in

check pump interface for leaks per

structions for modifying oil cooler drain sys

Fluid Leak Analysis (Ref. Sec. 63-20).

tem on early model helicopters to current

configuration.

7. Main Transmission Oil Cooler Bypass

(3). Remove oil drain tube and drain fitting.

Valve Replacement

(4). Detach oil cooler outlet duct.

(Ref. Figure 403) The oil cooler bypass valve

causes main transmission lubrication oil to

(5). Remove compressor cooling duct and

bypass the oil cooler when oil temperature is

pull oil cooler outlet duct away from oil

178° ±2°F (82° ±1°C) or less, or the following

cooler.

conditions exist: pressure differential of 25 psi

(6). Remove hardware that secures oil

(172 kPa) or higher across oil cooler with oil

cooler and oil cooler inlet duct to

temperature of 190°F (88°C) or higher.

firewall; remove oil cooler.

Excessive transmission oil temperature can be

caused by failure of oil cooler bypass valve to

(7). Remove covers from oil cooler by

seat in housing. Before installing new valve,

breaking lockwire and cutting sealant.

inspect seat within housing. If housing seat is

damaged, housing must also be replaced.

NOTE: MDHS Notice DN-23.2 contains infor

mation relative to installation of oil cooling

lines.

Consumable Materials

(Ref. Section 91−00−00)

B. Main Transmission Oil Cooler Installation

Item

Nomenclature

CM112

Anti-seize compound high temperature

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

(1). Prepare container for draining oil from

transmission oil cooler lines upstream

CM112

Anti-seize compound high temperature

of bypass valve housing through bypass

CM408

Adhesive, silicone rubber

valve port. Unscrew valve and drain oil

CM702

Lockwire CRES

in container. Install an AN806-12 plug

CM715

Tape, pressure sensitive

in housing to eliminate residual drip.

(2). Apply light coat of antiseize compound

(1).

Scrape old sealant and remnants of

(CM112) to valve threads and install

pressure-sensitive tape seals from oil

O-ring on valve. Torque valve to 50 -

cooler covers and reinstall covers with

60 inch-pounds (5.65 - 6.78 Nm).

(CM702) lockwire and sealant (CM408).

Use sealant to fill gaps (four places) at

(3). Replenish transmission oil lost during

ends of covers.

bypass valve removal (Ref. Sec.

12-00-00).

(2).

Make up four 0.125 inch (3.175 mm)

thick and four 0.250 inch (6.35 mm)

thick seals, all 0.750 inch (19.05 mm)

8. Main Transmission Oil Cooler

wide, from pressure-sensitive tape

Replacement

(CM715).

A. Main Transmission Oil Cooler Removal

(3).

Apply seals, fabricated in previous step,

on oil cooler and oil cooler covers. Cut

(1). Drain main transmission lubrication

holes in seals to accommodate bolts

system (Ref. Sec. 12-00-00).

(eight places).

(2). Remove two tubes that connect oil

(4).

Secure oil cooler and oil cooler inlet

cooler to oil cooler bypass valve hous

duct to firewall with four bolts, washers

ing.

and nuts.

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 20