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

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(b).

(369FF) Secure tail rotor transmis

to be 0.312-0.313 inch (7.9248-7.9502

sion to tailboom extension with four

mm) (Ref. CSP-COM-5 for bolt hole

bolts, eight washers and four nuts.

repair).

Torque nuts to 75 - 95 inch-pounds

(8.47 - 10.73 Nm) plus drag

(3). Check input shaft for:

torque.

(a). Axial play by moving shaft in and

(5). Apply torque stripe paint.

out; transmission must be cold. Axial

play is limited to 0.004 inch (0.102

(6). Between 2 and 10 hours of helicopter

mm) maximum.

operation (to allow parts to seat), check

the torque of each mounting nut as

(b). Measure runout; mark high and low

follows:

extremes on outer end of shaft with

grease pencil. Total indicated runout

(a). Using the drag torque previously

should be less than 0.002 inch (0.051

measured and noted, apply a torque

mm).

load of 75 - 95 inch-pounds (8.47 -

10.73 Nm) plus the noted drag

(4). Check output shaft for:

torque (noted for each individual

nut) to each mounting nut of the

(a). Axial play; no axial movement is

transmission.

permitted.

(b). Re-apply torque stripe paint.

(b). Measure runout; mark high and low

(7). Install tail rotor on tail rotor transmis

extremes on outer end of shaft with

sion (Ref. Sec. 64-20-00).

grease pencil. Total indicated runout

should be less than 0.0025 inch

(0.0635 mm).

(8). Connect chip detector wire. Torque nut

to 12 - 15 inch-pounds (1.36 - 1.69

Nm).

(5). While gently pulling out on input shaft,

check gearset backlash:

(9). Connect tail rotor drive shaft to main

transmission (Ref. Sec. 63-15-10).

(a). Two-bladed gearset backlash should

be 0.004-0.008 inch (0.102-0.203

(10). Drain residual preservative oil and

mm).

service transmission with lubricating

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

(b). Four-bladed gearset backlash should

be 0.0025-0.0050 inch (0.0635-0.127

3. Tail Rotor Transmission Inspection

mm).

(Ref. Figure 201)

NOTE: Although not required, placing marks

on end of output shaft provides guides for

NOTE: If following inspections reveal damage,

subsequent installation of tail rotor assem

repair according to instructions in CSP-

bly in a manner that reduces chances of

COM-5.

high frequency vibrations and lessens possi

bility of requirement for tail rotor balanc

(1). Check transmission for leaks, cracks

ing.

and corrosion. To evaluate oil leakage,

refer to Fluid Leak Analysis (Ref. Sec.

(6). Inspect all scoring or scratching of

12-00-00).

output shaft to determine if marks

penetrate through cadmium plating

(2). Inspect Sta. 284 bellcrank hole for

and into steel shaft. Penetration of steel

elongation; if elongation is suspected,

shaft is allowable to maximum depth of

measure hole diameter. Hole diameter

0.010 inch (0.254 mm).

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Revision 40

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

4. Tail Rotor Transmission Stripping

6. Tail Rotor Transmission Parts

Replacement

(Ref. Figure 201) Stripping of the tail rotor

transmission is not required following its

(Ref. Figure 202)

removal from the helicopter. Perform the

following stripping procedure if in preparation

Consumable Materials

for transmission shipment or storage only.

(Ref. Section 91−00−00)

Item

Nomenclature

Consumable Materials

CM114

Petrolatum

(Ref. Section 91−00−00)

CM222

1,1,1-Trichloroethane

Item

Nomenclature

CM311

Coating, logo white / Thinner

CM208

Barrier material

CM702

Lockwire CRES

(1). Remove coupling bolt and coupling from

NOTE: Replace liquid level plug, chip detector

input shaft.

and breather-filler using torque values in

following paragraphs. Lubricate mating

NOTE: For tail rotor transmission replace

bores of O-rings with petrolatum (CM114)

ment, further stripping is not required. A re

to prevent damage to O-rings. Repair other

placement transmission is equipped with all

components or replace tail rotor transmis

other accessories.

sion oil seals (Ref. COM).

(2). Drain oil from transmission (Ref. Sec.

(1). Chip Detector Torque valve body 50 -

12-00-00). Residual operating lubri

60 inch-pounds (5.65 - 6.78 Nm);

cant is approved internal preservative

detector 40 - 50 inch-pounds (4.52 -

for shipping or storage.

5.65 Nm). Safety with lockwire

(CM702).

(3). Wrap transmission in barrier material

(CM208) to protect shaft splines and

(2). Liquid Level Plug Torque liquid level

chip detector stud during handling,

plug to 50 - 60 inch-pounds (5.65 -

shipping or storage.

6.78 Nm). If level-lines and lettering of

liquid level plug cannot be made

5. Tail Rotor Transmission Buildup

parallel with axis of transmission

output shaft when plug is torqued

(Ref. Figure 201)

within 50 - 60 inch-pound (5.65 - 6.78

Nm) range, clean glass by firmly

rubbing with soft cloth, then mix white

Consumable Materials

coating (CM311) with equal amount of

(Ref. Section 91−00−00)

thinner and apply lines and lettering.

Item

Nomenclature

Safety with lockwire.

CM111

Grease, aircraft

CM112

Anti-seize compound high temperature

NOTE: Some models use an adapter with an

additional O-ring. On those models, install

adapter with O-ring, then install breather-

(1). Coat coupling splines with grease

filler.

(CM111) and coupling bolt threads with

(3). Oil Breather-Filler Torque breather-

anti-seize compound (CM112) before

filler to 45 - 55 inch-pounds (5.08 -

re-assembly.

6.21 Nm). If equipped with a 369A5429

(2). Install coupling and bolt. Torque

breather, hole in breather filler must be

coupling bolt to 250 - 300 inch-

directed rearward at final torque.

pounds (28.25 - 33.90 Nm) plus drag

Locating vent at any angle aft of output

torque. Check coupling bolt for drag

shaft centerline (viewed from above)

torque serviceability of 25 inch-

adequately directs vent rearward. One

pounds (2.82 Nm) minimum, 200

or two washers may be added between

inch-pounds (22.60 Nm) maximum.

O-ring and breather flange (one

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

washer changes orientation by approxi

(3). If contact occurs, rework tail rotor

mately 100 degrees). Safety with

transmission housing as follows:

lockwire.

(a). Chamfer the web on transmission

NOTE: If oil breather-filler assembly becomes

housing to dimensions shown in

clogged, use light air pressure, approxi

Figure 204.

mately 5 psig (34 kPa) or a 0.125 inch (3.175

Do not remove material in

mm) dia. rod applied into the threaded end

WARNING

excess of specified dimen

to dislodge debris. Ultrasonically clean

sion.

breather in solvent (CM222) for ten min

utes.

(b). Blend chamfer into existing radius at

the bottom and radius it at the top.

7. Input and Output Gearshaft Cover Oil

Width of chamfer must be

Leak Repair

0.060-0.090 inch (1.524-2.286 mm).

Repair oil leaks at input and output gearshaft

(c). Apply surface touchup treatment

cover by installing a protective sleeve (Speedi-

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

Sleeve) on the gearshaft area contacted by the

oil seal lip (Ref. COM).

(4). Record compliance of this rework in the

aircraft logbook.

8. Tail Rotor Transmission Housing

Assembly Rework (PN 369D25401)

AXIAL PLAY 0.005 IN.

(0.127 MM) MAX

(Ref. Figure 204) An interference condition

may exist between the tail rotor transmission

housing and the tail rotor control bellcrank

SIDE PLAY 0.004 IN.

with the tail rotor pedal at extreme right

(0.102 MM) MAX

position. The following procedure provides

inspection criteria and rework instructions, if

necessary, for the tail rotor transmission

housing to correct this condition should it

exist.

(1). With assistance, depress and hold right

tail rotor pedal to extreme right

position and inspect web area of tail

rotor transmission housing that comes

in close contact with tail rotor control

bellcrank. If adequate clearance exist

between transmission housing and

control bellcrank, no rework action is

necessary.

G63-2023A

(2). Sign off aircraft logbook to indicate

Figure 203. Tail Rotor Transmission Mount

completion of this inspection.

Stud Limits

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Revision 20

63-25-10

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

NOTAR® ANTI−TORQUE SYSTEM FAN TRANSMISSION

MAINTENANCE PRACTICES

1. Fan Transmission

B. Fan Transmission Installation

The function of the fan transmission is to step

(Ref. Figure 201)

up RPM from the main transmission output to

Do not carry or support trans

the fan via fan drive shaft, gears, and intercon

CAUTION

mission by coupling as damage

nect shaft. The transmission housing is made

can occur to coupling. During performance

of magnesium, and contains input and output

of maintenance on transmission, use extra

gear shafts, two angular contact bearings,

care to keep contaminants such as paint,

coupling, seals, packings, output cover assy,

dirt etc from areas around input and output

chip detector, sight glass, and oil breather

shaft seals.

assembly.

(1).

Install fan drive shaft (Ref. Sec.

2. Fan Transmission Replacement

63-15-30).

Remove and install fan transmission according

(2).

Locate and align transmission with

to the following procedures.

mounting holes on helicopter. Install

A. Fan Transmission Removal

four bolts and washers on transmission.

Torque bolts to 70 - 90 inch pounds

(Ref. Figure 201)

(7.90 - 10.17 Nm); torque-stripe bolts.

(1). Remove inlet screen, inlet fairing,

(3).

Connect previously identified chip

engine plenum access cover, and fan

detector wires.

hub transmission fairing (Ref. Sec.

53-30-30).

(4).

Remove cap and connect drain line on

elbow at bottom of transmission.

(2). Remove tailboom (Ref. Sec. 53-40-30).

(5).

Install fan interconnect shaft (Ref. Sec.

(3). Drain fan transmission of oil. Discon

63-15-30).

nect drain line and cap elbow at bottom

of transmission.

(6).

Install fan pitch control rod (Ref. Sec.

67-20-30).

(4). Remove fan drive shaft (Ref. Sec.

63-15-30).

(7).

Drain any residual preservative oil (if

new transmission) and service with

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

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

67-20-30).

(8).

Install fan hub transmission fairing

(6). Remove fan interconnect shaft (Ref.

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

Sec. 63-15-30).

NOTE: Identify chip detector wires for future

(9).

Install engine plenum access cover (Ref.

re-installation.

Sec. 53-30-30).

(7). Disconnect chip detector wires.

(10).

Install engine inlet fairing (Ref. Sec.

53-30-30).

(8). Remove four transmission mounting

bolts, washers, and transmission from

(11).

Install inlet screen (Ref. Sec.

helicopter.

53-30-30).

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Revision 36

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Fan Transmission Inspection

NOTE: Replace liquid level plug, chip detector,

and breather assy using torque values in the

(1). Check transmission for leaks, cracks,

following paragraphs. Lubricate O-rings

and corrosion. To evaluate oil leakage

with petrolatum (CM114) to prevent dam

refer to Component Fluid Leak Analy

age to O-rings. Repair other components or

sis (Ref. Sec. 12-00-00). For further

replace transmission oil seals if required

inspection criteria, please contact

(Ref. COM).

MDHC Customer Support Department.

Tube Support Inspection

(1).

Chip Detector Torque valve body (large

hex) to 50 - 60 inch pounds (5.65 -

(1). Inspect mount bolts for security and

6.78 Nm) or 40 - 50 inch pounds

corrosion, lockwire intact.

(4.52 - 5.65 Nm) (smaller hex).

(2). Inspect tube support for dents,

(2).

Liquid Level Plug Torque liquid level

scratches, nicks, gouges and corrosion,

plug to 50 - 60 inch pounds (5.65 -

none allowed.

6.78 Nm). If level lines and lettering of

(3). Inspect for visible step in splined area.

liquid level plug cannot are not parallel

with axis of transmission output shaft

(4). If step is evident:

when torqued within 50 - 60 inch

(a). Measure between splines using

pound (5.65 - 6.78 Nm) range, clean

0.0864 in. (2.19456 mm) diameter

glass by firmly rubbing with soft cloth,

pins.

then mix white coating (CM311) with

equal amount of thinner and apply

(b). Maximum measurement between

lines and lettering. Safety with lockwire

pins is 0.390 in. (9.906 mm).

(CM702).

Fan Transmission Parts Replacement

(3).

Oil Breather Assy Torque breather

(Ref. Figure 202)

assy to 45 - 55 inch pounds (5.08 -

6.21 Nm). Ensure breather hole is

facing up. Safety with lockwire

Consumable Materials

(CM702).

(Ref. Section 91−00−00)

Item

Nomenclature

NOTE: If oil breather assy becomes clogged,

CM114

Petrolatum

use light air pressure, approximately 5 psig

CM222

1,1,1-Trichloroethane

(34 kPa) or a 0.125 inch (3.175 mm) dia. rod

CM311

Coating, logo white / Thinner

applied into the threaded end to dislodge de

CM702

Lockwire CRES

bris. Ultrasonically clean breather in sol

vent (CM222) for ten minutes.

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63-25-30

Revision 33

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR STATIC MAST

MAINTENANCE PRACTICES

1. Main Rotor Static Mast

(1).

Apply silicone sealant (CM430) on

bottom surface of mast tube and base at

(Ref. Figure 201) The main rotor mast provides

drive shaft opening to seal base to mast

support for the main rotor, main transmission

support structure at installation.

and drive shaft, and consists of an assembled

machined steel tube with a machined alumi

num forged base.

(2).

Position main rotor mast so that holes

in base align with holes in mast support

2. Main Rotor Static Mast Replacement

structure.

(369D25100 Transmission Installation)

(3).

Install holddown bolts, washers and

A. Main Rotor Static Mast Removal

mast mounting nuts; torque nuts to 700

(369D25100 Transmission Installation)

- 820 inch-pounds (79.09 - 92.65

(Ref. Figure 201)

Nm).

Main rotor mast is highly

CAUTION

stressed. Do not allow tools to

(4).

Check underside of mast support

strike mast or mast to strike any object. Any

structure at left aft stud hole location.

impact damage may require replacement of

Stud-to-pan doubler surface must be

mast.

clean to bare metal for electrical

bonding. Install main transmission

(1). Remove main rotor hub (Ref. Sec.

mounting studs, plate spacers and nuts.

62-20-00/60).

Torque studs to 160 - 190 inch-

pounds (18.08 - 21.47 Nm).

(2). Remove main rotor controls (Ref. Chap.

67).

(5).

Using 0.0010-0.0015 inch

(3). Remove main transmission (Ref. Sec.

(0.254-0.0381 mm) feeler gage, check

63-20-00/25).

for gap between self-locking nuts and

plate spacers. No gap is allowed.

(4). Remove four studs, washers and nuts.

NOTE: Nuts securing studs have left-hand

(6).

If gap exists, remove nut and replace

threads.

with new self-locking nut. Torque studs

into replacement nuts to 160 - 190

(5). Remove shaft support holddown nuts,

inch-pounds (18.08 - 21.47 Nm) and

washers and bolts.

repeat step (5). above. Continue until

each nut is flush against its spacer.

(6). Lift main rotor mast from helicopter.

Seal bare bond area with clear lacquer

B. Main Rotor Static Mast Installation

(CM306).

(369D25100 Transmission Installation)

(7).

Install main transmission (Ref. Sec.

(Ref. Figure 201)

63-20-00/25).

Consumable Materials

(Ref. Section 91−00−00)

(8).

Install main rotor controls (Ref. Chap.

Item

Nomenclature

67).

CM306

Lacquer, clear

CM430

Sealant, solvent resistant

(9).

Install main rotor hub (Ref. Sec.

62-20-00/60).

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Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

HUB SLEEVE BEARING

SURFACE

MAIN ROTOR MAST

NUT (LEFT-

PLATE

HAND

SPACER

THREADS)

TAPE

MAST BASE

RIVET

MAST SUPPORT

STRUCTURE PAN

NOTE 2

DRAIN

HOLE

MAST SUPPORT FITTING

MAST MOUNTING

NUT

MAIN TRANSMISSION

MOUNTING STUD

NOTE 1

AFT BULKHEAD

CHANNEL

TUNNEL BEAM WEB

TUNNEL BEAM

WATERLINE 34.00

SIDE-CHANNEL

WATERLINE 45.36

NOTES:

THIS STUD REQUIRES ELECTRICAL BOND TO STRUCTURAL PAN.

MAIN ROTOR MAST IS SEALED TO STRUCTURE PAN (INSIDE MAST

TUBE AT BASE) WITH SILICONE RUBBER (CM430).

G63-3000A

Figure 201. Main Rotor Mast and Support Structure (369D25100 Transmission Installation)

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Revision 20

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

3. Main Rotor Static Mast Replacement

(4). Using 0.0010-0.0015 inch

(369F5100 Transmission Installation)

(0.0254-0.0381 mm) feeler gage, check

for gap between self-locking nuts and

(Ref. Figure 202)

plate spacers. No gap is allowed.

A. Main Rotor Static Mast Removal

(5). If gap exists, remove nut and replace

(369F5100 Transmission Installation)

with new self-locking nut. Torque bolts

into replacement nuts to 160 - 190

Main rotor mast is highly

inch-pounds (18.08 - 21.47 Nm) plus

CAUTION

stressed. Do not allow tools to

drag torque and repeat step e. above.

strike mast or mast to strike any object. Any

Continue until each nut is flush against

impact damage may require replacement of

its spacer. Seal bare bond area with

mast.

clear lacquer (CM306).

(6). Install main transmission (Ref. Sec.

(1). Remove main rotor hub (Ref. Sec.

63-25).

62-20).

(7). Install main rotor controls (Ref. Sec.

(2). Remove main rotor controls (Ref. Sec.

67-10).

(8). Install main rotor hub (Ref. Sec.

(3). Remove main transmission (Ref. Sec.

62-20).

63-25).

4. Main Rotor Static Mast Inspection and

(4). Remove four bolts, washers and nuts.

Repair

(5). Lift main rotor mast from helicopter.

(Ref. Figure 203)

B. Main Rotor Static Mast Installation

(369F5100 Transmission Installation)

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

Consumable Materials

CM115

Grease, oscillating bearing

(Ref. Section 91−00−00)

CM234

Solvent, dry-cleaning

Item

Nomenclature

CM235

Cleaner

CM306

Lacquer, clear

CM304

Enamel, epoxy

CM430

Sealant, solvent resistant

CM305

Lacquer, acrylic

CM318

Primer

(1). Apply silicone sealant (CM430) on

CM323

Primer

bottom surface of mast tube and base at

CM713

Tape, pressure sensitive

drive shaft opening to seal base to mast

CM802

Abrasive cloth, aluminum oxide

support structure at installation.

CM803

Crocus cloth

(2). Position main rotor mast so that holes

in base align with holes in mast support

(1). Inspect all areas of main rotor mast for

structure.

cracks, nicks, scratches and evidence of

impact damage.

(3). Check underside of mast support

structure at left aft stud hole location.

(2). Inspect bearing surfaces for scoring and

Stud-to-pan doubler surface must be

galling.

clean to bare metal for electrical

bonding. Install main transmission

(3). Inspect threads for damage.

mounting bolts, plate spacers and nuts.

Torque nuts to 160 - 190 inch-pounds

(4). Inspect rivets that secure base to mast

(18.08 - 21.47 Nm) plus drag torque.

tube for security.

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Revision 36

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(5). Check that tape (Ref. Figure 201) on

(b).

Remove main transmission (Ref. Sec.

forward edge of mast tube is secure and

63-20-00 or 63-20-25, Main Trans

undamaged; replace if defective.

mission Replacement).

(a). Peel defective tape from mast.

(c).

Remove static mast (Ref. Main Rotor

Static Mast Replacement).

(b). As required, polish area to remove

burrs and sharp areas with abrasive

(d).

Thoroughly clean interior tube with

cloth (CM802) or crocus cloth

Solvent (CM234).

(CM803).

(c). Clean mast thoroughly with cleaner

(e).

Inspect for any corrosion, none

(CM235) and allow to dry.

allowed.

(d). Apply primer (CM318) and paint

(f).

Remove paint from bad areas and

(CM305) to affected area.

lightly feather paint edge with crocus

cloth (CM803), remove any residue

(e). Apply pressure sensitive tape

from feathering.

(CM713) to mast.

NOTE: To inhibit corrosion of mast when oper

(g).

Apply primer (CM318), or (CM323),

ating in salt water environment, check tape

to repair areas.

at frequent intervals. Also, apply thin

grease film (CM115) to bearing journals.

(h).

Allow to cure per manufacturer's

instructions.

(6). Inspect internal bore for paint chipping,

orange peeling or flaking, none allowed.

(i).

Apply white paint (CM304) to

internal bore of mast.

NOTE: Chipping, orange peeling or flaking

paint will normally be at the base of the

(j).

Allow to cure per manufacturer's

static mast tube.

instructions.

(7). Re-apply finish to mast internal bore

(k).

Reinstall static mast.

as follows:

(a). Remove main rotor hub (Ref. Sec.

(l).

Reinstall main transmission.

62-20-00 or 62-20-60, Main Rotor

Hub Replacement).

(m).

Reinstall main rotor hub.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

MAXIMUM REMOVAL

REPAIRABLE

AREA

REPAIR PROCEDURE

DAMAGE

MATERIAL (DEPTH)

POLISH DEFECTIVE AREA SMOOTH WITH

CORROSION AND

0.010 IN.

ABRASIVE CLOTH (CM802 AND CM803) IF

SCRATCHES

(0.254 MM)

CADMIUM PLATING HAS BEEN PENE

TRATED. TREAT REWORKED AREA WITH

PRIMER (CM318).

CHIPPING OF CAD

THICKNESS OF CAD

POLISH AREA SMOOTH WITH ABRASIVE

MIUM PLATING (0.0035

CLOTH (CM802 AND CM803). TREAT RE

MIUM PLATING

IN. (0.0889 MM MAXI

WORKED AREA WITH PRIMER (CM318)

MUM)

AND LACQUER (CM306).

LONGITUDINAL

SCRATCHES THAT

DO NOT PENE

TRATE THROUGH

MUST NOT PENE

NICKEL PLATE.

TRATE NICKEL PLAT

SCRATCHES MUST

POLISH AREA WITH ABRASIVE CLOTH

ING, 0.003-0.007 IN.

BE A MINIMUM OF

(CM802 AND CM803) TO REMOVE BURRS

(0.076-0.178 MM)

0.25 IN. (6.35 MM)

AND SHARP EDGES ONLY.

THICK

APART. RADIAL

SCRATCHES ARE

NOT PERMITTED.

MUST NOT PENETRATE

THICKNESS OF SILVER

PLATING BY AN AREA

NO LARGER THAN 0.5

IN.² (3.2258 CM²). NO

MORE THAN TWO

SUCH AREAS NO

WIPE AREA CLEAN USING CHEESE CLOTH

CORROSION AND

CLOSER THAN 1.5 IN.

(CM820) DAMPENED IN SOLVENT (CM222).

SCRATCHES

(3.81 CM) APART MAY

SPRAY UNIFORM COATING, 0.002-0.005 IN.

EXIST. IF WEAR EX

(0.051-0.127 MM) THICK, ON WORN AREA

CEEDS LIMITS, CON

WITH LUBRICANT (CM103).

TACT MDHS WARRAN

AREA EN

TY REPAIR DEPART

CLOSED

MENT FOR REWORK

BY MAST

DISPOSITION. ONLY

BASE

MDHS CAN PERFORM

PLATING REPAIRS.

REMOVE DEFECTIVE TAPE. POLISH DE

FECTIVE AREAS TO REMOVE BURRS AND

CORROSION AND

SHARP SURFACES WITH ABRASIVE

REPLACEMENT OF

0.010 IN.

CLOTH (CM802 AND CM803). TOUCH UP

TAPE.

(0.254 MM)

REWORKED AREAS WITH PRIMER (CM318)

AND LACQUER (CM305). REPLACE TAPE

(CM713).

NOTE: FOR MAGNETIC PARTICLE INSPECTION,

REMOVE PAINT FROM APPLICABLE SURFACE

G63-3001B

Figure 203. Main Rotor Mast − Inspection and Repair

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MD Helicopters, Inc.

CSP−HMI−2

MAINTENANCE MANUAL

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

64-00-00 Anti-Torque Assembly (369D/E/FF - 500/600N)

Fault Isolation

101

1. Tail Rotor Assembly

101

2. Anti-Torque Fan Assembly

101

Table 101. Troubleshooting Tail Rotor and Vibrations

101

64-00-05 Four-Bladed Tail Rotor Assembly Initial Installation (369D/E)

Initial Installation

901

1. Four-Bladed Tail Rotor Initial Installation

901

A. Tail Rotor and Transmission Initial Installation

901

B. Existing Tail Rotor and Transmission Removal

901

C. Four-Bladed Tail Rotor Transmission Build-Up

901

D. Drive Shaft, Tail Rotor Transmission and Tail Rotor Installation

901

Figure 901. Tail Rotor Index Stripe Requirements

902

E. Tail Rotor Control Over-Center Trim System Rework

903

F. Two-Bladed Over-Center Trim System Removal

903

G. Four-Bladed Over Center Trim System Initial Installation

903

Figure 902. Over Center Trim System Installation

904

H. Four-Bladed Tail Rotor Controls Rigging

906

I. Horizontal Stabilizer Tip Weight Removal

906

J. N2 and NR (Rotor) Tachometer Indicator Replacement

906

K. Four-Bladed Tail Rotor System Completion of Installation

906

L. Weight and Balance

907

Table 901. Weight and Balance Data

907

Figure 903. Bracket Installation - Sta. 78.50 Canted Wall

908

64-10-00 Tail Rotor Blades (369D/E/FF)

Maintenance Practices

201

1. Tail Rotor Blades

201

2. Tail Rotor Blade Inspection

201

3. Abrasion Strip Dye Penetrant and Tap Test Inspection

201

Figure 201. Tail Rotor Blade

202

Figure 202. Inspection of Tail Rotor Blade Abrasion Strip

203

4. Tail Rotor Blade Tip Cap Repair

204

Figure 203. Installation of Tip Cap-To-Tail Rotor Blade Rivets

205

5. Tail Rotor Blade Replacement Procedure

206

6. Tail Rotor Abrasion Strip Riveting

207

Figure 204. Tail Rotor Blade Abrasion Strip Riveting

208

Page i

64 Contents

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CSP−HMI−2

MD Helicopters, Inc.

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

7. Tail Rotor Blade Abrasion Strip Modification

209

8. Tail Rotor Blade Protective Tape Installation

210

Figure 205. Tail Rotor Blade Abrasion Strip Modification

211

9. Tail Rotor Blade Leading Edge Crack Inspection

212

A. Tail Rotor Blades with New-Style Abrasion Strips

212

B. Tail Rotor Blades with Old-Style Abrasion Strips

212

Figure 206. Tail Rotor Blade Leading Edge Crack Inspection

214

64-20-00 Tail Rotor Hub and Fork (369D/E/FF)

Maintenance Practices

201

1. Tail Rotor Hub and Fork

201

2. Tail Rotor Hub and Fork Replacement

201

A. Tail Rotor Hub and Fork Removal

201

Figure 201. Tail Rotor Hub and Strap Pack

202

B. Tail Rotor Hub and Fork Installation

203

Figure 202. Hub and Fork Assembly Installation (Two-Bladed)

204

Figure 203. Hub and Fork Assembly Installation (Four-Bladed)

205

3. Tail Rotor Hub and Fork Inspection

206

4. Conical Bearing Inspection

206

5. Elastomeric Fork Bearing Inspection

206

Figure 204. Blade Flapping Resistance Check

207

6. Elastomeric Bearing Care and Cleaning

207

64-25-30 Anti-Torque Fan (500/600N)

Removal/Installation

401

1. Anti-Torque Fan Assembly

401

2. Anti-Torque Fan Replacement

401

A. Anti-Torque Fan Removal

401

B. Anti-Torque Fan Installation

401

3. Anti-Torque Fan Blade Replacement

401

A. Anti-Torque Fan Blade Removal

401

B. Anti-Torque Fan Blade Installation

401

Figure 401. Anti-Torque Fan

402

4. Fan Blade Strap and Pitch Horn Replacement

403

A. Fan Blade Strap and Pitch Horn Disassembly

403

B. Fan Blade Strap and Pitch Horn Reassembly

403

Page ii

Revision 42

64 Contents

MD Helicopters, Inc.

CSP−HMI−2

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

5. Retention Plate and Pitch Plate Replacement

404

A. Retention Plate and Pitch Plate Disassembly

404

B. Retention Plate and Pitch Plate Reassembly

404

6. Support Shaft Replacement

404

A. Support Shaft Disassembly

404

B. Support Shaft Reassembly

404

7. Fan Balance Stud Replacement

405

A. Fan Balance Stud Removal

405

B. Fan Balance Stud Installation

405

Figure 402. Anti-Torque Fan Support Shaft

406

8. Pitch Horn Counterweight Set Screw Replacement

407

Figure 403. Pitch Horn Counterweight Set Screw Replacement

407

Inspection/Check

601

1. Anti-Torque Fan Inspection

601

2. Support Shaft Inspection

601

3. Anti-Torque Fan Liner (Felt Metal Seal) Inspection

601

4. Fan Blade Inspection (100-Hour)

601

5. Fan Pitch Slider Inspection

602

Repairs

801

1. Anti-Torque Fan Liner (Felt Metal Seal) Replacement

801

A. Anti-Torque Fan Liner (Felt Metal Seal) Removal

801

B. Anti-Torque Fan Liner (Felt Metal Seal) Installation

801

C. Anti-Torque Fan Liner (Felt Metal Seal) Machining

801

Figure 801. Anti-Torque Fan Liner (Felt Metal Seal)

802

Figure 802. Anti-Torque Fan Liner Felt Metal Seal Machining

803

2. Anti-Torque Fan Bearing Regreasing

806

Figure 803. Fan Bearing Regreasing Procedure

806

Figure 804. Fan Bearing Regreasing Tool (ST614)

807

64-30-00 Tail Rotor Pitch Control Assembly (369D/E/FF)

Maintenance Practices

201

1. Tail Rotor Pitch Control Assembly

201

2. Tail Rotor Pitch Control Assembly Replacement

201

A. Tail Rotor Pitch Control Assembly Removal

201

Figure 201. Pitch Control Assembly - Wobble Check

201

Figure 202. Swashplate-to-Pitch Control Housing Clearance

202

B. Tail Rotor Pitch Control Assembly Installation

202

Page iii

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MD Helicopters, Inc.

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

3. Tail Rotor Pitch Control Link Replacement

202

Figure 203. Tail Rotor Pitch Control Assembly (Two-Bladed)

203

Figure 204. Tail Rotor Pitch Control Assembly (Four-Bladed)

204

4. Tail Rotor and Pitch Control Assembly Repair

205

5. Tail Rotor Pitch Control Assembly Inspection

205

6. Tail Rotor Blade Stop Inspection

206

7. Tail Rotor Pitch Control Link Inspection

206

8. Tail Rotor Conical Bearing Inspection

207

9. Tail Rotor Pitch Bearing Inspection

207

10. Tail Rotor Swashplate Bearing Regreasing

207

Figure 205. Tail Rotor Swashplate Bearing Regreasing

207

Figure 206. Tail Rotor Swashplate Bearing Regreasing Tool

208

Figure 207. Tail Rotor Swashplate Holding Block

209

Figure 208. Tang Washer Inspection and Application of Torque Stripe

210

Page iv

Revision 42

64 Contents

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

ANTI−TORQUE ASSEMBLY

FAULT ISOLATION

1. Tail Rotor Assembly

quick-release pins on top of pedal arms and

repositioning pedals.

The tail rotor, mounted on the tail rotor

transmission at the end of the tailboom,

The two-bladed tail rotor assembly consists

counteracts main rotor torque and controls

mainly of two tail rotor blades, a hub, drive

heading of the helicopter. The tail rotor control

fork, two pitch control links, and a pitch

system changes the pitch of the tail rotor

control assembly.

blades. The antitorque pedals move a system

of bellcranks and control rods routed through

The four-bladed tail rotor assembly consists

the fuselage and tailboom to a pitch control

of four tail rotor blades, two hubs, drive fork,

assembly which moves links that attach to

four pitch control links and a pitch control

blade-pitch arms on the blades.

assembly. The blades are held together on the

hub by a laminated tension-torsion strap pack

The pitch control assembly slides axially on

that permits the blades to rotate axially on the

the tail rotor transmission output shaft.

hub. The hub pivots in the drive fork. Control

Pushing forward on the left pedal changes

of blade pitch is from the pitch control assem

heading to the left; forward right pedal

bly through pitch control links that connect to

movement changes heading to the right.

pitch arms on the blade root fittings.

For two-bladed tail rotor system, blade pitch

2. Anti−Torque Fan Assembly

movement is -13 degrees to -15 degrees thrust

to the left and +27 degrees to +29 degrees to

The anti-torque fan is an axial fan with

the right.

thirteen variable pitch blades. The fan

For four-bladed tail rotor system, blade pitch

provides anti-torque by furnishing variable

movement is -13 degrees to -15 degrees thrust

flow of low pressure high volume air through

to the left, +31 degrees to +32 degrees thrust

the tailboom and thrusters.

to the right and +6.5 degrees to +8.5 degrees

thrust to the right at neutral.

During flight, pedal position and pressure

required to maintain a desired heading varies

During flight, pedal position and pressure

with main rotor torque variations, altitude and

required to maintain a desired heading varies

airspeed conditions. Control linkage includes a

with main rotor torque variations, altitude and

bungee spring that relieves left pedal forces in

airspeed conditions. Control linkage includes a

flight.

bungee spring that relieves left pedal forces in

flight.

When the helicopter is on the ground, pedal-

to-seat distance is adjusted by removing

When the helicopter is on the ground, pedal-

quick-release pins on top of pedal arms and

to-seat distance is adjusted by removing

repositioning pedals.

Table 101. Troubleshooting Tail Rotor and Vibrations

Symptom

Probable Trouble

Corrective Action

Heavy medium−frequency vibration

Tail rotor out of balance.

Rebalance tail rotor assembly (Ref.

in tail rotor assembly; vibration

Sec. 18−20−00).

sometimes felt in pedals as a

Runout of tail rotor transmission

Replace transmission if shaft runout

buzzing sensation.

output shaft excessive.

exceeds 0.0025 inch (0.0635 mm)

T.I.R. No axial play allowed. (Ref.

Sec. 63−25−10).

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MD Helicopters, Inc.

MAINTENANCE MANUAL

Table 101. Troubleshooting Tail Rotor and Vibrations

Symptom

Probable Trouble

Corrective Action

High frequency vibration, primarily

Tail rotor blades slightly out of

Rebalance tail rotor assembly (Ref.

in pedals as a buzzing sensation.

balance.

Sec. 18−20−00).

Tail rotor blade pitch bearings

Replace tail rotor pitch bearings (Ref.

worn.

COM).

Excessive wear in pitch control link

Replace pitch control link bearings

bearings.

(Ref. COM).

NOTE: High frequency vibrations in

Excessive wear of swashplate or

Replace swashplate or repair pitch

the helicopter can also be

large bearings in housing of pitch

control assembly (Ref. COM).

caused by components of other

control assembly.

systems (Ref. Sec. 18−20−00,

Excessive play in tail rotor fork

Replace fork bearings (Ref. COM).

53−40−00,

63−25−10 and

bearings.

Chap. 71).

Tail rotor hub−to−fork play.

Repair (Ref. COM).

Excessive dents in leading edge of

Replace blade(s) or tail rotor

blades.

assembly. (Ref. COM).

Insufficient torque on stabilizer

Retorque mount bolts (Ref. Chap.

mount bolts.

53).

Insufficient torque on tail rotor

Retorque retaining nut (Ref. Sec.

assembly retaining nut.

64−30−00).

Excessive play in pitch control link

Worn pitch control link bearings.

Replace pitch control link bearings

assemblies.

(Ref. COM).

High left pedal forces required in

Bungee spring (Sta. 63)

Reconnect or replace bungee spring

flight.

disconnected, broken or stretched.

(Ref. Sec. 67−20−00).

Pedals binding.

Excessive drag of pitch control

Clean swashplate bore and

swashplate on transmission shaft.

transmission shaft splines.

Re−lubricate splines.

Snapping noise heard in

Noise is normal action of strap

None required.

non−operating tail rotor when pitch

pack and caused by laminates

angle changed from one extreme

twisting and bending when blade is

to the other.

feathered without centrifugal load

present.

Page 102

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64-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FOUR−BLADED TAIL ROTOR ASSEMBLY

INITIAL INSTALLATION

1. Four−Bladed Tail Rotor Initial Installation

(5). Remove existing station 284 bellcrank

and tail rotor control rod (Ref. Sta. 284

This section contains procedures for initial

Bellcrank Removal).

installation of four-bladed tail rotor kit, which

C. Four−Bladed Tail Rotor Transmission

includes tail rotor; tail rotor transmission; and

parts for modifying over-center trim system

Build−Up

controls and engine/rotor tachometer indicator.

(Ref. Figure 901) Build-up the four-bladed tail

This kit may be installed on all Model 500D

rotor transmission as follows.

and 500E helicopters at the owner's/operator's

discretion.

Consumable Materials

NOTE: Components of the four-bladed tail ro

(Ref. Section 91−00−00)

tor drive system kit are assembled and bal

Item

Nomenclature

anced at the factory. Prior to installation of

CM112

Anti-seize compound high temperature

the kit, some existing equipment must be re

CM305

Lacquer, acrylic

moved from the helicopter, and other equip

ment must be modified.

Do not lift transmission assem

A. Tail Rotor and Transmission Initial

CAUTION

bly by coupling flange.

Installation

(1). Install shims, coupling and coupling

Install the four-bladed tail rotor transmission

bolt. Coat threads of bolt with anti-

and tail rotor assembly according to the

seize compound (CM112). Torque bolt to

following procedures.

250 - 300 inch-pounds (28.25 - 33.90

Nm) plus drag torque.

B. Existing Tail Rotor and Transmission

Removal

(2). Add stripe of white paint (CM305)

approximately 0.0125 inch (3.175 mm)

Remove the following equipment from helicop

wide between ends of decal to allow for

ter before installing four-bladed tail rotor

indexing of aft end of drive shaft.

transmission and tail rotor assemblies.

NOTE:

To locate new coupling index, use flash

(1). Remove existing two-bladed tail rotor

light and look through control tube rod hole

(Ref. Sec. 64-20-00).

in aft tailboom fitting. Rotate output shaft

until index stripe on coupling is at six o'clock

(2). Remove tail rotor transmission and

position.

driveshaft (Ref. Sec. 63-25-10).

D. Drive Shaft, Tail Rotor Transmission and

Tail Rotor Installation

NOTE: Retain bolt for use when building up

four-bladed tail rotor transmission, cou

(Ref. Figure 901) Install drive shaft, transmis

pling is a limited-life item. If sufficient ser

sion and tail rotor on helicopter as a unit. Do

viceable life remains on coupling, it may be

not install with blades mounted.

reused with four-bladed tail rotor installa

tion. If not, discard and replace coupling

bolt.

Consumable Materials

(Ref. Section 91−00−00)

(3). Remove bolt, coupling and shims from

Item

Nomenclature

transmission output shaft (Ref. Sec.

CM305

Lacquer, acrylic

63-15-10).

(4). Remove index stripe on drive shaft at

(1). Install existing drive shaft on tail rotor

Sta. 137.5.

transmission (Ref. Sec. 63-15-10).

Page 901

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CSP-HMI-2

MAINTENANCE MANUAL

(2).

Install assembled unit on helicopter

Install bungee installation

WARNING

(Ref. Sec. 63-15-10).

tool (ST508) before discon

necting any pilot's collective stick

(3).

Paint 0.125 inch (3.175 mm) wide and

hardware. There is strong bungee

0.125 inch (3.175 mm) long stripe

spring pressure present in stick link

(contrasting color to aft tailboom

age. If suddenly released, spring reac

fitting) at six o'clock position of control

tion in linkage can cause personal inju

rod in aft tailboom fitting to align stripe

ry or parts damage.

on coupling.

(3). Remove bellcranks and collective

(4).

Add white index stripe (CM305) on tail

bungee spring and bracket; disconnect

rotor drive shaft to match stripe on

and retract lateral cyclic trim actuator

doubler at Sta. 137.5.

assembly.

(5).

Install new tail rotor control rod.

Turn off electrical switches

WARNING

and disconnect any external

(6).

Attach new Sta. 284 bellcrank to new

power from helicopter prior to refuel

tail rotor pitch control assembly.

ing or defueling. Static discharge spark

in presence of fuel vapors can cause

(7).

Temporarily install bellcrank to new

fire or an explosion.

control rod assembly.

(8).

Install blades on hubs. Install inboard

(4). Drain all fuel from fuel cells; purge cells

blades first (Ref. Sec. 64-10-00).

with dry filtered compressed air.

E. Tail Rotor Control Over−Center Trim

(5). Fold and displace left fuel cell to permit

System Rework

bucking of rivets at aft side of canted

wall.

The tail rotor over-center trim system must be

reworked when four-bladed tail rotor is

G. Four−Bladed Over Center Trim System

installed. Necessary parts for this rework are

Initial Installation

included with four-bladed tail rotor kit.

(Ref. Figure 902)

F. Two−Bladed Over−Center Trim System

Removal

Special Tools

Prior to rework of over center trim system,

(Ref. Section 91−00−00)

following existing equipment must be removed

Item

Nomenclature

and preparations made.

ST508

Collective bungee installation tool

Special Tools

(Ref. Section 91−00−00)

(1). Locate and clamp fitting (1) and

Item

Nomenclature

serrated plate (2) together with serra

tions facing away from fitting. Drill one

ST508

Collective bungee installation tool

0.159 inch (4.0386 mm) diameter rivet

hole with a #21 bit and countersink

(1). Remove tail rotor bungee; disconnect

hole.

floor-routed tail rotor control rod and

remove and discard spring fitting from

(2). Locate serrated plate (3) and clamp to

rod. Remove tail rotor idler bellcrank

seat support structure (4). Ensure

under pilot seat.

serrations are facing away from seat

support structure. Mark rivet and

(2). Disconnect tunnel-routed tail rotor

screw holes on serrated plate (3) and

control rod and lateral mixer control

seat support structure. Remove ser

rod at lower rod end.

rated plate from seat support structure.

Page 903

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Revision 21

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(NOTE 2)

2 (REF)

3 (REF)

NOTE 1

1.00 IN.

(NOTE 2)

1.00 IN.

(2.54 CM)

0.612 IN.

2.50 IN.

(15.5448 MM)

(6.35 CM)

1.75 IN.

(4.445 CM)

1.00 IN.

2.00 IN.

(2.54 CM)

(5.08 CM)

3.31 IN.

(8.4074 CM)

PILOT'S FLOOR

(REF)

NOTES:

REMOVE 0.12-0.14 IN. (3.048-3.556 MM) ON 369A7304 BRACKET.

NOT REQUIRED WHEN 369D27304 BRACKET IS INSTALLED.

G64-0002A

Figure 902. Over Center Trim System Installation

Page 904

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CSP-HMI-2

MAINTENANCE MANUAL

Legend (Ref. Figure 902)

1. FITTING

19. RIVET

2. SERRATED PLATE

20. BOLT

3. SERRATED PLATE

21. WASHER

4. SEAT SUPPORT STRUCTURE

22. NUT

5. RIVET

23. COTTER PIN

6. RIVET

24. BOLT

7. BRACKET

25. BUSHING

8. BRACE

26. WASHER

9. BRACKET

27. NUT

10. BELLCRANK

28. COTTER PIN

11. BOLT

29. BOLT

12. BUSHING

30. WASHER

13. WASHER

31. NUT

14. WASHER

32. COTTER PIN

15. NUT

33. TAIL ROTOR BUNGEE

16. BOLT

34. SCREW

17. WASHER

35. WASHER

18. NUT

36. NUT

NOTE: Head of rivets not to protrude past base

(8). Install fitting (1) on seat support

of serrations.

structure using bolts (16), washers (17)

and nuts (18).

(3). Attach fitting (1) and serrated plate (2)

NOTE: Shim -BSC bracket (9), as required, for

together with one rivet (5).

proper fit on canted wall. Shims are not re

quired for -3 bracket (9).

(4). Locate and drill two 0.250-0.254 inch

(6.35-6.4516 mm) diameter screw holes

(9).

Locate and clamp bracket (9). Drill five

and two 0.098 inch (2.4892 mm)

0.193-0.199 inch (4.9022-5.0546 mm)

diameter rivet holes using a #40 bit

diameter holes using existing rivet

through seat support structure to

pattern (Ref. Figure 903).

match previously marked locations

(step (2).). Countersink rivet holes.

(10).

Attach bracket (9) to canted wall using

five rivets (19) or alternate method of

(5). Drill two 0.098 inch (2.4892 mm)

five screws (34), washers (35) and nuts

diameter rivet holes with a #40 bit thru

(36).

serrated plate (with round bolt holes)

(11).

Grasp brace (8) and hold against

using previously marked locations (step

bracket (9). Mark mating holes on brace

(2).). Attach serrated plate (3) to seat

(8) with those on bracket (9).

support structure using two rivets (6).

(12).

Remove brace (8) from bellcrank (10)

NOTE: Check part number of bracket (7). If

and bracket (7). Drill two 0.250-0.254

bracket is a 369A7304, proceed with step

inch (6.35-6.4516 mm) diameter holes

(6). If 369D27304 bracket is installed, brace

at locations marked in step (11)..

(8) and bracket (9) are not required, proceed

(13).

Install brace (8) on bracket (9) with

to step (14).

bolts (20), washers (21) and nuts (22).

(6). Remove 0.12-0.14 inch (3.048-3.556

Align opposite end of brace (8) between

bracket (7) and bellcrank (10).

mm) maximum material, as required,

from bracket (7) boss lug to achieve a

(14).

Install bolt (11), bushing (12) and

snug fit between brace (8), bracket (7)

washers (13, 14) thru bracket (7) and

and bellcrank (10).

bellcrank (10). Install nut (15) and

cotter pin (23).

(7). Temporarily attach bellcrank (10),

brace (8) and bracket (7) with bolt (11),

(15).

Reinstall tunnel-routed control rods

bushing (12), washers (13, 14) and nut

and floor-routed control rods, with

(15) finger tight.

spring fitting removed.

Page 905

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MD Helicopters, Inc.

MAINTENANCE MANUAL

Always use bungee installa

assembly of collective bungee. Coat

WARNING

tion tool (ST508) when re

parts with grease (CM111) as in

moving attaching hardware. Reaction

structed. Ensure that 0.120 inch (3.048

of spring when pressure is suddenly re

mm) of threads are visible between nut

leased can cause personal injury or

and rod end of bungee female bearing

parts damage.

assembly.

NOTE: Adjust tail rotor pedal force by tighten

Remove bungee installation

WARNING

ing or loosening the 0.120 inch (3.048 mm)

tool only as instructed.

thread adjustment on bungee female bear

There is strong bungee spring pressure

ing assembly. Tighten to maximum 0.120

present with four-bladed tail rotor

inch (3.048 mm) thread adjustment on bun

bungee installed. If suddenly released,

gee female bearing assembly increases ped

spring could cause personal injury

al force approximately five pounds; loosen

and/or parts damage.

ing decreases pedal force. Bungee spring

(2). Attach assembled bungee to fitting (1)

may be attached to any of four holes in fit

using attaching hardware (29 thru 32)

ting (1). If excessive left pedal force is re

and to bellcrank (10) using attaching

quired, position spring at lower hole.

hardware (24 thru 28). Ensure bushing

(25) extends 0.010-0.080 inch

H. Four−Bladed Tail Rotor Controls Rigging

(0.254-2.032 mm) beyond surface of

bungee rod end.

Consumable Materials

(Ref. Section 91−00−00)

I. Horizontal Stabilizer Tip Weight Removal

Item

Nomenclature

Tip weights installed in horizontal stabilizer

CM111

Grease, aircraft

for two-bladed tail rotor operation are not

used with four-bladed tail rotor system.

Special Tools

Remove and discard four screws securing tip

(Ref. Section 91−00−00)

plates and weights to horizontal stabilizer.

Item

Nomenclature

Reinstall tip plates using four new screws (P/N

NAS1403-15).

ST508

Collective bungee installation tool

ST510

Bungee spring compression tool rod and

J. N₂ and N_R (Rotor) Tachometer Indicator

channel

Replacement

ST606

T/R swashplate rigging tool

Remove and replace existing tach indicator

with indicator supplied in four-bladed tail

Rigging of four-bladed tail rotor controls is to

rotor kit (Ref. Sec. 95-30-00).

be done with tail rotor bungee spring removed.

K. Four−Bladed Tail Rotor System

Tail rotor pitch angles at 3/4 radius shall be:

Completion of Installation

Full right pedal

14° ±1°

Upon completion of kit installation, the

following actions must be completed.

Full left pedal

31° +1°−0°

Neutral pedal

7.5° ±1°

(1). Replace all components, access panels,

covers, etc. removed to gain access to

Rig tail rotor controls per Tail Rotor Controls

work area.

Rigging except use four-bladed tail rotor

(2). Check installation of four-bladed tail

control rigging tool (ST606). After rigging,

rotor control linkage for discrepancies.

reinstall tail rotor bungee and carefully

remove bungee installation tool (ST508) using

(3). Fill tail rotor transmission with oil (Ref.

bungee compression tool rod and channel

Sec. 12-00-00).

(ST510).

(4). Refuel helicopter and perform opera

(1). Assemble bungee using bungee installa

tional check of four-bladed tail rotor

tion tool (ST508) and instructions for

control system (Ref. PFM).

Page 906

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CSP-HMI-2

MAINTENANCE MANUAL

(5). Ensure that Pilot Flight Manual

L. Weight and Balance

Supplement is inserted in Section IX,

Rotorcraft Flight Manual.

Weight and balance changes resulting from

(6). Ensure that installation of four-bladed

installation of four-bladed tail rotor kit are

tail rotor kit and appropriate part

listed in Table 901. After kit installation,

numbers, serial numbers and limited-

incorporate changes in helicopter weight and

life data are recorded in helicopter log

balance record as instructed (Ref. Sec.

book.

08-10-00).

Table 901. Weight and Balance Data

Configuration

Weight

Arm

Moment

Pounds (kg)

inches (cm)

in−lb (kg cm)

Added

+9.4

(+4.2638)

257.2

(653.228)

+2417.68

(27854.574)

Removed

0.0

Net Change

+9.4

(+4.2638)

257.2

(653.228)

+2417.68

(27854.574)

Page 907

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MD Helicopters, Inc.

MAINTENANCE MANUAL

BL 0.00

BRACKET

BRACE

OK TO LEAVE

RIVET (5 REQ'D)

EXISTING RIVETS.

(USE EXISTING

(NOTE)

RIVET PATTERN)

WL 13.10

0.032 IN.

BRACKET

(0.8128 MM)

STATION 78.50

CANTED WALL

BL 0.00

BL 6.00 L.H.

-3

NOTE:

BL 0.00

OMIT THESE TWO RIVETS WHEN

INSTALLING 369D27003-5 ONLY.

BRACKET

BRACE

OK TO LEAVE

RIVET (4 REQ'D)

EXISTING RIVET

(USE EXISTING

RIVET PATTERN)

SHIM AS REQUIRED BETWEEN

BULKHEAD AND BRACKET

WL 13.10

BRACKET

0.032 IN.

SHIM AS REQUIRED BETWEEN

(0.8128 MM)

BULKHEAD AND BRACKET

BL 6.00 L.H.

BL 0.00

STATION 78.50

CANTED WALL

-BSC

G64-0003A

Figure 903. Bracket Installation − Sta. 78.50 Canted Wall

Page 908

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TAIL ROTOR BLADES

MAINTENANCE PRACTICES

1. Tail Rotor Blades

Scratches that do not exceed 0.020 inch

(0.508 mm) depth are permissible if

Blades are cambered for high thrust to provide

repaired.

directional control at high altitude. Each

(4). Loose or missing tip weights and

consists of an aluminum honeycomb spar,

aluminum skin, riveted aluminum blade

attachment hardware.

fittings and an aluminum tip cap; all structur

(5). Clogged drain openings.

ally bonded together.

(6). Adhesive separation at exposed edges.

At manufacture, static balancing moments of

(7). Debonding of tip cap from tail rotor

all blades are within plus or minus 40 gram

blade (Ref. Tail Rotor Blade Tip Cap

inches of each other by use of a special

Repair).

balancing fixture and prebalancing with tip

weights. Although erosion or allowable repairs

(8). Tip cap rivets for installation and

may cause minor balance moment changes,

condition (Ref. Tail Rotor Blade Tip Cap

such changes are considered negligible enough

Repair).

to allow direct replacement of any used blade

(9). Tail rotor blade pitch bearings for a

with a new one and interchangeable use of

maximum 0.250 inch (6.350 mm) play

blades with remaining service life. In any case

measured at tip of blade.

of blade selection or use, inspection, repair and

serviceability requirements must be complied

3. Abrasion Strip Dye Penetrant and Tap

with. Retirement schedule and remaining

Test Inspection

service life of a used blade should always be

considered when making decision to replace a

(Ref. Figure 202)

single blade (Ref. Sec. 04-00-00).

Consumable Materials

2. Tail Rotor Blade Inspection

(Ref. Section 91−00−00)

Item

Nomenclature

(Ref. Figure 201) Perform balance check at

CM729

Tape, masking, pressure sensitive

intervals specified (Ref. Sec. 05-20-00). If any

of following conditions exist, perform appropri

CM801

Abrasive paper, silicon carbide

ate detailed inspections and allowable repairs

(Ref. COM).

(1). Using a 1/8 inch (3.175 mm) drill bit

and a pencil, fabricate a tapping

(1). Surface cracks, scratches, nicks,

hammer by taping drill bit to pencil.

gouges, dents, pits or corrosion.

Drill bit should be a minimum of six

(2). Leading edge erosion or dents. Visually

inches (15.24 cm) from end of pencil

check abrasion strip for paint cracking

that is to be held while tapping.

or chipping along abrasion strip/airfoil

NOTE: Voids are indicated by a dull, dead tone.

bond line. Use 10X glass to check

Slight tone changes will occur near the tip

abrasion strip/airfoil bond line for

cap and along the length of the strip. These

debonding between epoxy adhesive and

should not be mistaken for voids.

abrasion strip. If debonding has

occurred, remove blade from service.

(2). Using the fabricated tapping hammer,

tap test the entire abrasion strip. Hold

NOTE: If abrasion strip debonding is sus

end of pencil opposite drill bit and tap

pected, but cannot be confirmed by visual

with shank (rounded) end of drill bit. If

inspection, (Ref. Abrasion Strip Dye Pene

void indications are noted, remove

trant and Tap Test Inspection).

blade from service.

(3). Root fitting cracks, scratches, nicks and

(3). Mask area of blade around abrasion

gouges. No cracks are allowable.

strip with masking tape (CM729).

Page 201

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Revision 34

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

Do not use chemical paint re

ure. Bond failure is indicated by penetrant

CAUTION

mover to remove paint from

bleedout from under the abrasion strip, and

abrasion strip. Chemicals can attack the

will appear as a line along the edge of the

abrasion strip to blade bonding agent.

strip. The 5X magnifying glass will aid dis

tinguishing between porosity voids and

(4). Using 220 grit abrasive paper (CM801),

bleedout from under the abrasion strip. It

sand dry, removing all paint from the

may be necessary to wipe off, then reapply

abrasion strip. Ensure abrasion to

the developer to distinguish between poros

airfoil bondline is exposed. Clean paint

ity voids and bond separations. The most

dust from blade.

positive indication of bond failure will nor

mally appear during the first one to seven

NOTE: Do not remove masking tape from blade

minutes following developer application.

until completion of dye penetrant inspec

tion.

(8). Using a 5X magnifying glass, examine

bond line to determine if penetrant dye

(5). Visually check abrasion strip to blade

is indicating a bond separation. If bond

bonding using a 10X magnifying glass.

separation is noted, remove blade from

If bond failure is obvious, remove blade

service.

from service.

(9). Remove masking tape from blade.

(6). Dye penetrant inspect, according to

manufacturer's instructions.

(10). Inspect blade for cleanliness and paint

damage. Clean and repair paint

(a). Inspect entire abrasion strip to blade

damage as necessary (Ref. Sec. 20-30).

bond line, including abrasion strip

bond in blade tip cap area.

NOTE: Do not repaint abrasion strip or abra

sion strip to blade bond line.

(b). Apply penetrant using a small brush

or swab to prevent damage to blade

(11). Check tail rotor balance (Ref. Sec.

paint, and to minimize clean-up.

18-20-00).

(c). Allow penetrant to remain on surface

(12). If blade is removed from service

of abrasion strip bondline for five

because of separation or voids, notify an

minutes minimum.

Approved MDHS Service Center or

Distributor for disposition. Those

(d). Use dry lint free cloth or paper towel

blades in which voids are found shall be

to remove excess penetrant.

sent to an approved repair station for

abrasion strip replacement.

(e). Apply remover to cloth or lint free

towel to remove remaining surface

4. Tail Rotor Blade Tip Cap Repair

penetrant.

(Ref. Figure 203)

NOTE: Never spray or flush area of inspection

with cleaner.

Consumable Materials

(f). Ensure thorough penetrant removal

(Ref. Section 91−00−00)

from surface before applying develop

Item

Nomenclature

er.

CM222

1,1,1-Trichloroethane

CM318

Primer

(7). Apply a light film of developer on the

area of examination.

CM411

Adhesive, epoxy

CM804

Emery cloth, fine

NOTE: The epoxy adhesive used to bond abra

sion strip to blade may have porosity voids.

The penetrant will form a circular pattern

(1). Remove tail rotor blade from helicopter

around voids resulting from porosity. These

(Ref. Tail Rotor Blade Replacement

circular patterns do not indicate bond fail

Procedure).

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CSP-HMI-2

MAINTENANCE MANUAL

0.60 IN. (1.524 MM)

0.250 IN. (6.35 MM)

(NOTE 1)

DIA HOLE

0.30 IN. (0.762 MM)

AFTER REMOVAL OF DEBRIS, SEAL 0.250 IN.

0.390 ± 0.060 IN.

(6.35 MM) DIA. HOLE WITH 2 PLIES OF 120

(9.91 ±1.524 MM)

FIBERGLASS CLOTH & 3135 A & B EPOXY

RESIN (CREST PRODUCTS OR EQUIVALENT)

AS SHOWN.

HOLE LOCATION

SURFACE PREPARATION: ABRADE SURFACE

WITH EMERY CLOTH AND WIPE WITH 1, 1,

1-TRICHLOROETHANE SOLVENT. DO NOT

ALLOW RESIN TO BUILD UP IN 0.250 IN. (6.35

MM) DIA. HOLE.

0.690 IN. (17.53 MM)

ALONG BLADE CONTOUR

NOTE 2

0.380 IN.

0.250 IN.

(9.65 MM)

(6.35 MM)

0.30 IN.

0.250 IN.

(7.62 MM)

(6.35 MM)

NOTE 2

0.50 IN. (12.70 MM)

ALONG BLADE CONTOUR

(NOTE 2)

NAS 1739B4-2 RIVET

(4 PLACES)

NOTES:

FIBERGLASS THIS AREA. DO NOT PLACE FIBERGLASS

CLOTH OVER OPENING FOR BALANCE WEIGHTS.

USE NO.27 DRILL AND 1005 COUNTERSINK WITH NO. 30

PILOT. COUNTERSINK TO MAXIMUM 0.035 IN. (0.889 MM) DEPTH.

INSTALL NAS 1739B4-2 RIVET. SEAL RIVET WITH CLEAR

EPOXY (CM411).

G64-1001A

Figure 203. Installation of Tip Cap−To−Tail Rotor Blade Rivets

Page 205

64-10-00

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CSP-HMI-2

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MAINTENANCE MANUAL

Handle blade carefully. Dents,

5. Tail Rotor Blade Replacement Procedure

CAUTION

nicks or scratches may cause

balance problems at reinstallation, or make

Consumable Materials

blade unserviceable.

(Ref. Section 91−00−00)

Item

Nomenclature

(2).

With blade on a clean hard surface,

CM318

Primer

measure and mark locations for rivet

holes.

NOTE: Always record number and location of

(3).

Using No. 27 drill, carefully drill holes

existing balance washers when replacing

at locations marked on outboard and

blade. This record aids in dynamic balance

inboard surfaces of blade.

troubleshooting.

(1). Remove cotter pin, nut, washer and

(4).

Using 100 ±1° countersink with No. 30

pitch arm bolt from outboard end of

pilot, countersink holes to 0.035 inch

pitch control link.

(0.889 mm) maximum depth.

Bolt, nut, washers and bushings

(5).

Apply primer (CM318) to holes and

CAUTION

may be reinstalled if service

install rivets while primer is wet.

able. If bushing and crush washers are to be

reused, they must be installed in the exact

(6).

Coat installed rivets with clear epoxy

location from which they were removed. If

(CM411).

either the blade or strap pack assembly from

which they were removed is replaced, re

(7).

Drill a 0.250 inch (6.35 mm) diameter

place crush washers and bushing. Bushings

hole through tip cap (Ref. Figure 203).

must be free of nicks and burrs.

Tip cap is 0.070 inch (1.778 mm) thick

NOTE: If same blade is to be reinstalled, retain

at point to be drilled.

intact for reuse. Note and record number

and type of balance washers and attach

(8).

Remove FOD from blade interior

ment hardware used on bolt at blade pitch

through hole.

arm.

Trichloroethane may damage

(2). Remove bolt that secures blade to

CAUTION

blade paint finish.

outboard strap pack shoes.

(3). Withdraw blade from hub trunnion.

(9). Abrade surface surrounding hole using

emery cloth (CM804); wipe clean using

Do not disassemble strap shoes

clean cloth dampened with trichloroe

CAUTION

from end of strap pack protrud

thane (CM222).

ing from trunnion. Strap pack parts are not

individually replaceable and must remain

Do not allow resin to build-up in

assembled. Avoid damaging strap pack.

CAUTION

hole.

Scratches or nicks on strap pack laminates

may make strap pack unserviceable.

(10). Bond two plies of 120 fiberglass cloth

over hole with 3135A and B epoxy resin

NOTE: No axial play is allowed in the strap as

or equivalent. Allow epoxy to cure

sembly shoes. Rotational movement is per

according to manufacturer's instruc

missible.

tions.

(4). If strap pack is to remain exposed for

any length of time, wrap exposed end of

(11). Reinstall tail rotor blade on helicopter

strap pack with wax paper or other

(Ref. Tail Rotor Blade Replacement

similar non-abrasive material to

Procedure).

protect from damage.

(12). Check and adjust tail rotor blade

(5). If blade being removed is to be rein

balance (Ref. Sec. 18-20-00).

stalled, do not remove blade tip screw,

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CSP-HMI-2

MAINTENANCE MANUAL

any balance washers or weight from

(13). Install pitch control links (Ref. Sec.

blade.

64-30-00).

NOTE: Remove old primer from mating sur

NOTE: If same blade that was removed is being

faces and attaching hardware prior to reas

reinstalled, install same number of balance

sembly.

washers on pitch arm bolt that were present

prior to removal of blade. For different

(6).

To install blade, remove any protective

blade, install balance washers required for

covering from strap pack extending

static chordwise balance of assembled tail

from hub trunnion.

rotor which have been determined with a

balance fixture.

(7).

Install O-ring and slide blade on hub

with blade leading edge facing in

(14). Balance tail rotor (Ref. Sec. 18-20-00).

counterclockwise direction. Use care to

keep blade correctly aligned so that hub

6. Tail Rotor Abrasion Strip Riveting

trunnion slides into blade pitch bear

ings. Do not use force.

(Ref. Figure 204) The following procedure is for

(8).

Align bolt holes in root fitting with hole

adding rivets at the outboard ends of the

through bushing in outboard shoes of

abrasion strip to provide a secondary failsafe

strap pack.

method of attachment.

(9).

Coat contacting surfaces of bushings,

This procedure is effective on tail rotor blades:

washers, nuts and bolts with unthinned

369A1613-7, -503, -505,

primer (CM318) and immediately

369D21606-BSC,

perform following steps.

369D21613-11, -31, -41, -51,

369D21615-BSC, -21,

(10).

Assemble and install bolt, bushings and

421-088

washers in sequence (Ref. Figure 201).

Make certain that direction of bolt is

opposite to that of opposing blade. Do

Consumable Materials

not force bolt; it must have an easy but

(Ref. Section 91−00−00)

snug fit through blade, shoes and

Item

Nomenclature

bushings.

CM222

1,1,1-Trichloroethane

NOTE: It is recommended that the MS 21250

CM318

Primer

bolt be replaced with any of the alternate

CM804

Emery cloth, fine

bolts with the higher torque at the operators

N/A

Fiberglass cloth, No. 120

earliest convenience.

N/A

Epoxy resin, Spec. 3135A and B or any 2

(11). If an MS 21250 bolt is installed, install

part (1:1) clear epoxy resin

nut and torque to 600 - 650 inch-

pounds (67.79 - 73.44 Nm) while

Do not attempt to perform this

primer is wet. If an HS5482-6,

CAUTION

procedure with the tail rotor

HS4441-6, or an LWB22-6 bolt is

blades installed on the helicopter. Failure to

installed, torque nut to 750 - 775

comply with this caution may result in de

inch-pounds (84.74 - 87.56 Nm).

fective rivet installation and possible blade

After blade is secured to strap

damage.

CAUTION

pack assembly, do not allow

blade pitch travel from neutral to exceed 30

(1). Remove tail rotor blades from helicop

degrees in either direction. Rotating blade

ter (Ref. Tail Rotor Blade Replacement

to excessive pitch angles may result in unde

Procedure).

tected damage to strap assembly.

(2). Using a 10X magnifying glass, perform

(12). Check that bolthead is flat against

a visual inspection of the tail rotor

bushing. No gap is permitted. If gap is

blade abrasion strip bond lines for

found, replace bolt and bushing.

debonding.

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MAINTENANCE MANUAL

(3). If abrasion strip debonding is suspected

(e). Inspect hole in abrasion strip.

but cannot be confirmed by visual

(11). Remove FOD from interior of blade as

inspection, perform Abrasion Strip Dye

follows:

Penetrant and Tap Test Inspection.

(a). Drill 0.250 inch (6.35 mm) hole

NOTE: Tail rotor blades removed for voids

through tip cap as shown.

must be removed in ship sets.

(b). Remove FOD from blade interior

(4). If voids are found in blade, remove and

through hole (there is space at tip cap

send to an authorized repair station for

end for debris to pass aft of spar).

repair.

(c). Install new rivet.

(5). Carefully secure tail rotor blade in a

suitable holding fixture.

(d). Abrade surface surrounding tip cap

hole using emery cloth (CM804); wipe

NOTE: When performing the following step,

clean using clean, lint-free cloth

use drill bit stop to prevent drilling through

dampened with 1,1,1-trichloroethane

both sides of blade.

(CM222).

(6). Using a No. 27 cobalt drill bit, drill

Do not allow resin to build up in

holes at locations shown (light center

CAUTION

hole.

punch prior to drilling is allowed).

(e). Bond two plies of fiberglass cloth over

(7). Deburr holes with a 100° countersink to

hole with epoxy resin.

a depth of not more than 0.011 inch

(0.2794 mm).

(12). Repeat inspection of abrasion strip.

(13). Reinstall tail rotor blades.

(8). Apply primer (CM318) to holes and

install CS2545-4-1 or CR3555-4-1

(14). Perform tail rotor balance (Ref. Sec.

rivets while primer is wet.

18-20-00, Tail Rotor Blade Balancing).

Installed rivet stems may be de

CAUTION

7. Tail Rotor Blade Abrasion Strip

burred using a file. Do not re

Modification

move material from locking collar.

(Ref. Figure 205) The following procedure is for

(9). Inspect installed rivets.

application of a 0.0027 inch (0.06858 mm).

thick strip of stainless steel tape over the

(10). If rivet installation is not satisfactory,

inboard end of the abrasion strip.

remove as follows:

This procedure is effective on tail rotor blades:

During removal of defective riv

CAUTION

369A1613-7, -503, -505, -509,

et, observe the following:

369D21606-BSC, -509,

Do not damage or enlarge hole.

369D21613-11, -31, -41, -51, -71,

Do not drive or force rivet stem from hole.

369D21615-BSC, -21, -41,

Do not remove rivets common to tip cap.

421-088

(a). Carefully grind off locking collar and

upper portion of rivet head.

Consumable Materials

(Ref. Section 91−00−00)

(b). Carefully push center stem through

Item

Nomenclature

rivet sleeve.

CM220

Naphtha aliphatic

(c). Using a drill stop, drill through rivet

CM801

Abrasive paper, silicon carbide

sleeve using care to prevent hole

enlargement.

NOTE: Abrasion strip must have rivets

(d). Push remaining rivet sleeve through

installed before applying stainless steel

hole.

tape.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

(1). Using a 10X magnifying glass, perform

8. Tail Rotor Blade Protective Tape

a visual inspection of the tail rotor

Installation

blade abrasion strip bond lines for

debonding.

Consumable Materials

(Ref. Section 91−00−00)

(2). If abrasion strip debonding is suspected

Item

Nomenclature

but cannot be confirmed by visual

inspection, remove blades and perform

CM220

Naphtha aliphatic

Abrasion Strip Dye Penetrant and Tap

CM304

Enamel, epoxy

Test Inspection.

CM801

Abrasive paper, silicon carbide

N/A

3M aerosol primer MITO-0081

NOTE: Tail rotor blades removed for voids

N/A

3M mylar tape P/N Y8671-1

must be removed in ship sets.

(3). If voids are found in blade, remove and

NOTE: This installation is only approved on

send to an authorized repair station for

tail rotor blades equipped with the new

repair.

abrasion strips.

(4). Lightly abrade faying surface of tail

In an effort to reduce the amount of erosion in

rotor blade in area where tape is to be

the area inboard of the abrasion strip, MDHS

installed with 400-grit abrasive paper

has approved the installation of mylar tape to

(CM801).

the blade leading edge. Installation of the tape

is optional.

(5). Wipe abraded area with naphtha

(CM220) to eliminate grease and dirt

The length of the tape can vary, up to 2.0

film.

inches in length, but must be equal on both

blades.

NOTE: Do not allow temperature to exceed

120°F (49°C).

It is recommended to start with 1.5 inch (3.81

cm) length and increase the length as erosion

(6). Using a heat gun, or equivalent, heat

occurs by replacing the tape.

abraded area.

Do not cut or trim tape after

CAUTION

(7). Remove backing and apply stainless

installation on blade, damage to

steel tape to leading edge of tail rotor

blade will occur.

blade.

(1). Measure length of eroded area on blade

(a). Apply tape so it overlaps each side of

with the most erosion.

blade equally.

NOTE: Tape must be of equal length on both

blades to ensure proper balance.

(b). Tape should overlap the inboard end

of abrasion strip 0.50 ±0.03 inch

(2). Cut tape long enough to cover erosion

(12.70 ±0.762 mm) at the leading

plus approximately 0.50 inch (12.70

edge of blade.

mm) overlap on leading edge abrasion

strip.

NOTE: Abrasion tape must be free of surface

wrinkles or air bubbles.

(3). Round off square corners of tape to

reduce peeling.

(8). Smooth and press tape into place by

hand.

(4). Lightly abrade faying surface of tail

rotor blade in area where tape is to be

(9). Re-apply pressure by hand following

installed with 400 grit abrasive paper

initial installation to ensure proper

(CM801).

bonding.

(5). Wipe abraded area with naphtha

(10). Perform tail rotor balance (Ref. Sec.

(CM220) to eliminate grease and dirt

18-20-00, Tail Rotor Blade Balancing).

film.

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MAINTENANCE MANUAL

(6). Treat any bare metal with epoxy-type

(2). If cracks are suspected, perform a dye

paint (CM304).

penetrant inspection of the suspect area

as follows:

NOTE: Do not allow temperature to exceed

(a). Lightly abrade faying surface of tail

120°F.

rotor blade in area where tape is to

(7). Using a heat gun, or equivalent, heat

be installed with 400-grit abrasive

abraded area.

paper (CM801).

(b). Wipe abraded area with naphtha

(8). Apply aerosol primer to bonding area

(CM220) to eliminate grease and dirt

and allow to dry.

film.

(9). Remove backing and apply tape to

(c). Perform dye penetrant inspection on

leading edge of blade.

the suspected area per MIL-I-25135,

or equivalent.

(a). Apply tape so it overlaps each side of

blade equally.

(d). Tail rotor blades with evidence of

cracking must be removed from

(b). Tape should overlap the inboard end

service.

of abrasion strip 0.50 ±0.03 inch

(12.70 ±0.762 mm) at the leading

NOTE: Tail rotor blades with the new abrasion

edge of blade.

strip configuration cannot be intermixed

with tail rotor blades that have the old abra

NOTE: Tape must be free of surface wrinkles or

sion strip configuration.

air bubbles.

(e). If there is no evidence of cracking,

(10). Smooth and press tape into place by

the blade can be cleaned and touch-

hand.

up epoxy paint applied to the affected

area.

(11). Re-apply pressure by hand following

(3). To reduce erosion, apply protective tape

initial installation to ensure proper

to the blades (Ref. Tail Rotor Blade

bonding.

Protective Tape Installation).

(12). Perform tail rotor balance (Ref. Sec.

(4). Perform tail rotor balance (Ref. Sec.

18-20-00).

18-20-00, Tail Rotor Blade Balancing).

9. Tail Rotor Blade Leading Edge Crack

B. Tail Rotor Blades with Old−Style

Inspection

Abrasion Strips

(1). Remove stainless steel tape from the

(Ref. Figure 206)

leading edge at the inboard end of the

abrasion strip.

Consumable Materials

(2). Inspect that area for evidence of cracks;

(Ref. Section 91−00−00)

no cracks are allowed.

Item

Nomenclature

CM220

Naphtha aliphatic

(3). If cracks are suspected, perform a dye

penetrant inspection of the suspect area

CM801

Abrasive paper, silicon carbide

as follows:

(a). By lightly abrading the blade skin,

Do not use any chemicals to re

CAUTION

carefully remove the paint from the

move the paint and do not pene

suspected area.

trate the metal skin of the blade.

(b). Perform dye penetrant inspection on

A. Tail Rotor Blades with New−Style

the suspected area per MIL-I-25135,

Abrasion Strips

or equivalent.

(1). Inspect leading edge for any evidence of

(c). Tail rotor blades with evidence of

cracking in the area shown; no cracks

cracking must be removed from

are allowed.

service.

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MAINTENANCE MANUAL

NOTE: Tail rotor blades with the new abrasion

(c). Using a heat gun, or equivalent, heat

strip configuration cannot be intermixed

abraded area.

with tail rotor blades that have the old abra

(d). Remove backing and apply stainless

sion strip configuration.

steel tape to leading edge of tail rotor

blade.

(d). If there is no evidence of cracking,

the blade can be cleaned and touch-

1). Apply tape so it overlaps each side

up epoxy paint applied to the affected

of blade equally.

area.

2). Tape should overlap the inboard

(4). Install new 0.0027 inch (0.06858 mm)

end of abrasion strip 0.50 ±0.03

thick stainless steel tape in the same

inch (12.70 ±0.762 mm) at the

location as follows (Ref. Figure 205):

leading edge of blade.

(a). Lightly abrade faying surface of tail

NOTE: Abrasion tape must be free of surface

rotor blade in area where tape is to

wrinkles or air bubbles.

be installed with 400-grit abrasive

(e). Smooth and press tape into place by

paper (CM801).

hand.

(b). Wipe abraded area with naphtha

(f). Re-apply pressure by hand following

(CM220) to eliminate grease and dirt

initial installation to ensure proper

film.

bonding.

NOTE: Do not allow temperature to exceed

(5). Perform tail rotor balance (Ref. Sec.

120°F (49°C).

18-20-00, Tail Rotor Blade Balancing).

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MAINTENANCE MANUAL

TAIL ROTOR HUB AND FORK

MAINTENANCE PRACTICES

1. Tail Rotor Hub and Fork

one inch in either direction. Unrestricted

rotation of blades on hub can excessively

(Ref. Figure 201) This section covers mainte

bend or stretch strap pack and cause un

nance of the hub, strap pack and fork as an

detected damage to strap pack and an

assembled unit. For all other maintenance

out-of-balance tail rotor when reas

instructions pertaining to hub and fork

sembled.

assembly, and the hub assembly, strap pack

D To prevent balance problems at reassemb

and fork assemblies as separately-maintain

ly of parts and hardware, mark exact

able components, Ref. COM.

number, locations and positions of all

items before removal for correct reinstal

When blades are removed from

CAUTION

lation.

hub, exposed ends of strap pack

should be protected with covering (Ref. Sec.

D On two-bladed tail rotor system do not

64-10-00). Hub and fork should be handled

remove hub-to-drive fork hinge bolt to

carefully to avoid damage to strap pack.

remove tail rotor assembly. On four-

bladed tail rotor system hub-to-drive

fork hinge bolt removal is required. This

2. Tail Rotor Hub and Fork Replacement

bolt should only be removed according to

instructions Ref. COM. Damage to strap

A. Tail Rotor Hub and Fork Removal

pack may occur if any other procedure is

used.

(Ref. Figure 202 and Figure 203)

(2). Disconnect pitch control links from

Special Tools

blade pitch control arms.

(Ref. Section 91−00−00)

Item

Nomenclature

(3). Pull rotating boot out of groove in fork.

ST607

Adapter, torque wrench

(4). On four-bladed tail rotor system

remove inboard and outboard blades

On four-bladed tail rotor

and hubs to access fork tang washer

WARNING

system, there is strong

and nut.

spring pressure in installed tail rotor

linkage. Disconnect the in-line bungee

NOTE: Helicopters Serial Nos. D0003 thru

before beginning disassembly. Failure

D1024 had a two-piece retaining nut and

to disconnect the bungee can result in

stop support. Helicopters subsequent to

personal injury and/or parts damage.

D1024 have a one-piece retaining nut and

stop support.

(1). On four-bladed tail rotor, disconnect

in-line bungee (Ref. Sec. 67-20-10) if

(5). Straighten tang of tang washer.

tail rotor is installed on helicopter.

(6). Using torque wrench adapter (ST607),

loosen retaining nut and slide tail rotor

CAUTION

outward on output shaft of tail rotor

D Whenever blades and hub are removed as

transmission to remove blade stop and

an assembly, or whenever pitch control

stop support.

links are disconnected, do not allow blade

pitch to exceed 30 degrees from neutral

(7). Remove nut, tang washer, tapered ring,

pitch position. This is equal to blade pitch

and split-ring halves that fit into recess

control arm movement of approximately

at inboard end of fork.

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MAINTENANCE MANUAL

Tail rotor tang washer must not

It is possible for pitch control

CAUTION

be reused.

swashplate to be misaligned by

one-half spline in relation to drive fork.

NOTE: Placing grease pencil mark on drive

Make sure drive fork, pitch links and swash

fork to key it to transmission output shaft

plate are in exact alignment with transmis

enables subsequent installation of tail rotor

sion shaft centerline. If incorrectly as

assembly at same position.

sembled, swashplate will be misaligned

approximately 10 degrees from drive fork.

Application of small painted matchmark

To correct this condition, remove tail rotor

next to centerline splined groove on both

assembly (leaving pitch control assembly in

pitch control assembly and tail rotor drive

stalled), rotate tail rotor assembly 180 de

fork aids reassembly at same position on

grees and reinstall it.

transmission shaft.

(3). Slide tail rotor assembly onto shaft

with drive fork-to-hub pivot bolt

One spline groove of fork is located directly

aligned with swashplate lugs. Position

on centerline passing through centers of the

tail rotor assembly on shaft so that

two fork bearings while, at opposite side of

approximately two threads at shaft end

spline bore, same centerline passes through

are exposed outboard of drive fork.

a spline tooth. A similar condition exists

with respect to swashplate splines, except

(4). Coat tapered ring with primer (CM318)

that reference centerline originates between

and install it on shaft, making certain

swashplate arms.

that tapered edge parallels chamfer in

fork. Perform the following steps while

For illustrations showing matchmarks and

primer is wet.

additional information, Ref. COM.

NOTE: Pre-assembly of tang washer, nut, stop

support and stop as a unit aids in their in

(8). Slide tail rotor assembly off output

stallation when performing steps (5). thru

shaft.

(7). below. Marking outer tang that is next to

inner key on tang washer, before assembly

B. Tail Rotor Hub and Fork Installation

of parts, simplifies alignment with keyway

on shaft. Teeter blades to start tang washer

(Ref. Figure 202 and Figure 203)

on shaft.

(5). Slip new tang washer over exposed

Consumable Materials

threads of shaft; key tang must face

(Ref. Section 91−00−00)

inboard toward gearbox. Install nut

Item

Nomenclature

approximately two full turns on shaft

threads to verify threads engaged.

CM115

Grease, oscillating bearing

CM318

Primer

(6). Slide tail rotor assembly outboard

against nut. Install stop support by

CM702

Lockwire CRES

inserting it in drive shaft end.

Special Tools

In next step do not force stop

CAUTION

(Ref. Section 91−00−00)

into position with screwdriver;

Item

Nomenclature

this can crack the stop.

ST607

Adapter, torque wrench

(7). Coat contacting surfaces of stop with

grease (CM115) and insert it in stop

support.

(1). Attach rotating boot; attach to pitch

(8). Install split ring halves in shaft groove

control assembly using safety wire

and slide fork inboard until ring halves

(CM702).

are secured by recess in fork.

(2). Install split ring on output shaft of

(9). Visually align a tang on tang washer

transmission.

with any convenient reference point.

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MAINTENANCE MANUAL

(10). Torque retaining nut, using torque

3. Tail Rotor Hub and Fork Inspection

wrench adapter (ST607), to:

(Ref. Figure 201) Hub inspection is accom

(a). Torque two-bladed retaining nut to

plished with tail rotor blades removed.

450 - 500 inch-pounds (50.84 -

(1).

Inspect areas on hub trunnions that

56.49 Nm).

mate with blade pitch bearings for

excessive wear and for damage.

(b). Torque four-bladed retaining nut to

550 - 600 inch-pounds (62.14 -

(2).

Check hub and fork for axial play or

67.79 Nm) and ensure wire-spring

bearing roughness when hub is pivoted

split ring halves are firmly imbedded

from one extreme to the other.

in fork recess.

(3).

Check torque of fork hinge bolt. Apply

NOTE: Tang washer movement of more than

125 inch-pounds (14.12 Nm) torque

one tang width is an indication that tang

to nut or bolt. If bolt or nut does not

washer inner key tang is sheared. This con

rotate, preload is correct. If bolt or nut

dition requires replacement of tang washer

rotates, retorque. (For repair limit,

and reassembly of parts according to initial

torquing requirements and replacement

installation procedure.

criteria, Ref. COM.)

(11).

Check that tang has not moved more

(4).

Check visible areas of strap pack for

than one tang width in relation to

nicks or scratches on strap laminates,

reference point noted in step (9).

cracked or kinked laminates and sharp

bends or permanent twists in lami

(12).

Measure clearance between tang

nates. Any one of these defects, except

washer and fork.

minor outer surface defects that can be

removed by abrasive polishing, requires

(13).

If clearance is less than 0.005 inch

replacement of strap pack. (For infor

(0.127 mm), replace tapered ring and/or

mation on allowable repairs, service

fork assembly.

ability requirements and replacement,

(14).

Bend two tangs on tang washer to lock

Ref. COM.)

retaining nut. When bending tangs, do

4. Conical Bearing Inspection

not force-form tang to match nut

contour; maintain natural bend radius

Visually inspect conical bearings installed in

that develops at tang root.

fork assembly, at intervals specified (Ref. Sec.

05-20-00).

(15).

Apply torque stripe paint across nut,

tang washer and fork assembly in

(1). Play is not permitted in conical drive

location that can be checked visually.

fork bearings.

(16).

Insert edge of rotating boot into groove

5. Elastomeric Fork Bearing Inspection

of drive fork.

Visually inspect elastomeric bearings installed

(17).

Install pitch control links (Ref. Sec.

in fork assembly, at intervals specified (Ref.

64-30-00).

Sec. 05-20-00) for damage and debonding

from fork as follows.

(18).

Position tail rotor pedals in neutral

position and recheck that drive fork,

Elastomeric materials can be

CAUTION

pitch links and swashplate are in exact

damaged by solvents, grease or

alignment with transmission shaft

oil. If cleaning is necessary, refer to Elasto

centerline.

meric Bearing - Care and Cleaning.

(1). Apply teetering force by hand to rotor

(19).

On four-bladed tail rotor system,

blades (stop-to-stop). Check for

reconnect bungee (Ref. Sec. 67-20-10).

fork-to-bearing bond failure. Failure is

(20).

Check rigging of tail rotor controls (Ref.

indicated by any motion between outer

Sec. 67-20-10).

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 22