CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

0.25 IN. (6.35 MM) R

6.80 IN.

(17.272 CM)

0.25 IN. (6.35 MM) R

(NOTES 2, 3)

TOP

SURFACE

NOTE 1

0.35 IN. (8.89 MM)

(NOTE 3)

0.38 IN. (9.652 MM)

0.38 IN.

NOTE 4

(9.652 MM)

1.00 IN.

0.00−0.10 IN.

1.00 IN.

(25.4 MM)

(0.00−0.254 MM)

(25.4 MM)

VIEW A−A

NOTES:

REMOVE DAMAGED END(S) IF THEY OCCUR WITHIN 1.00 IN. (25.4 MM) OF TAB ENDS.

0.25 IN. (6.35 MM) RADIUS CLEANUP. FINISH PER BASIC HMI.

MAXIMUM DEPTH OF REPAIR 0.35 IN. (8.89 MM).

NO MINIMUM LENGTH OF TAB REQUIRED. IF DAMAGE OCCURS AT BOTH ENDS.

IT IS PERMISSIBLE TO REMOVE BOTH ENDS.

ENTIRE TAB MAY BE REMOVED IF REQUIRED.

30−217A

Figure 7-11. Repair and Removal of Trim Tab, Main Rotor Blade

Cutting, grinding or filing to re−

15. Main Rotor Blade and Damper Attach Pin

CAUTION

move trim tab, and deburring of

Inspection and Corrosion Protection

reworked blade trailing edge, are to be per−

(Ref. Figure 7−12)

formed in a spanwise direction only. DO

NOT use shears or clippers to remove trim

(1). Inspect pin cam handle lobe for cracks

tab.

and excessive wear. Remove pin from

service if cracking or excessive wear is

noted.

(b). Use metal cutting saw or equivalent

to remove the 0.380 inch (9.652 mm)

NOTE: If hard anodizing surface of cam lobes is

wide trim tab, view A − A Deburr

worn, cam lobes can be re−anodized or

edges in a spanwise direction only.

treated with corrosion preventive oil (104,

Table 2−4).

(8). Peel and remove tape from blade and

(2). Inspect attach pin for evidence of

inspect area around repair; clean

corrosion or wear and straightness.

repaired area with cloth dampened in

solvent (aliphatic naphtha).

(a). Pay particular attention to area

along edges of barrel nut and bore in

cam handle.

(9). Apply chemical film treatment (Iridite)

to reworked area of blade trailing edge

(b). Remove pin from service if corrosion

or trim tab; apply a thin film of primer

or wear is noted or pin is bent.

and paint lightly.

Standard hardware (Ref. Figure 7−3)

may be used to replace faulty damper

attach pins.

(10). As applicable, reinstall main rotor

blade.

(c). If used, install at all four locations.

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: Corrosion protection treatment is to be

OIL

BARREL NUT

applied at each periodic inspection to ensure

continued serviceability of attach pin; and

at each pin removal, if subject to salt laden

OIL

atmosphere.

CAM HANDLE

THRUST

WASHER

(3). With attach pin removed, lubricate

mating surfaces of barrel nut and cam

BUSHING

SEGMENTS

handle, using corrosion preventive oil.

Rotate cam handle back and forth on

barrel nut several times to ensure that

oil penetrates all sections of pin

operating mechanism. Wipe excess oil

from pin surfaces.

SPACER

(4). Adjust pin at installation.

16. Main Rotor Blade and Damper Attach Pin

Disassembly and Special Inspection

(Ref. Figure 7−12) This inspection is to be

performed in event of a main rotor blade

strike.

Do not intermix bushings,

SAFETY LATCH

CAUTION

spacers and thrust washers be−

tween bolts. Components parts make up a

G62−1008

single bolt assembly.

Figure 7-12. Main Rotor Blade and Damper

(1). Remove adjusting nut and remove

Attach Pin

adjustable bushings, spacer and thrust

washers from pin.

17. Main Rotor Blade and Damper Attach Pin

Adjustment

(2). Using brush and clean cloth, clean

(Ref. Figure 7−3)

parts with isopropyl alcohol (71,

Table 2−4). Dry with clean cloth.

NOTE: Whenever a new attach pin is installed,

a main rotor blade is replaced, or the rotor

(3). Inspect pins as follows:

hub assembly is replaced, adjustment is re−

quired to ensure that the pin(s) properly

(a). Fluorescent inspect pin per MIL−

seize in the mating holes.

STD−6866.

(1). Check the main rotor blade and damper

(b). Magnetic particle inspection; thrust

arm attach pins for cracks, wear and

washers, bushings and spacers per

corrosion.

MIL−STD−1949.

(2). Support the blade tip to establish

(4). Reassemble pin in sequence as follows;

alignment of the holes in the blade root

install thrust washer, three (3) adjust−

fittings and lead−lag links; Install pin.

able bushings, spacer, three (3) adjust−

NOTE: After final adjustment of main rotor

able bushings, thrust washer and

blade and damper attach pins, thread pro−

secure with adjusting nut.

trusion from adjuster nut of 1/2 to 1 thread

is acceptable if attach pin safety latch is se−

(5). Lubricate mating surfaces of barrel nut

curely latched over the adjuster nut.

and cam handle with corrosion preven−

tive oil (104).

(3). Adjust the pin for correct seizure by

turning the small hex nut at end of pin

(6). Reinstall and adjust pin.

until 25 − 35 pounds (111 − 156 N)

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

hand pressure is required to snap the

(1). Visually inspect exposed portion of all

safety latch into place over the nut.

installed main rotor blade upper and

lower root fitting attach lugs, and main

NOTE: After adjustment, the installed length

rotor hub lead−lag link attach lugs for

of the pins, measured from the face of the

broken or cracked lugs, corrosion or

thrust washer to the outer edge of last bush−

other damage to the lug areas.

ing,

should be

0.99−1.04 inch

NOTE: If movement is suspected but cannot be

(25.146− 26.416 mm) for damper pins and

verified with the blades installed, remove

2.84− 2.89 inches (72.136− 73.406 mm) for

those blades and inspect bushings for move−

main rotor blade pins.

ment.

(4). For final installation, the locking levers

(2). Using a bright light, inspect slippage

of the two blade root fitting pins should

marks on the root fitting bushings to

be located inboard of (behind) the stop

ensure there has been no movement of

springs of the pitch housing lead−lag

the bushings.

links.

(a). If bushings have moved, replace

main rotor blade before next flight.

18. Main Rotor Blade Forward Tip Cap

Inspection and Corrosion Prevention

(b). Return those main rotor blades

where bushing movement has

(1). Inspect tip caps for evidence of corro−

occurred to MDHI for possible

sion, pay particular attention to mating

rework.

area of blade skin to tip weight inter−

face, verify integrity of sealant coating.

CAUTION

(2). If damage is evident, remove tip caps

D If broken or cracked lugs are noted in

and apply penetrating oil to blade tip

main rotor blade upper or lower root fit−

weight area. The oil will arrests any

tings, replace main rotor blade before fur−

corrosion between blade skin and

ther flight.

weight assembly.

D If broken or cracked lugs are noted in

main rotor lead−lag links, replace main

(3). Using brush and clean cloth, clean area

rotor hub.

with isopropyl alcohol (71, Table 2−4).

Dry with clean cloth.

D If cracking is suspected in either the rotor

blade or hub lead− lag link attach lugs,

(4). Spray area with light film of rust

perform dye penetrant (178, Table 2−4)

inhibitor (101); then apply thin film of

inspection of lugs per MIL− I− 25135. If

primer and paint lightly as required.

cracking is noted, replace main rotor

blade, or, replace or repair main rotor hub

19. Main Rotor Blade Upper and Lower Root

assembly, before further flight.

Fitting Attach Lug and Lead-Lag Link

NOTE: Lead−Lag link assemblies may only be

Inspection (25 Hour)

replaced by MDHI authorized personnel or

under MDHI supervision. Contact your local

(Ref. Figure 7−13 and Figure 7−14) The

MDHI Field Service Representative for fur−

following procedure pertains to helicopters

ther information.

equipped with 369A1100−501 thru −505 main

rotor blades and/or 369A1234, 369H1203−BSC

20. Main Rotor Blade Upper and Lower Root

thru −31 lead−lag link assemblies.

Fitting, Attach Lug and Lead-Lag Link

Inspection (100 Hour)

NOTE: Main rotor blades and hub assemblies

installed on helicopters operating in a salt

(Ref. Figure 7−13 and Figure 7−14) The

water or corrosive environment should be

following procedure pertains to helicopters

cleaned and washed on a daily basis as a

equipped with 369A1100−501 thru −511 and

preventative measure to arrest corrosion

369D21123−501 main rotor blades and/or

(Ref. Sec. 2, Main Rotor Hub Corrosion Pre−

369A1234, 369H1203−BSC thru −31 lead−lag

vention (Tri−Flow Wash Procedures)).

link assemblies.

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Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(1). Remove affected main rotor blades.

(b). Insert a 0.004 inch (0.102 mm) thick

piece of mylar/viewfoil between the

fitting and the doubler.

CAUTION

(c). If the mylar can be inserted, contact

D If broken or cracked lugs are noted in

Field Service Representative for

main rotor blade upper or lower root fit−

disposition of blade.

tings, replace main rotor blade before fur−

ther flight.

(d). If the insertion is 0.10 inch (2.540

D If broken or cracked lugs are noted in

mm) or greater, remove blade from

main rotor lead−lag links, replace main

service.

rotor hub.

NOTE: Measurement of the insertion is from

D If cracking is suspected in either the rotor

the edge of the root fitting.

blade or hub lead− lag link attach lugs,

perform dye penetrant (178, Table 2−4)

(e). Retorque root fitting outboard bolt to

inspection of lugs per MIL− I− 25135. If

60 − 65 inch−pounds (6.78 − 7.34

cracking is noted, replace main rotor

Nm) plus drag torque.

blade, or, replace or repair main rotor hub

assembly, before further flight.

NOTE: Lead−Lag link assemblies may only be

replaced by MDHI authorized personnel or

NOTE: Do not remove bushings or corrosion in−

under MDHI supervision. Contact your local

hibiting sealer.

Field Service Representative for further in−

formation.

(2). Using a bright light and 5X magnifying

glass, visually inspect the attach lugs of

(4). Inspect lead−lag link blade attach pin

all main rotor blade upper and lower

hole bushings for any indication of

root fitting and main rotor lead−lag

movement of the bushings in the links.

links for broken or cracked lugs,

If any of the bushings have movement,

corrosion or other damage to the lug

replace the link.

areas.

If required, apply a light but

CAUTION

(a). Pay particular attention to area

thorough coat of sealer or zinc−

around attach pin hole bushings in

chromate primer around bushings. Note

the lugs.

that excessive amounts of sealant or zinc−

chromate primer around the bushings are

(b). Pay particular attention to the

not desirable and can unbalance the main

cross−hatched areas.

rotor system.

(c). If slippage marks have already been

(5). If sealing compound (171) is not already

applied, inspect the root fitting for

installed or becomes loose, clean and

any indication of movement of the

seal all junctions between all the steel

bushings; no movement is allowed.

bushings and the main rotor blade root

fitting attach lugs with a film of sealing

(d). Return main rotor blades that have

compound or primer (4) without

root fitting bushing movement to

removing the bushings.

MDHI for possible rework.

(6). For the main rotor blade root fitting

(e). If slippage mark is degraded, reapply

attach lugs, carefully remove sufficient

per steps (6). and (8).

amount of sealant and paint from only

(3). Inspect main rotor blade root fitting for

the bushing in the area where the

missing (no squeeze−out) or cracked

slippage mark is to be applied (if not

adhesive/paint around the periphery of

already done).

the root fitting. If this condition exists,

(7). Using isopropyl alcohol (71), clean the

proceed as follows:

area where the slippage mark is going

(a). Loosen, but do not remove the

to be applied to allow adequate adher−

extreme outboard bolt.

ence of epoxy paint.

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Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE:

22. Main Rotor Blade Torque Event Inspection

D Locate slippage mark in a position that

(Ref. Figure 7−13)

can be viewed at subsequent inspections

NOTE: This inspection requires the use of a

with main rotor blade installed in the

bright light.

hub. Slippage marks should not be ap−

plied to cross−hatched areas to preclude

(1). Lifting from the outboard end of the

masking possible cracks.

blade, lift blade off the droop stop.

D Insure that slippage mark is applied to

(2). Inspect the bottom−side of the blade as

bushing at upper and lower root fitting in−

follows:

side surfaces.

(a). Inspect the area around the root

D Do not use torque seal.

fitting, doubler and skin for cracks.

(b). Inspect the attach lugs at the bush−

(8). Apply epoxy paint slippage marks to

ings for cracks.

four locations as shown.

(c). Inspect the entire length of the blade

(9). Install main rotor blades.

for cracks.

(d). Lower blade back onto droop stop.

21. Main Rotor Blade Leading Edge Abrasion

Strip Check

(3). With blade resting on the droop stop,

inspect the top−side of the blade as

The leading edge abrasion strip should be

follows:

checked prior to each flight or on every daily

check. The following is a comprehensive

(a). Inspect the area around the root

checklist:

fitting, doubler and skin for cracks.

(b). Inspect the attach lugs at the bush−

(1). Check for any blistering, bubbling or

ings for cracks.

lifting of the abrasion strip; this

indicates a void.

(c). Inspect the entire length of the blade

for cracks.

(a). Voids cannot be closer than 0.50 inch

(4). If any of the above defects are found,

(12.7 mm) to any outside edge of

the main rotor blade is to be rejected

abrasion strip.

and scrapped.

(b). Voids exceeding 1.5 square inch

23. Vibration Absorber

(9.6774 square cm) are unacceptable.

(Ref. Figure 7−15) One vibration absorber is

(c). Voids cannot be closer than one inch

installed on the lower inboard end of each

(25.4 mm) to any other void.

main rotor blade. Each vibration absorber

consists of two pendulums that pivot about a

(2). Number of acceptable voids depends

common axis. These pendulums are tuned to

upon length of abrasion strip.

cancel out the first and second harmonic beats

of the natural vibration frequency of each

(a). There cannot be more than three

individual blade. The largest pendulum

voids on either the top or bottom of

counteracts any 3−per−revolution vibrations;

the 36 inch long (91 cm) abrasion

the smallest pendulum counteracts any

strip surface.

5−per−revolution vibrations.

(b). There cannot be more than two voids

A. Vibration Absorber Removal

on either the top or bottom of the 18

(1). Remove bolt and washer at trailing

inch (46 cm) long abrasion strip

edge of blade; remove shim washer(s) if

surface.

installed.

(3). Record all voids in regards to size and

NOTE: Shim washers are installed between vi−

location in the helicopter log book and

bration absorber and main rotor blade as re−

check each void prior to each flight for

quired to compensate for minor variations

growth and acceptable criteria.

in blade contour.

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Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(2). Remove two nuts, radius blocks,

that the shorter of the bolts is in the

washers and bolts that attach absorber

outboard hole. Torque bolts to 50 − 60

to blade.

inch−pounds (5.65 − 6.78 Nm).

(3). Remove vibration absorber.

(3). If a gap exists between the trailing edge

of vibration absorber and main rotor

B. Vibration Absorber Installation

blade, shim with washers. If no gap

(1). Apply primer (4, Table 2−4) on the two

exists, install trailing edge bolt and

long bolts.

washer without shim washers. Apply

chromate primer to bolt and install bolt

(2). Align vibration absorber with holes in

and washer while primer is still wet.

main rotor blade. Install two long bolts

and washers while primer is still wet;

(4). Torque bolt to 15 − 20 inch−pounds

then install radius block nuts. Check

(1.69 − 2.26 Nm).

Page 7-36

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTES 2, 3 AND 4

DOUBLER

ROOT FITTING

NOTE 5

NOTES 1, 2 AND 3

USE BRIGHT LIGHT TO INSPECT

FOR CRACKS IN THIS AREA. PAY

PARTICULAR ATTENTION TO

BOTTOM SIDE OF BLADE.

VIEW LOOKING UP

NOTE 5

ROTATED

LOOSEN BUT DO NOT REMOVE BOLT.

RETORQUE BOLT TO 60 − 65 IN−LB

(6.78−7.34 NM) PLUS DRAG TORQUE.

UPPER ROOT FITTING ATTACH LUG

(TYP 2 PLCS) (NOTE 1)

NOTE 5

LEAD−LAG LINK ATTACH LUG

MAIN ROTOR BLADE

(TYP 8 PLCS) (NOTE 1)

LOWER ROOT FITTING

ATTACH LUG

(TYP 2 PLCS) (NOTE 1)

NOTES:

VISUALLY INSPECT AREAS OF ALL ROOT FITTINGS AND LEAD−LAG ATTACH LUGS FOR CRACKS OR

BREAKS. INSPECT BLADE ATTACH BUSHINGS FOR LOOSENESS. IF LOOSE, REPLACE LEAD−LAG LINKS.

PAY PARTICULAR ATTENTION TO AREA AROUND ATTACH PIN HOLES IN LUGS.

SEAL ALL JUNCTIONS BETWEEN BUSHINGS AND ATTACH LUGS WITH SEALER OR PRIMER (4, TABLE 2−4).

LEAD−LAG LINK ASSEMBLIES ARE SUB−ASSEMBLIES OF THE MAIN ROTOR HUB ASSEMBLY.

INSPECT MAIN ROTOR BLADE UPPER AND LOWER ROOT FITTING FOR MISSING OR CRACKED ADHESIVE.

USING BRIGHT LIGHT, INSPECT MAIN ROTOR BLADE DOUBLER FOR CRACKS. PAY PARTICULAR ATTENTION

TO BOTTOM SIDE OF BLADE, JUST BEYOND ROOT FITTING AND IN LINE WITH ROOT FITTING ATTACH BOLTS.

88−347F

Figure 7-13. Main Rotor Blade Root Fitting Attach Lugs and Lead-Lag Link

Assembly Inspection

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Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

C. Vibration Absorber Inspection

DRAIN HOLE

BRACKET

(1). Inspect bracket for presence of ballast

weights. Evidence of lost ballast will

require weighing of complete vibration

THRUST WASHERS

absorber (Ref. Vibration Absorber

PADS

Weighing).

RIVET

(2). Refer to Main Rotor Blade Inspection

SHAFT

BEARING

for installed absorber inspection

requirements.

5−PER REVOLUTION

BEARING

PENDULUM

D. Vibration Absorber Disassembly

(1). Remove rivet that secures pivot shaft to

BEARING

bracket.

3−PER REVOLUTION

PENDULUM

(2). Remove pivot shaft by inserting a pin

through the hole in the forward end of

THRUST WASHER

the bracket and pushing shaft out of

bracket.

Figure 7-15. Vibration Absorber

(3). Remove 5−per−revolution pendulum

(2). Using adhesive (19, Table 2−4), install

and 3−per−revolution pendulum.

new or rebond loosened thrust washers

to bracket or pendulums. Follow

(4). Do not remove shaft bearings or thrust

container instructions for adhesive

washers unless replacement is neces−

application.

sary.

(3). Using sealing compound (3), install new

(5). Use dry, low pressure compressed air to

or rebond loosened 3−per−revolution

blow out bearing bores and drain hole

and 5−per−resolution pads to bracket.

in bracket.

Follow container instructions for

compound application. After bonding,

(6). Inspect bores of bearings for evidence of

seal the edges of the pad with sealing

galling, scoring and wear. Maximum

compound. Ensure that center hole in

allowable bore dimension is 0.268 inch

pad at 5−per−resolution location does

(6.8072 mm).

not block the drain hole through the

bracket.

(7). Inspect shaft for distortion and wear.

F. Vibration Absorber Reassembly

E. Vibration Absorber Repair

NOTE: During reassembly, do not allow chro−

mate primer to get on to the shaft bearings.

Repair of the vibration absorber is limited to

disassembly and replacement of pivot shaft

(1). Using primer (4, Table 2−4), coat cavity

bearings, thrust washers and rubber pads on

in bracket where undrilled end of shaft

the bracket. The pendulum weights may be

will seat.

inter−changed subject to total weight restric−

tions (Ref. Vibration Absorber Weighing). The

(2). Align bores of pendulums with bracket.

weight shims must not be altered because the

(3). Install shaft so that rivet hole in shaft

weights and the assembly have been tuned.

aligns with matching hole in bracket

The absorber bracket may be either an

while primer is still wet.

aluminum or magnesium casting. Refer to

Section 2 for corrosion control and identifica−

(4). Install new rivet and flush the shop

tion of magnesium and aluminum alloys.

formed end.

(1). Use press to remove and install new

(5). Coat open hole in bracket with primer.

pivot bearing into pendulums.

Check that the pendulums rotate freely

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

on shaft, without binding, and that the

25. Main Rotor Hub Assembly Replacement

shaft is free of primer.

(Ref. Figure 7−16)

G. Vibration Absorber Weighing

A. Main Rotor Hub Assembly Removal

Vibration absorbers may have either an

(1). Remove four main rotor blades.

aluminum or magnesium bracket as part of

the assembly. The total weight of an assembled

(2). Remove main rotor drive shaft; then

magnesium absorber is 1360 grams ±0.1 gram

reinstall hoisting eyebolts, washers and

when installed in sets of four. The total weight

nuts in rotor hub.

of an assembled aluminum vibration absorber

(3). Remove lockwire and disconnect

is 1405−1425 grams maximum. Absorbers may

flexible boot from lower end of hub

be mixed in a ship set if additional weight is

liner.

added to magnesium absorber(s) to obtain the

equivalent aluminum damper total weight

(4). Disconnect scissors crank from main

(1405−1425 gram). Paint an identifying yellow

rotor hub or scissors link (Ref.

band on a magnesium bracket lug if so

Figure 7−24).

modified.

(5). Disconnect each pitch change rod from

(1). Add lead weights (lead shot or equiva−

pitch housing.

lent) as required to establish total

NOTE: Color code each pitch change rod to

weight of 1360 grams ±0.1 gram

match the pitch housing and blade to which

(magnesium absorber) or 1405−1425

it is attached, so that the main rotor can be

grams (aluminum absorber).

reinstalled in the same position from which

removed.

(2). Bond lead weight into recess cut area of

bracket with adhesive (24, Table 2−4).

(6). Cut lockwire and removed two screws

securing retainer to main rotor hub nut

24. Main Rotor Hub Assembly

(Ref. Figure 7−17).

(Ref. Figure 7−16) The main rotor hub

(7). Remove nut retainer.

assembly consist of a hub and four identical

(8). Using main rotor mast nut wrench (19,

pitch housing assemblies that are 90° apart

Table 2−2), remove nut from mast.

and slightly offset. Lead−lag links, a blade

damper and damper arm, a droop stop striker

NOTE: On mast having nut without safety−

strip and spacer, and a pitch control bearing

wired dual screw installation, main rotor

assembly are combined with each pitch

mast nut wrench (20), may be used.

housing to produce the pivoting axis, blade

flapping stop contact surfaces and lead−lag

(9). Using hub puller (22), break loose main

hinge for the rotor blades. Two laminated

rotor hub. (Ref. Figure 7−18). Remove

retention strap assemblies that are both

hub puller. Then remove main rotor

vertically and torsionally flexible extend

hub, using suitable hoisting adapter

through the pitch housings and connect to the

attached to eyebolts in hub.

lead−lag links. A lower shoe assembly attached

B. Main Rotor Hub Assembly Installation

to the central hub contains, a droop stop ring

and droop restrainers that support the blades

NOTE:

at rest and distribute droop loads at low blade

D Removal of the recessed spacer, upper

rpm.

bearing cone, upper seal and seal retainer

is not mandatory for installation of the

NOTE: MDHI HN− 11 defines mast modifica−

main rotor hub. If these items are in−

tion and replacement requirements for non−

stalled, perform steps (1). thru (4). and

lockwired main rotor hub nut and retainer

steps (11). thru (18). Caution should be

with safetywired dual screw retainer and

used when installing the hub to prevent

nut. Note also that prebalanced hub assem−

damage to these parts.

blies may have balancing hardware in−

stalled in the hollow cores of the lead−lad

D If recessed spacer, upper bearing cone,

bolts.

upper seal and seal retainer have been re−

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

moved, these parts should not be as−

(7). Install recessed washer, upper bearing

sembled in hub before installation of hub

cone, upper seal, and seal retainer in

on helicopter. These items are reas−

hub and lubricate components as

sembled in hub after seating hub on mast.

follows:

Prior to installing the main rotor hub, in−

(a).

Hand−pack hub cavity, between

sure that all bearings are adequately

sleeve bushing and hub, with grease

serviced with grease (21, Table 2−4).

(21, Table 2−4).

(1). Inspect for interference between

(b).

Place recessed washer, recess down,

damper housings and pitch housings. If

on top of sleeve bushing.

less than 0.002 inch (0.051 mm) gap

exists between the housings, rework

(c).

Hand−pack upper bearing cup and

area as required in step (2). below prior

cone with grease; then install cone in

to hub installation.

cup and use hub driver tool to fully

seat cone.

(2). Remove main rotor damper. Rework

pitch housing by smooth blending into

(d).

Fill remaining cavity up to level of

the surrounding area with grade 320

upper seal with grease.

abrasive cloth (20). Finish polish to

(e).

Position upper seal, with lip up, and

restore original finish with crocus cloth

press in hub counterbore.

(23). Maximum rework depth is limited

to 0.010 inch (0.254 mm). Clean

(f).

Using light mallet, carefully tap seal

reworked area with MEK (22), prime

to seat in counterbore. Wipe away

with primer (4) and repaint (Ref. Sec.

any excess grease.

2).

(g).

Install seal retainer, recess up, and

NOTE: The main rotor hub is a highly stressed

seat it against the top surface of the

component. Use extreme care to prevent if

upper bearing cone.

from striking any object. Any impact dam−

(h).

Apply grease (21) to exposed threads

age may require replacement of the hub.

on mast.

(3). Attach hoisting adapter to eyebolts in

Refer to CSP− H− 5 for a re−

main rotor hub and connect a suitable

WARNING

quired modification of the

hoist.

mast and replacement of the mast nut

and lockwasher with a lockwired dual

NOTE: If the hub assembly (with sleeve bush−

screw retainer and nut.

ing, spacer, upper bearing and seal retainer

installed) does not seat properly onto the

NOTE:

mast, do not attempt to force it into position.

D Ensure seal is properly positioned against

Remove hub assembly from mast and deter−

seal retainer and that seal retainer does

mine cause of hub not seating, correct the

not pinch seal. Check by inserting a loop

problem and follow the procedures for in−

of approximately 0.040 inch (1.016 mm)

stallation.

lockwire, round feeler gage or other suit−

able tool without sharp edges between

(4). Check; that rotor mast is clean. Hoist

seal lip and retainer.

main rotor hub and position over the

mast then lower hub onto mast.

D To insure that hub is seated onto the mast

properly before torquing, 2− 4 threads

NOTE: To inhibit mast corrosion when operat−

should be showing above the mast nut

ing in salt water environment, lightly coat

with nut installed finger tight.

bearing journals of mast with grease (21).

(8). Install mast nut using wrench (19,

(5). Remove adapter, hoist and eyebolts.

Table 2−2); torque nut to 200 foot−

pounds (271 Nm). Apply a coat of

(6). Use main rotor hub driver tool (24,

corrosion preventive compound (70,

Table 2−2) to ensure that main rotor

Table 2−4) to the screw holes in the

hub is fully seated on mast.

mast nut.

Page 7-40

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

MAIN ROTOR

DAMPER

30−60 IN. LB (3.39−6.78 NM)

50−70 IN. LB

(5.65−7.91 NM)

INSTALL WITH

TORQUE

CUTOUT AREA

ROTATED

INBOARD

WRENCH

0.690 IN. (17.526 MM)

ADAPTER

DAMPER

R (NOTE 2)

(369A9949)

ARM LINK

ARM

0.030 IN.

NOTE 3

(0.762 MM)

369A9949

ADAPTER

MAIN ROTOR

HUB

ELASTOMERIC

DAMPER

PITCH

HOUSING

ASSY

LOWER SHOE

SHIMS/SHIM

MODIFIED CONFIGURATION

WASHERS

(NOTE 5)

MAIN ROTOR

MAST

CURRENT CONFIGURATION

PITCH CONTROL ROD

FLEXIBLE BOOT

SCISSORS

CRANK

30−60 IN. LB

(3.39−6.78 NM)

NOTE 1

NOTES:

EDGE OF BUSHING MUST

PROTRUDE A MIN. OF 0.010 IN.

(0.254 MM) TO A MAX. OF 0.060 IN.

(1.524 MM) ABOVE OUTSIDE

ROTATING

SURFACE OF PART AFTER NUT

SWASHPLATE

NOTE 4

IS TIGHTENED.

RECESS NOT PRESENT ON ALL

ADAPTERS.

ADD WASHERS UNDER HEAD

AS REQUIRED FOR CLEARANCE

BETWEEN BOLT END AND

DAMPER HOUSING.

ADD WASHER(S) AS REQD FOR

BOLT END−TO−SWASHPLATE

BOOT CLEARANCE.

USE SHIMS/SHIM WASHERS TO

FILL GAP.

30−038B

Figure 7-16. Main Rotor Hub Installation

Page 7-41

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

CURRENT

CONFIGURATION

RETAINER

SCREW

LOCKNUT

(NOTE 3)

LOCKWIRE

MAST

DRIVE SHAFT

MAIN ROTOR MAST

SCREW

0.050 IN. (1.27 MM) MAX SCREW

LOCKWASHER

HEAD HEIGHT ABOVE HUB

RETAINER

EARLY

CONFIGURATION

MAST

(NOTE 1)

SEAL

SEAL RETAINER

MAST NUT

MAIN ROTOR HUB

LOCKWASHER

SEAL RETAINER

MAIN ROTOR

MAST

NOTE 2

MAST NUT

200−250 FT LB

(271−339 NM)

NOTES:

MANDATORY MOD TO THIS CONFIGURATION: REFER TO TEXT.

RELIEVED EDGE OF NUT MUST BE DOWN.

IF LOCKNUT AND RETAINER SCREW HOLES WILL NOT MATCH WITHIN

THE 200−250 FT LB (271−339 NM) RANGE, INVERT LOCKNUT.

30−156B

Figure 7-17. Main Rotor Mast Locknut Installation

Page 7-42

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SLEEVE BUSHING

ROTOR HUB OUTER LINER

SEAL

FRAME JAW CONTACT

POINT (EACH SIDE)

THRUST PAD

MAIN ROTOR PULLER

PULLER NUT

369A9932

ROTOR MAST

FRAME

ROTOR HUB

ROTOR MAST

30−040A

Figure 7-18. Pulling Hub Assembly

NOTE: If wrench (19, Table 2−2) is not avail−

NOTE: Be sure that no washers are used under

able, wrench (20) may be modified for use on

screwheads and that screwheads are free of

nut by hand−filing and increasing slot

burrs.

widths symmetrically to 0.343 ±0.007 inch

(8.7122 ±0.178) mm).

(12). Verify that screwheads do not project

more than 0.050 inch (1.270 mm) above

hub upper surface for adequate clear−

(9). Place retainer on nut and check

ance between screwheads and drive−

retainer to nut screw hole alignment.

shaft flange underside.

(10). Increase nut torque to not more than

(a). Place straight edge across hub upper

250 foot−pounds (339 Nm) to align

surface and extend straightedge to

holes in retainer and nut.

screw to make the check.

(13). Install four pitch change rods to pitch

NOTE: If holes cannot be aligned in the 200 −

housing.

250 foot− pound (271 − 339 Nm) torque

range, remove and invert the nut and repeat

NOTE: Be sure pitch change rods are rein−

procedures in Steps (8). thru (10). to align

stalled in the same position from which re−

holes.

moved.

(11). Secure retainer to nut with two screws

(14). Connect scissors crank to main rotor

and lockwire the screws.

hub lower shoe and/or to scissors link.

Page 7-43

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(15). Connect flexible boot to lower end of

found, repair or replacement droop stop

rotor hub liner and secure with lock−

ring.

wire (2, Table 2−4).

NOTE: To inhibit corrosion, spray droop stop

(16). Install main rotor driveshaft (Ref. Sec.

ring, rollers and pitch bearings with rust in−

19).

hibitor (101, Table 2−4).

(4). Inspect droop stop roller for flat spots,

(17). Install four main rotor blades.

pit marks and looseness on roller shaft.

(18). Perform main rotor blade droop angle

(5). Inspect striker plate for dents (brinel−

check if rotor hub is new or a replace−

ling) and pit marks that exceed 0.030

ment.

inch (0.762 mm) depth. Damage

exceeding this limit requires replace−

26. Main Rotor Hub Assembly Inspection

ment of striker plate.

(Ref. Figure 7−19)

(6). Press each pitch housing downward

several times and check for evidence of

(1). Inspect pitch housing for scratches,

a binding pitch bearing or droop

nicks and cracks.

restrainer follower.

(a). No cracks are permissible.

(7). Inspect visible portion of droop re−

strainer for cracks and the follower

(b). Scratches and nicks must be cleaned

spring for breaks.

up before measuring the depth of the

damage to determine housing ser−

NOTE: Do not remove tetrafluoroethylene

viceability.

(TFE) debris which works out of pitch bear−

ing edge. The debris is normal and helps lu−

(c). Accomplish repairs or replacement

bricate bearing. Removal of debris will in−

according to Pitch Housing Assembly

crease bearing wear rate.

Repair.

(8). Inspect each of the four main rotor hub

(2). Inspect sleeve bushing for snug fit in

lead−lag link assemblies after removing

pitch housing arm clevis lug; the lug

the bolt or pin attaching damper arm to

must not show evidence of wear caused

main rotor blade and blade attach pins.

by bushing movement.

Rotate blade about lead blade attach

pin and visually inspect for signs of

(a). Maximum allowable diameter for the

cracking around the blade pin hole in

bushed lug is 0.5004 inch (12.71016

the lug of the lag portion.

mm); for unbushed lug, not more

than 0.1320 inch (3.3528 mm).

(9). Use a bright light and 5X magnifying

glass to inspect all main rotor hub

(b). Inspect inner surfaces of all pitch

assembly lead−lag links for discolor−

housing arm clevis lugs for chafing

ation, pitting, intergranular cracks or

caused by misaligned pitch control

stress corrosion cracks.

rod end bearings.

(a). Any discoloration or pitting is

(c). Chafing will be in the form of cres−

evidence of more than superficial

cent−shaped grooves.

corrosion and the main rotor hub

must be removed for replacement of

(d). If chafing wear is found, accomplish

lead−lag links.

repair or replacement (Ref. Pitch

Housing Assembly Repair).

(b). Otherwise reinstall lag blade attach

pin and damper attach pin or bolt. As

(e). The chafed area must be cleaned up

applicable, torque nut to 30 − 60

before measuring the depth of the

inch−pounds (3.39 − 6.78 Nm);

damage to determine housing ser−

install cotter pin.

viceability.

NOTE:

Normal or premature overhaul requires

(3). Inspect the droop stop ring for corro−

visual inspection plus dye−penetrant inspec−

sion, dents and scratches. If defects are

tion of the links for the same conditions.

Page 7-44

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

HUB

MS20427M5 RIVET

(NOTE 1)

HOUSING

PITCH BEARING

MS20615−5M RIVET

(NOTE 2)

STRIKER PLATE

LEAD−LAG LINK

MS20427M5 RIVET

(NOTE 3)

LEAD−LAG

LEAD−LAG BOLT

LINKS

NOTE 5

50−70 IN. LB

NOTE 7

(5.65−7.91 NM)

DROOP SHIM WASHERS

NOTE 8

(NOTE 4)

LEAD−LAG STOP

SLEEVE BUSHING

SPACER

PITCH

HOUSING

PIVOT PIN

MAIN ROTOR

PITCH CONTROL

STRAP PACK

BEARING HOUSING

ONE−PIECE

ASSEMBLY

STRIKER STRIP

MAIN ROTOR

STRAP PACK

TWO−PIECE

STRIKER STRIP

NOTES:

COUNTERSUNK RIVET HEAD MUST BE FLUSH WITH HOUSING. IF STRIKER PLATE IS

COUNTERSUNK, COUNTERSUNK HEAD MUST BE FLUSH WITH PLATE.

SHOP−FORMED HEAD MUST BE FLUSH WITH PLATE.

COUNTERSUNK RIVET HEAD MUST BE FLUSH WITH PLATE IN ALTERNATE RIVET INSTALLATION.

2.50 IN.

CAUTION: WASHERS ARE INSTALLED BETWEEN SPACER AND STRIKER STRIP TO ESTABLISH

(6.35 MM)

CORRECT STATIC DROOP ANGLE BETWEEN HOUSING AND HUB. ENSURE THAT THE EXACT

NUMBER REMOVED ARE REINSTALLED. THE THREE PITCH BEARING HOUSING BOLTS MUST

EACH HAVE THE SAME NUMBER (THICKNESS) OF WASHERS WHEN SHIMMING IS NECESSARY.

0.25−0.50 IN.

SHOWN EXPLODED ONLY FOR CLARITY.

(6.35−12.7 MM)

CUT OUT 0.25−0.50 IN. (6.35−12.7 MM) PIECE OF THE STRIKER STRIP BETWEEN LOWER

(NOTE 6)

BOLT HOLES. DEBURR AND RADIUS CUT EDGES.

ONE−PIECE STRIKER STRIP

CAUTION: DO NOT SCRATCH STRAP PACK WHEN INSTALLING THROUGH STRAP ASSEMBLY.

INSTALLATION MODIFICATION

FOR STOP REMOVAL, PLACE WOOD DOWEL HERE, STRIKE SHARPLY WITH HAMMER TO

BREAK STOP BOND.

BOND ALL STOP−TO−LINK SHADED CONTACT SURFACES WITH ADHESIVE (90, TABLE 2−4).

30−041−1D

Figure 7-19. Repair of Main Rotor Hub Components (Sheet 1 of 3)

Page 7-45

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

0.360 IN. (9.144 MM) MIN. WALL

THICKNESS AROUND LUG

(NOTE 15)

OUTBOARD LUG

0.250 IN. (6.35 MM) MIN. WALL

OUTBOARD LUG

THICKNESS AROUND LUG

(NOTE 15)

INBOARD LUG

0.220 IN. (5.588 MM) MIN.

WALL THICKNESS

AROUND LUG

(NOTE 15)

INBOARD LUG

0.146 IN. (3.7084 MM) MIN.

0.200 IN. (5.08 MM) MIN.

LUG THICKNESS

MAIN ROTOR HUB PITCH

(NOTE 15)

HOUSING ASSEMBLY

0.125 IN. (3.175 MM) MAX.

0.4328 IN. (10.99312 MM) MIN.

PITCH PIVOT PIN

200−220 IN. LB

90% CIRCUMFERENCE OF 0.4328 IN.

(22.60−24.86 NM)

(10.99312 MM) MIN. DIAMETER MUST

(NOTES 9, 11)

BE UNDAMAGED

HUB

NOTE 14

NON−CAPTIVE NUT

SPECIAL WASHER

(NOTE 10)

HUB

NOTE 13

CAPTIVE NUT

NUT RETAINING BRACKET

(NOTE 12)

NOTES: (CONT)

LIGHTLY LUBRICATE THE THREADED SHANK WITH GREASE

12. THE NUT RETAINING BRACKET IS BONDED TO CURRENT

(18, TABLE 2−4) BEFORE INSTALLATION.

TYPE HUB AND IS REPLACEABLE AT OVERHAUL FACILITY.

10. APPLY WET PRIMER (4 TABLE 2−4) ON WASHER AND MATING

13. CURRENT TYPE PIVOT PIN HAS LETTER ‘‘M’’ ETCHED ON

SURFACES BEFORE INSTALLATION.

OUTER FACE OF FLANGE.

11. TORQUE WITH PITCH BEARING STUD WRENCH 369A9825.

14. DISCARD AT REPLACEMENT OF EARLY TYPE PIVOT PIN.

HOLD NON−CAPTIVE NUT WITH PITCH BEARING STUD WRENCH

SPECIAL WASHER REQUIRED UNDER CURRENT TYPE PIN

369A9826. BEFORE APPLYING THE LAST 20−30 IN. LB (2.26−3.39 NM)

FLANGE FOR INSTALLATION AND TORQUING.

OF REQUIRED TORQUE, USE A 0.002 IN. (0.051 MM) FEELER GAGE

15. MAINTAIN MINIMUM WALL THICKNESS AROUND LUG AND

AND CHECK FOR GAP BETWEEN THE PIN FLANGE AND MOUNTING

MINIMUM LUG THICKNESS FOR FIELD REPAIR OF CLEVIS

LUG SURFACE. NO GAP IS ALLOWED.

LUG.

30−041−2D

Figure 7-19. Repair of Main Rotor Hub Components (Sheet 2 of 3)

Page 7-46

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

BUSHING: 0.44 IN. (11.176 MM) O.D. X 0.25 IN. (6.35 MM) I.D. X 0.31 IN. (7.874 MM) LONG

BUSHING: 0.75 IN. (19.05 MM) O.D. X 0.56 IN. (14.224 MM) I.D. X 0.31 IN. (7.874 MM) LONG

BOLT: 0.250 IN. (6.35 MM) DIA X 1.38 (35.052 MM) LONG

WASHER: 0.250 IN. (6.35 MM) I.D. X 0.75 IN. (19.05 MM) O.D. X 0.060 IN. (1.524 MM) THICK (2)

REMOVAL OF OLD BUSHING

DRILL BUSHING

0.4990−0.4995 IN.

0.3775−0.3780 IN.

1.13 IN.

O.D. X

I.D. X

LONG

(12.6746−12.6873 MM)

(9.5885−9.6012 MM)

(2.8702 CM)

0.3760−0.3770 IN.

DIA

REAMER

(9.5504−9.5758 MM)

DRILL NO. U: 0.3680 IN.

(9.3472 MM) DIA

DRILL BUSHING

DRILL THEN

0.5625 IN.

REAM

DRILL BUSHING

(14.2875 MM)

0.375 X 0.250 X 0.31 IN.

LONG

(9.525 X 6.35 X 7.874 MM)

DRILL AND REAM OUTBOARD LUG

BACK SPOT FACE

TREAT SPOTFACE SURFACE & REAMED

0.5625 DIA X 0.250 DIA

HOLE WITH IRIDITE−CHEM. FILM

SHAFT

TREATMENT PER MIL−C−5541 CLASS 2

0.010−0.030 IN.

0.015−0.020 IN. (0.381−0.508 MM)

FILLET RADIUS

(0.254−0.762 MM)

0.146 IN. (3.7084 MM)

0.20 IN. (5.08 MM) MIN

BACK SPOTFACE OUTBOARD LUG

AFTER INSTALLATION OF BUSHING,

SEAL EDGE WITH PRIMER

GRIND OFF BUSHING TO

0.00−0.015 IN. (0.00−0.381 MM)

BELOW 0.750 IN. (19.05 MM) DIA.

SPOTFACE SURFACE; INSTALL

WITH LOCTITE

0.360 IN.

MIN

(9.144 MM)

INSTALL BUSHING WITH GREASE

0.015−0.025 IN.

0.00−0.015 IN.

(0.381−0.635 MM)X 45° CHAMFER (TYP)

(0.00−0.381 MM)

INSTALLATION OF SPLIT BUSHINGS

30−041−3A

Figure 7-19. Repair of Main Rotor Hub Components (Sheet 3 of 3)

Page 7-47

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(10). Inspect lead−lag link stop for broken

lag legs of the straps at these loca−

spring, cracks, breaks, or visible bond

tions.

line cracks.

NOTE: Do not pry at the strap pack with a

(11). Inspect ID of lead−lag bolts for presence

sharp or hard−edged tool. If edges become

of corrosion. Bolts having evidence of

nicked, the strap pack assembly must be re−

corrosion should be treated for corro−

placed.

sion.

(d). If no obvious strap failure is noted,

NOTE: There are prebalanced rotor hub assem−

use a blunt−nosed wooden or pheno−

blies in service. The lead−lag bolts in preba−

lic pin, pencil size with 0.0625 inch

lanced hub assemblies may contain balanc−

(1.5875 mm) radius point, to probe at

ing hardware. If such is the case, remove the

the upper and lower strap lamina−

balancing hardware to perform inspection.

tions at the outboard end of the blade

Each set of removed hardware should be

pitch housings. A failed strap, either

tagged or color−coded to ensure correct rein−

in the lead or lag of the pack, will

stallation.

move away from the other straps. If

the upper and lower strap lamina−

(12). Inspect each striker strip for cracks,

tions remain in tension under this

deformation and badly worn contact

probing operation, no failure has

surfaces.

occurred.

(13). Inspect all parts of main rotor hub for

(e). If a single strap failure is noted

cracks, breaks, scratches, and nicks.

during inspection, rotor operation

(Refer all questionable damage to

can still be continued. The pack must

MDHI for deposition.)

be inspected again in 300 hours.

When three straps to any one blade

(14). Visually inspect the main rotor reten−

are broken (at one side of the rotor

tion straps for gaps between the pack

hub) the strap pack assembly must

laminations (Ref. Figure 7−20).

be replaced.

(a). A single straight lamination gap not

NOTE: Ends of permissible broken straps must

in excess of 0.030 inch (0.762 mm) is

be taped to prevent scratching adjacent

permissible within the pack or next

straps.

to either the upper or lower outer

shoe.

(15). Whenever a new or replacement main

NOTE: On some strap packs the teflon may ap−

rotor hub has been installed, determine

pear wrinkled or extend past the end of the

that the droop angle of the main rotor

laminates obstructing the view. When this

blades does not exceed the maximum

condition exists, visual inspection should be

allowable angle of 6 degrees.

made from the leading and trailing edges of

the strap packs.

27. Main Rotor Strap Pack Lamination

Inspection

(b). Retention strap packs showing a

fanning or bowing of the laminations

(Ref. Table 7−7 and Figure 7−20)

indicate an improper condition and

the hub must be repaired. (Available

NOTE:

repair/overhaul information is

provided in CSP−H−5.)

D If a hub assembly or strap assembly (oth−

er than new parts in storage) are sub−

(c). Check for cracks or breaks in the

jected to extended periods of non−use,

strap pack laminations at the in−

whether installed on the helicopter or not,

board and outboard ends of the pitch

the strap assembly should be inspected

housing where the straps are accessi−

critically for corrosion and pitting due to

ble to view. Check both the lead and

corrosion before being returned to service.

Page 7-48

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

If corrosion is found on the strap pack as−

A laminate has failed:

CAUTION

semblies, contact MDHI for disposition.

D If a crack is found in tongue area of the

D Figure 7−20 depicts the main rotor hub

laminate.

and strap pack assembly disassembled for

clarity of location and area to be inspected

D If a crack is found in both legs (lead and

for cracks. Under no circumstances

lag) of the same laminate.

should the strap pack or main rotor hub

A strap pack is to be rejected

assembly ever be disassembled in the

CAUTION

(return hub for overhaul):

field. MDHI and MDHI Approved Licens−

D If three or more laminates in a single

ees are the only approved repair stations

strap pack have failed, as defined above.

for main rotor hub assembly overhaul.

D If three or more laminates in a single

D It is acceptable to operate a helicopter

strap pack are cracked in the same leg

with a hub assembly having a strap pack

(lead or lag).

with up to two failed laminates in any one

D If one laminate is cracked at the outboard

leg of the strap assembly. When a lami−

end (area between outboard shoes).

nate in the strap assembly fails, the re−

maining laminates pick up and carry the

D Two or more gaps in the same strap pack

load. This increased load causes slightly

requires main rotor hub replacement. A

more elongation in the remaining lami−

single gap in any one strap pack assembly

nates of that leg thus shifting the mass of

is allowed.

the rotor system. Any time a vibration de−

NOTE:

velops or there is an increase in vibration

D Do not pry at strap pack assemblies with

level over a short period of time, the main

sharp or hard edged tools. If edges become

rotor strap pack assembly should be in−

nicked or laminates get scratched, addi−

spected for cracked or failed laminates.

tional cracking can occur thus causing

D Conduct inspection indoors, if possible, or

hub replacement.

in a shaded area to eliminate glare of sun

D Where accessible, ends of acceptable

or bright outdoor light. To facilitate in−

cracked or broken laminates should be

spection, field fabricate and use plastic in−

taped to prevent scratching and damag−

spection tool.

ing of adjacent laminates.

(6). Visually inspect strap pack assemblies

(1).

Remove main rotor blades.

for evidence of corrosion. If corrosion is

found on strap pack laminates contact

(2).

Trim teflon from edges of laminates.

MDHI service department for disposi−

tion.

(3).

Field fabricate plastic tool per

(7). Using a blunt−nosed wooden or pheno−

Figure 7−20. Run plastic inspection tool

lic pin, pencil size, with 0.0625 inch

in both directions along each laminate,

(1.5875 mm) radius point, probe at the

feeling for a ‘‘catch’’ from a crack on a

upper and lower strap laminations at

single laminate.

the outboard ends of the blade pitch

housings for evidence of laminate

(4).

Using a light and mirror, visually

failure.

inspect each of the main rotor strap

pack assemblies for evidence of cracks

(a). A failed laminate, either at the lead

or breaks in strap pack laminates in the

or lag end of the strap pack, will

areas of the outboard shoes and pitch

move away from the other laminates.

housing assemblies.

(b). If the adjacent upper and lower

laminates remain in tension under

(5).

Using a 10X magnifying glass, visually

the probing operation, no laminate

inspect the edge of strap pack lami−

failures have occurred.

nates on both sides at outboard end of

blade pitch housing (area between

NOTE: Laminate failures are defined in step

outboard shoes).

(5). (Ref. CAUTION:).

Page 7-49

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 7-7. Strap Pack Inspection

Replace or Return

Inspect

Procedure (1)

For

Acceptable

Hub for Overhaul if:

Outboard end

Visually. Use blunt nosed

Failed laminates

Two or less per pack

Three or more

wooden or phenolic pin

(3)

laminate failures in

(Ref. Figure 7-20).

one pack.

Probe at upper and lower

end of pack. Failed

laminate in lead or lag

leg will move away from

other laminates

Visually.

Gaps between

Single straight gap

More than one gap

laminates

not exceeding 0.030

found; gap exceeds

inch (0.762 mm)

acceptable limit.

within pack or next to

either upper or lower

outer shoe

Visually using light and

Cracks or breaks

None

Cracks or breaks are

mirror (2)

noted.

In area of and

Visually with light and

Cracks or breaks

Two or less laminate

Three or more

within pitch

mirror (2)

failures per strap

laminate failures (2)

housing assem-

pack (2)

in a pack; three or

blies

more laminates in

pack with crack in

same leg (lead or

lag).

Shims at attach

Visually with light and

Cracks or breaks

Inspect top laminate

Top laminate is

points

mirror

around shim (4)

cracked in area of

cracked or broken

shim.

NOTE:

(1) Conduct visual inspections indoors or in shaded area to eliminate glare of sun or bright outdoor light.

(2) Removal of teflon covering is required for visual inspection of laminate edges. Use aluminum chisel

fabricated from stock 0.025 x 6.00 x 0.10 inch (0.635 x 152.4 x 2.54 mm) to carefully scrape excess

interlaminate teflon sheets from both sides of strap pack between top and bottom shoes at outboard

attachment bolt of all five strap packs. Remove excess teflon from a point 0.50 inch (12.7 mm) outboard

of bolt centerline to 1.50 inches (38.1 mm) inboard of bolt centerline. Field fabricate and use plastic tool

(Ref. Figure 7-20). Run plastic tool in both directions along each laminate feeling for cracked laminate.

Use of plastic tool will ensure that shreds of teflon still hanging free does not obscure small cracks.

(3) Laminate has failed if crack is found in tongue area or if crack is found in both legs (lead and lag).

(4) Pay particular attention to shim installed at upper side of lead leg of each strap pack assembly. Maximum

of two shims may have been installed on top side of lead leg of strap pack to accommodate tolerance

buildup during strap pack assembly. If more than one top shim is installed, pay particular attention to

lower shim when checking for cracks or breaks.

Page 7-50

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

0.125 IN.

(3.175 MM)

LAG LEG

LAMINATE HAS FAILED IF CRACKS OCCUR

ON BOTH LEAD AND LAG LEGS OF SAME

LAMINATE.

0.250 IN.

LEAD LEG

(6.35 MM)

PROBE

PLASTIC

LAMINATE HAS FAILED IF CRACK OCCURS

TOOL

6.00 IN.

TONGUE

IN TONGUE OF LAMINATE (SHADED AREA

(15.24 CM)

SHOWN BEYOND JOINT OF STRAP PACK

LEGS).

4.00 IN.

(10.16 CM)

1 1/2 INCH (REF)

TWO LAMINATE FAILURES AS DEFINED IN

AND/OR

2 ARE ALLOWED IN EACH STRAP

PACK ASSEMBLY. (TOTAL OF EIGHT LAMINATE

1.00 IN.

0.050−0.125 IN.

FAILURES PER HUB ASSEMBLY.)

(25.4 MM)

(1.27−3.175 MM)

FIELD FABRICATED INSPECTION TOOL

STRAP PACK IS REJECTED IF THREE OR MORE

LAMINATES IN SAME PACK HAVE FAILED AS

DEFINED IN

1 AND/OR

2 ABOVE.

STRAP PACK IS REJECTED IF THREE OR MORE

LAMINATES IN THE SAME PACK ARE CRACKED IN

THE LEG (LEAD OR LAG).

CAUTION:

DO NOT DISASSEMBLE STRAP PACK

FAILED LAMINATE IF CRACK

ASSEMBLY − LAMINATIONS ARE

IS FOUND ON EITHER EDGE

SHOWN SEPARATED ONLY TO DEPICT

OF LAMINATE.

POSSIBLE CRACK LOCATIONS.

IF ONE LAMINATE IS FAILED,

REMOVE HUB.

NOTE:

ANY CRACK IN LAMINATE IS CONSIDERED A BREAK.

THE LAMINATE HAS NOT FAILED HOWEVER, UNLESS

1 1/2’’

BOTH LEAD AND LAG LEGS ARE CRACKED, CRACK IS

LOCATED IN TONGUE AREA OF LAMINATE, OR IS

UNDER SHOES (SEE DETAIL 6).

44−060−2E

Figure 7-20. Strap Pack Lamination Inspection (Sheet 2 of 2)

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(8). Inspect upper, lower and center lami−

exceed 0.010 inch (0.254 mm) in any

nates for cracks and breaks.

area of the housing except the inner

surfaces of arm clevis lugs.

NOTE: Cracks, breaks or other noticeable dam−

age to the laminate/shims require main ro−

(3). A maximum (repaired) depth of 0.050

tor hub overhaul/replacement.

inch (1.270 mm) is acceptable in the

clevis lug with the sleeve bushing.

(9). Install main rotor blades.

(a). On the opposite clevis lug, a maxi−

(10). Perform tracking of main rotor blades.

mum (repaired) depth of 0.010 inch

(0.254 mm) is permissible in the area

(11). Record location of all cracked/broken

of the spot faces and maximum of

laminates in helicopter Log Book

0.050 inch (1.270 mm) in the area

including strap serial number, blade

outside the spot faces.

color, leg (lead or lag) and laminate

position, if possible numbering from the

(4). Repair elongated hole in unbushed side

top down.

of clevis lug (View E). Maximum hole

diameter is 0.3135 inch (7.9629 mm).

28. Main Rotor Strap Pack Repair

(a). Disconnect pitch control rod from

(Ref. Figure 7−20) Where accessible, ends of

clevis lugs on pitch control housing.

permissible cracks or broken laminates should

be taped to prevent scratching and damaging

(b). Remove existing bushing from

adjacent laminates.

inboard lug.

NOTE: Do not bend broken ends excessively

(c). Use drill bushing as guide and drill

and scratch adjacent straps.

elongated hole in outboard lug to

0.368 inch (9.3472 mm) diameter;

(1). Carefully wipe ends of broken strap

line ream hole to 0.375−0.376 inch

with a clean soft cloth moistened with

(9.525−9.5504 mm) diameter.

solvent (1, Table 2−4).

NOTE: Prior to back spot− facing, check out−

(2). Use mild blast of filtered air to dislodge

board lug two places for minimum wall

any foreign particles between broken

thickness of 0.146 and 0.20 inch (3.7084 and

strap ends and adjacent strap.

5.08 mm).

(3). Carefully tape broken ends of strap

(d). Use drill bushing as guide for spot−

with plastic electrical tape (74).

face pilot, and back spotface inside

surface of outboard lug to 0.5625 inch

29. Pitch Housing Assembly Repair

(14.2875 mm) diameter and

0.015−0.020 inch (0.381−0.508 mm)

(Ref. Figure 7−19)

depth. Add chamfer to clear bushing

in two places, as shown.

NOTE: During repair, use adequate covering

over engine air inlet fairing opening to pre−

(e). Use attach bolt or assembly pin as

vent entry of foreign objects into air intake.

guide to ensure proper alignment,

When reconnecting a pitch control rod, be

and install 369D21309 flanged

sure that the rod ends are centered in the

bushing and seal edges with Loctite

swashplate and housing arm clevis lugs. Re−

sealing compound.

align, if necessary, and hold rod to prevent

turning while tightening locknuts.

(f). Install slotted bushing with grease

(58) in inboard lug.

(1). Use grade 320 abrasive cloth (20,

Table 2−4) to smooth scratches, nicks

NOTE: Check outboard and inboard lugs of

and chafing wear in pitch housing.

pitch control horn for evidence of interfer−

ence with upper jam nut on pitch control

(2). After smoothing (removal of all sharp or

rod. If evidence of interference is noted, per−

raised edges) repair depth must not

form step (5).

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(g). Reconnect pitch control rod assembly

(3). Slide bearing assembly off pivot pin.

if check of pitch control rod lugs

Inspect pivot pin for grooving or

discloses no evidence of interference

excessive wear.

with rod upper jam nut.

NOTE: Do not remove TFE debris which works

(5). Remove pitch control horn lug interfer−

out of pitch bearing edge. The debris is nor−

ence with pitch control rod upper jam

mal and helps lubricate bearing. Removal of

nut clearance (View E).

debris will increase bearing wear.

(4). Remove and discard pitch bearing if

(a). Using file or portable grinder,

defective. Total radial looseness of

carefully trim off interfering corner of

assembled ball and pivot pin must not

pitch housing lugs so there is suffi−

exceed 0.010 inch (0.254 mm).

cient pitch control rod clearance. It is

not necessary to trim to minimum

(5). Replace striker strip if it is cracked or

wall thickness, and do not exceed

the flapping stop contact areas are

rework limitations shown.

worn through hard anodized surface.

(b). Reconnect pitch control rod assembly.

NOTE: Hub assemblies may have either one−

Check for proper clearance between

or two−piece striker strips.

outboard lug and upper jam nut on

pitch control rod.

(6). Prepare one−piece striker strip for

installation as follows:

(6). Touch up repaired areas with chemical

(a). Remove sealant between pitch

film (8) followed by primer (4); paint

housing and striker strip, use care

with matching color.

not to scratch pitch housing

(7). Remove main rotor hub assembly for

(b). Remove striker strip from pitch

pitch housing or hub replacement.

housing.

30. Pitch Housing Parts Repair or

(c). Cut old striker strip to facilitate

Replacement

removal from retention strap assem−

bly. Do not scratch strap assembly.

(Ref. Figure 7−19)

(d). Clean old sealant from pitch housing

NOTE: Use care during removal of parts from

using 1,1,1 trichloroethane (61,

around the strap pack. Any nicks or

Table 2−4).

scratches on the straps requires scrapping

(e). Cut out area of new striker strip

of the strap pack.

(View B), deburr, smooth and radius

A. Pitch Control Bearing Housing Assembly,

cut edges.

Spacer or Striker Strip Replacement

(f). Apply sealant (3) to faying surfaces of

the striker strip and pitch housing.

(1). Support blade and pitch housing from

beneath. Remove three nuts, six

(7). Position pitch control bearing housing

washers and three bolts that secure

on pivot pin.

bearing housing.

NOTE: If droop shim washers were removed

NOTE: Check if washers are installed between

from between spacer and striker strip, the

the spacer and the striker strip. These

exact thickness removed must be rein−

washers must be reinstalled to establish

stalled. There must be an equal number of

correct static droop angle between the pitch

washers on each of all three bolts. These

housing and hub.

washers establish correct static droop be−

tween pitch housing and the hub.

(2). Carefully remove spacer by sliding it

downward past striker strip. Retain

(8). Slide spacer into position between

exact number of droop shim washers, if

bearing housing assembly and striker

installed.

strip on pitch housing. Install exact

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

thickness of droop shim washers

(b). The shop−formed head of the

removed at time of disassembly. Align

MS20615−5M rivet must be flush

holes for the three bolts.

with the plate.

(c). An MS20427M5 rivet may be used as

(9). Install three bolts, six washers and

an alternate for the MS20615−5M

three nuts. Torque nuts to 50 − 70

rivet.

inch−pounds (5.65 − 7.91 Nm).

(d). When the alternate is used, install

(10). Seal all the parting lines (joints) of the

the rivet from the plate side of the

assembly with a bead of sealing

assembly.

compound.

(e). The heads of all countersunk rivets

B. Replacing Pitch Control Bearing

must be completely flush.

C. Lead-Lag Link Blade Stop Replacement

(1).

Drill out rivets to remove striker plate.

Discard striker plate if brinelling or

Replace a blade stop if it is broken or cracked,

pitting exceeds 0.030 inch (0.762 mm)

has a broken spring, or if there are visible

depth.

bond line cracks.

(2).

Press bearing from housing bore. Clean

NOTE: The lead−lag link assembly must not be

any residual primer from housing bore

removed from pitch control housing for this

with MEK solvent (22, Table 2−4).

repair, the retention bolt cannot be retor−

qued without a special adapter.

(3).

Rework minor surface abrasion in

(1). Remove lead−lag link stop as follows;

housing bore by polishing with crocus

cloth (23). Restore chemical film (8),

(a). Provide a backup support for the link

where removed.

assembly.

(4).

Apply one thin coat of primer (4) to the

(b). Use a 0.50 inch (12.7 mm) wood

bearing OD and the housing bore.

dowel and a hammer to drive stop

from link.

(5).

Press bearing into bore while primer is

still wet.

(c). Strike the dowel sharply to break the

adhesive bond.

(6).

Wipe away any excess primer using

(2). Using a sharp−edged metal scraper,

care to keep it out of bearing races.

carefully scrape any adhesive residue

from the link.

(7).

Check Teflon linings of bearing after

installation to determine that no

(a). If scraper penetrates through the

damage has occurred from the pressing

paint and chemical surface film, the

operation.

surface must be refinished.

NOTE: Outside edge of bearing outer race must

(b). The depth of gouges or nicks is

be at least flush with the face of the bearing

limited to 0.010 inch (0.254 mm)

housing. However, the bearing can be re−

maximum after rework.

cessed up to 0.015 inch (0.381 mm).

(c). Rework by smooth blending into the

surrounding area with grade 320

(8). Install striker plate with one

abrasive cloth (20).

MS20427M5 rivet (upper hole) and one

MS20615−5M rivet (lower hole).

(d). Final polish with crocus cloth.

Restore chemical film protection.

(a). If upper hole of striker plate is

countersunk, rivet must installed

(3). Clean the bond area of all contact

with shop−formed head flush with

surfaces by wiping with surface cleaner

the plate.

(10).

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(a). Flush−wipe the cleaned surface four

(3). Swab cleaned surface with methyl ethyl

times with a mixture of equal parts of

ketone (22) and apply unthinned primer

distilled water and isopropyl alcohol

(4).

(71) to remove all traces of the

(4). Reinstall balance hardware that was

phosphoric acid.

removed.

(b). Rinse the cleaned surface with tap

E. Taping Broken Strap Ends of Strap Pack

water, followed by a rinse of distilled

water until the surface is ‘‘water

NOTE: Be careful not to bend broken ends ex−

break" free.

cessively and scratch adjacent straps.

(c). Dry for 30 minutes minimum at

(1). Carefully wipe ends of broken strap

150°F (66°C).

with a clean, soft cloth moistened with

solvent (1, Table 2−4).

(4). Check the fit of the stop in the link.

(2). Use a mild blast of filtered air to

(a). The flange and radius contact

dislodge any foreign particles between

surfaces of the stop must mate with

broken strap ends and adjacent strap

the link within 0.010 inch (0.254

mm).

(3). Carefully tape broken ends of strap

with plastic electrical tape (74).

(b). Maximum clearance between the

stop and inside surfaces of the link

31. Pitch Control Bearing Pivot Pin Repair or

ears is limited to 0.020 inch (0.508

Replacement

mm).

(Ref. Figure 7−19) Minimum allowable pin

diameter is 0.4328 inch (10.99312 mm). Pivot

NOTE: This tolerance applies to either side of

pin grooving or excessive side wear may be

the stop.

polished to original finish as long as minimum

(5). Prepare a mixture of epoxy adhesive

allowable pin diameter remains after rework.

(91).

Replace any pin requiring more rework, as

follows:

(a). Apply a uniform coating of the mixed

NOTE: Due to tolerance build−ups in forging

adhesive to all contact surfaces.

and casting of individual main rotor hubs,

(b). Hand press the stop into place

insertion of the stud nut holding wrench (50,

between link ears until all mating

Table 2−2) may not be possible with some

surfaces are in firm contact.

hubs. If the holding wrench cannot be in−

serted properly to engage the stud attach

(c). Apply a suitable clamping device so

nuts, the hub assembly must be sent to an

that contact is maintained.

overhaul facility for stud replacement.

(d). Cure for a minimum of 8 hours at

(1). Hold nut with stud nut wrench (50) and

room temperature, or 2 hours at

remove pivot pin with pitch bearing

150°F (66°C).

stud wrench (49). The stud nut wrench

is not required when nut retaining

D. Corrosion Control - Lead-Lag Bolt

brackets are installed on the hub.

NOTE: Do not disturb the torque on the lead−

(2). Lightly lubricate the threaded shank of

lag bolts. A special adapter is needed to re−

the replacement pivot pin with grease

torque the lead−lag bolts.

(18, Table 2−4).

(1). Remove and tag or color−code each set

NOTE: Before applying the last 20 − 30 inch−

of balance hardware that is installed.

pounds (2.26 − 3.39 Nm) of the torque spe−

cified in steps (3). and (5). below, use a 0.002

(2). Remove corrosion with grade 180

inch (0.0508 mm) feeler gage and check for

abrasive cloth (20, Table 2−4) and finish

gap between the pin flange and mounting

with grade 400 abrasive cloth.

lug surface. No gap is allowed.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). If nut retaining brackets are not

side of the hub from the roller to be

installed;

installed. Install roller, shaft, and new

cotter pin.

(4). Install pivot pin in mounting lug and

secure with a washer coated with wet

(5). Install pitch control bearing housing

primer (4) and a nut.

assembly.

(a). Hold nut with stud nut wrench.

33. Droop Stop Ring Repair

(b). Using pitch bearing stud wrench,

(Ref. Figure 7−21)

torque pivot pin to 200 − 220 inch−

pounds (22.60 − 24.86 Nm).

(1).

The repair depth limit for corrosion,

nicks or scratches in the droop stop ring

(5). If nut retaining brackets are installed;

is 0.007 inch (0.1778 mm) for all

surfaces except the edges of the ring

(a). Install pivot pin in mounting lug

OD.

with washer.

The depth limit for the ring OD edges is

(b). Using pitch bearing stud wrench,

0.030 inch (0.762 mm) (Detail C).

torque pivot pin to 200 − 220 inch−

pounds (22.60 − 24.86 Nm).

All reworked areas must be blended

smoothly with a 15:1 ratio into the

32. Droop Stop Restrainer and Roller Repair

surrounding area.

or Replacement

(2).

Touch up repaired areas of cadmium−

(Ref. Figure 7−21) Replace a defective droop

plated rings, except the channel, with

stop roller if clearance between roller bearing

chemical film (8, Table 2−4) followed by

liner and shaft is more than 0.015 inch (0.381

primer (4).

mm), replace the worn part.

(3).

Repairs in the channel of cadmium−

Roller shaft OD must not be less than 0.437

plated rings and in all areas of stainless

inch (11.0998 mm).

steel rings should be sprayed with dry

film lubricant (25) only.

A defective follower or spring is replaceable

after removal of the droop stop ring (Ref.

(4).

Replace the droop stop ring if repair

Droop Stop Ring Replacement).

limits have been exceeded.

(1). Remove pitch control bearing housing

34. Droop Stop Ring Replacement

assembly that contacts the lower shoe

roller to be removed.

(Ref. Figure 7−21)

NOTE: Only one roller of each opposing pair of

(1). Turn the hub upside down. Support the

droop stop rollers can be removed at one

hub so that the pitch housings will

time. One droop stop restrainer must be

unload the cam followers and provide

pressed against the droop stop ring to force

maximum clearance between the

the opposite restrainer out and expose the

striker plates and droop stop rollers.

roller shaft for removal. The same condition

pertains during installation.

(2). Release the retaining (snap) ring of

each droop stop restrainer from its

(2). Press down on pitch housing that is

groove.

opposite to the roller to be removed.

Remove cotter pin and shaft.

(3). Move the retaining ring flush against

the T−head to provide additional

(3). Remove droop stop roller.

clearance and reduce the spring

tension.

(4). To install replacement roller, press

down on pitch housing at the opposite

(4). Remove the four droop stop rollers.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(5). Starting from either scissors crank

(16).

Orient the number 2 follower for correct

attach lug, number the four droop

(lower) position.

restrainers in a clockwise direction for

(17).

Pull the number 1 and 2 followers

identification during the replacement

outboard and engage the number 1 and

procedure.

2 T−heads in the new droop stop ring

(a). This number code should be replaced

channel.

on the outboard (roller) upper end of

(18).

Rotate the number 3 follower in the

the follower.

direction that has the greatest amount

(b). Guard against the accidental removal

of clearance between the T−head and

of the codes during the remaining

ring. Continue the rotation of the

steps.

number 3 follower until the T−head is in

the incorrect (lower) position and

NOTE: Designation of upper and lower droop

engages the ring channel.

restrainer followers is in relation to the hub

(19).

Rotate the number 4 follower 180°

as it sits, not as it is installed on the helicop−

which will position the T−head in the

ter. Notice that the odd numbered (1 and 3)

correct (lower) position and engage the

followers are in the upper position and the

ring channel.

even numbered (2 and 4) followers are in the

lower position.

(20).

Pull the number 3 follower outboard to

disengage the T−head from the ring

(6). Push the droop stop ring toward the

channel.

number 1 and 2 followers.

(21).

Rotate the number 3 follower 90° until

(7). Pull the number 3 and 4 follower

the T−head is perpendicular (vertical) to

T−heads from the droop stop ring

the ring channel.

channel.

(22).

Push down on the ring. Rotate the

(8). When the T−heads are free of the ring

number 3 follower 90° until the T−head

channel they should be turned perpen−

is in the correct (upper) position and

dicular (vertical) to the channel.

engages the ring channel.

NOTE: The followers can be easily rotated by

(23).

Check the number 1 and 3 followers for

the use of a non−metallic drift in the hole for

correct (upper) orientation.

the droop stop roller shaft.

(24).

Check the number 2 and 4 followers for

(9). Tilt the ring up on the number 3 and 4

correct (lower) orientation.

followers as far as possible.

(25).

Check the droop stop ring for correct

(10). While pulling upward on the ring, turn

(level) installation.

the number 4 follower to rotate the

(26).

Compress the droop restrainer spring

T−head under the ring.

and install the retaining (snap) ring in

(11). Continue pulling upward on the ring

its groove on each follower.

and turn the number 3 follower to

(27).

Reinstall the droop stop rollers.

rotate the T−head under the ring.

35. Droop Stop Plunger Inspection and

(12). Withdraw the number 1 and 2 T−heads

Replacement

from the ring channel.

(Ref. Figure 7−21)

(13). Remove the ring from the hub assem−

bly.

(1). Remove droop stop ring.

(14). Prepare for installation of replacement

(2). Remove pitch control bearing housing

droop stop ring by orienting the number

assembly that contacts the lower shoe

4 follower for incorrect (upper) position.

roller.

(15). Orient the number 1 and 3 followers for

(3). Remove cotter pin and shaft from droop

correct (upper) position.

stop follower assembly.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(4). Remove droop stop roller.

(3). Clean the hub bore, sleeve bushing,

seal retainer and reusable bearings,

(5). Push droop stop plunger out of lower

using filtered solvent (1) spray.

shoe.

(4). Check bearing cup hub bore for scoring.

(6). Check droop stop plunger for wear as

(a). Smooth out any roughness with

follows:

grade 400 to 600 abrasive cloth (20).

(a). The minimum acceptable diameter

(b). Restore chemical film protection (Ref.

after wearing in service, should be

Sec. 2), where removed.

0.996 inch (25.2984 mm).

(c). Maximum diameter of the hub bore

(b). The acceptable amount of wear

for upper bearing cup is 4.4335

through the anodized coating shall

inches (11.26109 cm), measured in

not exceed 40% or 2.1 square inches

any direction.

(13.55 square cm) of the total sliding

surface area of the cylinder.

(d). Maximum diameter of the hub bore

for lower bearing cup is 4.3095 inches

(c). The maximum wear condition may

(10.94613 cm), measured in any

exist in one spot or in several spots

direction.

totaling 2.1 square inches (13.55

square cm).

(5). Check upper seal retainer. No cracks,

sharp nicks or burrs are allowed. Minor

(7). Wet down and clean plunger and

corrosion or other surface defects may

mating shoe bushing with isopropyl

be polished out using crocus cloth (23).

alcohol (71, Table 2−4).

Grooving on seal contact surfaces must

not exceed 0.004 inch (0.1016 mm)

(8). Install droop stop plunger into lower

depth after polishing.

shoe.

The bearing cups are in−

(9). Install roller, shaft and new cotter pin.

WARNING

stalled in the hub by the dif−

ferential temperature (shrink−fit)

(10). Complete droop stop ring installation.

method. Take appropriate precautions

to prevent burns when handling parts

36. Main Rotor Hub Tapered Bearing

that have been cooled down to sub−

Replacement

zero temperatures.

(Ref. Figure 7−7) Replace tapered roller

(6). Place bearing cups in a closed container

bearing cup or cone if it has any flat spots,

of dry ice and cool down for not less

scoring, pitting, grooving, discoloration (blue)

than 20 minutes to −40°F (−40°C).

or if it feels rough when rotated. If a cone is

unserviceable, the mating cup must be

(7). Coat bore of hub with grease (21). Use

replaced, and vice versa.

care to maintain cup to hub bore

alignment and press cup into bore,

NOTE: The roller bearing cones and cups

using tools D and E until cup is seated.

should always be replaced as a set.

(8). Apply a film of grease to sleeve bush−

(1). Use pressing tools equivalent to items

ing. Use d pressing tool equivalent to

A and B (Ref. Figure 7−22) to press

tool C and press bearing cone onto

upper and lower bearing cups from hub

sleeve bushing.

assembly, press ram of 1 to 2 tons is

sufficient for removal.

(9). Install center seal in hub by hand

pressing it into place. Check that seal

(2). Press lower bearing cone from sleeve

lip is upward.

bushing.

(10). Apply a film of grease on mast. Install

NOTE: In next step, do not spin reusable bear−

preassembled sleeve bearing and

ings while cleaning. Coat bearings lightly

bearing cone on mast. Do not apply any

with oil (35, Table 2−4) after cleaning.

additional lubricant to roller bearing

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

set. Wipe any excess preservative oil

(19). Discard lead spacer after recessed

from bearing cone and cup.

washer is ground.

(11). Place assembled hub over mast and

NOTE:

seat on lower roller bearing cone.

D If the hub assembly (with sleeve bushing,

(12). Install a lead spacer 369A1224−5

spacer, upper bearing and seal retainer

(thickness gage substitute for upper

installed) does not seat properly onto the

seal retainer) over dummy mast. Rest

mast, do not attempt to force it into posi−

spacer on top of sleeve bushing.

tion. Remove hub assembly from mast

and determine cause of hub not seating,

NOTE: If a lead spacer 369A1224− 5 is not

correct the problem and follow the proce−

available, fabricate its equivalent from lead

dures for installation.

sheet. Spacer dimensions are: 2.96 inches

D To insure that hub is seated onto the mast

(7.5184 cm) OD; 2.68 inches (6.8072 cm) ID;

properly before torquing, 2 to 4 threads

0.075−0.085 inch (1.905−2.159 mm) thick.

should be showing above the mast nut

with nut installed finger tight.

(13). Install upper bearing cone into hub and

on top of lead spacer.

(20).

Install recessed washer, recess down,

NOTE: This step is not required. However, the

on the top of sleeve bushing.

use of a substitute washer for the retainer

will prevent unnecessary scoring of the re−

(21).

Reinstall upper bearing cone, the ring

tainer. Several tightening and loosening ac−

washer (or seal retainer) and mast nut.

tions might be required to get the correct ro−

tational drag on the hub bearings.

(22).

Tighten nut to 200 − 250 foot−pounds

(271 − 339 Nm) and check for rotation−

(14). Install a steel ring washer, equivalent

al drag of 10 − 20 inch−pounds (1.13 −

to tool F, as a substitute for packing

2.26 Nm). This will be 1.50 − 3.0

retainer.

pounds (6.67 − 13.34 N) on the spring

scale used as in step (15). above.

(15). Install mast nut on mast.

(23).

Remove hub and sleeve bushing with

(a). Tighten using mast nut wrench (19

lower bearing cone from mast.

or 20, Table 2−2) until bearings are

preloaded to 10 − 12 inch−pounds

(24).

Position hub upside−down on a suitable

(1.13 − 1.36 Nm) of rotational drag.

work bench. Hand−pack the lower hub

(b). Measure rotational drag using a 0 −

cavity and the bearing cone on sleeve

10 pound (0 − 44 N) spring scale,

bushing with grease (21, Table 2−4).

hooked over one of the hub fairing

bosses, 6.5 inches (16.5 cm) from hub

(25).

Install sleeve bushing with bearing

centerline.

cone in the hub.

(c). Read a 1.50 − 1.75 pound (6.67 −

(26).

Hand−pack the cavity between bearing

7.78 N) pull with hub in motion.

and the hub liner with grease; then

press in the lower seal with seal lip

(16). Remove mast nut, ring washer F or seal

toward top of hub. Wipe off excess

retainer, and upper bearing cone.

grease.

(17). Remove lead spacer and measure

(27).

With the aid of an assistant, turn hub

compressed thickness.

assembly right side up on the bench.

(18). Obtain a serviceable recessed washer of

the same thickness if one is available.

(28).

Complete reassembly of hub by install−

ing recessed washer, upper bearing

(a). If not, grind a new recessed washer

cone, upper seal, and seal retainer in

to the required dimension.

hub at installation of hub on the mast.

Page 7-61

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

2.875 INCH (7.3025 CM)

OUTSIDE DIAMETER

CUT OUT

0.50 INCH

AFTER BEVELING

12.7 MM)

3.50 INCH (8.89 CM)

OUTSIDE DIAMETER

3.875 INCH

11.0 INCH

(9.8425 CM)

(27.94 CM)

53°

5.75 INCH

(14.605 CM)

0.375 INCH

3.375 INCH

(9.525 MM)

(8.5725 CM)

0.1875 INCH (4.7625 MM)

0.203125 INCH (5.159375 MM)

4130 STEEL PLATE

WALL STEEL PIPE

4.40 INCH

4.30 INCH

(11.176 CM)

(10.922 CM)

2.58 INCH

0.30 INCH

(6.5532 CM)

(7.62 MM)

3.50 INCH

(8.89 CM)

2.0 INCH

(5.08 CM)

ALUMINUM ALLOY

STEEL RING WASHER

TOOL USE:

A & B − PRESS BEARING CUPS OUT OF HUB

C − PRESS LOWER BEARING CONE ON SLEEVE BUSHING

D − PRESS UPPER BEARING CUP INTO HUB

E − PRESS LOWER BEARING CUP ONTO HUB

F − IN PLACE OF UPPER SEAL RETAINER WHILE ADJUSTING ROTATIONAL DRAG

G − HUB BEARING REMOVAL − FABRICATION

G62−2010−1

Figure 7-22. Main Rotor Hub Tapered Bearing Tools

Page 7-62

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

37. Main Rotor Hub Assembly Droop Angle

installation procedures for main rotor

Check

drive shaft in Section 9.

When a new or replacement main rotor hub is

38. Main Rotor Hub Assembly Droop Angle

installed or whenever excessive droop angle is

Adjustment

suspected, measure the static droop angle of

(Ref. Figure 7−19) If static droop angle exceeds

all four rotor blades. Droop angle must be

6 degrees, adjust as follows.

between 5 and 6 degrees.

(1). Remove main rotor blades.

(1). Install cyclic lateral rigging fixture (14,

Table 2−2), cyclic longitudinal rigging

(2). Use ‘‘AN960

" (C416, C416L,

KD416 or KD416L) flat washers to

fixture (12) and collective rigging

adjust the spacing between spacer and

fixture (9).

striker strip.

(2). Position main rotor with one blade over

NOTE: Any one type, or combination, of the

the tailboom.

washers specified may be used; however, an

identical washer selection (thickness) must

(3). Raise and support the forward blade

be installed on each of the three bolts that

until the droop stop roller of the

secure the pitch control bearing assembly to

forward blade is no longer in contact

the pitch housing.

with the striker plate.

(3). Remove nuts and washers and separate

(4). Place an accurate prop protractor (63)

spacer from striker strip.

beside head of main rotor driveshaft

and seat protractor on flat machined

NOTE: The use of one thick 0.016 inch (0.4064

surface of main rotor hub. Adjust

mm) washer will raise the static droop angle

protractor to zero setting.

approximately one−half a degree.

(4). Add sufficient washers to adjust droop

NOTE: If sufficient flat surface area is not

angle to within the range of 5 to 6

available on hub to properly support pro−

degrees. Reinstall nuts and washers.

tractor, four bolts, nuts and associated

washers securing driveshaft maybe re−

(5). If more than 0.063 inch (1.6002 mm)

moved and a metal plate with four equal

spacing (above factory spacing) is

length spacers can be temporarily attached

required, inspect striker plate, droop

at the four holes to provide a flat level sur−

stop roller, follower and ring for

face for the protractor.

excessive wear; Replace as required.

(5). Place the protractor on the machined

NOTE: The average factory spacing on new and

surface of the outboard end of the aft

rebuilt hubs is 0.032 inch (0.8128 mm).

blade pitch housing, alongside the

(6). Reinstall blades. Repeat the measure−

lead−lag bolthead (Ref. Figure 7−18).

ment of static droop angle to recheck

Measure and record the static droop

the droop angle.

angle.

(7). Check track of main rotor blades

(6). Repeat steps (2). thru (5). for the

following reinstallation or replacement

remaining blades.

of parts.

(7). The maximum allowable static droop

39. Main Rotor Damper (Friction Type, P/N

angle is 6 degrees. If the measured

369A1400)

droop angle exceeds 6 degrees, inspect

the striker plate and roller for excessive

(Ref. Figure 7−16) A main rotor damper is

wear and adjust the droop angle.

attached to each pitch housing of the rotor hub

assembly. The damper is connected to the

(8). If metal plate and spacers were used to

inboard trailing edge of the associated main

provide surface for protractor, remove

rotor blade by a damper arm link to prevent

plate, spacers and reinstall removed

lateral vibrations from occurring in the main

bolts, washers and nuts as specified in

rotor blades.

Page 7-63

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

The damper contains spring−loaded friction

NOTE: Slight looseness of damper attaching

plates and associated parts in an oil filled

studs is allowable. The maximum displace−

housing. The damper functions as a rotary

ment of the threaded end (tip) of the stud is

friction damper with either three or four

limited to 0.015 inch (0.381 mm). The large

consecutive separate torque stages through an

portion of the stud must be below the

overall torque range of 300 − 1950 inch−

mounting surface on the pitch housing.

pounds (2.12 − 13.77 Nm). A damper torque

Damper attaching studs not meeting these

adjustment bolt retains the components inside

requirements require replacement. Refer to

the housing and provides the means for torque

CSP−H−5 for available repair and overhaul

adjustment.

information.

(2). Install three washers and nuts. Torque

The main rotor damper is designed to operate

the nuts to 50 − 70 inch−pound (5.65 −

as a sealed unit and does not require the

7.91 Nm).

addition of hydraulic oil at regular intervals.

Refer to CSP−H−5 for maintenance informa−

(3). Inspect for a minimum of 0.002 inch

tion such as torque adjustment, internal

(0.0508 mm) gap between damper and

phasing, weight adjustment (if applicable),

pitch housing. If gap is insufficient,

detail parts inspection, repair and overhaul.

rework pitch housing.

(4). Align damper arm link with damper;

NOTE: The main rotor damper may be a basic

install bolt with head down, washer

four−stage, uniform four−stage or uniform

and nut.

three−stage damper. The basic four− stage

(a). Install washers under bolthead as

damper is not weight controlled. Both the

required to provide additional

uniform four−stage and uniform three−stage

clearance between bolt end and

dampers are weight controlled to maintain a

damper housing.

completely balanced main rotor hub config−

uration.

(b). Torque nut to 30 − 60 inch−pounds

(3.39 − 6.78 Nm). Install new cotter

A. Main Rotor Damper Removal (Friction

pin.

Type, P/N 369A1400)

NOTE: Cutout (scalloped) area on damper arm

link must be installed towards damper. If in−

NOTE: If more than one damper is being re−

correctly installed, interference between

moved, the main rotor blades should be re−

arm and damper can occur.

moved.

(5). Attach damper arm link to fitting on

blade with bolt, two washer and nut.

(1). If in use, unlock damper arm link

attach pin, but do not remove.

(a). Torque nut to 30 − 60 inch−pound

(3.39 − 6.78 Nm) and install new

cotter pin.

(2). Remove cotter pin, nut, washer and bolt

that attach damper arm link to damper.

(b). If damper arm attach pin is in use,

install pin and lock into place.

(3). Swing damper arm link aside.

NOTE: Ensure damper arm (blade) attach pins

are adjusted correctly.

(4). Remove three nuts and washers that

(6). If removed, reinstall main rotor

mount damper and remove damper.

blade(s).

C. Main Rotor Damper Inspection (Friction

B. Main Rotor Damper Installation (Friction

Type, P/N 369A1400)

(1). Inspect bearing in arm of damper for

(1). Position main rotor damper on studs of

looseness, binding and galling or

pitch housing.

scoring in bore.

Page 7-64

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(a). Bearing radial play is limited to

(6). Move arm slowly toward lag stop from

0.010 inch (0.254 mm) maximum;

phased position through first stage

axial play is limited to 0.020 inch

travel (approximately 5 to 10 degrees).

(0.508 mm) maximum.

(a). Minimum allowable torque required

to move arm can vary according to

(b). Bearing roughness is not permissible.

temperature as indicated in

Table 7−8.

(c). If these limits are exceeded, or the

bearing outer race is loose in the arm

(b). Maximum torque required to move

bore, the damper must be replaced.

arm must not exceed 240 inch−

pounds (27.12 Nm) on current

(2). Inspect housing and cap for cracks and

dampers, or 385 inch−pounds

breaks, for evidence of oil leakage and

(43.50 Nm) on early dampers,

lockwire for security. Replace a leaking

regardless of temperature.

damper.

(c). If torque is outside these range

NOTE: Damper repair must only be performed

limits, torque must be adjusted or the

according to CSP−H−5.

damper replaced, or repaired.

NOTE:

D. Main Rotor Damper Torque Check

(Friction Type, P/N 369A1400)

D Reducing damper torque to the minimum

allowable setting for low temperature op−

When trouble has been experienced with rotor

eration may smooth out damper perfor−

vibration, refer to Table 7−8. Check damper

mance and eliminate one−to−one lateral

phasing and first stage torque as follows.

vibrations (Ref. Table 7−1).

D It is important that the correct minimum

(1). If in use, unlock damper arm link

torque value be used. This especially so

attach pin but do not remove.

when adjusting damper torque at ex−

treme low temperatures.

(2). If recessed torque wrench adapter (23,

Table 2−2) is used, disconnect damper

D For optimum results, damper should be

arm link at blade and rotate link to

(set) to the ambient (indoor or outdoor)

align with arm of damper.

temperature. For temperature of +40°F

(+4°C), minimum damper torque setting

(3). If non−recessed adapter is to be used,

would be 289 inch−pounds (32.65 Nm);

disconnect link from arm of damper.

or at

−20°F (−29°C), it is 265 inch−

pounds (29.94 Nm), etc. (Intermediate

NOTE: Do not use vibration dampers for turn−

settings within each temperature range

ing main rotor or handholds. Such use can

listed would be proportional; for instance,

damage damper bracket.

between 0° and +40°F (− 17° and +4°C),

the correction would be 1 inch−pound

(4). Move rotor blade out of the way, as

(0.113 Nm) per each 3.5°F (1.5°C)

necessary and attach torque wrench

change.)

adapter to damper arm; then attach a

(7). Remove torque wrench and adapter and

suitable tool and cycle the damper

reposition damper arm link.

through the first stage approximately

50 times.

(8). If non−recessed adapter was used,

reinstall bolt, head down, washer and

NOTE: Repeated cycling of the damper prior to

nut. Torque nut to 30 − 60 inch−pound

torque check will provide an in−service

(3.39 − 6.78 Nm), and install new

condition for a true check of damper torque

cotter pin. If recessed adapter was used,

setting.

reinstall attach pin or standard hard−

ware in blade.

(5). Remove tool and attach dial indicating

torque wrench so torque wrench can be

(9). If in use, lock the attach pin and check

used to move arm.

tightness.

Page 7-65

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Table 7-8. Temperature vs Damper Torque

(4). Carefully push same main rotor blade

in a lag direction and again release

Ambient Temperature

Minimum Damper Torque

pressure when a positive increase in

F (C)

in. -lb

(Nm)

friction is felt.

+70 (+21)

300 (33.90)

(5). Repeat step (3).

+40 (+4)

289 (32.65)

(a). Obtain or fabricate a main rotor

(-18)

278 (31.41)

damper check tool for installed

-20

(-29)

265 (29.94)

dampers (a template is provided in

CSP−H−5) and chock for correct

-40

(-40)

243 (27.46)

damper arm tang position by mea−

surement.

E. Installed Main Rotor Damper Phasing

Check (Friction Dampers Only, P/N

(b). One inch (2.54 cm) between lag edge

369A1400)

of tang and lag stop of housing is

approximate dimension required.

Phasing of the main rotor dampers may be

necessary if there is ground rocking or if a

NOTE: If phasing is correct, an aid to any fu−

one−to−one lateral (main rotor) vibration occurs

ture check of phasing would be to apply ver−

during certain flight maneuvers. A check of

tical paint marks on the damper housing to

damper internal phasing can be made as

indicate the lead and lag positions of the

outlined below. The phasing should be

damper arm (link attach bolt) centerline for

accomplished by two persons.

correct first stage travel.

(6). Release drive system, rotate main rotor

NOTE:

blades and repeat the above procedure

D Do not use vibration dampers for turning

for the remaining three dampers.

main rotor or handholds. Such use can

damage vibration damper bracket.

40. Main Rotor Damper (Elastomeric Type,

P/N 369D21400-503)

D To move the damper arm back and forth

through the first (low torque) stage, only

(Ref. Figure 7−16) A main rotor damper is

10 − 15 pounds (44.48 − 66.72 N) of fin−

attached to each pitch housing of the rotor

gertip pressure is required at the tip of

hub. The damper is connected to the inboard

the main rotor blade.

trailing edge of the associated main rotor blade

by an adjustable clevis to prevent lateral

D If pressure in excess of approximately 19

vibrations from occurring in main rotor blades.

pounds (84.52 N) is applied to blade tip

Neither damper travel nor stiffness is adjust−

in a lag direction, the internal friction

able on the helicopter. Phasing of rotor blades

plates can be shifted out of phase with

is affected by turnbuckle adjustment. Any

each other and only rephasing by the

phasing problem caused by a defective damper

bench method outlined in CSP−H−5 will

should be corrected by replacing damper.

restore the damper for proper operation.

If light pressure at the blade tip will not

NOTE:

move the blade, check damper for proper

D Excessive lead− lag load applied to the

torque.

main rotor blades during ground handl−

ing can result in damage to the elastomer−

(1). Rotate and position one main rotor

ic damper buns and failure of the damper

blade over the tailboom.

assembly. Operators and maintenance

personnel should use extra caution to

(2). Engage rotor brake (if installed) or hold

avoid lead−lag loads in excess of 35

tail rotor blades to prevent rotation of

pounds (156 N) at the tip of the main ro−

main rotor blades.

tor blades.

(3). Carefully push the main rotor blade at

D If one or more main rotor blades strike an

right side of helicopter in a lead

object while rotating or the drive system

direction and when a positive increase

has been subjected to sudden stop, inspect

in friction is detected, release pressure.

damper.

Page 7-66

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

A. Main Rotor Damper Removal

(5). Install main rotor blade.

(Elastomeric Type, P/N 369D21400-503)

(6). Connect damper to blade.

(1). Note and record location from which

(7). Remove blade support.

damper is to be removed from main

rotor hub.

C. Main Rotor Damper and Attachments

Inspection (Elastomeric Type, P/N

NOTE: At reinstallation, if damper is not rein−

369D21400-503)

stalled at same location, main rotor balanc−

ing is required.

NOTE: Excessive lead−lag load applied to the

main rotor blades during ground handling

(2). Remove main rotor blade.

can result in damage to the elastomeric

damper buns and failure of the damper as−

(3). Remove damper.

sembly. Operators and maintenance person−

nel should use extra caution to avoid lead−

NOTE:

lag loads in excess of 35 pounds (156 N) at

D If damper is to be reinstalled at same lo−

the tip of the main rotor blades.

cation, do not disturb damper clevis, jam

nuts or turnbuckle setting.

(1). Inspect bearing in rotor blade and

bearing in the pitch housing for

D If damper is not to be reinstalled, remove

looseness around outer race. No degree

bushing from damper ear and retain with

of radial or axial play is permitted.

hub.

(2). Inspect pitch housing and blade

B. Main Rotor Damper Installation

bearings for binding, galling, or scoring

(Elastomeric Type, P/N 369D21400-503)

in bore and for wear.

(1). Check, and if necessary, preset main

(a). No radial play is permitted.

rotor damper length (center−to−center

dimension between mounting holes in

(b). Maximum allowable axial play is

damper ears and clevis) to approxi−

0.015 inch (0.381 mm).

mately 8.229 inches (209.0166 mm).

Leave jamnuts fingertight.

(3). Inspect clevis bushings for wear and

looseness.

NOTE: Ensure that bushing is installed in

(4). Inspect damper flange bushing for wear

large hole of damper ears.

and play.

(2). With damper rotational direction decal

(5). Inspect lower bolt hole in damper

facing outboard so it can be read, attach

flange for wear.

damper ears to pitch housing lug with

bolt (head up), washers, and nut.

(6). Inspect damper housing (including

Torque nut to 30 − 60 inch−pounds

flanges) for damage.

(3.39 − 6.78 Nm) and install cotter pin.

(7). Inspect damper turnbuckle, jamnuts

(3). Adjust main rotor blade phasing for

and safetywire for security. No end play

associated main rotor blade.

is permitted when manually tested.

(4). After final phasing adjustments, torque

NOTE: When performing lead−lag of main ro−

jamnuts to 95 − 110 inch−pounds

tor blades, apply rotor brake (if installed) or

(10.73 − 12.43 Nm). Safety jamnuts to

have assistant hold main rotor hub from

turnbuckle with new lockwire. Lock−

moving. A second assistant is recommended

wire must be located out−board, away

to measure approximate damper extension

from pitch housing.

and compression.

NOTE: Threaded end of damper turnbuckle

(8). Lead−lag each main rotor blade in turn

shaft must protrude through clevis base a

to provide approximately 0.10 inch

minimum of two full threads and must clear

(2.54 mm) extension and compression of

blade damper attach fitting.

the damper elastomer.

Page 7-67

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(9). Visually check each damper in turn for

(5). If extension exceeds 0.063 inch (1.6002

cracks in elastomer or in elastomer−to−

mm), replace the damper assembly.

metal bond at end face of damper:

(6). Reinstall existing damper; or as

(a). If bonding or elastomer cracks are

required; install replacement damper.

noted, measure depths of cracks,

using depth gage fabricated of shim

NOTE: If replacement damper is installed, re−

stock or equivalent having a 0.20

cord part number, serial number, and other

inch (0.508 mm) indication.

pertinent information in Components Re−

cord of helicopters Log Book.

(b). If depth of crack exceeds 0.20 inch

(0.508 mm), remove and check

E. Blade Phasing Procedure (Elastomeric

damper.

Type, P/N 369D21400-503)

D. Main Rotor Damper Weight Loading and

(1). Remove all four main rotor blade

Extension Check (Elastomeric Dampers

dampers from helicopter.

Only, P/N 369D21400-503)

(2). Store all four dampers together in

(Ref. Figure 7−23)

horizontal position for minimum of six

hours. Preferred ambient temperature

(1). Remove damper assembly.

during storage is 55° − 85°F (13° −

(2). Attach dial indicator or equivalent to

29°C).

outer case of damper; position indicator

(3). Set damper length, centerline−to−cent−

arm on center aluminum disc as shown.

erline of bolt attach holes, to 8.229

NOTE: Fabricate holding bar or fixture capable

±0.015 inch (209.0166 ±0.381 mm) for

of sustaining 100 pound (45.36 kg) static

initial installation.

load.

(4). Install dampers on helicopter.

(3). Attach damper end cap to holding bar

or fixture.

NOTE: If ground rock or stick shake is noted,

complete step (5).

NOTE: Perform weight loading and extension

check at ambient temperature of 70° ±l0°F

(5). Length of damper may be adjusted

(21° ±5°C). Apply total 100 pound (45.36 kg)

after initial setting by checking main

weight load to damper at one time, not in

rotor system balance (Ref. Main Rotor

weight increments.

Balancing). Check of main rotor system

balance should be accomplished only

(4). Using hydraulic jack or equivalent,

after main rotor blades have been

raise and attach 100 pound (45.36 kg)

tracked.

weight load at damper clevis end.

Slowly lower jack to avoid shock

NOTE: If more than four flats turn of turn−

loading. After period of two minutes

buckle adjustment is necessary to correct

under load, measure damper extension

balance, return to step (1). and repeat proce−

on dial indicator.

dure.

Page 7-68

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

41. Main Rotor Controls

NOTE: Rods are color coded to prevent rein−

stallation in the wrong locations. Observe

coding and location at time of removal. If

(Ref. Figure 7−24) The main rotor controls

coding is no longer visible, reapply appropri−

consist of a scissors assembly, rotating

ate color identity.

swashplate, stationary swashplate, mixer

controls (lateral bellcrank, longitudinal idler,

(3). Measure rod length before replacing.

collective pitch mixer bellcrank, longitudinal

bellcrank, longitudinal control−mixer link,

B. Pitch Control Rod Installation

longitudinal link, and two mixer links) and

four pitch control rods.

(1). If pitch control rods are badly out of

adjustment, or if the rod end bearing

have been replaced, set length of the

Movement of collective pitch stick and cyclic

affected pitch control rod(s).

control sticks is transferred to mixer controls

through control rods routed up through the

(a). For blades with a lower−tracking

controls tunnel at the center of Sta. 78.50

data decal, set pitch control rods,

bulkhead. The mixer controls transfer the

between rod end bearing centerlines,

required combination of collective, longitudinal

to the applicable strap pack pitch

and lateral travel to the main rotor blades

link length specified on the decal of

through the main rotor swashplate assembly.

the mating blade.

(b). For blades without a decal, set pitch

CAUTION

control rods to 6.60 inches (16.764

cm) between rod end bearing center−

D Ensure main rotor controls do not strike

lines for the two blade attached to

or get struck by any object. Many of the

the hub upper strap pack, and 6.35

components are highly stressed and must

inches (16.1544 cm) for the two

not be returned to service if surface dam−

blades attached to the lower strap

age occurs.

pack.

D When maintenance work is being per−

(2). Observe the ground track before

formed near the engine air inlet use care

making addition adjustments.

to prevent entry of foreign objects. Tape

covers of cardboard or other suitable ma−

(3). Install O−ring and pitch control rod.

terial in place over the engine inlet screen

and oil cooler air inlets. Do not remove

NOTE:

covers until work is completed and debris

D Check pitch control rods for location color

is thoroughly cleaned out of the area. Af−

code.

ter removing covers, verify that area

D Blades must be tracked if rod length is

around base of mast, inlet to plenum, and

changed. Be sure that rod end threads are

entire plenum chamber is free of foreign

engaged beyond witness hole in rod body

material.

(hole blocked).

D After proper bearing alignment (center−

42. Pitch Control Rods

ing) in swashplate lugs and pitch housing

lugs, tighten locknuts and install lock−

(Ref. Figure 7−24) Four pitch control rods

wire.

transfer pitch control from the rotating

D Rod ends must be centered; if not cen−

swashplate to main rotor blades.

tered, fitting wear will result.

D Be sure that pitch rod bolts are installed

A. Pitch Control Rod Removal

with the bolthead in the direction of rota−

tion (counter−clockwise as viewed from

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

above).

from each end of pitch control rod.

(4). Install bolt, washer and nut in upper

(2). Remove pitch control rod and O−ring.

end of rod. Torque nut to 100 − 140

Page 7-70

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

inch−pound (11.30 − 15.82 Nm) and

inch−pounds (1.69 − 2.26 Nm). Install

install new cotter pin.

new cotter pin.

NOTE: If castellation alignment is not possible

Scissors crank must be posi−

CAUTION

with the torque specified in step (5). below,

tioned with hole in crank web

add another washer. Do not exceed the max−

down and decal, if present, up.

imum torque value.

NOTE: Ensure crank− to− hub lower shoe lugs

are not preloaded.

(5). Install bolt, washer, and nut in lower

end of rod. Torque nut 30 − 60 inch−

(3). Position scissors crank and required

pound (3.39 − 6.78 Nm) and install

shim washers on hub lower shoe lugs.

new cotter pin.

(a). Install bolts with bolt heads facing

43. Scissors Assembly

outward and a washer under the

head of the bolt.

(Ref. Figure 7−24) The scissors assembly is a

pivoting link that provides a movable connec−

(b). Torque nut to 30 − 60 inch−pounds

tion between the rotating swashplate and the

(3.39 − 6.78 Nm). Install new cotter

main rotor hub.

pin.

NOTE: Shim washers may be required on

A. Scissors Assembly Removal

shouldered bushing side of clevis.

Removal of all pitch control rods

CAUTION

(4). Position O−ring and lower end of pitch

is recommended prior to scissors

control rod in swashplate lug and

removal. Failure to observe this precaution

install attaching hardware.

could result in damage to pitch control rods,

swashplate and/or hub.

(a). Nut is to be adjacent to bushing in

swashplate.

(1). Disconnect lower end of pitch control

rod that is in line with scissors link in

(b). Torque nut to 30 − 60 inch−pounds

rotating swashplate.

(3.39 − 6.78 Nm). Install new cotter

pin.

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

bolt from each leg of scissors crank.

C. Scissors Disassembly

Disconnect crank from hub lower shoe,

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

use care to prevent loss of shim wash−

bolt that join link and crank.

ers.

(2). Remove two bushings from link only if

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

replacement is necessary.

bolt connecting scissors link to swash−

plate; remove scissors assembly.

(3). Do not remove bearing from link.

Replace complete link if bearing is

B. Scissors Assembly Installation

defective.

(1). Place scissors assembly link in mount−

(4). Remove two lotted bushings and two

ing position, chamfered edge of link

bearings from crank, only if replace−

must face outboard.

ment is necessary,

(2). Check that slotted bushing is in

NOTE: During cleaning, do not allow solvent to

swashplate web and install attaching

enter the races of scissors assembly bear−

hardware. Torque nut to 15 − 20

ings.

Page 7-71

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

ROTOR HUB

SHIMS/SHIM

INITIAL ROD LENGTH AND BEARING ANGULARITY

LOWER SHOE

WASHERS

CONTROL

DIM

ANGLE

ASSY PART

(NOTE 5)

SLOTTED BUSHING

ROD ASSY

L − IN. (CM)

NUMBER

(NOTE 1)

369A1020−3 OR

MAIN ROTOR PITCH

6.35

IN LINE

369A1008−3

NAS464P4−17

(LOWER STRAP PACK)

(16.1544)

MAIN ROTOR PITCH

6.60

IN LINE

369A1008−3

(UPPER STRAP PACK)

(16.764)

SHIM WASHER

(NOTE 3)

30−60 IN. LB (3.39−6.78 NM)

PART NO. 369A1011 ROD

DECAL

END HAS LH THREAD

SCISSORS

(NOTE 4)

CRANK

MAX ALLOWABLE LOOSENESS

30−40 IN. LB

0.040 IN. (1.016 MM)

(3.39−4.52NM)

BUSHING

BEARING

BUSHING

BEARING

SCISSORS LINK

BEARING

SLOTTED BUSHING

(NOTE 1)

60−140 IN. LB

(6.78−15.82 NM)

PITCH CONTROL ROD

(NOTE 2)

ROTATING SWASHPLATE

O−RING

SLOTTED BUSHING

(NOTE 1)

TRACKING INTERRUPTER

(369A9946−29)

30−60 IN. LB

(3.39−6.78 NM)

COLLECTIVE PITCH

CONTROL ROD

30−60 IN. LB

(3.39−6.78 NM)

LONGITUDINAL PITCH

CONTROL ROD

NOTES:

EDGE OF BUSHING MUST PROTRUDE A MIN. OF 0.010 IN.

(0.254 MM) TO A MAX. OF 0.060 IN. (1.524 MM) ABOVE

LATERAL PITCH

OUTSIDE SURFACE OF PART AFTER NUT IS TIGHTENED.

CONTROL ROD

COLOR−CODED TO MATCH BLADE.

ADD WASHERS UNDER HEAD AS REQUIRED FOR

SLOTTED BUSHING

CLEARANCE BETWEEN BOLT END AND SWASHPLATE BOOT.

(NOTE 1)

ON CURRENT CONFIGURATION ONLY.

USE SHIMS/SHIM WASHERS TO FILL GAP.

30−023F

Figure 7-24. Pitch Control Rods and Swashplate Scissors Assembly Installation

Page 7-72

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

D. Scissors Inspection

Do not allow sealant to enter

CAUTION

bearing race.

Any evidence of failure,

(e). Apply a small fillet of sealant to the

WARNING

damage, or deformation of

faying edges of the bearing housing.

crank or link is justification for re−

placement of either crank, link, or the

(f). Use cellophane or masking tape to

complete scissors assembly. Failure of

exclude air and allow sealant to cure

any of these component in flight can re−

for 24 hours at ambient temperature

sult in failure of movable flight con−

or force cure by heating to

trols, loss of helicopter, and possible in−

140°−160 °F (60°−71 °C) for 1 hour

jury or loss of life.

prior to use of assembly.

(1). Inspect crank and link for evidence of

(3). If bushings were removed from link

impact damage and deformation. If

during disassembly, install new

condition is questionable, perform a

bushings. Dimension between outside

fluorescent dye penetrant inspection.

faces of bushings is 1.616−1.628 inches

(4.1046−4.1351 mm).

(2). Inspect bearings for binding, looseness

(4). Align bore of link with bore of crank;

in mating bore and wear. Maximum

install bolt, washer and nut. Torque nut

wear limits are 0.010 inch (0.254 mm)

to 30 − 40 inch−pounds (3.39 − 4.52

radial and 0.020 inch (0.508 mm) axial.

Nm). Install new cotter pin.

(3). Inspect bushings for condition.

44. Main Rotor Swashplate

(Ref. Figure 7−25) The main rotor swashplate

E. Scissors Reassembly

consists primarily of a rotating swashplate,

stationary swashplate, a bearing assembly and

(1). If bushings were removed from the

retainer, and a counterweight.

crank during disassembly, install new

bushings. Use lubricant (25, Table 2−4);

A. Swashplate Assembly Removal

do not use primer. Seat bushings until

ends are flush with inside surface of

(1). Tag or color−identify the four pitch

crank inboard ears.

control rods to facilitate their replace−

ment in the same location.

(2). If bearings were removed from crank

Failure to reinstall the four

during disassembly, reinstall using the

CAUTION

pitch control rods in the correct

following procedure:

location will most likely result in the main

rotor blades being badly out of track.

(a). Clean bearing outerace, counterbore,

(2). Disconnect pitch control rods from the

and faying surfaces with trichloroe−

rotating swashplate.

thane (61).

(3). Remove scissors assembly.

(b). Coat the faying surfaces with Locquic

Activator (28) as per manufacturer’s

(4). Remove main rotor hub.

instructions.

(5). Disconnect longitudinal link from

stationary swashplate.

(c). Apply Loctite Sealant A (29) to faying

surfaces and press bearing until

(6). Disconnect right and left side mixer

outer face is seated firmly against

links from stationary swashplate.

shoulder of counterbore.

(7). Remove protective boot from groove in

(d). Remove excess sealant.

lower side of stationary swashplate.

Page 7-73

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

TRACKING INTERRUPTER

(369A9946−27; NOTE 1)

(369A9946−25 OR −23; NOTE 1)

STATIONARY

SWASHPLATE

NOTE 2

COUNTERWEIGHT

GROOVE

BOOT INSTALLED

NOTE 3

30−60 IN. LB

(3.39−6.78 NM)

BOOT

ROTATING

NYLON STRAP

SWASHPLATE

15−20 IN. LB

(1.69−2.26 NM)

MAST

15−20 IN. LB

(1.69−2.26 NM)

DRAIN HOLES

STATIONARY

(HIDDEN; NOTE 4)

TRACKING INTERRUPTER

SWASHPLATE

(369A9946−25 OR −23; NOTE 1)

NOTES:

INDEX

COLOR CODE TO MATCH BLADES AND MAINTAIN SEQUENCE

COAT BOLT WITH GREASE (21, TABLE 2−4).

DRAIN HOLES

EXTRA WASHERS FOUND IN THIS LOCATION ARE PART OF

(2 PLCS)

COUNTERWEIGHT.

DRAINAGE PROVISIONS FOR WATER ENTRAPMENT AREA IN

STATIONARY SWASHPLATE LOWER FORWARD FLANGE.

(REF. MDHS SERVICE INFORMATION NOTICE HN−39.)

30−024C

Figure 7-25. Main Rotor Swashplate Assembly

Do not strike rotating swash−

NOTE: To inhibit mast corrosion when operat−

CAUTION

plate or bearing assembly with

ing in salt water environment, fresh water

tools or in any way deface these compo−

rinse and thoroughly dry the sliding swash−

nents. The rotating swashplate is a stressed

plate area of mast and lightly coat area with

part that has had all surfaces shot peened.

grease film (18, Table 2−4).

Use particular care to protect Teflon liner in

bearing bore. A damaged swashplate bear−

(3). Engage upper end of boot in groove at

ing must not be retained in service. (Refer to

lower side of stationary swashplate.

HN−1 12 if stiff main rotor controls traceable

Secure boot with self−clinching nylon

to excessive preload torque on main rotor

strap.

swashplate bearing occurs.)

(4). Align longitudinal link with stationary

swashplate (Ref. Figure 7−26).

(8). Lift swashplate assembly carefully up

and off of mast.

(5). Install flanged bushing (if removed),

bolt, two washers, nuts and new cotter

(9). To remove boot from mast, remove

pin to secure upper end of longitudinal

self−clinching nylon strap.

link.

B. Swashplate Assembly Installation

(6). Align upper ends of mixer links with

stationary swashplate. Install slotted

(1). If swashplate lower boot was removed,

bushing (if removed), bolt, two washers

install boot on mast.

nut and new cotter pin to secure each

link to swashplate.

(2). Position swashplate over main rotor

mast and carefully lower into place.

(7). Install scissors assembly.

Page 7-74

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(8). Using color code, reinstall pitch control

NOTE: The swashplate bearing assembly will

rods at same locations from which

normally show some signs of grease leakage

removed.

for the first 10−15 hours of operation after a

new installation.

(9). Check track of main rotor blades

(3). Inspect swashplate spherical ball and

following installation of any removed or

double row ball bearing for condition.

replaced parts.

(a). Maximum radial play between

sliding surface liner and the station−

C. Swashplate Disassembly

ary mast is 0.020 inch (0.508 mm).

Disassembly other than as illustrated is

(b). Maximum axial play between spheri−

considered a part of swashplate overhaul.

cal ball and Teflon liner is 0.010 inch

Refer to CSP−H−5 for this type of information.

(0.254 mm).

If tracking interrupters are removed, mark

(c). If play is suspected in double row ball

them to match the blade color code so that they

bearing, turn rotating swashplate

may be returned to the original positions. Also

until arms line up with those of

note the number and type of washers used

stationary swashplate and check

under the nut at the counterweight location.

motion between the arms at the

These are a part of the counterweight required

control bolt in the stationary swash−

for rotating swashplate balance.

plate. A maximum total vertical

movement of 0.015 inch (0.381 mm)

D. Swashplate Assembly Inspection

is allowable.

(d). Nicks and dents that do not deform

When cleaning swashplate as−

CAUTION

ID chamfered edge of the hard

sembly for inspection, use care

anodized ball and that do not extend

to prevent solvent from entering the race

more than 0.040 inch (1.016 mm)

area of either the spherical ball bearing or

along spherical ball surface from

the double row ball bearing. Use a cloth,

edge are allowed.

moistened in alcohol (71, Table 2−4) to wipe

clean the spherical ball, ball bore liner and

(4). Check the existing preload on the

exterior of double row ball bearing.

spherical bearing.

(a). Hold the ball to prevent rotation;

NOTE:

then hook a spring scale over one of

the bolts securing the stationary

D The swashplate may be constructed of ei−

swashplate to the bearing flange.

ther magnesium or aluminum alloy. Ref.

Sec. 2 for corrosion control and identifica−

(b). With the stationary swashplate in

tion of magnesium and aluminum alloys.

motion, drag should be no more than

30 pounds (13.61 kg). (Use the

D In the following inspection, the rotating

average of two readings taken 90

and stationary swashplates must be dis−

degrees apart.)

connected (Ref. Swashplate Assembly Re−

moval/Installation).

(5). Perform a careful visual inspection of

the stationary and rotating swashplate

(1). Inspect swashplate bearing assembly

for cracks, wear in bolt and bushing

for evidence of binding in either radial

bores and fork inner surfaces, and for

or axial movement.

corrosion, nicks and dents. Perform dye

penetrant check on questionable areas.

(2). Inspect Teflon liners for good condition.

(6). Check that counterweight is securely

Ensure that all flexible rubber seals

bonded in rotating swashplate.

enclosing ball bearing races are in

E. Swashplate Reassembly

place; inspect for deterioration and

indication of grease leakage. Refer to

Reinstall tracking interrupters in original

CSP−H−5 for re−greasing and seal

color coded positions and torque nuts to the

replacement.

values shown.

Page 7-75

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: When installing tracking interrupter at

Do not allow solvent to enter

CAUTION

the counterweight position, apply grease

bearing races when cleaning

(21, Table 2−4) to the bolt and to the 0.250

mixer control components to prevent wash−

inch (6.35 mm) diameter bore areas. Also be

ing of dirt into bearing surfaces or grease

sure to reinstall all washers that were origi−

out of the bearings.

nally installed under the nut. These area

B. Mixer Controls Installation

part of the counterweight required for rotat−

ing swashplate balance.

(1). Position support bracket over forward

lug on mast base.

45. Mixer Controls

(2). Install the two aft bolts and washers in

the support bracket and mast base.

(Ref. Figure 7−26) The mixer controls consist

Install two thin washers and nuts;

of various links, bellcranks, idlers, a support

torque nuts to 80 − 100 inch−pounds

bracket and associated fasteners that secure

(9.04 − 11.30 Nm) plus drag torque.

these components in place and to the control

tubes and main rotor swashplate.

(3). Using a ball hole gage and standard

micrometer, check that misalignment

A. Mixer Controls Removal

between the forward bolt hole bore in

the support bracket and the bore in the

(1). Remove air intake forward fairing for

mast base lug is 0.015 inch (0.381 mm)

access (Ref. Sec. 2).

or less.

(2). Disconnect upper end of the collective

NOTE: If necessary, loosen the aft two bracket−

mixer, lateral mixer and longitudinal

to−fitting nuts, position support bracket to

mixer control tubes.

minimize misalignment and retighten nuts.

(4). Install mixer support attaching bushing

NOTE: The control tubes are attached by

in bracket and mast base lug.

slightly different length bolts. Reinstall

each bolt in its bellcrank following control

(5). Check that the sleeve bushing is in

tube removal to facilitate reinstallation of

place; then install bolt, two washers

the correct size.

and nut. Torque nut to 80 − 100

inch−pounds (9.04 − 11.30 Nm).

(3).

Remove mixer links. (Mixer link

bearings are not replaceable.)

(6). Position longitudinal pitch idler and

collective pitch mixer bellcrank on

(4).

Disconnect longitudinal link.

support bracket.

(a). Position washer between right side of

(5).

Disconnect each end of longitudinal

longitudinal pitch idler bearing and

control−mixer link and remove link.

center bearing of mixer support

(6).

Disconnect lateral bellcrank and lift

bracket.

from collective pitch mixer bellcrank.

(b). Install left−hand bearing, bolt, two

washers, nut and new cotter pin.

(7).

Disconnect longitudinal pitch mixer

bellcrank and carefully remove bell−

(7). Position lateral bellcrank between

crank.

collective pitch mixer bellcrank bear−

ings and install bolt, two washers, nut

(8).

Remove hardware from hingeline of

and new cotter pin.

support bracket, longitudinal pitch idler

(8). Position longitudinal bellcrank with

and collective pitch mixer bellcrank.

collective pitch mixer bellcrank.

Separate the three parts.

(a). Insert the two flanged bushings into

(9).

Disconnect support bracket from mast

place.

base and remove.

(b). Install two bolts, six washers (two

(10).

Remove the mixer support attaching

under each nut), two nuts and new

bushing.

cotter pins.

Page 7-76

Revision 16

NOTES:

LONGITUDINAL LINK DETAILS ROTATION

DIRECTION OF BOLT OPTIONAL.

FOR CLARITY.

EDGE OF BUSHING MUST PROTRUDE

NOT PART OF SUPPORT BRACKET.

A MIN. OF 0.010 IN. (0.254 MM) TO A MAX.

* LONGITUDINAL

MUST BE PULLED OUT FIRST TO REMOVE

OF 0.060 IN. (1.524 MM) ABOVE OUTSIDE

PITCH MIXER

SLOTTED

LONGITUDINAL CONTROL

BELLCRANK.

SURFACE OF PART AFTER NUT IS

BUSHING

SPHERICAL BEARING WITH TEFLON OR

MIXER LINK

TIGHTENED.

(NOTE 2)

EQUIVALENT LINING. WEAR LIMIT

0.008 IN. (0.203 MM) RADIAL OR 0.040 IN.

(1.016 MM) AXIAL.

ASTERISK ( * ) INDICATES PARTS MAY BE

MIXER LINK

NOTE 6

SLOTTED BUSHING

EITHER MAGNESIUM OR ALUMINUM ALLOY.

NOTE 6

(NOTE 2)

* LATERAL MIXER

REF. SEC. 2 FOR ALLOY IDENTIFICATION

BELLCRANK

AND CORROSION CONTROL.

STATIONARY

SWASHPLATE

BEARING

SLOTTED BUSHING

(NOTE 2)

NOTE 6

FLANGED

MIXER LINK

BUSHING

BEARING

STATIONARY

(NOTE 6)

SWASHPLATE

BEARING

NOTE 6

80−100 IN. LB

(9.04−11.30 NM)

MIXER SUPPORT

BRACKET

SLOTTED BUSHING

LONGITUDINAL LINK

NOTE 1

FLANGED BUSHING

(NOTE 2)

(NOTE 3)

NOTE 1

(NOTE 5)

MIXER

BEARING

SUPPORT

ATTACHING

BUSHING

* COLLECTIVE PITCH

BEARING

MIXER BELLCRANK

BEARING

SLEEVE

BEARING

BUSHING

FLANGED

(NOTE 4)

BUSHING

(NOTE 5)

* LONGITUDINAL

PITCH MIXER

NOTE 1

BELLCRANK

MAST BASE

80−100 IN. LB

(9.04−11.30 NM)

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(9). Position longitudinal control−mixer link

(a). Wear limit is 0.008 inch radially and

between longitudinal pitch idler and

0.040 inch (1.016 mm) axially.

longitudinal pitch mixer bellcrank.

(b). Replace complete mixer link if

(a). Check that two slotted bushings are

bearings are faulty.

in place.

(c). Inspect bearings in other linkage for

binding and looseness in mating

(b). Install bolt, three washers (two

bores.

under each nut), nut and new cotter

pin at each end of link.

D. Mixer Control Repair

(10). Position longitudinal link between

Repair minor surface defects such as

longitudinal, pitch mixer bellcrank

scratches, nicks and corrosion using abrasive

bearings. Install bolt, two washers, nut,

cloth (20, Table 2−4), grade 400−600 to smooth

and new cotter pin.

out and blend in such defects. The following

depth limits represent total limits, including

(11). Position mixer links in stationary

the effects of all previous repair to any given

swashplate and lateral bellcrank; check

area.

that slotted bushings are in place.

Install bolt, two washers, nut, and new

(1).

Cast and forged surfaces may be

cotter pin at each end of link.

reworked to a depth of 0.020 inch (0.508

mm).

(12). Place the collective mixer, lateral mixer,

and longitudinal mixer control tubes in

(2).

Flat machined surfaces, except clevis

position.

inner ears, may be reworked to a depth

of 0.015 inch (0.381 mm). Clevis inner

(a). Check that slotted bushings are in

ear surfaces may be reworked to a

place.

depth of 0.020 inch (0.508 mm).

(3).

Machined holes, may have 0.003 inch

(b). Install bolt, two washers, nut, and

(0.0762 mm) removed from the bore

new cotter pin to secure each rod end.

wall in an area no greater than 15

(13). Install air intake forward fairing.

percent of the circumference and 50

percent of the depth.

(14). Check rigging of collective and cyclic

(4).

All edges may have 0.030 inch (0.076

controls following installation of any

mm) removed except round machined

removed or replaced parts.

holes which are limited to 0.010 inch

(0.254 mm) chamfer.

C. Mixer Controls Inspection

(5).

All rework must be smoothly blended

(1). Inspect all bushings for security of fit.

into the adjacent surfaces and the

finish must be restored on magnesium

(2). Inspect longitudinal link, support

parts and aluminum parts (Ref. Sec. 2).

bracket, longitudinal control−mixer

link, mixer links, longitudinal pitch

(6).

Replace defective bearings and bush−

idler, longitudinal pitch mixer bell−

ings, except swaged spherical bearings

crank, lateral bellcrank and collective

in mixer links which require link

pitch mixer bellcrank for scratches,

replacement.

cracks, corrosion and similar surface

defects. Perform a fluorescent dye

(a). Remove bearings or bushings by

penetrant inspection on components

pressing out the old part.

that are questionable.

(b). Install a new bearing of the correct

(3). Inspect spherical, Teflon (or equivalent)

type with surface primer and grade A

lined bearings for binding/looseness in

locking compound (28 and 29)

link bore and wear.

according to container instructions.

Page 7-78

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: The left−hand bearing in the support

Use care during removal of con−

CAUTION

bracket is not supplied as a part of the

trol tubes. Any surface damage

bracket. This bearing is installed at the time

caused by hasty removal may result in un−

the support bracket and longitudinal pitch

serviceable control tubes.

idler are assembled. Install a new bearing

(7). Grasp upper end of control tube and

by seating flush with inner face of support

carefully withdraw tube until lower end

bracket flange.

clears the cover.

B. Tunnel-Routed Control Tube Installation

(7). Mixer links at the lateral mixer

bellcrank are either smooth contoured

(1). Hand turn main rotor blades to obtain

or octagonal shaped with check nuts.

clear space for tube installation.

Do not disassemble or intermix types.

Use care during installation of a

CAUTION

control tube to avoid striking

other installed control tubes.

46. Tunnel-Routed Control Tubes

(2). With the riveted rod end at the lower

(Ref. Figure 7−27) Each tunnel−routed control

position, carefully lower tube through

tube consists of two rod end bearings and an

cover opening into tunnel.

anodized aluminum alloy tube. The control

(3). Install control tunnel cover boot and

tubes mechanically transfer displacement of

secure with self−clinching nylon strap.

the flight controls to the associated bellcranks

and idler at the front of the main rotor mast

Do not tighten loosened jam

CAUTION

base. All the tunnel−routed control tubes are

nuts on rod end bearings with−

removed, inspected, repaired and installed in

out holding the rod end with a wrench.

the same manner.

(4). Align lower rod end with mating

bellcrank. Install bolt, two washers,

A. Tunnel-Routed Control Tube Removal

nut, and new cotter pin.

(5). Align upper rod end of control tube with

Before disconnecting collective

mating idler or bellcrank. Install bolt,

CAUTION

pitch control tube, install collec−

two washers, nut, and new cotter pin.

tive bungee installation tool to prevent

(6). Remove bungee installation tool used

spring reaction due to droop stop load on

for removal of collective control tube.

control tube.

(7). Perform controls rigging check follow−

ing installation of removed or replaced

(1). Install collective bungee installation

parts.

tool (26, Table 2−2).

C. Tunnel-Routed Control Tube Inspection

(2). Gain access to lower tube ends by

(1). Inspect rod end bearings for binding

removing controls access door at base of

and excessive wear, 0.040 inch (1.016

canted bulkhead in cargo compartment.

mm) maximum axial play.

(2). Inspect control tube for surface damage

(3). Disconnect lower tube end from

and evidence of bending.

bellcrank or fitting.

(3). Inspect for loose rivets at fixed rod end

(lower end).

(4). Hand turn main rotor blades to obtain

clear space for tube removal.

(4). Inspect longitudinal mixer control tube.

Control tube is an ‘‘On Condition" item.

(5). Remove cotter pin, two washers, and

When tightening loosened jam

CAUTION

bolt securing upper end of control.

nut on rod ends as in step (5).

Disconnect upper end of control tube.

below, always hold rod end with wrench.

(5). Determine if excessive rod end loose−

(6). Remove boot from control tunnel cover.

ness exists in tunnel−routed control

Page 7-79

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

tube assemblies by checking the upper

(h). Disconnect rod end from control

end as follows.

system.

(i). Screw rod end completely out of

Do not disconnect rod ends from

CAUTION

control tube.

mixer assembly to perform this

inspection except as instructed.

(j). Use 0.339 inch (8.6106 mm) diameter

drill to check tube threads.

(a). Loosen jam nut a minimum of two

threads.

(k). If drill can be inserted, tube assembly

is unserviceable and must be re−

(b). Apply light finger pressure to the top

placed.

of the rod end to preload it against

one side of attaching clevis. This will

(l). If drill cannot be inserted, tube is

eliminate play other than where

serviceable.

inspection is desired.

(m). Reinstall rod end, reconnect tube to

(c). Use a dial indicator or position a 6

control system and tighten jam nut.

inch (15 cm) rule horizontally at the

upper end of the tube (where the tube

(n). Check rigging of reconnected control

end enters). Lightly deflect tube

system.

laterally from one extreme to other.

D. Tunnel-Routed Control Tube Repair

NOTE: Maintain the preload of the rod end

bearing to eliminate the effect of bearing

(1). Perform straightness check on control

looseness.

tube that appears bent or bowed.

(d). Measure the total movement of the

(a). Total length of any tunnel−routed

top of the tube where the tube end

tube (excluding rod ends) must be

centers.

straight within 0.050 inch (1.270

mm), with straightness variation

limited to maximum of 0.010 inch

(e). If total lateral movement from one

(0.254 mm) in each foot of length.

extreme to the other is in excess of

0.0625 inch (1.5875 mm), the entire

Dye−check for cracking must

tube assembly must be replaced with

WARNING

always be performed after

serviceable parts.

cold− straightening. Replace cracked

tube, or cracked or bent rod end.

NOTE: Because of normal tolerance build some

play or looseness is expected. Play or loose−

(2). Cold−straighten bent tube that is not

ness less than 0.0469 inch (1.1906 mm) is no

within tolerance (step (1). above)

cause for concern.

provided there are no nicks or sharp

dents in bent length. Do not use rod

(f). If the total lateral movement is less

ends to support tube during straighten−

than 0.0469 inch (1.1906 mm), the

ing.

tube assembly is serviceable; tighten

the jam nut. Movement of less than

Use care when drilling to re−

0.0469 inch (1.1906 mm) is consid−

CAUTION

move or install riveted rod end;

ered negligible.

the rod end is steel and the tube is alumi−

num.

(g). If the lateral movement is

0.0469−0.0625 inch (1.1906−1.5875

(3). Replace a control rod end if bearing

mm), the rod end should be further

axial play is more than 0.040 inch

inspected for serviceable steps (h).

(1.016 mm). Set initial control tube

thru (n). below.

length and bearing angularity.

Page 7-80

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

LONGITUDINAL PITCH IDLER

COLLECTIVE PITCH

MIXER BELLCRANK

LATERAL BELLCRANK

LONGITUDINAL MIXER

CONTROL ROD

COLLECTIVE MIXER

CONTROL ROD

TAIL ROTOR CONTROL ROD

LATERAL MIXER CONTROL ROD

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

CONTROL

DIM L

ANGLE

ASSY PART

ROD ASSY

IN.(CM)

NUMBER

COLLECTIVE

56.51−56.67

LONGITUDINAL MIXER

IN LINE

369A7011

PITCH FITTING

(143.535−143.942)

55.67

LATERAL MIXER

IN LINE

369A7012

(141.402)

53.14

COLLECTIVE MIXER

IN LINE

369A7009

(134.976)

2.0 IN. (5.08 CM)

RIVET

(NOTE)

SERIAL NO.

PLATE

MAX ALLOWABLE LOOSENESS

0.040 IN. (1.016 MM)

CONTROLS

SUPPORT

BRACKET

LONGITUDINAL IDLER

BELLCRANK

LATERAL IDLER

BELLCRANK

NOTE:

INSPECT FOR WEAR. REPLACE RODS WITH

WEAR DEPTH EXCEEDING 0.020 IN. (5.06 CM) OR

HAVING O.D. LESS THAN ALLOWABLE MINIMUM.

30−045C

Figure 7-27. Tunnel-Routed Control Tubes

Page 7-81

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

47. Tunnel-Routed Control Tube Inspection

(c). Measure outside diameter of control

and Sleeve Installation

tube end and select proper sleeve.

(Ref. Figure 7−28) The following procedures

(d). Temporarily install sleeve onto

are for inspection and installation of reinforc−

control tubes.

ing sleeves to the tunnel−routed control tubes.

(e). Align sleeve and control tube witness

A. Control Tube Tapered Area Sleeve

hole.

Installation

(f). If sleeve protrudes past end of control

(1). Remove all four control tubes (Ref.

tube, trim end of sleeve flush, 0.0

Tunnel−Routed Control Tube Replace−

inch (0.0 mm), or back 0.080 inch

ment).

(2.032 mm) from end of tube.

(2). Using paint remover (11, Table 2−4)

NOTE: Bond integrity is dependent on clean

remove paint approximately six inches

surfaces.

(15 cm) back from end of each tube,

(g). Thoroughly clean end of control tube

tape and cover−rap remaining area of

and interior surface of sleeve with

tube.

lint free cloth and MEK (22) or

NOTE: Control tubes that are cracked must be

equivalent.

removed from service.

(h). Mix epoxy adhesive (121) per

(3). Dye penetrant inspect external surface

manufacturer’s instructions.

of stripped area for cracks.

(i). Remove excessive adhesive with lint

(a). Cracks are indicated by heavy bleed

free cloth moistened with MEK or

out.

equivalent. Do not saturate the

cleaning cloth. Remove adhesive from

NOTE: It may be necessary to wipe off and

witness holes.

reapply the developer to distinguish be−

tween surface defects caused during swag−

(j). Plug end of control tube to prevent

ing operation.

adhesive from entering threads. Bond

sleeve to control tube. Apply adhesive

(b). Light penetrant indications are not

to both surfaces and install sleeve.

cause for rejection.

Align witness/rivet hole in sleeve and

tube.

(4). If no cracks are found; inspected control

tube can be reworked for sleeve instal−

Do not use heat gun. Use of heat

lation. All four control tubes are to be

CAUTION

lamp is acceptable.

reworked as follows:

(k). Allow to cure for 24 hours at mini−

(a). Measure and record length of control

mum ambient temperature of 68°F

tubes for reinstalling rod ends and to

(20°C); alternate cure 4 hours at

prevent rerigging after tube rein−

115°−140 °F (46°−60 °C).

stallation.

(l). Repeat procedure for ends of each

Drilled out rivets may damage

control tube.

CAUTION

threads upon removal. Visually

inspect control tube threads for damage

(m). Using primer (4), touch−up repaired

from rivet and rod end removal. Replace

area(s) of control tube.

damaged control tubes. Drilled rod ends are

(n). Install rod ends into ends in which it

matched drilled to each control tube and

was removed. On fixed rod end, align

must be reinstalled into control tube end

witness/rivet hole in sleeve and tube

from which removed.

with rivet hole in rod end. Drill (#40)

(b). Remove rod ends, MS20470AD3

thru opposite end of sleeve. Rivet

rivets must be removed from fixed

fixed end with MS20470AD3−15

end.

rivet.

Page 7-82

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

0.097−0.102 IN.

0.340 IN.

CONTROL

(2.4638−2.5908 MM)

(8.636 MM) *

SLEEVE

TUBE

0.750 IN.

DIA

(19.05 MM)

7°

0.00−0.080 IN.

0.5°

(0.00−2.032 MM)

0.720 IN.

(18.288 MM)

0.910 IN.

(23.114 MM) *

54−412A

Dimensional Table

Sleeve No.

Dim A

Tube O.D.

Tube No.

369D27013

inch (mm)

-1

0.540-0.545

(13.716-13.843)

0.501-0.530

(12.7254-13.462)

369A7007

369A7009

-2

0.510-0.515

(12.954-13.081)

0.470-0.500

(11.938-12.7)

-3

0.590-0.595

(14.986-15.113)

0.551-0.580

(13.9954-14.732)

369A7011

-4

0.560-0.565

(14.224-14.351)

0.520-0.550

(13.208-13.97)

369A7012

-5

0.570-0.575

(14.478-14.605)

0.530-0.560

(13.462-14.224)

NOTE:

(1) Material; 2024-T351 or T4 (QQA 225/6) bar or round stock.

(2) Break sharp edges 0.005-0.015 inch (0.127-0.381 mm).

(3) Surface finish 125 RMS.

(4) Chemical film per MIL-C-5541.

(5)

* - Tolerance ±0.010 inch (0.254 mm).

Figure 7-28. Sleeve Fabrication and Installation

Page 7-83

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(o). Adjust each control tube to its

B. Control Tube Straight Area Sleeve

previously measured length and

Installation

paint the control tube ends with

primer. Paint adjustable ends of

This repair is permissible on the straight area

control tube flat black.

of the tube only and increases the outside

diameter.

(p). Re−identify , with permanent ink, the

control tubes that have been re−

NOTE: Ensure adequate clearance exists prior

worked (Ref. Table 7−9).

to performing the repair. Determine and re−

(q). Rework control tube boot (Ref.

pair condition that caused damage. Maxi−

Figure 7−29).

mum length of repair sleeve is 6 inches. Two

sleeve repairs permitted per control tube.

If control tube is not accurately

CAUTION

measured, flight controls will

(1). Remove damaged control tube(s) (Ref.

require re−rigging.

Tunnel−Routed Control Tube Replace−

ment).

(r). Reinstall control tubes. Reinstall

trimmed boot with vertical seam

facing aft. Check flight controls for

(2). Tape around area to be repaired.

interference or binding.

(3). Using paint remover (11, Table 2−4),

Table 7-9. Control Tube Re-Identification

strip paint 1.0 inch (2.54 cm) beyond

area of repair.

Old Part Number

New Reworked Part Number

369A7007

369A7007-5

(4). Polish out burrs and sharp edges.

369A7009

369A7009-5

Ensure defects do not exceed allowable

limits (Ref. Table 7−10). Dye penetrant

369A7011

369A7011-5

inspect area per MIL−I−25135; no

369A7012

369A7012-5

cracks allowed.

Table 7-10. Control Tube Straight Area Repair Limits

Nicks and Gouges (2)

Dents and Depressions (2)

Repair Sleeve (3)

Control

Max. Depth

Wall

Tube

W/O Repair

With Repair

W/O Repair

With Repair

O.D.

Thickness

(4)

(1)

(4)

(1)

0.006 inch

0.015 inch

0.010 inch

0.025 inch

1.375 inch

0.049 inch

369A7007

(0.152 mm)

(0.381 mm)

(0.254 mm)

(0.635 mm)

(3.4925 cm)

(1.2446 mm)

0.008 inch

0.020 inch

0.010 inch

0.025 inch

1.50 inch

0.049 inch

369A7009

(0.203 mm)

(0.508 mm)

(0.254 mm)

(0.635 mm)

(3.810 cm)

(1.2446 mm)

369A7011

0.010 inch

0.025 inch

0.010 inch

0.025 inch

1.625 inch

0.049 inch

369A7012

(0.254 mm)

(0.635 mm)

(0.254 mm)

(0.635 mm)

(4.1275 cm)

(1.2446 mm)

NOTE:

(1) Sleeve repair not permitted in tapered area. Two sleeve repairs per control tube. Maximum defect area

0.375 in² (2.41935 cm² ) per sleeve.

(2) Must be free of burrs and sharp areas.

(3) Aluminum tube 6061-T6 WW-T-700/6 or 2024-T3 WW-T-700/3. Alternate: field fabricate from

2024-T351 or 2024-T4 (QQ-A-225/6 or QQ-A-200/3). Inside diameter to be 0.010-0.025 inch

(0.254-0.635 mm) larger than outside diameter of tube to be repaired. Outside diameter as listed in table,

±0.010 inch (0.254 mm) and concentric to inside diameter 0.005 inch (0.127 mm). Maximum length of

repair sleeve 6 inches (15.24 cm). Break sharp edges 0.005-0.015 inch (0.127-0.381 mm).

(4) Maximum defect area without repair 0.10 in² (0.64516 cm²) total. For threaded area, last 2 inches (5.08

cm) of both ends, maximum depth of defect 0.020 inch (0.508 mm).

Page 7-84

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SEWN SEAMS

2 PLCS

0.40−0.50 IN.

(10.16−12.7 MM)

(NOTE 1)

DOUBLE BOOT

SINGLE BOOT

NOTES:

TRIM BOOTS BELOW HORIZONTAL SEAM.

CAUTION:

DO NOT USE SOLVENTS OR PETROLEUM BASED

CLEANING

FLUIDS ON VINYL BOOTS.

CLEAN INSIDE AND OUTSIDE OF VERTICAL SEAM AND TOP OF

BOOT WITH CLEAN CLOTH DAMPENED WITH ISOPROPYL ALCOHOL.

COAT BOTH SIDES OF VERTICAL SEAM WITH CONTACT CEMENT.

APPLY THIN COAT OF CONTACT CEMENT ALONG TRIMMED EDGE

AND 0.125−0.250 IN. (3.175−6.35 MM) DOWN INSIDE AND OUTSIDE

SURFACES OF BOOTS TO PREVENT FRAYING.

G67−1036A

Figure 7-29. Control Tube Boot Rework

NOTE: Bond integrity is dependent on clean

mounts below the pilot’s seat cover, between

surfaces.

the right and left inboard sides of the seat

structure. The bracket provides the hingeline

(a). Thoroughly clean repair area of

for the longitudinal and lateral idler bell−

control tube and interior surface of

cranks, the tail rotor bellcrank, and the engine

sleeve with lint free cloth and MEK

droop control bellcrank, which are also made of

(22) or equivalent.

magnesium. It also provides the inboard

support for the collective torque tube.

(b). Mix epoxy adhesive per manufactur−

er’s instructions.

A. Controls Support Bracket and Bellcrank

(c). Apply adhesive (121) to both surfaces

Removal

and install sleeve.

(1). Remove foot fairings and controls

(d). Remove excessive adhesive with lint

access door (Sta. 78.50), and remove

free cloth moistened with MEK or

pilot’s seat cover.

equivalent. Do not saturate the

cleaning cloth.

(2). Remove collective bungee.

Do not use heat gun. Use of heat

(3). Disconnect tunnel−routed control tubes.

CAUTION

lamp is acceptable.

(4). Remove cotter pin, nut, two washers

(e). Allow to cure for 24 hours at mini−

and bolt; disconnect upper end of each

mum ambient temperature of 68°F

cyclic trim actuator.

(20°C); alternate cure 4 hours at

115°−140 °F (46°−60 °C).

(5). Disconnect floor−routed tail rotor

control tube from tail rotor bellcrank.

(f). Using primer (4), touch−up repaired

area(s) of control tube.

(6). Disconnect Sta. 70 lateral control tube

from lateral idler bellcrank.

48. Controls Support Bracket and Bellcranks

(Ref. Figure 7−30) The controls support

(7). Disconnect one−way lock from longitudi−

bracket is a cast magnesium bracket that

nal idler bellcrank.

Page 7-85

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

COLLECTIVE TORQUE

BUNGEE SUPPORT BRACKET

TUBE

WASHER

(SPECIAL)

* * CONTROLS SUPPORT

BRACKET

DROOP CONTROL

OVERRIDE LINK

COUNTERSUNK

* * TAIL ROTOR BELLCRANK

BEARING

BUSHING

BEARING

NOTE 2

(NOTE 3)

LAT IDLER

BELLCRANK

0.1875 IN.

FLOOR−ROUTED

BEARING &

(4.7625 MM)

TAIL ROTOR

SPACER

DIA

CONTROL ROD

BUSHING

(NOTE 3)

0.250 IN.

(6.35 MM)

BEARING

DIA

STA 70 LAT

CONTROL ROD

MAX. TORQUE

COUNTERSUNK

50 IN. LB (5.65 NM)

NOTE 4

BEARING

ELECTRICAL

SPACER

FLAT

WASHER

* * LONGITUDINAL

(NOTE 5)

IDLER BELLCRANK

LATERAL CYCLIC

ONE−WAY

TRIM ACTUATOR

LOCK

STA 72 DROOP

CONTROL

BELLCRANK

LONGITUDINAL CYCLIC

TRIM ACTUATOR

NOTE 4

BOLT INSTL

HOLE

SHIM WASHERS USED AS REQUIRED TO OBTAIN NO SIDELOAD ON

ONE−WAY LOCK.

MUST ROTATE FREELY IN ACTUATOR BEFORE INSTALLATION; MUST

NOT ROTATE AFTER INSTALLATION.

BOND JUMPER ATTACHMENT AT ACTUATOR MAY BE EITHER

NOTES:

CONFIGURATION SHOWN.

ASTERISK ( * ) IDENTIFIES SLOTTED BUSHINGS. EDGE OF BUSHING

ON CURRENT CONFIGURATION ONLY. INSTALL AT FIRST OPPORTUNITY.

MUST PROTRUDE A MIN. OF 0.010 IN. (0.254 MM) TO A MAX. OF 0.080 IN.

DOUBLE ASTERISK ( * * ) INDICATES PARTS THAT MAY BE EITHER

(2.032 MM) ABOVE OUTSIDE SURFACE OF PART AFTER NUT IS

MAGNESIUM OR ALUMINUM ALLOY. REF. SEC. 2 FOR ALLOY

TIGHTENED.

IDENTIFICATION AND CORROSION CONTROL.

30−046D

Figure 7-30. Installation of Controls Support Bracket, Idler Bellcranks and

Cyclic Trim Actuators

Page 7-86

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(8).

Remove pilot’s collective pitch stick.

NOTE: Parts identified with a double asterisk

(∗∗) may be either magnesium or aluminum

(9).

Provide support for collective torque

alloy. Ref. Sec. 2 for corrosion control and

tube. Remove two bolts, four washers,

identification of magnesium and aluminum

and two nuts securing bungee support

alloys.

bracket and collective torque tube to

controls support bracket.

D. Control Support Bracket and Bellcrank

Repair

(10).

Remove cotter pin, nut, three washers,

(1). Replace unserviceable bearings. Install

and bolt (Detail A); disconnect aft end

a new bearing of the correct type with

of droop control override link from

surface primer and grade A locking

collective torque tube bracket.

compound (28 and 29, Table 2−4),

(11).

Remove cotter pin, nut, two washers,

according to container instructions.

bolt, and Sta. 72 droop control bellcrank

NOTE: Ensure that the idler bellcrank spacers

from support bracket (Detail B).

are reinstalled between bearings whenever

idler bellcrank bearings are replaced.

(12).

Remove six screws, six washers, and six

nuts securing support bracket to seat

(2). Replace bellcranks or the controls

structure.

support bracket for distortion, cracks,

or enlongated holes.

(13).

Remove support bracket; use care to

avoid striking any of the bellcranks and

E. Controls Support Bracket and Bellcrank

push tubes.

Reassembly

B. Controls Support Bracket and Bellcrank

(1). Install longitudinal idler bellcrank with

Disassembly

bolt, two washers, nut, and new cotter

pin. Check that the slotted bushing is

(1). Remove cotter pin, nut, two washers,

in place in the support bracket lug, and

bolt, and lateral idler bellcrank. Do not

reinstall the shim washers used

remove slotted bushing unless replace−

between the bellcrank and bracket for

ment is necessary.

no sideload of the one−way lock.

(2). Remove cotter pin, nut, two washers,

(2). Install lateral idler bellcrank, bolt, two

bolt, and tail rotor bellcrank. Do not

washers, nut, and new cotter pin.

remove slotted bushing unless replace−

Check that the slotted bushing is in

ment is necessary.

place in the support bracket lug.

(3). Remove cotter pin, nut, two washers,

(3). Install tail rotor bellcrank, countersunk

bolt, and longitudinal idler bellcrank.

head bolt two washers (one counter−

Do not remove slotted bushing unless

sunk), nut, and new cotter pin. Check

replacement is necessary.

that the slotted bushing is in place n

the support bracket lug.

NOTE: The shim washers between the longitu−

dinal idler bellcrank and support bracket

F. Controls Support Bracket and Bellcrank

are used to align the one−way lock for no

Installation

sideload. Keep the washer selection with the

bracket for use during reassembly.

(1). Carefully position assembled support

bracket and bellcranks between the

C. Controls Support Bracket and Bellcrank

seat structure bulkheads and secure

Inspection

with six screws, six washers, and six

nuts.

(1). Inspect bearings in bellcranks for

binding.

(2). Position Sta. 72 droop control bellcrank

in support bracket and install with bolt,

(2). Perform a fluorescent dye penetrant

two washers, nut, and new cotter pin

inspection on any suspected part.

(Detail B).

Page 7-87

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: The cap is matched to the cradle of each

collective pitch stick, the collective bungee

control support bracket. Check that the

installation, and the interconnecting shafts

numbers on each part are the same before

and linkage. All components, except the stick

accomplishing step (a). below.

and tunnel−routed collective mixer control

tube, are located within the pilot’s seat

(3). Position collective torque tube and

structure.

bungee bracket on support bracket

cradle and install cradle bolts, four

Dual control provisions are incorporated into

washers, and two nuts.

the pilot’s compartment collective controls

installation. Refer to CSP−HMI−3, HMI

(a). Check that two slotted bushings are

Supplement M, as applicable for information

in place in the bungee support

on dual collective controls.

bracket.

(b). Check that index groove in edge of

50. Pilot’s Collective Pitch Control Stick (Left

Position)

cap that clamps torque tube to

support bracket cradle mates with

(Ref. Figure 7−32) The pilot’s collective pitch

matching index at bracket cradle

stick consists primary of a switch housing,

parting surface.

throttle grip and friction mechanism, collective

(4).

Install pilot’s collective pitch stick.

stick tube and friction mechanism, and gas

producer control shafts having right angle

(5).

Connect aft end of droop control

(pinion and bevel gear) drive. Collective pitch

override link to collective torque tube

stick controls include: the N₁ throttle and idle

droop control bracket.

stop release ring, an N₂ governor trim switch,

a landing light switch, a stick friction adjust−

(6).

Connect one−way lock to longitudinal

ment grip, a throttle friction nut, and a

idler bellcrank.

starter−ignition switch.

(7).

Connect Sta. 70 lateral control tube to

A. Pilot’s Collective Pitch Stick Removal

lateral idler bellcrank. Check that

(Left Position)

slotted bushing is in place in the

bellcrank ear.

Install bungee installation

WARNING

(8).

Connect floor−routed tail rotor control

tool (26, Table 2−2) before

tube to tail rotor bellcrank. Check that

disconnecting any pilot’s collective

slotted bushing is in place in bellcrank

stick hardware. There is strong bun−

ear.

gee spring pressure present in the

stick linkage; if suddenly released,

(9).

Connect upper end of each cyclic trim

spring reaction in the linkage can

actuator with bolt, two washers,

cause personal injury or parts dam−

bushing, nut, and new cotter pin.

age.

(a). Check that slotted bushing is in place

(1). Remove outboard collective stick cover

in bellcrank ear.

(Ref. Sec. 2).

NOTE: Lateral actuator upper hingeline has

(2). Disconnect pilot’s collective pitch stick

0.1875 inch (4.7625 mm) ID; longitudinal

electrical plug.

has 0.25 inch (6.35 mm) ID.

(3). Install bungee installation tool (26,

(10). Connect lower ends of tunnel−routed

Table 2−2) on collective bungee (Ref.

control tubes.

Collective Bungee Installation).

(11). Install collective bungee.

(4). Remove attaching hardware that

49. Collective Controls

secures the guide to the seat structure

bracket.

(Ref. Figure 7−31) The pilot’s compartment

collective controls consist of the left position

(5). Remove collective bungee.

Page 7-88

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

COLLECTIVE MIXER TUNNEL−ROUTED

INBOARD COLLECTIVE

CONTROL ROD

STICK SOCKET ASSY

NOTE 3

GAS PRODUCER

CONTROL ROD

BUNGEE OVER−CENTER ADJUSTMENT BOLT

(NOTE 1)

COLLECTIVE CONTROL INTERCONNECTING

TORQUE TUBE

GAS PRODUCER INTERCONNECTING

TORQUE TUBE

BUNGEE

INSTL

N₂ DROOP

BUNGEE SPRING

CONTROL

ADJUSTMENT RETAINER

OVERRIDE LINK

(NOTE 2)

COLLECTIVE STICK FRICTION

MECHANISM AND GUARD

THROTTLE

FRICTION

PILOT’S COLLECTIVE

THROTTLE

NOTE 4

FUSELAGE

PITCH STICK ASSY

NOTE 5

SKIN

GUIDE

SLEEVE BUSHING

NOTE 5

NOTES:

TURN CW TO INCR, CCW TO DECR OVERALL COLLECTIVE DOWNLOADS.

TURN CW TO INCR, CCW TO DECR BUNGEE PRELOAD.

CAUTION: DO NOT ADJUST BUNGEE SPRING TENSION WHILE BUNGEE INSTL

TOOL (369A9936) IS INSTALLED. USE OVERCENTER ACTION OF STICK TO

COMPRESS SPRING TO REMOVE TOOL.

BUSHINGS MUST PROTRUDE A MIN. OF 0.010 IN. (0.254 MM) AFTER BOLT IS TIGHTENED.

TORQUE PER TABLE 2−5; APPLY EQUALLY AND BY SMALL INCREMENTS.

ARRANGE WASHERS TO LINE UP GUIDE WITH STICK; SPACE LOOSELY WITH

THREE WASHERS.

30−048B

Figure 7-31. Pilot’s Compartment Collective Controls

Page 7-89

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(6). Remove inboard collective socket

D At mid−travel, two pilot’s throttle grip at−

assembly;

taching bolts should be approximately

straight down.

(a). Disconnect droop control override

D The inboard pinion and outboard grip

link.

should be set to and held at these posi−

tions while socket and stick gearing is in−

(b). Slide bungee bracket to side.

terconnected by gas producer intercon−

nect torque tube.

(c). Remove cradle cap and slide collec−

D If mid−travel positions are not synchro−

tive torque tube inboard (Ref. Collec−

nized, further adjustment of installation

tive Control Interconnecting torque

is required.

Tube Removal).

(3). Complete insertion of collective torque

(7). Remove nuts, washers, and bolts that

tube, install cradle cap, position bungee

connect stick housing to torque tube.

bracket in mounting position, connect

droop control override link, install

(8). Remove stick by sliding it outboard and

collective socket assembly and install

off torque tube.

collective bungee.

(4). Position friction guide in the seat

B. Pilot’s Collective Pitch Stick Installation

structure bracket.

(Left Position)

(a). Arrange three washers and bushings,

(1). Lubricate stick housing socket with

loosely spaced between bracket ears,

grease (26, Table 2−4).

so that guide is in line (parallel) with

the stick.

(2). Install stick by sliding housing on

collective control interconnecting torque

(b). Install bolt, two washers, nut and

tube.

new cotter pin.

(a). Align matching holes and install

(5). Connect the electrical plug.

bolts, washers and nuts.

(6). Install outboard collective stick cover.

(b). Tighten nuts equally and by small

Check that wiring will not foul when

increments until correct torque is

stick is raised and lowered.

applied (Ref. Table 2−5).

(7). Remove snap plug from exterior skin.

NOTE:

(a). Rotate throttle and visually check for

D On completing attachment of pilot’s col−

zero backlash between gas producer

lective pitch stick and inboard collective

interconnect torque tube and the

socket assembly on collective control in−

hexagonal ID of the drive gearshaft

terconnect torque tube, ensure both pi−

in the stick housing.

lot’s throttle grip and inboard socket N₁

pinion gear are at mid−travel position.

(b). Eliminate any backlash by tightening

pipe plug in end of torque tube; zero

D At mid−travel, wide tooth−space of inboard

backlash is required at both ends of

socket pinion gear will be at approximate−

tube.

ly one o’clock as viewed looking aft into

open end of socket.

(8). Check that inboard stick socket gears

D Gas producer control rod−to−inboard stick

are at mid−travel when pilot’s stick

assembly idler bolt holes should be in line

throttle grip is set to mid−travel. If not,

with centerline of stick assembly housing

adjust collective pitch stick(s) gas

cap.

producer control linkage.

Page 7-90

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

MOUNTING DISTANCE SHIM

(CUT)

BEARING

(NOTE 2)

GAS PRODUCER

COVER

CONTROL TUBE

PINION

HOUSING SOCKET

(NOTE 1)

BEARING

(NOTE 2)

BACKLASH SHIM

GEARSHAFT

NYLON STRAP

BACKLASH SHIM

ELECTRICAL

WIRING

STICK TUBE

BEARING

(NOTE 2)

CONNECTOR

(NOTE 1)

CAP

SETSCREW

WIRE GUIDE

ADJUSTMENT NUT

SETSCREW

THROTTLE GRIP

GRIP ATTACH BOLT

NOTES:

SURFACES IN CONTACT DURING ROTATION

TO BE LUBRICATED OR OTHERWISE NOTED,

WITH GREASE (26, TABLE 2−5).

SETSCREW

INSTALL BEARINGS WITH GRADE A LOCKING

COMPOUND (29, TABLE 2−5) AFTER SHIMMING

SWITCH HOUSING

FOR MOUNTING DISTANCE AND BACKLASH.

44−162A

Figure 7-33. Copilot’s Collective Pitch Stick (R/H Command)

Page 7-92

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

C. Pilot’s Collective Pitch Stick Disassembly

(b). Remove pinion and bearing from

(Left Position)

control tube only if replacement is

necessary.

(1). Cut the two nylon straps, and remove

stick friction mechanism guard.

D. Pilot’s Collective Pitch Stick Inspection

(Left Position)

(2). Remove setscrews that secure switch

(1). Inspect bearings for binding or loose−

housing.

ness.

NOTE: Removal of an additional setscrew is

(2). Inspect all gears for cracks and chipped

also required on helicopters equipped with a

or broken teeth.

cargo release mechanism.

(3). Inspect stick tube and gas producer

(3). Cut nylon strap or twine that secures

control tube for corrosion, deformation,

electrical wiring to stick tube.

and loose rivets.

(4). Push wire slack into stick, carefully

NOTE: The pitch stick housing and cap may be

pull housing and wiring from end of

either a magnesium or aluminum alloy cast−

stick tube and disconnect wiring from

ing. (Ref. Sec. 2 for corrosion control and

switches (Ref. Sec. 19).

identification of magnesium or aluminum

alloys.)

(5). Remove setscrew and wire guide from

forward end of stick. Tie a ‘‘fish’’, string

E. Pilot’s Collective Pitch Stick Repair (Left

on each wire bundle to aid reassembly

Position)

and remove wiring.

(1). Replace bearings if corroded, excessive−

(6). Remove spring and idle stop release

ly worn, or if the outer or inner races of

ring.

bearings rotate on mating surfaces and

locking compound is inadequate to

(7). Remove grip attach bolts and slide

prevent rotation.

throttle grip, friction washer and discs,

and friction nut from stick tube.

(2). Replace loose rivets in the gas producer

control tube.

(8). Remove friction mechanism and guide

(3). Replace a friction drive gear or idler

from stick fitting.

gear having cracked, chipped or broken

(9). Remove idler gear from stick fitting.

teeth.

NOTE: Do not remove bearing from cap unless

(4). Replace friction drive gear if it does not

replacement is necessary.

rotate freely on stick tube, or if the

rotating stop is damaged (Ref.

(10). Remove cap from stick housing.

Figure 7−35, Detail B). Drill out rivets

that attach throttle friction nut fitting

NOTE: Keep backlash shims with gear shaft

to the stick to remove gear.

and do not remove bearing from stick hous−

ing unless replacement is necessary.

NOTE: Before replacing a drive gear for bind−

ing, clean and then relubricate the ID with

(11). Remove gear shaft assembly.

grease (26, Table 2−4) . Reinstall gear on

stick tube and recheck for free rotation. If

(12). Remove cover from back of stick

gear still binds it must be replaced.

housing.

(5). Replace the phenolic friction washers

(13). Remove gas producer control tube

that slide against the guide if worn to

through access hole at back of stick

less than 0.03125 inch (0.79375 mm)

housing.

thickness.

(a). Remove mounting distance shim only

(6). Replace the friction gear assembly if

if necessary to adjust pinion gear

the driven gear has cracked, chipped or

mounting distance.

broken teeth, or if the cam pin is bent.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(7). Replace a damaged idle stop release

(7). Reinstall mounting distance shims

ring. The ring must slide freely on the

forward side of pinion bearing if

tube and in the throttle grip.

removed during disassembly.

NOTE: One edge of shim must be cut for instal−

F. Pilot’s Collective Pitch Stick Reassembly

lation.

(Left Position)

(8). Establish gas producer control tube

(1). Check gear shaft bearings in housing

pinion mounting distance (Ref.

cap and housing for security of outer

Figure 7−34).

races.

(9). After mounting distance shimming is

(a). Use grade A locking compound (29,

correct.

Table 2−4) to install replacement

bearings.

(a). Remove gas producer control tube

and apply grade A locking compound

(b). Use care to prevent compound from

to outside diameter pinion bearing

entering bearings, and make sure

outer race and stick housing bore.

that each bearing is seated against

(b). Reinstall control tube, and check that

its bore shoulder.

compound does not enter bearing and

that bearing outer race and shims

(2). Using grease (26), lubricate the stick

are firmly seated against housing

tube interior where the gas producer

bore.

control tube fitting makes contact.

(10). Install throttle friction nut, friction

(3). Attach ‘‘fish’’ strings routed through the

discs and washers.

stick tube during disassembly, and

thread the electrical wire bundles from

(11). Using grease, lubricate interior of

the plug through the exit hole, throttle

throttle grip and install grip on stick

friction nut, friction washers and discs,

tube.

throttle grip, idle stop release ring, and

the spring.

(a). Align grip and gas producer control

tube fitting and install grip attach

(4). Pull wiring out through front end of

bolts.

stick tube.

(b). When tightened, bolts must be flush

or not more than 0.010 inch (0.254

(5). Install wire guide so that it divides the

mm) below outer surface of grip.

switch wiring, three wires in one cutout

and four in the other.

(12). Establish gas producer control tube

pinion and shaft assembly bevel gear

(a). Align guide with matching hole in

backlash (Ref. Figure 7−34).

stick tube and install set−screw.

(13). After backlash shimming is correct,

(b). When tightened, setscrew must be at

remove housing cap and gear shaft.

least flush and not recessed more

than 0.010 inch (0.254 mm) below

(14). Lubricate teeth of pinion gear and shaft

outer surface of tube.

assembly bevel gear with grease.

(15). Apply grade A locking compound to

NOTE: Ensure gas producer control tube is

gear shaft and to ID of bearings.

installed into stick tube housing with elon−

gated area of fitting facing down.

NOTE: With throttle grip at mid−travel the two

grip attach bolts will be positioned approxi−

(6). Install gas producer control tube

mately straight down.

through access hole in back of stick

housing, and through stick tube until

(16). Install housing cap on shaft assembly

control tube fitting engages wire guide

and seat with hand pressure while

bore.

slowly rotating the grip back and forth.

Page 7-94

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Secure cap to side of housing and cover

NOTE: If gears are correctly aligned and

to back of housing.

mated, do not perform steps (4). thru (6).

and continue with step (7). If gears are mis−

(17).

Using solder (48), connect wiring to

aligned, continue with step (4).

stick switches.

(4). Disconnect link from idler and remove

link and bellcrank as an assembly from

(18).

Pull electrical wiring slack out through

gearshaft of inboard collective pitch

exit holes in stick tube, position release

stick socket by removing bolt, two

ring and. spring and install switch

washers and nut (Ref. Figure 7−38).

housing with setscrews.

NOTE: During gear shaft rotation to establish

(19).

Using nylon strap, or twine (30), secure

correct mid−position for gearshaft and pin−

electrical wiring to stick tube approxi−

ion in the next step, the gearshaft cutout

mately one inch (25.4 mm) aft of exit

can be seen through the hole in back of the

holes.

socket assembly housing.

(20).

Install friction cam and driven gear

(5). Rotate end of the gas producer intercon−

assembly on stick fitting. Temporarily

nect torque tube in the pilot’s stick

mesh idler gear and driven gear, and

socket housing until the gearshaft−

rotate friction drive gear counter−clock−

to−N₁ pinion gearmesh is at mid−travel

wise to maximum stop (Ref.

and N₁ pinion gear wide toothspace is

Figure 7−35, Detail B).

positioned at approximately one o’clock.

View pinion by looking aft into open

(21).

Hold drive gear at stop and re−mesh

end of collective stick socket.

idler gear and driven gear so that gear

NOTE: The inboard collective N₁ pinion gear

assembly pin is at high point of cam

must be held in correct position while steps

(Detail C).

(7). thru (9). below are performed. If avail−

able, the optional co−pilot’s collective pitch

(22).

Use shim washers sufficient to limit

stick can be used to hold the gear in position

gear end play to maximum of 0.010 inch

by setting the copilot’s throttle grip attach

(0.254 mm) (Detail A), and secure idler

bolts at approximately seven o’clock (look−

gear with cotter pin.

ing aft) before engaging the stick and socket.

(23).

Assemble remainder of friction mecha−

(6). Reattach inboard collective pitch stick

nism.

socket bellcrank to the gearshaft and

link to the idler. Bellcrank attachment

(24).

Adjust collective friction mechanism.

bolt must be installed with head

slightly down and forward.

51. Gas Producer Linkage Adjustment

(7). With inboard collective pitch stick

(Ref. Figure 7−34) The following procedure is

socket N₁ pinion gear held at position

for adjustment of gas producer linkage in

described in step (5)., rotate pilot’s

installed collective pitch stick(s) and/or

collective pitch stick throttle grip to

inboard socket assembly.

mid−travel position (grip attaching

bolts approximately straight down).

(1). Remove cap and outboard bearing from

(8). Install backlash shims and gear shaft

pilot’s collective pitch stick housing.

in pilot’s collective stick socket housing

(Ref. Figure 7−32). Be sure that

(2). Remove backlash shims and gear shaft

gearshaft and pinion are aligned and

assembly from socket housing.

mated when pilot’s throttle grip is at

NOTE: Note locations and mark removed shim

mid−travel.

thicknesses to ensure proper reassembly.

NOTE: Be sure that shims are installed in orig−

inal locations.

(3). Ensure inboard collective pitch stick

socket internal gears are aligned and

(9). Reinstall outboard bearing and cap on

mated.

pilot’s stick housing.

Page 7-95

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

GAS PRODUCER

TORQUE TUBE

STEP 1

STEP 2

STEP 3

STEP 4

TOP VIEW

IDLE STOP

6°

GRIP MID−TRAVEL

GENERAL NOTE:

SELECT SHIMS AS REQUIRED. CRES SHIMS

N₁ CLOSED

PROVIDED IN 0.001, 0.002, 0.005, 0.012 AND

0.032 IN. (0.0254, 0.0508, 0.127, 0.3048 AND

0.8128 MM) THICKNESS.

N₁ OPEN

15°

BELLCRANK ON INBD COLLECTIVE

70° 40’

STICK SOCKET ASSY

73° 30’

15°

STEP 5

LEFT SIDE VIEW

STEP 1

STEP 4

INSTALL MTG DISTANCE SHIMS TO GET 0.699−0.709 IN.

INSTALL BACKLASH SHIMS TO OBTAIN 0.003 IN. (0.0762 MM)

(17.7546−18.0086 MM) AFTER SHIMMING IS CORRECT, INSTALL

MAX. BACKLASH.

BEARING IN HOUSING WITH GRADE A LOCKING COMPOUND

CAUTION: HSG AND CAP BEARINGS MUST BE SEATED

(29, TABLE 2−4).

AGAINST BORE SHOULDER, GEARS MUST NOT BIND AND

NOTE: SHIMS ARE CUT THRU ONE EDGE FOR INSTALLATION.

PINION MTG DISTANCE MUST BE CORRECT.

STEP 2

STEP 5

APPLY10 LB (45 N) MIN. LOAD TO END OF PINION DURING

AFTER SHIMMING IS CORRECT, INSTALL SHAFT ASSY SO

CHECK OF MTG DISTANCE DIMENSION.

THAT C OF GEAR TOOTH CUTOUT MATCHES LOF STICK.

NOTE: TIGHTENING THE THROTTLE FRICTION NUT WILL

USE GRADE A LOCKING COMPOUND (29, TABLE 2−4) TO

APPLY ENOUGH LOAD.

BOND SHAFT TO I.D. OF BEARINGS.

NOTE:

STEP 3

POSITION THROTTLE GRIP AT MID−TRAVEL.

LOF SHAFT ASSY GEAR CENTER TOOTH IS 2° −50’ OFF

THE CUTOUT

NOTE: ONE PINION GEAR TOOTH EQUALS 5° 38’.

30−051B

Figure 7-34. Gas Producer Drive Mounting Distance and Backlash Adjustment

(Pilot’s Collective Pitch Stick)

Page 7-96

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(10). Check that both the pilot’s throttle grip

hex end of gas producer interconnect

and the inboard collective pitch stick

torque tube.

socket N₁ pinion gear wide toothspace

(8). Measure distance between inboard end

are correct at mid−travel.

of pilot’s collective stick assembly

(11). Remove snap plug from skin, rotate

housing and inboard face of gas produc−

pilot’s throttle grip and visually check

er gearshaft in pilot’s collective stick

for evidence of backlash between gas

assembly.

producer interconnect torque tube and

(9). Subtract measurement taken in step

hexagonal ID of the gear shaft.

(8). from measurement taken in step

(a). Zero backlash is preferred and 10

(7). Remainder is engagement of gas

degree is maximum allowed.

producer interconnect torque tube with

gearshaft in pilot’s collective stick

(b). If necessary, remove cover and gear

assembly.

shaft from torque tube and eliminate

(10). Subtract engagement (remainder) from

any excessive backlash by tightening

0.750 inch (19.05 mm).

pipe plug in end of torque tube.

(a). In addition to thickness of external

(c). Zero backlash is preferred at both

snap ring, add AN960−C816 washers

ends of the tube.

to end of gas producer interconnect

(12). Reinstall snap plug.

torque tube to a total thickness equal

to the remainder from 0.750 inch

52. Gas Producer Interconnect Torque Tube

(19.05 mm) less engagement.

Shimming

(b). Equivalent washers varying in

thickness may be made from corro−

(Ref. Figure 7−36)

sion resistant steel sheet and used in

(1).

Remove pilot’s seat cover and controls

combination with AN960C816

access door.

washers.

(2).

Make an index mark on end of collec−

(11). Reinstall pilot’s collective stick assem−

tive torque tube fitting flush with

bly.

inboard end of pilot’s collective stick

NOTE: If the normally installed plug does not

assembly housing.

expand tube, a 1/8− 27 internal−wrenching

pipe plug 0.380 inch (9.652 mm) long may be

(3).

Remove bolts securing pilot’s collective

substituted. Whichever plug is used, it must

stick assembly to end of collective

not protrude more than 0.030 inch (7.62

torque tube fitting

mm) when tightened.

(4).

Loosen pipe plug in end of gas producer

(12). Tighten pipe plug of gas producer

interconnecting torque tube which

interconnect torque tube to obtain zero

secures it to the gas producer gearshaft

backlash between torque tube and

in pilot’s collective stick assembly.

gearshaft in pilot’s collective stick

(5).

Remove pilot’s collective stick assembly.

assembly.

(13). Reinstall pilot’s seat cover and controls

(6).

Using rubber mallet or equivalent soft

tool, tap gas producer interconnecting

access door.

torque tube assembly toward copilot’s

53. Pipe Plug Adjustment for Zero Backlash

collective socket assembly. Avoid

damage to gas producer interconnect

(Ref. Figure 7−37)

torque tube hex end or pipe plug

threads.

(1). Remove pilot seat cover for access to

under seat controls (Ref. Sec. 2).

(7).

Measure distance between index mark

on end collective torque tube fitting and

(2). Remove snap plug from exterior skin.

Page 7-97

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

GUARD

WASHER(S)

(NOTE 1)

STICK FITTING

COTTER

PHENOLIC WASHERS

TEFLON

WASHER RETAINER

HOUSING

CCW MAX FRICTION

IDLER GEAR

COTTER PIN

FRICTION

DRIVE GEAR

NUT

(ROTATING

STOP)

CW MIN

FRICTION

WASHER

DRIVEN GEAR

SPRING

STICK FITTING

STOP

(FIXED STOP)

GEAR ASSY

GUIDE

(NOTE 2)

AL ALY WASHER

CAM

SPACER

GUARD ATTACHMENT

NYLON STRAP

NOTES:

SHIM AS REQD FOR 0.010 IN. (0.254 MM) MIN. END

PLAY. GEAR TRAIN MUST ROTATE FREELY.

GEAR ASSY MUST SLIDE AND ROTATE FREELY IN

GEAR ASSY PIN

FITTING. APPLY GREASE (26, TABLE 2−4) TO SHAFT.

(NOTE 4)

ACCEPTABLE MINIMUM FRICTION POSITION.

DESIRED MINIMUM FRICTION POSITION

NOTE 5

(CAM LOW POINT).

NOTE 3

CORRECT MAXIMUM FRICTION POSITION

(CAM HIGH POINT).

UNACCEPTABLE MAXIMUM FRICTION POSITION.

NOTE 6

30−050C

Figure 7-35. Collective Pitch Stick Friction Adjustment

Page 7-98

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CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 5