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

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE: It is recommended that the MS 21250

Perform first run−up in a cau−

CAUTION

bolt be replaced with any of the alternate

tious manner so that vibrations

bolts called out with the higher torque at the

from an unbalanced tail rotor will not cause

operators earliest convenience.

damage.

(23). Balance the tail rotor using vibration

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

analyzer and strobe light.

nut and torque to 600 − 650 inch−

pounds (67.79 − 73.44 Nm) while

18. Pitch Control Assembly

primer is wet. If an HS 5482−6, HS

805−6, HS 3532−6 or a HS 84208−6 bolt

(Ref. Figure 8−4) The pitch control assembly

is installed, torque nut to 750 − 775

consists of a swashplate assembly that rotates

inch−pounds (84.74 − 87.56 Nm)

in a double−row bearing inside a housing.

while primer is wet.

A self−aligning bearing at the underside of the

housing provides the pivot for transferring

After blade is secured to strap

motion of Sta. 282.00 bellcrank to the housing.

CAUTION

assembly, do not allow blade

Two clevis ears on each end of the swashplate

pitch travel from neutral to exceed 30 de−

provide for connection of pitch control links.

grees in either direction (Ref. Figure 8−5).

Rotating the blade to excessive pitch angles

Movement of the Sta. 282.00 bellcrank shifts

may result in undetected damage to the

the housing axially on the output shaft of the

strap assembly.

tail rotor transmission and moves pitch control

links inward and outward to change pitch of

the tail rotor blades.

(18). Attach outboard end of pitch control

link to pitch control arm of blade with

Two types of pitch control assemblies are in

spring washer, special (reduced OD)

service. The swashplate on the current pitch

washer, pitch arm (extended balance or

control assembly has oilite bronze liners. The

NAS) bolt, washer at outer side of pitch

early type swashplate has a nylon composition

control arm and nut.

liner.

The replaceable swashplate on the current

(19). Torque nut to 50 − 80 inch−pounds

pitch control assembly is retained in the

(5.65 − 9.04 Nm) and safety with cotter

housing by a washer and locknut. Parts of an

pin coated with primer.

early type pitch control assembly without a

locknut are not individually replaceable.

NOTE: Standard NAS bolts may be used as al−

The self−aligning bearing is swaged in place in

ternates at the pitch arms if extended bal−

the pitch control housing.

ance bolts are not available.

19. Pitch Control Assembly Replacement

(20). If the same blade that was removed is

being reinstalled with the original

(1). Remove complete tail rotor assembly

remaining blade, reinstall the same

including the pitch control assembly.

hardware and number of balance

(2). Disconnect ends of pitch control links

washers on the pitch arm bolt that were

from clevis ears of swashplate and

present at initial removal of the blade.

remove pitch control assembly.

(21). For a replacement blade, install balance

NOTE: Ensure matchmarks are aligned when

washers required for static cordwise

performing step (3). below.

balance of the assembled tail rotor

(3). Connect ends of pitch control links to

which have been determined by using

clevis ears on swashplate pitch control

an appropriate balance fixture.

assembly.

(22). If fiberglass blades were replaced with

(4). Install tail rotor and pitch control

metal blades, rig tail rotor controls.

assembly.

Page 8-33

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

20. Pitch Control Assembly Inspection

(b). If greater amount of wobble is

present replace the swashplate or

(1). If tail rotor control system drag or

pitch control housing double−row

friction is suspected, use a spring scale

bearing or the complete assembly, as

(Ref. Figure 8−5) to measure drag

applicable.

(sliding friction) of the pitch control

assembly on the output shaft of the tail

NOTE: Wobble may be accurately measured by

rotor transmission.

attaching a dial indicator support to the tail

rotor drive fork, with the indicator probe in

NOTE: Pitch control links, Sta. 282.00 bell−

contact with the swashplate clevis ear loca−

crank and rubber boots must be detached

tion shown in Figure 8−5. Use care not to al−

from the assembly during the drag check.

low the pitch control assembly to slide on

the output shaft while measuring wobble.

(2). If drag exceeds 3 pounds (13.34 N),

remove the pitch control assembly and

(8). Perform following inspections for pitch

clean the swashplate and output shaft

control bearings at the time specified in

splines. Use solvent (1, Table 2−4) and

CSP−H−4 and when bearing condition

grade 400 emery paper or crocus cloth

is questionable.

(23).

NOTE: An early type pitch control assembly

without swashplate nut should not be disas−

NOTE: If tail rotor swashplate with a bronze

sembled. If it has defective bearings, the

liner is installed, coat the output shaft

complete pitch control assembly should be

splines with a light film of grease (18).

replaced.

(3).

If surface defects such as nicks,

(a). Remove cotter pin, nut, washers and

scratches, dents or corrosion are found,

bolt securing Sta. 282.00 bellcrank to

make detailed inspections and perform

transmission.

allowable repairs according to limits

and procedures in CSP−H−5.

(b). Separate pivot pin on bellcrank from

pitch control assembly (Ref.

(4).

If brinnelling wear of the inner surfaces

Figure 8−4).

of the swashplate clevis ears is de−

tected, 0.003 inch (0.0762 mm) depth is

(c). Rotate pitch control housing by hand:

allowable without rework or repair. For

wear of greater depth refer to CSP−H−5

1). Check for rough binding or hard

for limits and allowable repairs.

turning.

2). Inspect for grease leakage.

(5).

If there is evidence of swashplate

contact with housing, check that

3). If any of these conditions are

minimum clearance of 0.010 inch (0.254

noted, remove pitch control assem−

mm) exists through 360 degrees of

bly and inspect bearing for further

rotation with axial loading applied. If

evidence of damage.

contact is apparent, replace swashplate;

or double−row bearings if axial play can

(d). To inspect double−row bearing,

be measured.

remove grease seal at gearbox end of

bearing housing by first removing

(6).

(Early type only) If there is evidence of

seal lockring with thin sharp blade.

slippage between double−row bearing

inner race and swashplate, replace the

NOTE: Pitch control double−row bearing may

pitch control assembly.

be repacked or replaced, as appropriate.

(7).

Check pitch control wobble on output

(e). Check that self−aligning bearing on

shaft (Ref. Figure 8−5).

underside of pitch control housing is

adequately lubricated (packed

(a). Up to 0.020 inch (0.508 mm) pitch

approximately 40% full) with grease

control wobbles on the transmission

(18, Table 2−4), is movable and is

output shaft is allowable.

serviceable.

Page 8-34

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

FORK BOLT

FORK

SPRING WASHER SPECIAL WASHER

(REDUCED OD)

SPHERICAL

BALANCE WASHER(S)

BEARING

PITCH ARM

PITCH ARM BOLT

(NOTE 3)

HUB

WASHER

WASHER, NUT & COTTER PIN

50−80 IN−LB (5.65−9.04 NM)

EARLY CONFIGURATION

SPHERICAL BEARINGS

BALANCE BOLT

NUT

SHOULD BUSHING

(NOTE 7)

SPECIAL WASHER

BLADE LEADING EDGE

CRUSH WASHER

(REDUCED OD)

(NOTE 7)

PITCH CONTROL LINK

TENSION−TORSION

SPRING WASHER

STRAP ASSEMBLY

PITCH ARM

(NOTE 1)

BALANCE WASHER(S)

GREEN DOT

OUTBOARD

NUT

(NOTE 2)

STRAP SHOE

O−RING

(NOTE 1)

FORK

PITCH ARM BOLT

BLADE BOLT

BLADE PITCH

CONICAL BEARING

(FEATHERING)

BEARINGS

HUB

INBOARD STRAP SHOE

BLADE SPAR (FIBERGLASS BLADE)

(NOTE 1)

OR ROOT FITTING (METAL BLADE)

DUST COVER

NUT 50−54 FT−LB (68−73 NM)

HUB TRUNNION

SLEEVE

NOTES:

BUSHING

CAUTION: DO NOT REMOVE SHOES FROM STRAP

(NOTE 6)

ASSEMBLY. AVOID DAMAGING STRAP ASSEMBLY.

SCRATCHES OR NICKS ON STRAP LAMINATES MAY

MAKE STRAP ASSEMBLY UNSERVICEABLE.

FORK BOLT

USE COLORED LACQUER (6, TABLE 2−4).

(NOTE 4)

MAY BE MODIFIED TO CURRENT CONFIGURATION

OUTBOARD

USING EXTENDED BALANCE BOLT. SEE TAIL ROTOR

STRAP SHOE

BLUE DOT

BALANCING FIGURE.

(NOTE 1)

(NOTE 2)

COAT FORK BOLT HEAD AND NUT AREA WITH

SPECIAL WASHER

PRIMER (4, TABLE 2−4) TO PREVENT CORROSION.

WASHER, NUT & COTTER PIN

USED ONLY WITH EARLY CONFIGURATION METAL

(COUNTERSUNK)

50−80 IN−LB. (5.65−9.04 NM)

(NOTE 5)

BLADES.

SPECIAL

BOLT

USED WITH FIBERGLASS AND EARLY CONFIGURATION

WASHER

METAL BLADES.

(FLAT)

USED ON CURRENT CONFIGURATION METAL BLADES.

30−201−1B

Figure 8-10. Assembled Tail Rotor Hub and Blades - Cross Section View

Page 8-35

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(f). Make sure that pivot pin on Sta.

(b). Rotate bearings while greasing.

282.00 bellcrank is lubricated with

(8). Remove plastic wedge (or equivalent

grease. Position bellcrank to engage

plug) and regreasing tool.

pivot pin with pitch control assembly.

Secure bellcrank to gearbox with

(9). Hand rotate bearing to remove excess

bolt, washers, nut and cotter pin.

grease.

NOTE: For any questionable and all other

NOTE: Ensure seal is serviceable. If new seal is

items, refer to the complete and detailed in−

required, seals and bearings must come

spection, damage, wear and repair limits

from the same vendor.

and requirements for the pitch control as−

sembly provided in CSP−H−5.

(10). Install serviceable seal, new tang

washer and nut.

21. Tail Rotor Swashplate Regreasing

(11). Install nut with a new tang washer.

Using wrench and holding block, torque

(Ref. Figure 8−12)

nut to 400 − 450 inch−pounds (45.19 −

(1). Remove tail rotor and swashplate from

50.84 Nm).

helicopter (Ref. Tail Rotor and Pitch

(12). Bend one tang of washer into any

Control Assembly Removal).

aligned slot on nut.

(2). Remove pitch control links from

NOTE: Avoid getting alcohol in bearings.

swashplate assembly.

(13). Clean surface of locknut and swash−

Tail rotor swashplate bearings

plate with a lint−free cloth dampened

CAUTION

cannot be removed from hous−

with alcohol (71).

ing without damage to the bearings. If bear−

ings are removed from housing, install new

NOTE: Avoid getting torque seal in swashplate

bearings.

splines.

(3). Using wrench (44, Table 2−2) and

(14). Apply a 0.125 inch (3.175 mm) wide

holding block (45), Remove nut and

torque strip, using torque seal or

tang washer from threaded end of

equivalent, to surface of swashplate

swashplate. Discard tang washer.

assembly and locknut in two places.

(4). Carefully remove bearing grease seal at

22. Tail Rotor Hub and Fork Assembly

gearbox end of housing (seal will be

(Ref. Figure 8−10) The hub, with internal

reused at reassembly).

tension−torsion strap assembly, is held inside a

(5). Inspect seal for damage; no damage is

drive fork assembly by a fork bolt, shims,

allowed.

washer, nut and cotter pin to form a hub and

fork assembly.

(6). Install regreasing tool (Ref.

Types of bearings in service include the early

Figure 8−13) and plug tang washer

type spherical and conical bearings and

groove with locally fabricated plastic

current type elastomeric bearings. Conical

wedge (or equivalent plug).

spherical and elastomeric teeter bearing differ

NOTE: The following procedure provides 100%

in size and configuration. The existing tail

grease fill. Normal grease fill is 20 to 40%.

rotor drive fork may be replaced with a new

Excess grease will extrude past seals for

drive fork assembly equipped with elastomeric

several hours of operation until the proper

bearings. Refer to CSP−H−5 for modification

level is met.

instructions.

(7). Purge bearings with grease (21,

The tension−torsion strap assembly consists of

Table 2−4).

a strap pack to which inboard shoes are

riveted with shims, collars and rivets and

(a). Purge bearings slowly to prevent

outboard shoes containing bushings. The strap

damage to outer seal.

pack consists of 20 (or 19, as required for

Page 8-37

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

correct thickness) corrosion−resistant (cold

C. Parts Replacement Information

rolled and tempered) steel straps, each

(1). Replace bearing in and reinstall an

approximately 0.009 inch (0.2286 mm) thick,

original serviceable fork assembly on an

that form a pack. A bushing threaded into the

original hub as specified in CSP−H−5.

hub against the inboard shoe holds the center

of the strap pack assembly in place inside the

(2). Removal of the strap pack assembly

hub.

from the hub is accomplished according

to CSP−H−5.

23. Hub and Fork Assembly Maintenance

(3). Disassembly of the strap pack assembly

is not recommended; parts should not

A. Inspection of Hub and Fork Assembly -

be removed from the strap pack

Blades Removed

assembly.

After removal of blades and before installation

24. Tail Rotor Pedal Installation (Left Position)

of replacement blades, inspect components of

fork and hub assembly as follows:

(Ref. Figure 8−14) The tail rotor pedal installa−

tion consist of a pair of adjustable pedals,

(1). Two types of hubs are in service: one is

pedal arms with interconnecting linkage, a

a 4340 steel hub with chrome plated

pedal mounting bracket for the left control

trunnions and the current type is

position, a torque tube with control rod fitting

marriaging steel.

and torque tube mounting bracket.

Forward pressure on the right pedal rotates

(2). For hub with chrome plated trunnions,

the torque tube rearward, moving control

check surface area on trunnion that

system linkage to increase tail rotor blade

mate with blade pitch (feathering)

pitch. Pressure on the left pedal decreases tail

bearing for wear. Wear through chrome

rotor blade pitch.

platting is not allowed and requires hub

replacement

(CSP−H−5).

A bungee spring is installed on the aft end of

the floor−routed control rod in the underseat

(3). Check visible areas of tension−torsion

tail rotor control linkage of helicopters with

strap assembly for nicks or scratches on

the cambered metal−blade tail rotor. This

strap laminates, cracked laminates and

spring relieves left pedal forces during flight

kinks, sharp bends or permanent twist

and causes the left pedal to remain in the

in laminates.

forward position when the helicopter is on the

ground and not operating.

(a). Any one of these defects, except

NOTE: Parts identified in Figure 8−14 with an

minor outer surface defects that can

(*) may be either magnesium or aluminum

be removed by abrasive polishing

alloy. Refer to Section 2 for corrosion control

requires replacement of the strap

and identification of magnesium and alumi−

pack assembly.

num alloys.

NOTE: For information on allowable repairs,

25. Tail rotor Pedal Installation Replacement

serviceability requirements and replace−

ment, refer to CSP−H−5.

(Ref. Figure 8−14)

A. Tail rotor Pedal Installation Removal (Left

B. Strap Pack Assembly Precautions

Position)

(1). When blades are removed from the hub

(1). Pull the two hinge pins from pilot’s

and fork assembly, the exposed ends of

compartment floor access door hinges

the strap pack assembly should be

and remove door. Remove the access

protected with a covering and the hub

panel from each side of the instrument

and fork assembly should be handled

panel lower support structure.

carefully to avoid damage to the strap

pack assembly.

(2). Remove battery.

Page 8-38

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TAIL ROTOR SWASHPLATE

BEARNG ASSEMBLY

REGREASE TOOL

GH08−002

Figure 8-12. Tail Rotor Swashplate Bearing Regreasing

0.75 IN.

(19.05 MM)

0.35 IN.

(8.89 MM)

1.173−18 UNJS−3B THREADS

PER MIL−S−8879

3.0 IN.

2.25 IN.

(7.62 MM)

(5.715 MM)

SEAL MATERIAL

0.50 IN.

MS15002−1 GREASE FITTING 1/4−28 TAPER

(12.7 MM)

SECTION A−A

THREADS 0.093 IN. (2.3622 MM) THRU HOLE

MATERIAL:

MATERIAL 6061−T651 ALUM PER QQ−A−250/11, OR EQUIVALENT.

SURFACE FINISH 125 RMS.

BREAK SHARP EDGES 0.002−0.015 IN. (0.0508−0.381 mm).

CHEMICAL FILM TREAT PER MIL−C−5541.

DIMENSIONAL TOLERANCE ±0.030 IN. (±0.762 MM); DIAMETERS TO BE

CONCENTRIC TO CENTERLINE WITHIN 0.002 IN. (0.0503 MM).

GH08−001A

Figure 8-13. Tail Rotor Swashplate Bearing Regreasing Tool

Page 8-39

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(3). Remove pins securing pedals to pedal

(4). Add skim washers as required at

arms and remove pedals.

bracket attachment points to maintain

the bearing alignment established in

(4). On a helicopter with a metal−blade tail

step (1). above.

rotor, perform steps (a). thru (d). below.

(5). Install two bolts, four washers and two

(a). Gain access to the bungee by remov−

nuts.

ing the access cover between the

pilot’s seat and/or by removing the

(6). On a helicopter with a metal−blade tail

left passenger’s footwell on the aft

rotor, perform steps (a). and (b). below.

side of the canted bulkhead.

(a). Install forward eyebolt on replace−

ment bungee and then hook aft end

(b). Block the left tail rotor control pedal

of bungee into eyebolt on floor−routed

in the full forward position to relieve

control rod fitting.

tension on bungee.

(b). Stretch bungee into position at Sta.

(c). Remove eyebolt at Sta. 63.00 with

63.00 bracket, install washer and nut

bungee attached.

on eyebolt and tighten.

(d). Disconnect bungee from eyebolt on

(7). Check that slotted bushing is in place;

fitting at the aft end of the floor−

then install floor−routed control rod in

routed control rod and remove

torque tube fitting and install bolt, two

bungee.

washers, nut and cotter pin.

(5). Remove cotter pin, two washers and

(8). Check rigging of tail rotor control and

bolt that connect floor−routed control

pedal−to−canopy clearance following

rod to torque tube fitting.

installation of any removed or replaced

parts.

(6). Remove two nuts, four washers, any

shim washers and two bolts that secure

26. Disassembly of Tail Rotor Pedal

torque tube bracket to bulkhead. (Keep

Installation (Left Position)

shim washer selection with bracket to

facilitate torque tube alignment during

(Ref. Figure 8−14)

reinstallation.)

(1).

Disconnect links from pedal arms and

(7). Remove four nuts, eight washers, any

bellcrank; remove links.

shim washers and four bolts that secure

(2).

Remove bellcrank from pedal bracket.

pedal bracket to bulkhead. Remove the

control pedal installation. (Keep shim

(3).

Remove nut washer of the two bushing

washer selection with bracket.)

assemblies that secure the left pedal

arm and control rod fitting to torque

B. Installation of Tail Rotor Pedal Installation

tube. Carefully remove ABC bushing

(Left Position)

bolt and reinstall washer and nut on

bolt.

(1). Install pedal bracket with four bolts,

eight washers and four nuts.

(4).

Side pedal bracket and pedal arms off

end of torque tube.

(2). Add shim washers as required at pedal

bracket attachment points to keep

(5).

Do not remove the two teflon−lined

centerline alignment of pedal bracket

bushings from the right pedal arm

bearings within 0.010 inch (0.254 mm).

unless replacement is required.

NOTE: Correct alignment is indicated by free

(6).

Do not remove the two stop bolts, stop

rotational movement of torque tube after

nuts (if installed) on stop bolts or

the nuts are tightened.

bearings from the pedal bracket unless

replacement is required.

(3). Position torque tube bracket over

mating holes in bulkhead and check

(7).

Slide torque tube bracket and control

alignment with bulkhead.

rod fitting off torque tube.

Page 8-40

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

A. Reassembly of Tail Rotor Pedal

inforced bushing liners for deteriora−

Installation (Left Position)

tion.

(Ref. Figure 8−14)

(2). Inspect pedal−to−arm quick−release

locking pin for condition and positive

(1).

If previously removed, thread a stop

spring action.

nut on each of the two stopbolts and

install the two stopbolts into thread

(3). Inspect links and bellcrank for cracks

inserts of pedal bracket.

and bends, and bearings for excessive

looseness.

(2).

Slide torque bracket and control rod

fitting onto torque tube.

(4). Inspect control rod fitting, torque tube

mounting bracket, and pedal mounting

(3).

Locate pedal bracket and pedal arms

bracket for cracks and corrosion.

for correct position on torque tube; slide

bracket and arms onto torque tube.

(a). Using an 8X−power magnifying

glass, a mirror and a flashlight,

inspect the pedal link bellcrank

(4).

Fasten left pedal arm and control rod

fitting of the pedal bracket in the

fitting to torque tube with adjustable

center forward area where the fitting

bushing assemblies; install the bushing

(fork piece) joins the tubular section.

bolt so that the shank at the bolt head

end protrudes at least 0.002 inch

(b). If any cracks are detected, replace

(0.0508 mm). Torque nut to 50 − 80

the bracket assembly.

inch−pounds (5.65 − 9.04 Nm) plus

drag torque. Do Not allow the bolt to

(c). Inspect bracket bearing for excessive

turn.

looseness.

(5).

Check that each end of the bushing

(5). Inspect torque tube for cracks,

assembly shank protrudes at least

scratches, nicks, dents and similar

0.002 inch (0.0508 mm). If not, loosen

surface defects.

and repeat step (4). above.

A. Tail Rotor Pedal Installation Repair (Left

(6).

Check that slotted bushing is in place;

Position)

then attach bellcrank to pedal bracket

with bolt, two washers, nut and cotter

(1). Replace parts that are cracked, or have

pin.

elongated attachment holes.

(7).

Check that slotted bushings are in

Do not attempt to straighten a

place; then fasten each link to bellcrank

CAUTION

bent torque tube or pedal link.

with bolt, two washers nut and cotter

pin.

(2). Replace unserviceable pedal covers.

Apply cement (3, Table 2−4) to approxi−

(8).

Check that slotted bushings are in

mately 30 percent of the upper and

place; then fasten each link in pedal

lower edge surfaces that contact the

arm lugs with bolt, two washers, nut

metal; cure according to container

and cotter pin.

instructions.

27. Tail Rotor Pedal Installation Inspection

(3). Replace complete pedal link if it is

(Left Position)

cracked or contains unserviceable

bearings; bearings are not replaceable.

(Ref. Figure 8−14)

(4). Replace unserviceable bearings in the

(1). Inspect pedals and pedal arms for

mounting brackets or pedal link

cracks, elongated pedal attach holes,

bellcrank. Install replacement with

and open drain holes. Inspect teflon−re−

grade A locking compound (29).

Page 8-41

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

STA 95 BELLCRANK

CONTROL

DIM L

ANGLE

ASSY PART

ROD ASSY

IN.

(CM)

NUMBER

STA. 78.50

57.95

(147.193)

IN LINE

369A7007

FLOOR

30.06

(76.3524)

IN LINE

369A7006−3

MS 20470 RIVET

CONTROLS SUPPORT

STA 78.50

BRACKET

(TUNNEL−ROUTED)

CONTROL ROD

MAX. ALLOWABLE

NOTE 6

LOOSENESS

0.040 IN. (1.016 MM)

STA 63.00

AFT EYEBOLT

BUNGEE

FORWARD EYEBOLT

TAIL ROTOR

SPRING

IDLER BELLCRANK

NOTE 2

SPRING FITTING

FLOOR−ROUTED CONTROL ROD

NOTE 2

BUSHING ASSY

TORQUE TUBE

(NOTE 4)

NOTE 3

* TORQUE TUBE BRACKET

NOTE 1

NOTE 3

(NOTE 5)

FITTING

WASHER

(NOTE 7)

NOTE 1

NOTE 4

BEARING

* LEFT PEDAL

STOP BOLT

STOP NUT (NOTE 7)

* RIGHT PEDAL

NOTE 2

PEDAL

NOTE 3

COVER

NOTE 1

* PEDAL BRACKET

NOTE 1

BUSHING

NOTES:

* PEDAL ARM

(TEFLON−LINED)

SHIM BETWEEN BRACKET AND BULKHEAD WITH

AN960PD416 AND/OR −416L WASHERS AS REQUIRED

FOR ALIGNMENT WITHIN 0.010 IN. (0.254 MM)

NOTE 2

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

NOTE 4

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

OUTSIDE SURFACE OF PART AFTER NUT IS TIGHTENED.

DIRECTION OF BOLT IS OPTIONAL.

BUSHING ASSY

ADJUSTABLE BUSHING MUST HAVE A MIN. PROTRUSION

(NOTE 4)

OF 0.002 IN. (0.0508 MM) AT EACH END.

INSTALL WITH BEARING RECESS FACING FITTING.

LINK

ON HELICOPTERS WITH METAL−BLADED TAIL ROTOR ASSY.

NOT ON ALL HELICOPTERS; AS REQUIRED.

NOTE 2

BEARING

ASTERISK ( * ) INDICATES PARTS THAT MAY EITHER

MAGNESIUM OR ALUMINUM ALLOY. REFER TO SECTION 2

BELLCRANK

FOR ALLOY IDENTIFICATION AND CORROSION CONTROL.

30−066F

Figure 8-14. Pilot’s Compartment and Intermediate Tail Rotor Controls

Page 8-42

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

The right pedal arm bushings

(4). Disconnect control rod from pedal

CAUTION

are glass− filled phenolic. En−

torque tube fitting or from tail rotor

sure bushing does not cock during replace−

idler bellcrank (Ref. Figure 8−14).

ment, and that it is fully seated in arm bore.

Remove metal tail rotor control bungee

Keep tools from contact with bushing liners

spring if installed.

to avoid fraying.

NOTE: Check rigging of tail rotor controls fol−

lowing installation of any removed or re−

(5). Replace bearings in right pedal arm

placed parts.

when teflon−reinforced liner is galled or

frayed. Pull bushing to remove; press to

(5). Accurately measure and record distance

install.

between un−chamfered edge of rod end

jamnut and center of rod end bearing

28. Floor-and-tunnel-Routed Control Rods

hole. Record measurement.

(Ref. Figure 8−14) The floor−and−tunnel−

Use care when drilling to re−

CAUTION

routed control rods interconnect the tail rotor

move or install riveted rod end;

pedal installation with the upper fuselage and

the rod end is steel and the rod is aluminum.

tailboom control linkage (Ref. Figure 8−15).

(6). Drill out rivet(s) (as applicable), loosen

jam nut and unscrew rod end.

The control rods, each an anodized, aluminum

alloy tube with two rod end bearings, are

(7). Screw replacement rod end into rod,

linked by a cast magnesium tail rotor bell−

and adjust jam nut to obtain same

crank mounted on the under−seat control

measurement made in step (5). above.

support bracket. An aluminum alloy tail rotor

(8). Align control rod ends so that the

bellcrank may be installed to replace the

bearings have equal space for angular

magnesium bellcrank. (Refer to Control

throw; hold rod end and tighten jam

Support Bracket and Bellcranks, Section 7.)

nut.

29. Floor-Routed Tail Rotor Control Rod

(9). As applicable, install rivet(s) to secure

Repair

rod end.

(1). Replace rod end if bearing axial play is

(10). Check that slotted bushing is in place;

then secure control rod in torque tube

more than 0.040 inch (1.016 mm).

fitting or idler bellcrank with bolt, two

NOTE:

washers, nut and cotter pin.

D The riveted rod end bearing is replaceable

(11). Reinstall metal tail rotor control

without removal if located at forward end

bungee spring as required.

of rod. If riveted rod end is aft, rod remov−

(12). Reinstall access doors.

al is required to replace the rod end bear−

ing.

30. Sta. 78.50 Tail Rotor (Tunnel-Routed)

D The floor−routed control rod will normally

Control Rod

not require replacement unless the heli−

(Ref. Section 7, Tunnel−Routed Control Rods)

copter has received extensive impact or

All the tunnel−routed control rods are re−

crash damage.

moved, inspected, repaired and installed in

same manner. Ref. Figure 8−14 for initial

(2). On current configuration helicopters,

length and rod end angularity.

remove the control rod forward through

the landing light wiring grommet hole

31. Tail Rotor Idler Bellcrank

after the landing light is removed.

(Ref. Section 7, Control Support Bracket and

(3). Early configuration helicopters may be

Bellcranks)

modified for this purpose by relocating

32. Upper Fuselage and Boom Tail Rotor

the landing light wire hole and opening

Control Linkage

up the hole to 1.25 inch (3.175 cm); then

install a 369H4011 grommet after the

(Ref. Figure 8−15) Upper fuselage tail rotor

control rod is reinstalled.

controls consist of the Sta. 95 bellcrank and

Page 8-43

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

support at the front of the main rotor mast

of engine air inlet screen (Sta. 119.50) if

base, the Sta. 100 control rod and the Sta. 142

installed.

bellcrank inside the boom fairing.

(8). Disconnect control rod from upper end

The boom linkage consist of the tailboom

of bellcrank.

control rod, supported by six nylon bushings or

B. Sta. 100 Control Rod or Sta. 142

teflon grommets, and the Sta. 282 bellcrank

Bellcrank Installation

that is mounted on the tail rotor transmission.

The Sta. 142 bellcrank and Sta. 100 control

The Sta. 95 bellcrank support and the Sta. 100

rod must be installed as an assembled unit by

and 142 bellcranks are either cast magnesium,

routing assembled end of bellcrank and control

or forged or cast aluminum; the control rods

rod through boot support tube at air inlet

are aluminum alloy. Aluminum alloy parts

screen (when installed) and through boot

may be installed to replace magnesium parts.

support tube at plenum chamber Sta. 137.50.

33. Sta. 100 Control Rod Sta. 142 Bellcrank

(1). Gain access to bellcrank support

Replacement

bracket through access door in boom

fairing.

(Ref. Figure 8−15)

(2). Check that slotted bushings are in

A. Sta. 100 Control Rod Sta. 142 Bellcrank

place at each end of bellcrank.

Removal

(3). Position riveted rod end in bellcrank

The Sta. 142 bellcrank and Sta. 100 control

and install bolt, two washers, nut and

rod must be removed as an assembled unit.

cotter pin.

NOTE: Check to be sure that the hump of the

(1). Remove tail rotor control bellcrank

bellcrank will face forward.

access door from left side of boom

fairing.

(4). Carefully feed assembled control rod

and bellcrank through forward air

(2). Disconnect tailboom control rod from

intake at left side of control mixer

lower end of Sta. 142 bellcrank.

installation while an assistant guides

(3). Remove hardware that secures Sta. 142

the assembly through boot support

tubes to the bellcrank support bracket.

bellcrank to boom fairing brackets.

(5). Position rubber boot or fabric boot and

(4). Remove plenum chamber access door

grommet in place at Sta. 137.50, and

(early type) or open hinge−mounted

also at front air inlet screen if installed.

access door (current type) on engine

inlet aft fairing.

(6). Position Sta. 142 bellcrank in support

bracket and install bolt, two washers,

(5). Remove clamp on boot support tube at

nut and cotter pin.

front of engine air inlet screen (Sta.

119.50) if screen is installed.

Check Sta. 142.00 bellcrank for

CAUTION

clearance with support struc−

(6). Disconnect forward end of Sta. 100

ture. Pay particular attention to area above

control rod from Sta. 95 bellcrank.

369A7951−23 bearing when top of bellcrank

is in forward position. If contact is noted,

NOTE: The Sta. 95 bellcrank must also be de−

machine surface of bellcrank (machine sur−

tached from its support to get clearance

face with interference only)

(Ref.

from the air inlet fairing for rod end bolt re−

Figure 8−16).

moval.

(7). Check that slotted bushing is in place

(7). Carefully pull at forward end of control

in Sta. 95 bellcrank.

rod and withdraw assembled and

bellcrank out through boot support tube

(8). Install forward rod end in bellcrank

at plenum chamber Sta. 137.50 and

with bolt (head to left), two washers,

also through boot support tube at front

nut and cotter pin.

Page 8-44

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

BELLOWS−TYPE BOOT

NOTE 2

(ONE OR TWO PLACES)

(RUBBER−TYPE

STA. 137.50

PREFERRED)

DRAIN SLOT

(NOTE 6)

STA. 119.50

* STA. 142

STA. 282

BELLCRANK

NYLON STRAP

BEARING

(TWO PER BOOT)

NOTE 2

STA. 100

* STA. 95

CONTROL ROD

NOTE 4

BELLCRANK

(NOTE 1)

TAIL BOOM

CONTROL ROD

DRAINAGE HOLES

HS308−616L

(NOTE 3)

(HIDDEN; NOTE 6)

WASHER

* SUPPORT

(NOTE 5)

MAX. ALLOWABLE

LOOSENESS

0.040 IN. (1.016 MM)

BEARING

MS20470AD

ADAPTER

RIVET

NOTES:

MIN. OF 0.060 IN. (1.524 MM) CLEARANCE FOR FULL RANGE OF

TRAVEL THRU STA. 137.50 BULKHEAD.

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 SURFACE OF

INITIAL ROD ASSY LENGTH AND

PART AFTER NUT IS TIGHTENED.

BEARING ANGULARITY (BEFORE RIG)

MIN. OF 0.010 IN. (0.254 MM) CLEARANCE FOR FULL RANGE OF

CONTROL

DIM

ANGLE

ASSY PART

TRAVEL BETWEEN BOOM AND TAIL ROTOR TRANSMISSION.

ROD ASSY

NUMBER

MUST BE CHROME PLATED OR NITRIDED.

USE TO PREVENT DISSIMILAR METAL CONTACT; INSTALL AT

45.88 IN.

STA. 100

IN LINE

369A7006−5

EARLIEST OPPORTUNITY.

(116.5352 CM)

DRAINAGE PROVISIONS FOR WATER ENTRAPMENT AREAS

141.70 IN.

(REFER TO MDHI HN−39).

TAILBOOM

63°

369A7518

(359.918 CM)

ASTERISK ( * ) INDICATES PARTS THAT MAY BE EITHER ALUMINUM

OR MAGNESIUM ALLOY. REFER TO SECTION 2 FOR ALLOY

IDENTIFICATION CONTROL.

30−067G

Figure 8-15. Upper Fuselage and Boom Tail Rotor Control Linkage

Page 8-45

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(9). Reinstall Sta. 95 bellcrank in its

35. Tailboom Control Rod Replacement

support with bolt, two washers, nut and

(Ref. Figure 8−15)

cotter pin.

A. Tailboom Control Rod Removal

(10). Secure grommet to fabric boot with

nylon strap and boot to support tube

(1). Disconnect control rod from Sta. 282.00

with nylon strap.

bellcrank.

(2). Accurately measure and record distance

(11). If rubber boot is used:

between un−chamfered edge of forward

rod end bearing jam nut and center of

(a). Secure end at support tube with

bearing attach bolt hole.

nylon strap.

(3). Hold forward rod end, loosen jam nut

(b). Clamp tail rotor pedals in neutral.

and un−thread control rod from rod end

by turning aft end of rod.

(c). Set free length of bellows portion of

boot at approximately 5.50 inches

(4). Slowly pull at aft end of control rod and

(13.97 cm) and secure end to control

withdraw rod out through opening in

rod with nylon strap.

tail rotor transmission mounting frame.

(12). Check rigging of tail rotor controls after

B. Tailboom Control Rod Installation

installation of any removed or replaced

NOTE: Tailboom control rod is routed through

parts.

the boom with the forward rod end removed.

Use of special grommet installation tool (57,

34. Sta. 282.00 Bellcrank Replacement

Table 2−2) simplifies installation of tail ro−

tor control rod grommets. For replacement

(Ref. Figure 8−15)

of grommets, refer to CSP−H−6.

A. Sta. 282.00 Bellcrank Removal

(1).

Guide control rod through boom aft

frame opening and carefully route

(1). Disconnect bellcrank from tailboom

through the six control rod grommets.

control rod.

Rotate the rod slightly to start it

through each grommet.

(2). Disconnect bellcrank from tail rotor

transmission arm. Disengage bellcrank

(2).

Check that slotted bushing is in place

pitch control pin from tail rotor assem−

in lower lug of Sta. 282 bellcrank; then

bly and remove bellcrank.

attach aft rod end to bellcrank with

bolt, two washers, nut and cotter pin.

B. Sta. 282.00 Bellcrank Installation

(3).

Using measurement recorded at time of

(1). Position tail rotor pitch control assem−

rod removal, install forward rod end

bly to align with pitch control pin in

bearing. Align rod ends so that the

bellcrank and engage pin.

bearings have equal space for angular

throw; hold rod end and tighten jam

(2). Position bellcrank to align with mating

nut.

hole in tail rotor transmission arm and

(4).

Check that slotted bushing is in place

install bolt, two washers, nut and cotter

in lower end of Sta. 142 bellcrank; then

pin.

attach forward rod end to bellcrank

with bolt, two washers, nut and cotter

(3). Check that slotted bushing is in place

pin.

in lower lug of bellcrank; then attach

tailboom control rod to bellcrank with

(5).

Check rigging of tail rotor controls

bolt, two washers, nut and cotter pin.

following installation of any removed or

replaced parts.

(4). Check rigging of tail rotor controls after

installation of any removed or replaced

(6).

Reinstall or close plenum chamber

parts.

access door as applicable (Ref. Sec. 2).

Page 8-46

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

36. Sta. 95 Bellcrank and Support

(4). Inspect the rubber boot, or fabric boot

Replacement

with grommet, at Sta. 137.50 bulkhead

and, when applicable, at front of engine

(Ref. Figure 8−15)

air inlet screen for good condition.

A. Sta. 95 Bellcrank and Support Removal

(5). Clean any accumulation of dirt from the

grommet in the fabric boot to minimize

(1). Disconnect tunnel−routed control rod

abrasive wear on the control rod.

from bellcrank.

(6). Inspect Sta. 100 control rod for chafing

of the surface that feeds through the

(2). Disconnect bellcrank from support.

fabric boot grommet; serviceable wear

is limited to 0.004 inch (0.1016 mm)

(3). Disconnect bellcrank from Sta. 100

measured from adjacent undamaged

control rod and remove bellcrank.

area.

(4). Remove hardware that secures support

NOTE: A fabric boot with grommet may be re−

to mast structure; remove support.

placed with a rubber bellows type boot

369A8415 to eliminate grommet chafing of

B. Sta. 95 Bellcrank and Support Installation

rod.

(1). Install bellcrank support to mast

(7). Inspect for wear of the tailboom control

structure with three bolts, seven

rod surfaces that pass through the

washers and three nuts. (The forward

control rod grommets.

bolt requires an extra washer

(AN960PD416) under the bolthead).

(a). Serviceable wear is limited to the

thickness of the hard anodic coating.

NOTE: Two thin washers are used at all three

locations.

(b). Check that all grommets are secure.

(2). Torque nuts to 80 − 100 inch−pounds

(8). Inspect bellcranks for scratches,

(9.04 − 11.30 Nm).

corrosion and similar surface defects.

(9). Inspect bellcrank bearing for looseness

(3). Check that slotted bushings are in

and binding.

place in bellcrank; then attach Sta. 100

control rod to bellcrank with bolt (head

(10). Check that Sta. 282 (tail rotor gearbox)

to left), two washers, nut and cotter pin.

bellcrank drain slot, if provided, is free

of obstruction.

(4). Install bellcrank in support with bolt,

two washers, nut and cotter pin.

(11). Replace Sta. 282.00 bellcrank pivot pin

if worn or corroded. Install washer

(5). Attach tunnel−routed control rod to

HS308−616L between pin and bell−

bellcrank with bolt, two washers, nut

crank.

and cotter pin.

38. Upper Fuselage and Boom Tail Rotor

37. Upper Fuselage and Boom Tail Rotor

Control Linkage Repair

Control Linkage Inspection

(1). Perform a straightness check on a

(1). Inspect rod end bearing for binding and

control rod that appears bent or bowed.

excessive wear, 0.040 inch (1.016 mm)

maximum axial looseness.

(a). The total length of Sta. 100 control

rod, excluding rod ends, must be

(2). Inspect for loose rivet at fixed rod end.

straight within 0.040 inch (1.016

mm), with straightness variation

(3). Inspect control rod for surface damage

limited to a maximum of 0.010 inch

and evidence of bending.

(0.254 mm) in each foot of length.

Page 8-47

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). The total length of the tailboom

(a). Install replacement bearing with

control rod, excluding rod ends, must

grade A locking compound (29,

be straight within 0.120 inch (3.048

Table 2−4). Check that bearing seats

mm), with straightness variation

against bore shoulder.

limited to a maximum of 0.010 inch

NOTE: The installation direction of Sta. 142

(0.254 mm) in each foot (30.48 cm) of

bellcrank bearing may be from either side,

length.

depending on location of bearing shoulder.

A dye− check for cracking

There must not be less than 0.010 inch

WARNING

must always be performed

(0.254 mm) protrusion of bearing inner race

after cold− straightening. Replace a

beyond the sides of the bellcrank after the

cracked rod, or a cracked or bent rod

bearing is installed.

end.

(6). Repair minor surface defects such as

(2). Cold−straighten a bent rod that is not

scratches, nicks and corrosion on

within tolerance provided there are no

bellcranks and support bracket.

nicks or sharp dents in the bend length.

(a). Use abrasive cloth grade 400−600

DO NOT use the rod ends to support

(20) to smooth out and blend in such

the rod during straightening process.

defects.

Use care when drilling to re−

(7). The following rework limits represent

CAUTION

move or install riveted rod end;

total limits, including the effects of all

the rod is steel and the rod and bearing

previous repairs to any given area.

adapter are aluminum.

NOTE: Parts identified in Figure 8−15 with an

(3). Replace a control rod end if bearing

asterisk (*) may be either magnesium or

axial play is more than 0.040 inch

aluminum alloy. Refer to Section 2 for corro−

(1.016 mm). Set initial control rod

sion control and identification of magne−

length and bearing angularity as shown

sium and aluminum alloys.

in Figure 8−15.

(a). Cast surfaces may be reworked to

(4). Replace unserviceable control rod

depth of 0.020 inch (0.508 mm).

bearing adapter.

(b). Flat machined surfaces, except clevis

NOTE: Use the trammel method, or equivalent,

inner ears, may be reworked to depth

to establish rod length when replacing an

of 0.015 inch (0.381 mm).

adapter.

(c). Clevis inner ear surfaces may be

(a). Measure length and record position

reworked to depth of 0.020 inch

of rod end in adapter; then remove

(0.508 mm).

affected rod end.

(d). Machined holes may have 0.003 inch

(b). Observe the CAUTION above and

(0.0762 mm) removed from the bore

drill out rivets securing adapter to

wall in an area no greater than 15

rod and aft rod end.

percent of the circumference and 50

percent of the depth.

(c). Install rod end in replacement

adapter and position at recorded

(e). All edges may have 0.030 inch (0.762

measurement.

mm) removed except around ma−

chined holes, which are limited to

(d). Fit adapter into rod and position to

0.010 inch (0.254 mm) chamfer.

fit recorded trammel position.

(f). All rework must be smoothly blended

(e). Drill through existing rivet holes in

into the adjacent surfaces and the

rod and install rivets to secure

finish must be restored. Refer to

adapter to rod.

preceding NOTE.

(5). Replace unserviceable bellcrank and

(8). Repair surface abrasion on Sta. 100

support pivot bearings.

control rod by smoothing the area with

Page 8-48

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

grade 400 abrasive cloth (20) and

(10). Replace split or torn boot or a cracked

restoring protective finish with primer

grommet:

(4). Replace rod if wear or depth of

(a). Remove Sta. 100 control rod.

repair exceeds 0.004 inch (0.1016 mm).

NOTE: A fabric boot with grommet may be re−

placed with a rubber bellows type boot

369A8415.

(9). Replace tailboom control rod if hard

anodic coating is worn through and

(b). Replace boot, as required, and

aluminum base metal is visible.

reinstall Sta. 100 control rod.

BELLCRANK AND SUPPORT

(2 PLS) (NOTE 1)

(NOTES

0.002 IN.

A S

2 & 3)

(0.0508 MM)

0.750 IN.

(19.05 MM)

(NOTES

MIN.

2 & 3)

0.090 IN. (2.286 MM) R

369A7951−23

(TYP)

BEARING

NOTES:

0.010 IN. (0.254 MM) MIN. CLEARANCE REQUIRED IN THIS AREA.

TREAT MACHINED AREA (5, TABLE 2−4).

TOUCH−UP (COLOR 34151 GREEN).

44−475A

Figure 8-16. Rework of Sta. 142 Bellcrank Assembly

Page 8-49/(8-50 blank)

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 9 Transmissions and Drives System .

9−1

Power Train System

9−1

Power Train System Troubleshooting

9−1

Table 9−1. Troubleshooting the Power Train System

9−1

Figure 9−1. Power Train System

9−4

Main Transmission

9−5

A. Main Transmission Removal

9−5

Figure 9−2. Main Transmission Installation

9−6

B. Main Transmission Installation

9−7

C. Main Transmission Inspection

9−7

D. Main Transmission Stripping

9−8

E. Main Transmission Buildup

9−8

F. Main Transmission Repair

9−8

Figure 9−3. Main Transmission Cross−Section

9−9

Lubrication Pump and Oil System Accessories

9−10

A. Lubrication Pump Removal

9−10

B. Lubrication Pump Installation

9−10

C. Lubrication Pump and Oil System Accessories Inspection .

9−10

D. Transmission Filter Replacement

9−10

E. Chip Detector Replacement

9−10

F. Tachometer Generator Replacement

9−11

G. Oil Pressure Sender and Temperature Switch Replacement .

9−11

H. Liquid Level (Sight) Plug Replacement

9−11

Application of Markings on Liquid Level Plug

9−11

J. Repair and Replacement of Transmission Drains and Tubing .

9−11

Figure 9−4. Main Transmission Drain Tubing

9−12

Main Rotor Drive Shaft

9−13

A. Main Rotor Drive Shaft Removal

9−13

B. Main Rotor Drive Shaft Installation

9−14

C. Main Rotor Drive Shaft Inspection

9−14

Figure 9−5. Main Rotor Drive Shaft

9−15

D. Main Rotor Drive Shaft Exterior Repair

9−16

Main Transmission Drive Shaft

9−16

A. Main Transmission Drive Shaft Removal

9−16

B. Main Transmission Drive Shaft Installation

9−16

C. Main Transmission Drive Shaft Inspection (Bendix)

9−17

D. Main Transmission Drive Shaft Inspection (Kamatic)

9−18

Page 9−i

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

E. Main Transmission Drive Shaft Couplings Corrosion Removal .

9−18

F. Main Transmission Drive Shaft Repair (Bendix)

9−19

G. Main Transmission Drive Shaft Repair (Kamatic)

9−19

Oil Cooler Blower

9−19

A. Oil Cooler Blower Removal (Early−Type, Belt−Driven) . .

9−19

Figure 9−6. Main Transmission Driveshaft and Early Type Belt−Driven

Oil Cooler Blower (Sheet 1 of 2)

9−20

B. Oil cooler Blower Installation (Early−Type, Belt−Driven) .

9−22

C. Oil Cooler Blower Removal (Current−Type, Belt−Driven) .

9−24

D. Oil Cooler Blower Installation (Current−Type, Belt−Driven) .

9−24

Figure 9−7. Main Transmission Driveshaft and Current Type Belt−Driven

Oil Cooler

9−25

E. Oil Cooler Blower Inspection (Belt−Driven)

9−27

Figure 9−8. Belt−Driven Oil Cooler Blower (Screw−Assembled), Exploded

View

9−28

Figure 9−9. Early Type Belt−Driven Oil Cooler Belt Tension and Pulley

Alignment

9−29

F. Oil Cooler Blower Removal (Shaft−Driven)

9−30

G. Oil Cooler Blower Installation (Shaft−Driven)

9−30

H. Oil Cooler Blower Inspection (Shaft−Driven)

9−31

Oil Cooler Blower Disassembly (Belt−Driven)

9−31

Oil Cooler Blower Reassembly (Belt−Driven)

9−32

Figure 9−10. Main Transmission Driveshaft and Shaft−Driven Oil Cooler

Blower

9−33

K. Oil Cooler Blower Repair

9−34

Figure 9−11. Cutaway View of Belt−Driven Oil Cooler Blower .

9−35

Overrunning Clutch

9−36

A. Overrunning Clutch Removal

9−36

B. Overrunning Clutch Installation

9−36

Figure 9−12. Overrunning Clutch Repair or Replacement .

9−37

C. Overrunning Clutch Inspection

9−38

D. Overrunning Clutch Sub−Assembly and Ball Bearing Inspection .

9−38

E. Overrunning Clutch Sub−assembly Replacement

9−38

F. Overrunning Clutch Repair/Overhaul

9−38

Tail Rotor Transmission

9−38

A. Tail Rotor Transmission Removal

9−38

Figure 9−13. Tail Rotor Transmission and Drive Shaft Installation with

Kamatic Couplings Installed (Sheet 1 of 2)

9−39

Figure 9−14. Tail Rotor Transmission and Drive Shaft Installation with

Bendix Couplings Installed (Sheet 1 of 2)

9−41

Page 9−ii

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

B. Tail Rotor Transmission Installation

9−43

C. Tail Rotor Transmission Inspection

9−43

D. Tail Rotor Transmission Stripping

9−43

E. Tail Rotor Transmission Buildup

9−43

Figure 9−15. Replacement of Tail Rotor Transmission Liquid Level Plug and

Breather−Filler

9−44

F. Protective Sleeve (Speedi−Sleeve) Installation, Output Gearshaft .

9−45

Figure 9−16. Protective Sleeve Installation/Replacement, Output Gearshaft .

9−46

G. Protective Sleeve (Speedi−Sleeve) Replacement, Output Gearshaft

9−47

10. Tail Rotor Drive Shaft

9−47

A. Tail Rotor Drive Shaft Removal

9−47

B. Tail Rotor Drive Shaft Installation with Kamatics Couplings .

9−47

C. Tail Rotor Drive Shaft Installation with Bendix Couplings .

9−49

D. Tail Rotor Drive Shaft Twist Inspection

9−51

E. Tail Rotor Drive Shaft Index Stripe Application

9−52

F. Tail Rotor Drive Shaft Inspection

9−52

Figure 9−17. Drive Shaft Twist Check

9−53

G. Tail Rotor Drive Shaft Repair

9−54

11. Tail Rotor Drive Shaft Damper

9−54

A. Tail Rotor Drive Shaft Damper Inspection

9−54

B. Tail Rotor Drive Shaft Damper Replacement

9−54

Figure 9−18. Tail Rotor Drive Shaft Damper Friction − Checking .

9−55

C. Tail Rotor Drive Shaft Damper Friction Adjustment

9−56

12. Tail Rotor Drive Shaft Couplings

9−56

A. Tail Rotor Drive Shaft Coupling Removal

9−56

B. Tail Rotor Drive Shaft Coupling Inspection (Bendix)

9−56

C. Tail Rotor Drive Shaft Coupling Inspection (Kamatic) . .

9−56

D. Tail Rotor Drive Shaft Coupling Repair (Bendix)

9−56

E. Tail Rotor Drive Shaft Coupling Repair (Kamatic)

9−57

F. Tail Rotor Drive Shaft Coupling Installation

9−57

Page 9−iii

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 9

TRANSMISSIONS AND DRIVES SYSTEM

1. Power Train System

Main transmission output through the tail

rotor drive shaft to the tail rotor transmission

(Ref. Figure 9−1) The power train system

is 2045 rpm in a clockwise direction: tail rotor

starting at the engine power take−off pad,

transmission output to the tail rotor is 3018

consists of the overrunning clutch, drive shafts

rpm, also clockwise.

and transmissions.

Engine input through the clutch to the main

2. Power Train System Troubleshooting

transmission is 6000 rpm in a clockwise

direction: main transmission output to the

main rotor is 470 rpm, also clockwise.

(Ref. Table 9−1)

Table 9-1. Troubleshooting the Power Train System

Symptom

Probable Cause

Corrective Action

Main drive shaft vibrates

Loose attaching bolts on main drive

Retorque bolts to 50 - 70

shaft

inch-pounds (5.65 - 7.91 Nm).

Shaft dented or bent

Check drive shaft limits for

serviceability.

Excessive noise or vibration in oil

Defective impeller or damaged scroll

Replace impeller or scroll.

cooler blower assembly

Overrunning clutch will not

Defective overrunning clutch

Replace overrunning clutch.

operate

Main transmission requires

Leakage at main transmission input

If leakage is found at input pinion,

frequent addition of oil

or output seals

replace the face seal according to

applicable instructions in CSP-H-5,

HMI Appx C. If leakage is past either

output seal, replace the defective

seal.

Oil leak around accessory drive

Tighten cover or replace

cover

transmission.

Oil temperature warning light

Defective oil temperature switch

Replace oil temperature switch.

comes on when oil temperature is

normal

Oil temperature warning light

Blockage of cooling air

Check airflow paths for blockage.

comes on when oil temperature is

Low oil level or oil above full level in

Establish correct oil level (Ref. Sec.

excessive

main transmission

2).

Defective lube pump

Replace lube pump.

Defective bearings or gears

Replace transmission.

NOTE: Noise that signals a defective transmission should not be confused with normal gear backlash noise at

rundown or low rpm and power conditions.

Excessive noise in main

Inadequate oil supply

Service main transmission (Ref. Sec.

transmission

2).

Defective bearings or gears in main

Replace transmission.

transmission

Page 9-1

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 9-1. Troubleshooting the Power Train System (Cont.)

Symptom

Probable Cause

Corrective Action

Oil pressure warning light on (oil

Low oil level in main transmission

Service main transmission (Ref. Sec.

pressure low). Light should go out

2).

at approximately 55% N₂

Defective oil pressure sender

Replace oil pressure sender.

Defective main lube pump

Replace lube pump.

Filter clogged

Clean filter (Ref. Sec. 2).

NOTE: Rapid or abrupt maneuvers that involve extreme changes in aircraft attitude and/or produce negative

G-forces, can result in transmission oil pressure caution warning light illuminating briefly.

Tail rotor drive shaft damper

Damper out of adjustment

Adjust damper friction.

vibrates

Damper defective

Replace damper.

Tail rotor drive shaft bent or dented

Check tail rotor drive shaft condition.

Replace shaft if straightness or tir is

beyond limits.

Tail rotor out of balance

Adjust tail rotor balance (Ref. Sec.

8).

Tail rotor transmission output

Worn or damaged bearings or gears

Replace tail rotor transmission.

shaft vibrates

in tail rotor transmission

Bent shaft or excessive shaft run-out

Replace tail rotor transmission.

Excessive noise in tail rotor

Inadequate oil supply

Service tail rotor transmission (Ref.

transmission

Sec. 2).

Defective bearings or gears in tail

Replace tail rotor transmission.

rotor transmission

Chip detector caution light on

Metallic chips in either main or tail

Inspect and clean chip detector

rotor transmissions

magnetic plugs. If there are heavy

chip deposits (chips larger than

0.125 inch (3.175 mm) in any

direction), replace the transmission.

If chips are smaller, drain and refill

transmission with new oil. Reinstall

chip detector and check after 4 hours

of flight. If more chips are found,

replace the transmission.

Defective chip detector

Replace chip detector.

Page 9-2

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 9-1. Troubleshooting the Power Train System (Cont.)

Symptom

Probable Cause

Corrective Action

NOTE: High frequency vibrations in the helicopter can also be caused by components in other systems (Ref. Sec.

5, 8, and 10).

High frequency vibration

Loose tail rotor drive shaft couplings Retorque couplings bolt to 250 - 300

inch-pounds (28.25 - 33.90 Nm),

plus allowable drag torque.

Tail rotor drive shaft couplings

Check shimming: correct as

shimmed improperly

required.

Loose, mismatched or bottomed

Tighten or install proper hardware

hardware retaining tail rotor drive

and be sure hard ware is installed

shaft couplings to main transmission correctly.

Oil cooler blower impeller has

Replace impeller.

cracks, loose rivets, defective blades

or other damage

Tail rotor drive shaft damper out of

Adjust damper friction.

adjustment

Defective overrunning clutch

Replace overrunning clutch.

Tail rotor drive shaft bent, dented or

Check tail rotor drive shaft condition.

otherwise damaged.

Replace shaft if straightness or tir is

beyond limits

NOTE: Drag is excessive when force required to rotate the transmission input shaft exceeds 25 inch-pounds

(2.82 Nm) with all shafting disconnected and transmission temperature between 50°F (10°C) and 100°F

(38°C).

Abnormal drag in the drive

Excessive rotational drag in main

Replace transmission if drag torque

system

transmission

exceeds 25 inch-pounds (2.82 Nm).

Page 9-3

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3. Main Transmission

(4). Remove tail rotor driveshaft (Ref. Tail

Rotor Drive Shaft Removal).

(Ref. Figure 9−2) The main transmission is

mounted on the main rotor mast support

NOTE: Removal of the main rotor driveshaft,

structure. The transmission is a two−stage,

step (5)., is optional. If help is not available

speed reduction unit, utilizing the first

to rotate the rotor hub for spline alignment,

reduction stage for the tail rotor drive system

shaft removal could facilitate reinstallation

and accessory drive trains, and the second

of the transmission.

stage to further reduce rpm for the main rotor.

(5). Remove main rotor driveshaft (Ref.

All of the gears are spiral−bevel type, except

Main Rotor Drive Shaft Removal).

for the accessory drive gears which are spur

type.

(6). Disconnect wiring from tachometer

generator, two chip detector, and oil

The transmission housing is magnesium alloy.

pressure and temperature senders.

The input pinion drives the input bevel gear

(7). Drain oil from transmission.

which is concentrically mounted on the tail

rotor output pinion.

(8). Obtain assistance to support the

transmission, then remove four nuts

The output pinion simultaneously drives the

and washers.

output bevel gear, main rotor drive shaft, tail

rotor drive shaft and accessory drive train.

Lower the transmission with ex−

CAUTION

The accessory gear train drives, at 4200 rpm,

treme care to prevent contact

both the rotor tachometer generator and the

between the tail rotor drive coupling and the

transmission oil pump which are mounted on

surrounding structure. Any dents, nicks or

drive pads at the back of the transmission.

scratches on the coupling diaphragm re−

quires that the coupling be scrapped. Use

Transmission cooling is accomplished by the

care to protect temperature sender and chip

lubrication oil and by air drawn over the

detector terminal studs from damage during

housing by the oil cooler blower and ram air

handling or when placing transmission on

routed to the gearbox by the two side ducts in

any surface.

the forward end of the air inlet fairing.

(9). With help from assistant, carefully

A. Main Transmission Removal

lower transmission from mounting

studs; Blower impeller is left attached

(1). Remove the sound insulation and

on helicopter with shaft −driven oil

transmission access covers.

cooler blower.

(2). Remove main transmission driveshaft

(Ref. Main Transmission Drive Shaft

(10). Keep output seal with transmission by

Removal).

tapping or tying in place to prevent loss

during handling, shipping or storage.

(3). Remove belt−driven oil cooler blower

(Ref. Oil Cooler Blower Removal,

NOTE: Apply covering over the top opening of

Current Type, Belt−Driven) or scroll

the transmission to prevent entry of dirt or

from shaft−driven oil cooler blower (Ref.

water. The residual operating lubricant is

Oil Cooler Blower Removal, Shaft−Driv−

an approved preservative for transmission

en).

shipment or storage.

Page 9-5

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3°

90°

C OUTPUT SHAFT

0.650 IN.

0.050 IN.

0.060 IN. (15.24 MM)

DECAL

(16.51 MM)

(12.7 MM)

MAIN ROTOR

NEW FULL

DRIVE SHAFT

MARKINGS

ORIGINAL

DECAL MARKINGS

PAINTED MARKINGS

MARKINGS

MAST BASE

SHAFT−DRIVEN BLOWER

BLOWER SCROLL

COUPLING BOLT 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

TAIL ROTOR

(NOTES 2, 4)

DRIVE SHAFT

50−70 IN. LB

(5.65−7.91 NM)

WASHER (REDUCED OD)

SHIMS

OUTPUT

(NOTE 1)

SEAL

LUBE PUMP & FILTER

O−RINGS

TAIL ROTOR DRIVE

DEBRIS SEAL

SHAFT COUPLING

(NOTE 3)

ROTOR TACHOMETER

FILLER

GENERATOR

SCREEN

O-RING

OIL

LIQUID LEVEL PLUG

80−90 IN. LB

(9.04−10.17 NM)

O−RING

BOND

JUMPER

60−80 IN. LB

(6.80−9.04 NM)

NOTES:

BELT-DRIVEN BLOWER

ALUMINUM ALLOY; 0.002−IN. LAMINATIONS.

DRAG TORQUE FOR BOLT (SELF LOCKING) IS 25 IN LBS. (2.82 NM) MIN.,

200 IN LBS. (22.60 NM) MAX.

COAT COUPLING SPLINES WITH CORROSION PREVENTIVE COMPOUND

(70, TABLE 2−4) BEFORE ASSEMBLY.

COAT COUPLING BOLT THREADS WITH ANTISEIZE COMPOUND (36) BEFORE

ASSEMBLY.

30−072G

Figure 9-2. Main Transmission Installation

Page 9-6

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Main Transmission Installation

When reinstalling main rotor

CAUTION

drive shaft, check that there is

no gap between shaft mounting flange and

Install only a 369A5100− 705,

CAUTION

rotor hub before tightening installation

− 705M,

−707,

−707M, or

−709

bolts. Gap indicates that shaft splines are

main transmission on helicopters equipped

not correctly meshed in transmission.

with a 250−C20 engine. In addition, a

369A5186−1 1 temperature switch is also re−

(8). If main rotor drive shaft has been

quired with either of these transmissions if

removed, apply coating of oil (35,

the transmission is not already identified

Table 2−4) on shaft before reinstalla−

with a 0.50 inch (12.7 mm) white dot located

tion. Install drive shaft.

next to the identification plate. Refer to

CSP− H− 5 for addition main transmission

(9). Install blower on helicopter equipped

qualifying information.

with belt−driven oil cooler blower, or

blower scroll for shaft−driven oil cooler

blower. Install drain assembly, drain

(1). If transmission is a replacement,

lines, and aft cover on transmission.

perform buildup.

(10). Install main transmission drive shaft.

CAUTION

(11). Ground run helicopter according to the

Pilot’s Flight Manual and check drive

system for excessive vibration and

D If transmission is new, remove output

unusual noise. Check transmission for

seal from shipping container and install

correct warning light operation and oil

on transmission.

leakage (Ref. Sec. 2, Fluid Leak

D Damage to main rotor drive shaft or main

Analysis). Replace unserviceable output

transmission splines can occur during in−

seals.

stallation. Care should be taken while

(12). Install access covers and sound insula−

meshing driveshaft splines into transmis−

tion.

sion output splines to prevent damage.

NOTE: If a 250− C20 engine is installed, a

(2).

Apply petrolatum (34, Table 2−4) to

transmission cover with airflow baffles

outer edge of output seal. Press firmly

must be used to assure adequate cooling.

into recess in top of transmission

C. Main Transmission Inspection

housing.

(1). Remove the sound insulation and

(3).

With help from an assistance, carefully

transmission access covers.

lift and position transmission in place

(2). Inspect transmission for oil leaks,

on mounting studs.

cracks, corrosion, secure electrical

connections, and proper oil level.

(4).

Install four washers and nuts; torque to

Evaluate oil leakage according to Fluid

60 − 80 inch−pounds (6.78 − 9.04

Leak Analysis.

Nm).

(3). Inspect the four mounting flanges on

main transmission housing for corro−

(5).

If transmission is new, drain any

sion and cracks. Check that transmis−

residual preservative oil. Service

sion mounting studs and nuts are

transmission with lubricating oil (2,

secure. This should be accomplished

Table 2−3).

from the fuselage interior as well as the

exterior at the main rotor mast base.

(6).

Connect wiring to tachometer genera−

(4). Check that all safety wiring is intact

tor, two chip detectors and oil pressure

and secure.

and temperature sender switch.

(5). Reinstall transmission access covers

(7).

Install tail rotor drive shaft.

and sound insulation.

Page 9-7

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(6). Inspect internal ring gear bolts in the

shaft coupling and tighten against shim

main transmission as follows.

with internal wrenching bolt.

(a). Drain the main transmission.

(3). On helicopter equipped with shaft−driv−

en oil cooler blower, install oil cooler

(b). Remove liquid level (sight) plug.

blower impeller; install input gearshaft

coupling.

(c). Using an adequate light source,

rotate main rotor 360 degrees while

(4). Install tachometer generator.

visually checking that all sixteen (16)

ring gear bolts and lockwire are

(5). Install transmission input gearshaft

intact. Also check visible areas of the

seal drain tube if not already in place.

ring gear and carrier for cracks and

other discrepancies.

F. Main Transmission Repair

NOTE: If damage (bolt heads sheared, lockwire

(Ref. Figure 9−2 and Figure 9−3) Replace

broken, crack or other discrepancies) is vis−

electrical components, the breather−filler

ible, replace transmission or overhaul (Ref.

and/or screen, the output seal, externally

CSP−HMI−5).

accessible O−rings, the lubrication pump

(d). Reinstall liquid level plug.

and/or filler, and the output pinion gearshaft

oil seal when they become defective. Repair

(e). Fill main transmission.

housing outer surface damage within the

limits outlined below. Replace or repair other

D. Main Transmission Stripping

components of the main transmission accord−

ing to applicable instructions in CSP−H−5.

(Ref. Figure 9−2 and Figure 9−3)

(1). If the depth of a depression does not

(1). Remove tachometer generator.

exceed 0.030 inch (0.762 mm) and the

area is no greater than 0.60 square inch

(2). Remove shaft−driven oil cooler impeller

(3.87096 square cm), repair according to

from transmission.

steps (3)., (4). and (6)..

(3). Remove internal wrenching bolt, tail

(2). If the depth of a depression exceeds

rotor drive coupling and shims. Keep

0.030 inch (0.762 mm) but does not

shims with coupling for reuse.

exceed 0.10 inch (2.54 mm) and the

area is no greater than 0.60 square inch

(4). Install suitable covers and plugs to

(3.87096 square cm), repair according to

protect seal ports, stud threads and the

steps (3). thru (6).

tachometer generator pad.

NOTE: Any evidence of lubricating oil leakage

NOTE: Further disassembly is not required.

in a repaired area requires replacement of

the transmission.

E. Main Transmission Buildup

(3). Clean area with solvent (1, Table 2−4)

(Ref. Figure 9−2 and Figure 9−3)

and remove sharp edges with grade 320

abrasive paper (9).

(1). Install one preliminary 0.010 inch

(0.254 mm) shim on transmission

(4). Apply a coat of primer (4) on the

output (tail rotor drive) gearshaft to

repaired surface.

prevent internal wrenching bolt from

bottoming against end of gearshaft.

(5). Fill depression with epoxy adhesive (19)

(2). Coat coupling splines with corrosion

and blend to surrounding surfaces.

preventive compound (70, Table 2−4)

before assembly. Install tail rotor drive

(6). Touch up the reworked area with paint

Page 9-8

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TAIL ROTOR DRIVE HOUSING COVER

ACCESSORY DRIVE PINION

TACHOMETER GENERATOR

DRIVE SHAFT

ACCESSORY DRIVE GEAR

TAIL ROTOR DRIVE OUTPUT PIN−

ION GEARSHAFT

ACCESSORY DRIVE PINION

INPUT BEVEL GEAR

50−70 IN. LB

(5.65−7.91 NM)

LUBE PUMP DRIVE SHAFT

LUBE PUMP & FILTER

OUTPUT SHAFT

FILLER CAP & BREATHER

SPLINES

65−75 IN. LB

OIL JET FOR COUPLING

50−60 IN. LB

INPUT BEVEL GEAR

(7.34−8.47 NM)

(5.65−6.78 NM)

OUTPUT SEAL

TAIL ROTOR DRIVE HOUS−

(NOTE 1)

SHIM & O−RING

ING COVER NUTS: 50−70 IN.

LB (5.65−7.91 NM)

OUTPUT COVER

NUTS: 50−70 IN. LB

OIL SEAL

(5.65−7.91 NM)

OUTPUT PINION

SCAVENGE OIL

GEARSHAFT

RETURN TUBE

(DISCHARGE)

SEAL RETAINER

OUTPUT BEVEL GEAR

DRAIN TUBE

OIL PRESSURE SENDER

30−40 IN. LB (3.39−4.52 NM)

OIL TEMPERATURE SWITCH

12−25 IN. LB (1.36−2.82 NM)

SELF−CLOSING DRAIN

SCAVENGE PUMP

VALVES (NOTE 2)

65-75 IN. LB (7.34-8.47 NM)

CHIP DETECTORS

BLOWER SPACER

FACE SEAL

SHROUD MOUNT

INPUT SEAL DRAIN

INPUT PINION GEARSHAFT

BLOWER SPACER (MATCHED TO TRANSMISSION

FOR IMPELLER−TO−SHOUD MOUNT CLEARANCE)

BLOWER BRACKET MOUNT

INPUT SEAL DRAIN

NOTE:

SHROUD MOUNT FOR SHAFT−DRIVEN BLOWER

INSTALLED AT INSTALLATION.

TORQUE TO 50−60 IN. LB (5.65−6.78 NM).

30−073E

Figure 9-3. Main Transmission Cross-Section

Page 9-9

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

4. Lubrication Pump and Oil System

B. Lubrication Pump Installation

Accessories

(Ref. Figure 9−2)

(Ref. Figure 9−3) The main transmission has a

(1).

Remove plugs from pressure ports in

self−contained oil system.

pump and transmission.

A lubrication pump draws oil from the main

(2).

Install new O−rings in ports and

sump of the transmission housing and

O−ring groove of pump sleeve. Apply a

provides oil flow to the oil pressure sender,

light coating of petrolatum (34,

bearings, gears and the output spline for the

Table 2−4) to both the O−ring and

main rotor drive shaft.

mating bore in transmission to prevent

damage to O−ring.

The pump is a positive−displacement, vane−

type with a non−adjustable discharge pressure

(3).

Align square drive of pump with drive

of 25−50 psi (172−345 kPa). It is driven at

shaft in transmission and carefully

4200 rpm by the accessory drive gear splined

press pump into place on mating

to the tail rotor output gearshaft.

surface.

(4).

Install three washers and nuts; torque

A relief valve that cracks open above 60 psi

50 − 70 inch−pounds (5.65 − 7.91

(414 kPa), with full flow bypass at 100 psi (690

Nm).

kPa) maximum, and a filter are integral parts

of the lubrication pump housing.

(5).

Ground run the helicopter according to

the Owner’s Manual and check pump

A vane−type scavenge pump, with a discharge

parting surfaces for leaks, and pressure

pressure of 10−20 psi (69−138 kPa) is mounted

warning light for proper operation.

on the upper end of the input pinion.

Refer to Fluid Leaks Analysis (Ref. Sec.

2). Replace defective O−rings. Contin−

The scavenge pump draws oil from the input

ued excessive leakage requires pump

gearshaft sump and pumps the oil to a

replacement.

discharge tube mounted inside the top of the

transmission housing.

(6).

Reinstall access covers and sound

insulation.

The tube is perforated to direct oil against the

interior sides of the transmission housing to

C. Lubrication Pump and Oil System

produce cooling as the oil drains down to the

Accessories Inspection

main sump.

(1). Inspect for external leaks around

mounting pad and ports, and for cracks

Externally mounted oil system accessories

or corrosion.

include a combined filler/breather, a liquid

level plug, two chip detectors, an oil pressure

(2). Check that all safetywire is intact.

sender and temperature warning switch.

(3). Check sender, switch, tachometer, and

A. Lubrication Pump Removal

electrical connections for security.

D. Transmission Filter Replacement

(Ref. Figure 9−2)

Refer to Transmission Lubrication Pump Oil

(1). Remove sound insulation and transmis−

Filter Cleaning (Ref. Sec. 2) for removal,

sion access covers.

cleaning, inspection and installation of the

filter.

(2). Remove three nuts and washers that

secure pump housing to mounting pad.

E. Chip Detector Replacement

(3). Remove pump and discard the three

Refer to Main Transmission Draining (Ref. Sec

O−rings. To exclude foreign matter,

2) for removal and installation instructions.

plug inlet and discharge ports in pump

Refer to Section 17 for functional test of

housing, and the drive bore.

detector circuit.

Page 9-10

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

F. Tachometer Generator Replacement

(3). Remove sight plug by unscrewing

counterclockwise.

(Ref. Section 17)

(4). Remove and inspect O−ring. Install new

G. Oil Pressure Sender and Temperature

O−ring, if required on sight plug.

Switch Replacement

NOTE: When a new sight plug is to be

installed, use the S−51HL bullseye type that

(Ref. Figure 9−3)

may be torqued to any position.

NOTE: When oil temperature switch is to be re−

(5). Install sight plug by screwing clock−

placed, drain oil from transmission.

wise. Torque sight plug to 80 − 90

inch−pounds (9.04 − 10.17 Nm);

(1).

Cut safetywire from temperature

install safetywire.

switch.

I. Application of Markings on Liquid Level

(2).

Remove electrical wire from terminal

Plug

post.

(Ref. Figure 9−2) If decal type oil level mark−

(3).

Unscrew switch or sender in a counter−

ings are not available, paint markings can be

clockwise direction. Catch any residual

applied to the sight gage after it is torqued into

oil from the transmission port in an

the transmission. Use the dimensions shown

absorbent cloth.

in detail A, and proceed as follows.

(4).

Apply a light coat of antiseize com−

(1). Using a machinists level and scale,

pound or tightly wrap two to three

scribe an ADD line horizontally on both

turns of teflon tape (36 or 79,

outer faces of the sight plug, Do NOT

Table 2−4) on the replacement sender

mark the window.

or switch.

(2). Scribe the FULL line horizontally on

both outer edges of the sight plug. DO

(5).

Install oil pressure sender; torque to 30

NOT mark the window.

−

40 inch−pounds (3.39 − 4.52 Nm).

Application of any paint not ex−

(6).

Install oil temperature switch; torque to

CAUTION

pressly made for polycarbonate

12 − 25 inch−pounds (1.36 − 1.69

plastic or any cleaning material other than

Nm).

soap and water to the sight plug window

may cause it to craze.

(7).

Safetywire the temperature switch hex

to adjacent lug on transmission hous−

(3). Using white paint (6, Table 2−4), paint

ing.

four 0.050 inch (1.27 mm) wide lines

with the edges touching the scribe

(8).

Connect electrical wire to terminal post.

marks as shown in detail A. DO NOT

paint the surface of the window.

NOTE: If the oil pressure sender is the dual

contact type used in conjunction with a run−

J. Repair and Replacement of Transmission

ning time meter, refer to wiring diagram in

Drains and Tubing

CSP− H− 3 to be sure wire connections are

(Ref. Figure 9−4)

properly made.

(1). Removal

(9). Service transmission (Ref. Sec. 2).

(a). Disconnect transmission drains tubes

H. Liquid Level (Sight) Plug Replacement

from transmission components and at

the firewall drain fitting.

(Ref. Figure 9−2)

(b). Release supporting nylon straps and

(1). Drain oil from transmission until oil

remove drain tubes.

level is well below edge of sight plug

and port.

(c). Remove attaching clamp on engine

compartment lower firewall drain

(2). Remove safetywire from sight plug.

tube and remove drain tube.

Page 9-11

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

FAN AND BEARING MOUNT

MAIN TRANSMISSION DRAIN TUBE

ASSY DRAIN TUBE

(TAIL ROTOR DRIVE OUTPUT SEAL)

MAIN TRANSMISSION

BULKHEAD CHANNEL

FAN DRAIN TUBE

PLENUM CHAMBER DRAIN

FIREWALL DRAIN FITTING

STA. 124.00 CANTED FRAME

MAIN TRANSMISSION DRAIN TUBES

(WITH BELT−DRIVEN BLOWER)

DRAIN TUBE

MAIN DRIVE SHAFT

INPUT PINION SEAL

NYLON GROMMET

DRAIN TUBE

NOTE 1

0.250 IN.

(6.35 MM)

NOTE 2

1.00 IN (25.4 MM)

0.375 IN.

FWD

1.62 IN.

(9.525 MM)

(41.148 MM)

STRAP

0.62 IN.

(1.5748 MM)

0.062 IN.

0.065 IN.

45°

CHANNEL CLIP

(1.5748 MM)

(16.51 MM)

BULKHEAD

CHANNEL

NYLON STRAP

SAFETY WIRE

(TYPI)

RUBBER CHAFE STRIP

BLOWER SCROLL DRAIN TUBE

SAFETY WIRE

(TYPICAL)

DRAIN ASSY SHROUD

DRAIN TUBE

FIREWALL DRAIN

FITTING

MAIN TRANSMISSION DRAIN TUBE

(TAIL ROTOR DRIVE OUTPUT PINION

SEAL DRAIN)

MAIN TRANSMISSION DRAIN TUBES

NOTES:

(WITH SHAFT−DRIVEN BLOWER)

TYGON TUBING (TYPE R3603).

2024−T3 ALUMINUM ALLOY TUBE

(FEDERAL SPEC WW−T−700/4).

30−074E

Figure 9-4. Main Transmission Drain Tubing

Page 9-12

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE: Remove main transmission input pin−

(d).

Position transmission drain assembly

ion drain and bushing (detail C) whenever

and install bolts. Check that trans−

the transmission is replaced. The flex−tube

mission flex−tube will drain directly

and bushing are not normally part of a spare

into mating assembly port.

transmission assembly.

(e).

Attach upper ends of drain tubing to

(d). Grasp the flex−tube and pull out to

transmission drain assembly; secure

release the bond. Insert a 5/16 or 3/8

with double wraps of 0.032 inch

inch tap or easy−out into tube ID and

lockwire.

rotate to pull out bushing.

(f).

Route drain tubing and secure with

(2). Inspection

nylon straps as shown in detail B.

Position tubing so that drainage

Inspect drains and tubing for service−

traps are formed.

ability and repair as necessary.

(g).

Secure lower ends of drain tubing to

(3). Repair

firewall drain fitting with double

wraps of 0.032 inch lockwire.

(a). Repair a damaged polycarbonate

plastic drain assembly according to

(h).

Position engine compartment firewall

the criteria and methods specified for

drain tube; wrap tube with one layer

for acrylic plastic in FAA AC

of 1 inch (2.54 cm) width pressure−

43.13−1A, Aircraft Inspection and

sensitive polyurethane tape (42) at

Repair. Use dichloromethane (38,

clamp−attach point, and install

Table 2−4) or ethylene dichloride (39)

clamp.

as the bonding agent.

Main Rotor Drive Shaft

(b). Repair deteriorated or otherwise

damaged mounting gasket segments

(Ref. Figure 9−5) The main rotor drive shaft is

on the plastic drain assembly by

a shot−peened, nitrated steel alloy forging

replacing with new gasket material

having a spline coupling at one end that mates

(40).

with the main transmission output shaft, and

an octagon shaped head that attaches to the

(c). Repair damaged flexible drain tubing

main rotor hub with four bolts and four

with tape (41).

hoisting eyebolts.

(4). Installation

The main rotor drive shaft is a

CAUTION

highly stressed part. Do not al−

(a). On newly installed main transmis−

low tools to strike the shaft, or the shaft to

sion clean mating surfaces of flex−

strike any object. Any impact damage may

tube, bushing and transmission drain

require replacement of the drive shaft.

outlet with solvent (1).

A. Main Rotor Drive Shaft Removal

NOTE: A replacement flex− tube and bushing

may be fabricated using materials and di−

mensions shown in detail C.

(1). Remove the nuts, washers, bolts, and

hoisting eyebolts.

(b). Bond flex−tube to bushing and

bushing to transmission with sealing

Whenever the drive shaft is re−

CAUTION

compound (3), according to container

moved, cover the opening in the

instructions.

top of the main rotor hub to prevent possible

entry of foreign matter into the hub, mast,

(c). Remove excess sealing compound and

and the transmission.

scarf the flex−tube 45 degrees (detail

C).

(2). Lift drive shaft clear of main rotor hub.

Page 9-13

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Main Rotor Drive Shaft Installation

according to Specification ASTM E1444.

No surface or sub−surface defects are

Damage to main rotor drive

permissible.

CAUTION

shaft or main transmission

splines can occur during installation. Care

(3). Inspect all external surfaces of drive

should be taken while meshing driveshaft

shaft for corrosion. Remove corrosion as

splines into transmission output splines to

follows.

prevent damage.

(a). Degrease corroded area of drive shaft

(1).

Position drive shaft over main rotor hub

with clean cloth saturated in trichlo−

with gear coupling down.

roethane.

Surface cleaner irritates hands

(2).

Slowly and carefully lower drive shaft

CAUTION

on repeated exposure. Rubber

through main rotor hub and mast until

gloves should be worn.

rotor shaft splines and transmission

shaft splines engage.

(b). Swab shaft exterior with diluted

solution of surface cleaner (10,

(3).

Rotate drive shaft head to align holes in

Table 2−4) (Mix one part surface

flange with holes in hub.

cleaner with four parts water). Keep

wet with solution for 10 minutes or

(4).

Install in every other hole, four hoisting

until corrosion appears to be re−

eyebolts, each with a countersunk

moved. Wipe clean and inspect.

washer (beveled next to head).Then

Repeat as necessary until there is no

install the nuts, each with two standard

further evidence of corrosion.

thin flat washers; do not tighten nuts.

(c). Rinse with water and dry thoroughly

(5).

Install the four remaining bolts, with

with compressed air.

washers and nuts in the same manner.

Exercise care when removing

(6).

Align hoisting eyebolt so that a center−

CAUTION

pits to ensure that shot peening

line through the eyebolt flats intersects

is not completely penetrated. Also, remove

the drive shaft axis. Using torque

only minimum material necessary to re−

wrench adapter (32, Table 2−2), torque

move pits.

all nuts to 120 − 140 inch−pounds

(13.56 − 15.82 Nm).

(d). Light abrade corroded surface with

crocus cloth to remove pits. If pit

C. Main Rotor Drive Shaft Inspection

removal exceeds depth of 0.0012 inch

(0.03048 mm) in area 2, shaft is

(1). Inspect all surfaces of drive shaft for

unserviceable and must be replaced.

dents, nicks scratches, and evidence of

deformation. Inspect splines on end of

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

drive shaft for excessive wear. No

damage of any kind is permissible in

(f). Spray two coats of primer (4,

the area within 2 inches (5.08 cm) of

Table 2−4) on shaft exterior. DO NOT

the spur gear. Dents less than 0.050

primer spline teeth of mounting

inch (1.27 mm) deep and 0.050 inch

surface.

(1.27 mm) diameter are permissible in

other areas. A dent is defined as a

(4). Apply preservative oil to spline teeth

smooth depression on the surface with

and mounting surface.

no sharp edges or abrupt changes in

contour. No nicks or scratches are

(5). Immediately reinstall main drive shaft.

permitted.

(6). Apply 0.060 inch (1.524 mm) bead of

(2). If shaft condition is questionable,

sealing compound around interface of

perform a magnetic particle inspection

hub and drive shaft.

Page 9-14

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

HOISTING EYEBOLT

8 IN. (20.32 CM)

NOTE 1

NOTE 2

5.4 IN. (13.716 CM)

CORK

(NOTE 3)

AREA 4

AREA 1: MAXIMUM PIT DEPTH 0.0012 IN. (0.03048 MM).

AREA 2: MAXIMUM PIT DEPTH 0.0008 IN. (0.02032 MM)

AREA 3: MAXIMUM PIT DEPTH 0.0020 IN. (0.0508 MM)

AREA 4: CHECK SPLINES BY MEASURING ACROSS

TWO 0.108 IN. (2.7432 MM) DIA. PINS PLACED

IN OPPOSITE SPLINE GROOVES. MEASURED

DIMENSION SHOULD BE 2.2643 IN.

(5.751322 CM) MIN.

120−140 IN. LB

(13.56−15.82 NM)

120−140 IN. LB

TORQUE WRENCH ADAPTER

(13.56−15.82 NM)

(369A9957)

TOOTH CONTACT

0.010 IN. (0.254 MM)

0.050 IN. (1.27 MM)

AREA

MAX DEPTH

MAX

0.050 IN. (1.27 MM)

MAX

NOTES:

FLAT OF EYEBOLT HEADS TO INTERSECT DRIVE SHAFT AXIS.

INSPECTION DATA

INSTALL WITH COUNTERSINK NEXT TO EACH BOLTHEAD.

OTHER WASHERS ARE STANDARD FLAT.

INSTALL WITH SEALING COMPOUND (3, TABLE 2−4).

30−075E

Figure 9-5. Main Rotor Drive Shaft

Page 9-15

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

D. Main Rotor Drive Shaft Exterior Repair

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

carefully grind, blend and polish out

nicks and chips which are outside the

No repair of drive shaft is permitted except for

critical (active) spline tooth contact

removal of light surface corrosion and polish−

areas (see Area 4 profile and end

ing of minor nicks and chips in noncritical

views for permissible repair areas).

spline areas indicated below.

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

(1). Remove corrosion as follows:

operation extends beyond limits

shown, or if any tooth damage exists

(a). Degrease corroded area of drive shaft

within the critical tooth contact area,

with clean cloth saturated with

shaft is unserviceable and must be

trichloreothane (61, Table 2−4).

replaced.

(c). Perform magnetic particle inspection

Surface cleaner used in 2 be−

according to Specification

WARNING

low irritates hands on re−

MIL−I−6868. No surface or sub−sur−

peated exposure. Rubber gloves should

face defects are permissible.

be worn.

6. Main Transmission Drive Shaft

(b). Swab shaft exterior with diluted

(Ref. Figure 9−6, Figure 9−10 and Figure 9−7)

solution of surface cleaner (10) (Mix

The main transmission drive shaft is a

one part surface cleaner with four

dynamically pre−balance steel shaft equipped

parts water). Keep wet with solution

with a flexible diaphragm−type joint and

for 10 minutes or until corrosion

mounting flange (coupling) at each end. The

appears to be removed. Wipe clean

shaft interconnects the overrunning clutch and

and inspect. Repeat as necessary

the transmission input shaft.

until there is no further evidence of

corrosion.

A. Main Transmission Drive Shaft Removal

(c). Rinse with water and dry with

(1). Remove sound insulation and main

transmission access cover over main

compressed air.

transmission drive shaft in cargo

compartment.

Exercise care when removing

CAUTION

pits to ensure that shot peening

(2). Remove eight bolts and washers that

is not completely penetrated.

secure shaft to couplings.

(3). Remove drive shaft; use care to keep it

(d). Lightly abrade corroded surface with

from striking any object.

crocus cloth (23) to remove pits. If pit

removal exceeds depth of 0.0012 inch

NOTE: The clutch oil level should be checked

(0.03048 mm) in Area 1 or 0.0008

any time engine or main drive shaft is re−

inch (0.02032 mm) in Area 2, shaft is

moved (Ref. Sec. 2).

unserviceable and must be replaced.

B. Main Transmission Drive Shaft

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

Installation

(1). Check overrunning clutch for proper oil

(f). Spray two coats of epoxy primer and

level, indications of oil seepage, drive

catalyst reducer (128 and 129), mixed

shaft couplings for corrosion and that

per manufacturer’s instructions, on

the bolt securing the clutch coupling

shaft exterior. Do not prime spline

seated properly. With anti−seize

teeth or mounting surface.

compound (36, Table 2−4) on threads,

torque bolt to 250 − 300 inch−pounds

(2). Polish out minor nicks and chips on

(28.25 − 33.90 Nm) plus drag torque.

shaft spline teeth as follows:

Check coupling bolt for drag torque

Page 9-16

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

serviceability of 25 inch−pounds (2.82

DO NOT USE clutch coupling

CAUTION

Nm) minimum, 200 inch−pounds

shims under transmission input

(22.60 Nm) maximum.

coupling. The ID of clutch coupling shims

are 1.260−1.270 inches (32.004−32.258

Compression of the drive shaft

mm), that’s approximately 0.070 inch (1.778

CAUTION

diaphragms (static state) is lim−

mm) larger than the ID of shims used at the

ited to 0.020 inch (0.508 mm). Do not stress

transmission coupling, while the OD is the

the diaphragms by forcing the drive shaft

same. The difference in ID can cause an im−

into position for installation in step (2). be−

properly seated shim, misalignment and

low.

cocking of the coupling.

NOTE: If original shaft and couplings are being

(4). Attach driveshaft to clutch coupling

reinstalled, a check of shimming as de−

with four bolts and washers. Torque

scribed below is not necessary. Install drive

bolts to 50 − 70 inch−pounds (5.65 −

shaft to clutch and transmission couplings

7.91 Nm).

as described in steps (1). and (4).

(5). Manually align the driveshaft and

(2). Position drive shaft alongside the

transmission input coupling flange.

transmission input and clutch cou−

Using a feeler gage, measure the gap

plings. If compression will be required

between the flanges (detail A). If gap is

to fit driveshaft between the couplings,

0.010 inch (0.254 mm) or less, attach

continue with step (3). If there is a gap

upper end of driveshaft to transmission

between the drive shaft flanges and the

input coupling according to step (4). If

coupling flanges continue with step (4).

gap exceeds 0.010 inch (0.254 mm),

repeat step (3)., except install a thick−

NOTE: Removal or addition of shims should be

ness of shims equal to the measured

accomplished at transmission input cou−

gap, plus 0.010 inch (0.254 mm)

pling only. Shims at overrunning clutch cou−

additional thickness. A nominal 0.010

pling are predetermined thickness to pro−

inch (0.254 mm) compression of the

vide 0.035−0.055 inch (0.889−1.397 mm) gap

shaft diaphragm is the preferred static

to prevent O−ring packing damage and oil

state condition.

leakage.

(6). Install access door and sound insulation

(3). Remove coupling bolt that secures

over main transmission driveshaft.

transmission input coupling and

remove coupling. Remove sufficient

C. Main Transmission Drive Shaft Inspection

shims so there is no compression of

(Bendix)

shaft flexible coupling. A minimum of

0.010 inch (0.254 mm) shim is required

(1). Inspect drive shaft diaphragms for

between end of drive input shaft and

dents, cracks, scratches, nicks, rust

coupling; to prevent coupling bolt from

spots and evidence of joint separation

bottoming out on bolt seating surface

from shaft or outside edges. Evidence of

and end of shaft input. Lubricate input

any such defects on either diaphragm

shaft splines with grease (21) Coat bolt

requires removal of shaft from service.

threads with anti−seize compound (36).

Reinstall coupling and bolt. Check

(2). Inspect drive shaft tube between

coupling bolt for drag torque service−

diaphragms for dents, scratches, cracks

ability of 25 inch−pounds (2.82 Nm)

or corrosion pits.

minimum, 200 inch−pounds (22.60

(a). Measure depth and diameter of

Nm) maximum. Torque bolt to 250 −

dents. Dents that blend smoothly into

300 inch−pounds (28.25 − 33.90 Nm)

surrounding surface area with no

plus drag torque.

sharp change in contour and do not

NOTE: Transmission input coupling shims are

exceed 0.015 inch (0.381 mm) depth

laminated stock. Each lamination is 0.002

are acceptable. Dents not within

inch (0.0508 mm) thick. Peel away as re−

these limits require removal of shaft

quired.

from service.

Page 9-17

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Measure depth of cracks, nicks,

(a).

Measure depth and diameter of

corrosion pits, or scratches; length

dents. Dents that blend smoothly into

and direction are not limited. Maxi−

surrounding surface area with no

mum depth allowed before rework is

sharp change in contour and do not

0.003 inch.

exceed 0.010 inch (0.254 mm) in

depth are acceptable. Dents not

(c). Check suspected cracks using dye

within these limits require removal

penetrant. If crack indication ap−

of shaft from service.

pears, remove black (phenolic com−

(b).

Measure depth of cracks, nicks,

pound) coating from area (Ref. Main

corrosion pits or scratches; length

Transmission Drive Shaft Repair

and direction are not limited. Maxi−

(Bendix).

mum depth allowed before rework is

0.005 inch (0.127 mm).

NOTE: Drive shaft is coated with special phe−

nolic thermosetting compound. It is a brittle

(c).

Check suspected cracks using dye

coating that may indicate a crack that does

penetrant. If crack indication ap−

not penetrate tube.

pears, remove coating from surface.

(d).

Re−inspect suspected area using

(d). Reinspect suspected area using

magnetic particle or dye penetrant

magnetic−particle or dye−penetrant

methods. If crack does not reappear,

touch up cleaned area with primer

coating (4, Table 2−4) and return part

to service.

to service. If shaft is found to be

cracked, remove shaft from service.

NOTE: Perform inspections in steps (3). and

Kamatic parts cannot be inter−

(4). only if shaft damage is suspected.

CAUTION

changed between drive shafts.

(3). Inspect shaft tube for out−of−round

(3). Inspect all attaching hardware for

condition. Ovality shall not exceed

serviceable condition. Discard and

0.060 inch (1.524 mm) tir.

replace defective hardware.

NOTE: Perform the following inspections if

(4). Inspect shaft for straightness. Shaft

shaft damage is suspected.

shall be within 0.030 inch (0.762 mm)

tir at all locations relative to the

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

centerline of the two flange mounting

condition not to exceed 0.060 inch

bolt pattern.

(1.524 mm).

(5). Inspect all attaching hardware for

(5). Inspect shaft for straightness. Shaft

serviceable condition. Check nut plates

shall be straight within 0.030 inch

for drag torque. Discard defective

(0.762 mm) at all locations relative to

hardware.

centerlines of two flange mounting bolt

patterns.

D. Main Transmission Drive Shaft Inspection

E. Main Transmission Drive Shaft Couplings

(Kamatic)

Corrosion Removal

(1). Inspect drive shaft for dents, cracks,

(1). Prior to installing original drive shaft

scratches, nicks, rust spots and evi−

coupling (369A5512 or 369H5560 only),

dence of joint separation from shaft or

inspect flange face of coupling for

outside edges.

fretting corrosion. Evidence of fretting

may be removed by hand lapping the

(2). Inspect drive shaft tube between

effected parts using a sheet of # 440 (or

couplings for dents, scratches, cracks or

finer) emery cloth (49, Table 2−4) or wet

corrosion pits.

or dry abrasive paper (9) placed on a

Page 9-18

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

surface table with a figure eight motion,

(c). After rework, check shaft tube wall

using care not to let the part rock.

thickness in repair area.

NOTE: Coupling may be reused if flange thick−

(d). Apply primer coating (4) for corrosion

ness is not less than 0.10 inch (0.254 mm)

protection.

after cleanup; Recheck shimming.

7. Oil Cooler Blower

F. Main Transmission Drive Shaft Repair

The belt−driven blower is mounted to a

(Bendix)

bracket on the back underside of the main

transmission and coupled to the transmission

(1). Repair of drive shaft diaphragms is not

input shaft through a pulley drive.

permissible.

The blower consists of a riveted and brazed

(2). Repair all damage that is no deeper

impeller assembly of a casting and aluminum

than 0.003 inch (0.0762 mm).

blades within a polycarbonate plastic scroll

(a). Completely remove defect. Maintain

enclosure.

smooth transition into surrounding

The fiberglass scroll enclosure is used on the

surface.

current configuration helicopter and those

with the optional 250−C20 Series engine.

(b). Use grade 400 wet or dry abrasive

paper (9, Table 2−4) for preliminary

The belt driven impeller is dynamically

finishing, and then polish with crocus

balanced for operation at approximately

cloth (23). Restore surface until it

12,000 rpm.

equals original finish of shaft.

On the shaft−driven blower, the impeller is

(c). After rework, check shaft tube wall

mounted directly on the transmission input

thickness in repair area. Wall thick−

pinion gearshaft and is enclosed in a scroll

ness shall not be less than 0.025 inch

that is attached to the transmission housing.

(0.635 mm).

The shaft−driven impeller is dynamically

(d). Apply primer coating (4) for corrosion

balanced and rotates at approximately 6000

protection.

rpm.

G. Main Transmission Drive Shaft Repair

The blower draws cooling air over the main

(Kamatic)

transmission in addition to supplying forced

ambient air to the engine oil cooler, compart−

(1). Repairs of Kamatic drive shaft flexible

ment heating system and the engine area.

couplings are limited. Repairs to spring

Sections 10 and 13 provide information on the

area are not allowed. No cracks are

engine cooling and oil cooler ducting

allowed.

A. Oil Cooler Blower Removal (Early-Type,

(2). Repair drive shaft tube area damage

Belt-Driven)

that is no deeper than 0.005 inch (0.127

mm). Maximum depth after repair is

(Ref. Figure 9−6)

0.010 inch (0.254 mm). The maximum

(1). Remove main transmission driveshaft.

thickness of material removed shall not

be more than 10 percent of the original

(2). Remove belt−driven blower and

material thickness.

attached idler drive unit as follows.

(a). Completely remove defect. Maintain

(a). Remove four screws and nylon

smooth transition into surrounding

washers that attach blower belt drive

surface.

shroud to sides of transmission fan

mount assembly and mounting

(b). Use grade 400 wet or dry abrasive

bracket on idler drive unit. Remove

paper (9, Table 2−4) for preliminary

blower belt drive shroud.

finishing, then polish with crocus

cloth (23). Restore surface until it

(b). Disconnect drain tube and loosen

equals original finish of shaft.

scroll clamps.

Page 9-19

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

0.010 IN. (0.254 MM) MAX.

GAP; 0.020 IN. (0.508 MM)

MAX. COMPRESSION

BLOWER DRIVE

(NOTE 3)

SHROUD

NYLON

DRIVE SHROUD

WASHER

MOUNTING

(NOTE 6)

BRACKET

NYLON WASHER

BLOWER

SCROLL CLAMP

IDLER DRIVE UNIT

GASKET

NYLON WASHER

(NOTE 5)

FAN MOUNT

ASSEMBLY

DRAIN

INPUT SHAFT

DRAIN

DRIVE PULLEY

TUBE

COUPLING SHIMS

(NOTE 1)

65−75 IN. LB

(7.34−8.47 NM)

TRANSMISSION IN−

BELT (2)

PUT COUPLING

(NOTE 4)

COUPLING BOLT, 250−300 IN. LB

LOCKWIRE

(28.25−33.90 NM) PLUS DRAG TORQUE

(NOTES 2, 7)

MAIN TRANSMISSION DRIVE SHAFT

50−70 IN. LB

(5.65−7.91 NM)

50−70 IN. LB

(5.65−7.91 NM)

NOTES:

CORROSION RESISTANT STEEL SHIM, 0.002 IN.

(0.0508 MM) LAMINATIONS.

CAUTION: ID MUST NOT BE MORE THAN 1.20 IN. (30.48 MM).

DRAG TORQUE FOR BOLT (SELF−LOCKING) SERVICEABILITY

IS 25 IN. LB (2.82 NM) MIN., 200 IN. LB (22.60 NM) MAX.

CLUTCH COUPLING

CHECK WITH LOWER END OF SHAFT ATTACHED.

REPLACE ONLY AS A MATCHED SET.

BOND TO SHROUD WITH ADHESIVE (91, TABLE 2−4).

USE AS REQUIRED TO CLOSE SHROUD TO BRACKET GAP.

COAT COUPLING BOLT THREADS WITH ANTI−SEIZE COMPOUND

(36) BEFORE REASSEMBLY.

30−076−1F

Figure 9-6. Main Transmission Driveshaft and Early Type Belt-Driven

Oil Cooler Blower (Sheet 1 of 2)

Page 9-20

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

IDLER FAN SPRING

SHIMMING WASHER

(NOTE 9)

IDLER SHAFT

IDLER FORK

65−75 IN. LB

(7.34−8.47 NM)

IDLER PULLEY

BEARING

RETAINING

RING

DRIVE SHROUD MOUNT−

ING BRACKET

65−75 IN. LB

(7.34−8.47 NM)

IDLER FORK ASSEMBLY

LOCKWIRE

65−75 IN. LB

(7.34−8.47 NM)

IDLER DRIVE UNIT AS−

(7.34−8.47 NM)

SEMBLY

(160-190 IN. LB)

LOCKWIRE

CRES WASHER

(NOTE 8)

DRIVEN PULLEY

FAN MOUNTING BRACKET

IDLER MOUNTING

65−75 IN. LB

BRACKET

(7.34−8.47 NM)

BLOWER

IDLER FORK HOLD−

ING BRACKET

SPLIT

WASHER

(NOTE 7)

LOCKWIRE

SPACER

BUMPER

(NOTE 7)

IDLER FORK

IDLER FORK AD−

ASSY

JUSTMENT

SCREW

(NOTE 10)

BELTS

LOCKWIRE

NOTES: (CONT)

APPLY PRIMER (4, TABLE 2−4).

USE AS REQUIRED TO ALIGN IDLER PULLEY GROOVES WITH

DRIVE PULLEY GROOVES. (SEE BELT TENSION

AND PULLEY ALIGNMENT FIGURE.)

10. USE TO ADJUST IDLER FORK HOLD POSITION. (SEE BELT

TENSION AND PULLEY ALIGNMENT FIGURE.)

30−076−2F

Figure 9-6. Main Transmission Driveshaft and Early Type Belt-Driven

Oil Cooler Blower (Sheet 2 of 2)

Page 9-21

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(c). Cut lockwire from idler fork adjust−

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

ment adjustment screw sufficiently

any shimming washers that attach

so that idler fork can be positioned to

idler fork to idler shaft.

release belt tension.

(g). Remove idler yoke with attached

(d). Move idler fork to release belt

idler pulley, washer and any shim−

tension and disengage both belts

ming washers from idler shaft.

from main transmission input shaft

NOTE: The shaft bushing is factory installed

drive pulley.

by temperature−difference or press fit meth−

(e). Remove the lockwire, bolts and

od and is to remain in idler yoke.

washers that attach idler drive unit

(h). Remove idler fan spring from shaft

to the transmission fan mount

remaining on idler mounting bracket.

assembly.

(i). Remove nut, washer and bolt attach−

(f). Remove the assembled fan and idler

ing idler pulley to idler yoke.

drive unit.

NOTE: Retain shim washers with idler yoke.

(g). As required, remove coupling bolt,

transmission input coupling shim(s)

(j). Remove retaining ring to remove

and drive pulley from transmission

bearing from idler pulley.

input shaft. Keep shim(s) with

(k). Remove cotter pin, nut and CRES

couping for reuse.

washer securing idler shaft in

(3). Remove components from the idler

mounting bracket; remove idler shaft

drive unit only to the extent required

and split washer from idler mounting

for maintenance, as follows.

bracket.

(l). Remove idler fork holding bracket.

(a). Remove nylon bumper from idler fork

adjustment screw and adjustment

B. Oil cooler Blower Installation (Early- Type,

screw from fork holding bracket on

Belt- Driven)

idler mounting bracket.

(1). Install belt−driven blower and idler

(b). Remove lockwire, bolts, and washers

drive unit as follows:

that attach fan mounting bracket to

idler mounting bracket

(a).

Reassemble components on the idler

mounting bracket, to the extent

(c). Remove spacer, belts fan and at−

disassembled for maintenance, by

tached fan mounting bracket from

reversing the order of disassembly

idler mounting bracket. Keep spacer

and complying with the following

with fan mounting bracket for reuse.

instructions. See Figure 9−9 for stack

of parts.

The impeller must be hand−

CAUTION

held for pulley attachment nut

(b).

Assemble idler pulley parts but do

removal. Do not hold impeller blades with

not torque nut at this time.

tools or other devices to remove nut. Such

action can physical damage.

(c).

Reinstall shim washers on sides of

idler fork attachment end as required

(d). Remove cotter pin, pulley attachment

so that dimensions ‘‘B’’ and ‘‘C" (Ref.

nut and driven pulley for access to

Figure 9−9) are equal and provide

fan mounting bolts. Nut is removed

0.001−0.020 inch (0.0254−0.508 mm)

by reaching through blower scroll

coaxial clearance.

primary air outlet and carefully

(d).

Install idler spring on idler shaft so

hand−holding the impeller.

that spring hook will be approximate−

(e). Remove lockwire, bolts and washers

ly 3 O’clock on the shaft centerline

attaching fan to fan mounting

looking aft (at idler fork free posi−

bracket; remove fan.

tion).

Page 9-22

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(e). Apply primer (4, Table 2−4) to inside

(k). Install shroud mounting bracket on

of square hole in idler mounting

idler mounting bracket, using

bracket and split washer when

washers and bolts. Torque bolts to 65

installing idler spring shaft and idler

−

70 inch−pounds (7.34 − 7.91 Nm).

fork. Torque nuts attaching idler fork

(l). Install hard−anodized driver pulley

to idler spring shaft to 65 − 75

on splined transmission input shaft.

inch−pounds (7.34 − 8.47 Nm).

Reinstall existing shims and output

Ensure free movement of idler spring

coupling. Coat coupling threads with

is not hampered.

anti−seize compound (36) and install

bolt. Check that bolt self−locking

(f). Torque bolts that attach fan to fan

torque is not less than 25 inch−

mounting bracket to 65 − 75 inch−

pounds (2.82 Nm) or more than 200

pounds (7.34 − 8.47 Nm).

inch−pounds (22.60 Nm). Torque

bolt to 250 − 300 inch−pounds

Impeller must be hand−held

CAUTION

(28.25 − 33.90 Nm) plus drag

when torquing pulley nut. DO

torque.

NOT use tools or other devices to hold im−

peller while torquing pulley attachment

(m). Position drive belt on driver, driven

nut.

and idler pulleys.

(g).

Reach through scroll primary air

(2). Check for proper alignment of all three

outlet and hand−hold impeller.

pulleys as follows

Torque nut attaching driven pulley to

(a). Clamp alignment tool 369H9008 to

impeller shaft to 160 − 190 inch−

left side upper surface of the driver

pounds (18.08 − 21.47 Nm).

pulley.

(h).

Position drive belt on driven pulley

NOTE: Alignment tool is designed so that if

and attach fan mounting bracket

idler pulley and driven pulley are in perfect

(with blower assembly) to idler

alignment with the driver pulley, 0.030 inch

mounting bracket. Install spacer with

(0.762 mm) feeler gage will just fit under off−

primer and torque fan mounting

sets in tool at both idler and driven pulley

bracket bolts to 65 − 75 inch−

surfaces. This tool is required to ensure

pounds (7.34 − 8.47 Nm).

alignment each time belt drive components

are removed and replaced.

(i).

Rotate the idler arm to extreme

(b). If misalignment of driver pulley to

position away from holding bracket.

driven pulley exceeds 0.020 inch

Position strap so that side of slot

(0.508 mm), perform one or both of

closest to spring touches the slot bolt.

the following.

Torque the idler pulley bolt to 65 − 75

inch−pounds (7.34 − 8.47 Nm).

1). Loosen four bolts attaching idler

Check movement of idler strap by

mounting bracket to transmission

pivoting idler arm. If necessary,

mounting pad and slide bracket in

adjust strap position to assure full

direction desired. Re−secure and

travel within limits of slot.

torque bolts to 65 − 75 inch−

pounds (7.34 − 8.47 Nm).

NOTE: Prior to installation, inspect all ducting

inlets and outlets and entire blower fan and

2). If adjustment in step 1). is not

scroll area for blockage or foreign objects.

sufficient and driven pulley still

needs to be raised, remove the

(j). Position and install assembled drive

driver pulley from the transmis−

belt unit (with blower) on transmis−

sion input shaft and transfer

sion mounting pad, using existing

369A5625 coupling shims, as

washers and bolts. Do Not torque

required, to upper side of driver

bolts at this time. Reconnect scroll

pulley. Reinstall driver pulley and

ducting and rubber connectors.

coupling bolt.

Page 9-23

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(c). Align idler pulley to driven pulley, as

C. Oil Cooler Blower Removal

required, by transferring shims

(Current-T ype, Belt-Driven)

between dimensions ‘‘B" and ‘‘C" (Ref.

(Ref. Figure 9−7)

Figure 9−9); hold to 0.020 inch (0.508

mm) maximum misalignment.

(1). Remove main transmission driveshaft.

Ensure that idler arm is not ham−

pered.

(2). Remove transmission input coupling

bolt, input coupling, coupling shims and

input shaft drive pulley. Retain shim for

(d). Remove and clamp alignment tool on

reinstallation.

right (opposite) side of driver pulley

and recheck alignment to driven

(3). Cut lockwire and remove four bolts

pulley on that side. Alignment should

attaching mounting bracket to trans−

agree within 0.015 inch (0.381 mm)

mission fan mount assembly. Retain

to measurement obtained in step (b).

laminated shims for reinstallation.

(3).

Adjust idler fork for proper belt tension.

(4). Cut lockwire and remove four bolts

attaching mounting bracket to fan

mounting bracket.

(4).

Reconnect blower scroll drain tube.

Reinstall channel assemblies, as

(5). Disconnect blower scroll drain tube.

applicable, using eight screws, washers

Loosen scroll duct clamp and roll back

and nuts. Do not use rivets.

rubber connectors; disconnect scroll

ducts.

(5).

Install guard, using existing shroud

hardware. Install transmission input

NOTE: The capstrip on the right channel, adja−

shaft seal drain tube on right side of

cent to blower, may be removed if required

guard, using clamp shown in

for access.

Figure 9−6, view C. Pull drain tube

(6). Remove fan mounting bracket (with

downward and secure to helicopter

blower scroll, pulley and belt) from

structure with tie−strap.

helicopter.

(6).

Connect blower scroll drain tube and

The impeller must be hand−

CAUTION

check for excess slack and close proxim−

held for removal of driven pulley

ity to driveshaft. Reposition and secure

attachment nut. Do not hold impeller blades

drain tube with tie−strap to helicopter

with tools or other devices to remove nut.

structure, as required, to eliminate

Such action can affect impeller balance as

slack or possible interference with

well as cause physical damage.

driveshaft. Check drain tube for kinks.

(7). Remove nut and washer securing

driven pulley on impeller shaft.

(7).

Install main transmission driveshaft.

(8). If required, cut lockwire and remove

(8).

Rotate driveshaft by hand and check

bolts attaching fan mounting bracket

pulley operation.

tom blower assembly.

D. Oil Cooler Blower Installation

(9).

Lockwire in pairs: the four bolts

(Current- Type, Belt- Driven)

securing the idler mounting bracket to

the transmission mounting pad; and

(1). Install fan mounting bracket on blower

the four bolts securing idler mounting

assembly.

bracket to fan mounting bracket.

NOTE: Before tightening bolts, remove bolt

hole slack in the belt tension direction by

(10).

Perform operational check of belt−driv−

moving blower toward, and bracket away

en oil cooler blower system.

from, the transmission driveshaft side.

(11).

Install main transmission access covers

(2). Torque bolts to 65 − 75 inch−pounds

and trim cover panel.

(7.34 − 8.47 Nm).

Page 9-24

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

65−75 IN. LB

0.010 IN. (0.254 MM) MAX. GAP

(7.34−8.47 NM)

0.020 IN. (0.508 MM) MAX. COM−

160−190 IN. LB

PRESSION

(18.08−21.47 NM)

(NOTE 3)

THIN WASHER (5710−84−16)

(NOTE 5)

DRIVE PULLEY

COUPLING−T O−DRIVE

DRIVEN PULLEY

SHAFT ATTACHMENT

THICK WASHER (AN960−916)

(NOTE 5)

SCROLL CLAMP

(65 - 75 IN. LB)

MOUNTING BRACKET

LAMINATED

SHIM (2)

BLOWER

FAN MOUNT ASSY

SPACER

FAN MOUNTING

BRACKET

INPUT SHAFT

DRIVE PULLEY

COUPLING SHIMS

(65 − 75 IN. LB)

(NOTE 1)

DRAIN

BELT (TIMING−

TRANSMISSION IN−

TYPE)

BLOWER SCROLL

PUT COUPLING

DRAIN TUBE

SCROLL CLAMP

COUPLING BOLT, 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

(NOTES 2, 4)

MAIN TRANSMISSION

DRIVE SHAFT (BENDIX)

50−70 IN. LB

(5.65−7.91 NM)

(NOTE 4)

CLAMP, INPUT SEAL

DRAIN TUBE

CLUTCH

COUPLING

SECURING DRAIN

TUBE

MAIN TRANSMISSION

DRIVE SHAFT (KAMATIC)

NOTES:

CORROSION RESISTANT STEEL SHIM, 0.002 IN. (0.0508 MM) LAMINATIONS

CAUTION: ID MUST NOT BE MORE THAN 1.20 IN. (30.48 MM).

DRAG TORQUE FOR BOLT (SELF−LOCKING) SERVICEABILITY IS 25 IN. LB

(2.82 NM) MIN., 200 IN. LB (22.60 NM) MAX.

CHECK WITH LOWER END OF SHAFT ATTACHED.

COAT COUPLING BOLT THREADS WITH ANTISEIZE COMPOUND (36, TABLE 2−4)

BEFORE ASSEMBLY.

REPLACE ANY EXISTING ALUMINUM WASHER WITH STEEL WASHER INDICATED.

30−162F

Figure 9-7. Main Transmission Driveshaft and Current Type Belt-Driven Oil Cooler

Page 9-25

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Impeller must be hand−held

Do not use levers or tools on belt

CAUTION

when torquing pulley nut. Do

or in any way force belt onto

not use tools or other devices to hold impel−

driver pulley.

ler while torquing pulley attachment nut.

(8). Install four mounting bolts, washers

and two laminated shims. Reconnect

NOTE: When performing step (3). below, re−

scroll ducting and rubber connectors.

place any original aluminum washers with

thick and thin steel washers.

(9). Adjust belt tension as follows:

(a).

Check that laminated shims are in

(3). Install pulley on impeller shaft with a

position between mounting bracket

thick washer under pulley and a thin

and transmission fan mount assem−

washer under shaft nut. Reach through

bly. Tighten the four mounting bolts.

scroll primary air outlet and hand−hold

Rotate pulley by hand a few turns to

impeller. Torque nut attaching driven

even out belt tension.

pulley to impeller shaft to 160 − 190

inch−pounds (18.08 − 21.47 Nm).

(b).

Measure belt deflection at approxi−

mate center of one of the spans. The

force required to deflect the belt

(4). Position timing−type belt on driven

0.170−0.200 inch (4.318−5.08 mm)

pulley and attach fan mounting bracket

must be 1.00−1.75 pounds

(with blower assembly to mounting

(4.448−7.784 N). This load is to be

bracket. Install spacer with primer (4,

applied at a right angle to the outside

Table 2−4).

face of the belt.

NOTE: Before tightening bolts, remove all bolt

(c).

If the tension is too high, greater

hold slack in the belt tension direction by

than 1.75 pounds (7.784 N): Tension

moving mount bracket away from the trans−

can be reduced by peeling off a layer

mission driveshaft side.

of the laminated shim, one at a time

alternately from shim to shim, until

tension falls into proper range.

(5). Torque bolts to 65 − 75 inch−pounds

(7.34 − 8.47 Nm) and then safetywire.

(d).

If the tension is to low: Add layers

from a spare shim in the same

NOTE: Prior to installation of blower assembly,

manner as removed in step (c). above,

inspect all ducting inlets and entire blower

until tension falls into proper range.

fan and scroll area or foreign objects.

(e).

Make a final check of bolt torque, 60

− 75 inch−pounds (6.78 − 8.47 Nm)

(6). Install timing−belt type driver pulley

and then safetywire.

on splined transmission input shaft; do

not hammer or strike on pulley if force

(10). Install transmission input shaft seal

fit. Reinstall existing shims and output

drain tube on right side of transmission

coupling. Coat coupling threads with

fan mount, using clamp shown in

anti−seize compound (36) and install

Figure 9−7. Pull drain tube downward

bolt. Check that bolt self−locking torque

and secure to helicopter structure with

is not less than 25 inch−pounds (2.82

tie−strap.

Nm) or more than 200 inch−pounds

(11). Connect blower scroll drain tube and

(22.60 Nm). Torque bolt to 250 − 300

check for excess slack and proximity to

inch−pounds (28.25 − 33.90 Nm) plus

driveshaft. Reposition and secure drain

drag torque.

tube with tie−strap to helicopter

structure, as required, to eliminate

(7). Position assembled drive belt unit and

slack or possible interference with the

blower assembly on transmission

driveshaft.Check the drain tube for

mounting pad, without shims, washers

kinks.

and bolts. Position belt on driver pulley

and check position on driver pulley.

(12). Install main transmission driveshaft.

Page 9-26

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(13). Rotate driveshaft by hand and check

(c).

On installation with a slotted idler

pulley operation.

strap, check that idler fork is free to

move under spring tension. If the

slotted strap binds to prevent move−

(14). Perform operational check of belt−dri−

ment of fork, loosen the idler pulley

ven oil cooler system.

bolt and strap bolt and reposition

strap for free movement. Tighten

E. Oil Cooler Blower Inspection

idler pulley bolt. The strap bolt

(Belt-Driven)

should be loose enough to allow strap

movement.

(Ref. Figure 9−8 and Figure 9−9) For recom−

(d).

Check idler spring tension using a

mended replacement intervals of bearings and

spring scale attached to the idler

belt, refer to CSP−H−4.

pulley bolt. Spring tension should be

4 − 5.5 pounds (17.8 − 24.5 N) just

(1). Early Type Installed Blower−Belt

as idler pulley contacts belt. Spring

Condition:

tension is adjusted by rotating the

square idler shaft bolt in the idler

mounting bracket (Ref. Figure 9−6,

(a). Remove plug buttons (or tape) from

detail C).

inspection ports on main transmis−

sion trim cover panel

(e).

Rotate drive pulley by hand a few

turns so that belt tension is evened

(b). Visually inspect drive belt for proper

out under the spring tension.

seating in pulley grooves and for

(f).

Adjust stop by turning in the stop

condition of belt.

screw until the stop bumper just

contacts the idler fork arm. If screw

NOTE: Belt should be fully seated in pulley

head bottoms on bracket, additional

grooves. Cracking or separation of the belt

extension is available by turning the

between pulley grooves is acceptable. Visu−

stop.

ally monitor propagation. Belt should be re−

placed if any one separation exceeds 3.00 in−

(g).

After contact is made, lock the nut

ches (7.62 cm) in length or if total separation

against the stop. Check for over−ex−

exceeds 50% of the peripheral length of the

tension of stop by inserting wire

belt.

through safety hole to determine that

stop screw is not retracted beyond

the safety hole.

(c). Install plug buttons (or tape) at

inspection ports of trim cover panel.

(h).

Install the main transmission access

cover and trim panel.

(2). Early Type Installed Blower−Belt

(3). Installed Blower General Inspection:

Tension:

(a). Check oil cooler blower and drive

(a). Remove main transmission access

components for smoothness and

cover and trim panel.

correct operation while hand−turning

main rotor through several complete

revolutions, first clockwise and then

NOTE: Whenever belt drive components are re−

counter−clockwise. Listen and feel for

moved and/or replaced at specified inter−

evidence of rubbing or chafing

vals, belt should be adjusted per steps (b).

between impeller and blower scroll.

thru (g). below.

No rubbing or noise is permissible.

Belts should remain seated and be a

(b). Loosen bumper stop jam nut and

snug fit in pulley grooves while

back off stop screw for free movement

rotating. Also check for parallel

of idler fork.

alignment of belts between pulleys.

Page 9-27

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

12−14 IN. LB

(1.36−1.58 NM)

PRIMARY AIR OUTLET

SPLINE

(NOTE)

SHIM (REFER

TO TEXT)

SHAFT HUB

SHAFT KEYWAY

AIR INLET ASSEMBLY

SPACER

KEY

DRAIN

IMPELLER

SCROLL

IMPELLER HUB

SECONDARY AIR OUTLET

WASHER

KEYWAY

FIBER LOCKNUT,

250−300 IN. LB

(28.25−33.90 NM)

(NOTE)

12−14 IN. LB

(1.36−1.58 NM)

SCROLL COVER

NOTE:

HOLD ONLY THE SHAFT HUB SPLINE WHEN LOOSENING OR TIGHTENING

THE FIBER NUT.

CAUTION:

DO NOT HOLD IMPELLER WITH TOOLS OR OTHER DEVICES. TOOLS WILL DAMAGE THE PRECISION

BALANCE OF THE IMPELLER. ALL ROTATING COMPONENTS ARE MATCHED AND BALANCED AND

MUST BE REASSEMBLED TOGETHER TO MAINTAIN DYNAMIC BALANCE.

30−157B

Figure 9-8. Belt-Driven Oil Cooler Blower (Screw-Assembled), Exploded View

Page 9-28

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Check ducting and shrouds for

(b). Visually inspect (minimum 10X

cracks. Also check boots, if installed,

magnification) all blower rotating

for condition. Ducting is to be re−

components for wear, cracks,

paired as required. Replace boots if

scratches and any other damage.

wear, damage or deterioration is

Handle rotating components

noted.

CAUTION

carefully, especially impeller, to

(c). Check blower scroll for condition

prevent damage and imbalance. Any impel−

(Ref. Oil Cooler Blower Inspection

ler damage requires blower replacement.

(Shaft−Driven)) and security of

(c). Visually inspect vanes for deforma−

attaching hardware. Check drain

tion,separation and cracks.

tube for freedom from obstruction.

Check drain tube for kinks, collapsed

(d). Dye−penetrant inspect impeller root

walls and proper position.

area for cracks, scratches and

notches.

(d). Visually inspect impeller for cracks

and separated or deform vanes.

(e). Inspect for foreign material attached

Direct a light through duct openings

to impeller; foreign material attach−

in scroll. An impeller having any

ment is not is not allowable.

damage, including scratches, cracks,

(f). Check for free end play between

notches and deformation, requires

blower shaft and internal bearings in

replacement of the blower.

hub; no play is permitted.

(4). Removed Blower Inspection When

(g). Inspect for surface damage; use an

Assembled:

electroprobe or a gage of equivalent

accuracy to measure depth of

NOTE: The following inspection procedures are

scratches and nicks. Any metal

to be performed whenever the blower is re−

surface damage is not allowable.

moved.

F. Oil Cooler Blower Removal

(a). Inspect normally inaccessible areas

(Shaft-Driven)

for damage (Ref. Oil Cooler Blower

Inspection (Shaft−Drive)).

(Ref. Figure 9−10)

(b). Visually inspect (minimum 10X

(1). Remove main transmission driveshaft.

magnification) or dye−penetrant

(2). Loosen scroll clamp.

inspect impeller root areas for cracks,

scratches and notches. Impeller

(3). Remove the bolts and washers that

scratches and notches in excess of

attach scroll to main transmission.

0.006 inch (0.1524 mm) depth,

(4). Remove scroll, lower end of drain tube,

deformation, and any other impeller

aft cover, and main transmission drain

damage is not allowable.

assembly.

Any impeller damage requires

CAUTION

(5). Remove coupling bolt, transmission

blower replacement.

input coupling, shim(s) and impeller.

Keep shim(s) with coupling for reuse.

(5). Removed Blower Inspection When

Disassembled:

G. Oil Cooler Blower Installation

(Shaft-Driven)

NOTE: The following applies only to the screw−

assembled blower, not a riveted blower as−

(1). Position impeller on transmission input

sembly.

shaft.

(a). Inspect scroll areas inaccessible on

(2). Install coupling shim(s) and transmis−

an assembled blower for damage

sion input coupling. Coat coupling bolt

(Ref. Oil Cooler Blower Inspection

threads with anti−seize compound (36,

(Shaft−Driven)).

Table 2−4) and install bolt. Check that

Page 9-30

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

bolt self−locking drag torque is not less

NOTE: There may be small irregular− shaped

than 25 inch−pounds (2.82 Nm) or

voids in the cement between the cemented

more than 200 inch−pounds (22.60

pieces. Such voids should not be considered

Nm). Torque bolt to 250 − 300 inch−

as delamination (separation).

pounds (28.25 − 33.90 Nm) plus drag

torque.

(d). Check for scroll wear caused by

impeller rubbing.

(3).

Position scroll to engage oil cooler and

(e). Check rectangular gasket for deterio−

heater system ducting. Position aft

ration.

cover and yoke−type drain assembly.

Install bolts and washers to secure

(f). Inspect teflon seal ring that is

scroll to transmission. Torque the bolts;

bonded to the transmission shroud

torque should not exceed 5 − 10 inch−

and bearing−retainer mount. Seal

pounds (0.56 − 1.13 Nm).

ring must be completely bonded

around the mount perimeter.

(4).

Tighten scroll clamp and connect output

seal drain tube. Secure drain tube.

(2). Impeller:

Secure drain tube with a double wrap of

lockwire.

(a). Inspect for cracks and separated or

deformed vanes. A cracked impeller

(5).

Turn impeller and check for clearance

or one having damaged vanes shall

with scroll.

be considered unserviceable and be

replaced.

(6).

Install main transmission driveshaft.

(b). Inspect for surface damage; use an

(7).

Install capstrip on right channel, if

electroprobe or gage of equivalent

removed, main transmission access

accuracy to measure depth of

cover and trim cover panel.

scratches and nicks. Scratches and

nicks not exceeding 0.006 inch

H. Oil Cooler Blower Inspection

(0.1524 mm) depth are repairable if

(Shaft-Driven)

impeller imbalance does not result.

I. Oil Cooler Blower Disassembly

(Ref. Figure 9−10)

(Belt-Driven)

(1). Scroll:

(Ref. Figure 9−8) The following information

provides disassembly procedures that apply

(a). Inspect for surface damage; use an

only to the screw−assembled belt−driven

electroprobe or a gage of equivalent

blower and is intended for use to the extent

accuracy to measure depth of

required for inspection of specific components.

scratches and nicks. Scratches and

The riveted belt−driven blower should not be

nicks that do not exceed 0.012 inch

disassembled.

(0.3048 mm) depth are repairable.

The blower assembly is a bal−

CAUTION

(b). Inspect for and measure length of

anced unit and must be handled

cracks. Cracks that do not exceed 3

carefully to prevent damage that could re−

inches (7.62 cm) in length, do not

sult in assembly imbalance. The blower con−

extend to the hardware mounting

tains match−balanced rotating components

holes and will not impair the function

and assemblies that must be reused togeth−

of the scroll are repairable.

er. Retain all rotating parts for subsequent

reassembly. Disassembly only to the extent

(c). Inspect ribs and seams for separa−

specified in the procedures.

tion, and thread nutplates or inserts

for stripped threads or looseness in

(1). Remove scroll cover from scroll by

flange.

removing screws and washers.

Page 9-31

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

In the following steps, do not

assembly with screws, washers and

CAUTION

use tools or other devices to hold

nuts (spacer and nut ring on fiberglass

impeller. Tool damage can affect the preci−

assemblies). Torque screws to 12 − 14

sion balance of the impeller. Do not use any

inch−pounds (1.36 − 1.58 Nm).

type of holding device that will place a

strain on the blower scroll. The holding de−

(2).

Install spacer and impeller on shaft.

vice must be capable of holding the shaft

with 250 − 300 inch−pounds (28.25 − 33.90

Nm) torque applied to the fiber nut.

(3).

Install washer and locknut on end of

shaft. Using a holding device on splined

(2). Secure pulley (splined) end of impeller

end of shaft, tighten locknut sufficiently

shaft with a holding device that will

to remove all end clearance from the

prevent shaft and impeller rotation

stack−up of parts.

while removing fiber nut that secures

impeller hub to shaft.

(4).

Check for minimum clearance between

(3). While holding the pulley (splined) end

impeller and shroud lip, using a feeler

of the impeller, loosen and remove fiber

gage through the larger air outlet port.

nut and washer securing impeller hub

on shaft.

(5).

Remove impeller and spacer and grind

Be careful to prevent impeller

CAUTION

or file spacer to remove the minimum

damage. Slight impeller de−

clearance measured in step (4). Coat

formation or damage can cause imbalance.

reworked end of spacer with primer (4,

Protect shaft threads and use non−metallic

Table 2−4).

mallet when performing step (4). below.

(4). Manually support impeller with the

fingers and separate impeller from

(6).

Reinstall spacer, impeller, washer and

blower shaft by carefully tapping

locknut. Tighten to remove all end

impeller hub end of shaft.

clearance and then rotate impeller and

check for rubbing. If impeller rubs

(5). Remove impeller from inside scroll. As

shroud, disassemble and install shim(s)

impeller slides off shaft end, remove

369H5654, 0.002 inch (0.0508 mm)

and retain shaft key, spacer and shims

thick, between bearing inner race and

(if any) for reuse.

spacer to eliminate rubbing.

(6). Detach shaft hub from blower air inlet

assembly by removing screws, washers

NOTE: This procedure (steps (4). thru (6).

and nuts (spacer and nut ring on

above) ensures that impeller is at minimum

fiberglass assemblies).

clearance without rubbing shroud lip.

NOTE: If spacer is removed from splined end of

shaft retain spacer and shims (if any) for re−

(7). When clearance is properly adjusted,

use.

remove impeller, and install shaft key,

J. Oil Cooler Blower Reassembly

impeller, washer and locknut. Torque

(Belt-Driven)

locknut 250 − 300 inch−pounds (28.25

− 33.90 Nm). Use care to avoid placing

(Ref. Figure 9−11)

stress on the impeller or scroll. Hold the

Review the Cautions in Oil

splined end of the shaft in a suitable

CAUTION

Cooler Blower Disassembly

device.

(Belt− Driven) regarding holding, handling

and reuse of belt− driven blower blower

(8). For fiberglass scrolls, install scroll

matched− balanced rotating component.

cover with a bead of sealant (3) between

These components must be handled careful−

mating surfaces. Secure cover to scroll

ly to avoid damage.

with screws and washers. Torque

(1). Insert impeller shaft into blower scroll

screws to 12 − 14 inch−pounds (1.36 −

and install shaft blower air inlet

1.58 Nm).

Page 9-32

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SCROLL

0.010 IN. (0.254 MM) MAX. GAP

0.020 IN. (0.508 MM) MAX. COMPRESSION

(NOTE 3)

5−10 IN. LB

(0.56−1.13 NM)

COUPLING TO DRIVE

SHAFT ATTACHMENT

STUD

SCROLL STUD

5−10 IN. LB

(0.56−1.13 NM)

AFT COVER

0.010 IN. (0.254 MM)

OUTPUT PINION

(BETWEEN END OF

SHROUD MOUNT SEAL RING

SEAL DRAIN

SHAFT AND BOLT SEAT−

(TEFLON)

TUBE

ING SURFACE ON COU−

PLING)

GASKET

IMPELLER

SCROLL CLAMP

COUPLING BOLT, 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

(NOTES, 2, 4)

MAIN TRANSMIS−

SION DRAIN ASSY

LOCKWIRE

50−70 IN. LB

(5.65−7.91 NM)

50−70 IN. LB

COUPLING SHIMS

(5.65−7.91 NM)

(NOTE 1)

TRANSMISSION IN−

PUT COUPLING

SCROLL

NOTES:

SCROLL DRAIN

GASKET

CORROSION RESISTANT STEEL SHIM, 0.002 IN. (0.0508 MM)

TUBE

LAMINATIONS.

MAIN TRANSMISSION

CAUTION: ID MUST NOT EXCEED 1.20 IN. (30.48 MM)

DRIVE SHAFT

DRAG TORQUE FOR BOLT (SELF−LOCKING) SERVICEABILITY IS

50−70 IN. LB

25 IN. LB (2.82 NM) MIN., 200 IN. LB (22.60 NM) MAX.

(5.65−7.91 NM)

CHECK WITH LOWER END OF SHAFT ATTACHED.

COAT COUPLING BOLT THREADS WITH ANTI−SEIZE COMPOUND

(36, TABLE 2−4) BEFORE ASSEMBLY.

30−152E

Figure 9-10. Main Transmission Driveshaft and Shaft-Driven Oil Cooler Blower

Page 9-33

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

K. Oil Cooler Blower Repair

(d). Repair small areas of rib or seam

separation by injecting ethylene

dichloride into the void area and

(Ref. Figure 9−8 and Figure 9−10)

clamping together under light

pressure. On shaft−driven blower,

(1). Scroll:

repair deteriorated or otherwise

damaged gasket by replacing with

0.50 inch (12.7 mm) thickness of

The early type scroll is made of acrylic

gasket material (40).

plastic while the later type is of lami−

nated fiberglass. For fiberglass repair

(e). On a shaft−driven blower, repair a

refer to CSP−H−6 and use only the

teflon seal ring that is not completely

applicable portions of the following

secure around outside edge of trans−

procedure.

mission shroud and bearing−retainer

mount. Bond the loose area with a

mixture of 100 parts of resin to 74

NOTE: All permissible patching repairs must

parts of activator (43). Cure at 150°F

be made on exterior surfaces so that inter−

(66°C) for 1 hour or for 8 hours at

nal airflow is not restricted. Any repair

room temperature.

made must not restrict airflow. Patching or

repair that prevents proper duct mating and

(2). Impeller:

sealing, or that results in interference at

(a). Replace impeller that is cracked or

installation, is not allowable. On the belt−

that has damaged vanes or loose

driven blower, patching is not permissible

rivets securing adapter to impeller or

on the upper flat and depressed attachment

balance weights to impeller.

areas of the inlet assembly. Patching is per−

missible on shroud flat and circular surface

(b). Repair scratches and nicks not

areas.

exceeding 0.006 inch (0.1524 mm)

depth by sanding. Use grade 320

abrasive paper to blend defect into

(a).

Repairs cracks that do not exceed 3

surrounding surface area.

inches (7.62 cm) in length, do not

extend to the hardware mounting

(3). Bearing Replacement (Belt−Driven

holes and will not impair the function

Blower):

of the scroll. Such scroll damage is

(a).

Disassemble belt−driven oil cooler

repairable by bonding a patch

blower assembly.

according to the criteria and methods

specified for acrylic in FAA AC

(b).

Remove snap ring, washer and wave

43.13−1A, Aircraft Inspection and

washer from impeller end of shaft.

Repair. Use dichloromethane (38,

(c).

Install existing nut on splined end of

Table 2−4) or ethylene dichloride (39)

shaft.

as the bonding agent.

(d).

Using fiber/rubber mallet or equiva−

lent, tap gently on nut to remove

(b).

Repair scratches and nicks not

shaft and bearings from hub; remove

exceeding 0.012 inch (0.3048 mm)

nut.

depth by sanding the affected area to

blend smoothly with surrounding

(e).

Using a arbor press or equivalent

surface area. Use grade 320 abrasive

tool, press bearing from shaft. When

paper (9).

removing bearing from splined end of

shaft, retain the shim (if installed)

and spacer for reinstallation. Check

(c).

On a shaft−driven blower, replace

spacer for 0.5630−0.5645 inch

inserts that are stripped or loose. Use

(14.3002−14.3383 mm) ID. Ream if

self−locking inserts NAS1394−3L for

necessary and coat reworked surface

replacement. (Drill and tap the scroll

lightly with primer (4).

according to the NAS insert specifica−

tion.)

(f).

Discard old bearings.

Page 9-34

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SHAFT

BEARING 369H5655−5

(NOTE 2)

SCREW

SPACER

CAVITY FILLED WITH GREASE

(26, TABLE 2−4)

NUT RING

BEARING 369H5655−3

(NOTE 2)

HUB

BLOWER SCROLL

WASHER

(FIBERGLASS TYPE SHOWN)

RETAINING RING

CLEARANCE

IMPELLER SPACER

(NOTE 1)

KEY

IMPELLER

WAVE

WASHER

SHIMS 369H5654; AS REQUIRED

WASHER

SEALANT

(NOTE 1)

COVER

(3, TABLE 2−4)

LOCKNUT 250−300 IN. LB

(28.25−33.90 NM)

NOTES:

ADJUST CLEARANCE TO MINIMUM (WITHOUT RUBBING).

BEARING GREASE SEALS TO FACE OUTWARD.

30−175B

Figure 9-11. Cutaway View of Belt-Driven Oil Cooler Blower

(g).

Clean the shaft and interior of hub

(k). Fill hub cavity with grease up to

with solvent (1).

about half the width of the lower

bearing land in hub.

(h).

Lightly coat bearing journal or

splined end of shaft and ID of bearing

(l). Position bearing 369H5655−3 on

369H5655−5 with grease (26) Posi−

shaft with rubber grease seal out−

tion bearing on shaft with rubber

ward (toward impeller). Press against

grease seal outward. Press against

bearing inner and outer races

bearing inner race until bearing is

simultaneously to seat bearing in

seated on shaft shoulder.

hub and on shaft journal.

(i).

Install shims (if applicable) on

(m). Wipe away excess grease that is

splined end of shaft; then press on

forced from bearing seals at both

the upper spacer with larger OD end

ends of shaft.

toward bearing inner race.

(j).

Lightly coat interior of hub with

(n). Install a nut temporarily on splined

grease; then install the shaft and

end of shaft. Using a fiber/rubber

upper bearing assembly. Press

mallet, tap on nut to extend lower

against bearing outer race if neces−

bearing out of hub enough for excess

sary.

to hub interior.

Page 9-35

Revision 20

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(o). Remove approximately 1/4 teaspoon

369A5528 and packing MS29561−017

of grease from hub interior an then

or suitable plug in the output shaft

reinstall shaft and bearings in hub;

(clutch inner race bore) to prevent

secure with wave washer, washer

contamination during clutch handling,

and snap ring.

shipping or storage.

NOTE: Ensure that wave washer is installed

NOTE: The operating lubricant is an approved

next to bearing on impeller end. Also check

preservative for shipping or storage.

that OD of the washer is completely seated

against the outer race of bearing.

(6). Wrap clutch in barrier material (44,

Table 2−4) to protect splined areas of

(p). Rotate shaft by hand to check

race shaft.

smoothness of operational. Reas−

semble blower.

B. Overrunning Clutch Installation

8. Overrunning Clutch

NOTE: Trapped oil can be removed by inverting

the clutch a minimum of three times.

(Ref. Figure 9−12) The overrunning clutch

transmits power from the engine to the main

(1). If clutch is new, remove tag, drain

transmission driveshaft in a clockwise

residual (trapped) preservative oil and

direction. The purpose of the clutch is to

add lubricating oil (9, Table 2−3).

disengage the engine from the remainder of

the drive system (allow free−wheeling) in case

NOTE: The −11, −21 and −31 clutch assembly

of engine failure and during auto−rotations.

capacity is 1.52 U.S. Oz (45cc).

The clutch contains a sprag unit that disen−

The −41 and −51 clutch assembly capac−

gages automatically when N₂ rpm is less than

ity is 1.01 U.S. Oz (30cc).

the corresponding main rotor rpm.

(2).

Check fluid level of clutch assembly

A. Overrunning Clutch Removal

before installing clutch coupling.

NOTE: Refer to Overrunning Clutch Assembly

(3).

Temporarily install coupling bolt and

Replacement for removal of only the inter−

packing.

nal clutch subassembly as an alternative to

complete clutch removal.

(4).

Coat clutch splines with grease (21,

Table 2−4). Insert overrunning clutch

(1). Remove engine (Ref. Sec. 10).

outer−race spline into engine and

install six washers and nuts.

(2). Remove the bolts, washers, nuts and

engine shaft firewall seal from the

(5).

Remove coupling bolt and shim cou−

clutch.

pling so that there is 0.035−0.055 inch

(0.889−1.397 mm) gap from end of

NOTE: Removal of the clutch coupling from the

clutch shaft to edge of coupling recess

clutch in step (3). is unnecessary unless the

(surface that bolt head contacts).

clutch is being replaced.

Measure gap with feeler gage. Install

new O−ring. Check that bolt self−lock−

(3). Remove coupling bolt, packing, clutch

ing torque is not less than 25 inch−

coupling and coupling shim(s). Keep

pounds (2.82 Nm) or not more than

shim(s) with coupling for reuse.

200 inch−pounds (22.60 Nm) drag

Reinstall bolt and packing to prevent

torque. Torque bolt to 250 − 300

spillage of lubricating oil from clutch

inch−pounds (28.25 − 33.90 Nm) plus

housing during final steps of removal.

drag torque.

(4). Remove nuts and washers that secure

the overrunning clutch; remove clutch.

(6).

Install engine shaft firewall seal, bolts,

washers and nuts.

(5). If the clutch is being replaced, install a

spare coupling bolt 369A5513 or

(7).

Reinstall engine.

Page 9-36

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

CLUTCH

SHIM AS REQUIRED

COUPLING−T O−CLUTCH

SHIMMING

0.035−0.055 IN.

MAIN TRANSMISSION

(0.889−1.397 MM) GAP

DRIVE SHAFT

(NOTE 3)

COUPLING BOLT, 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

COUPLING

(NOTES 1, 4)

O−RING

CLUTCH COUPLING

OVERRUNNING

(NOTE 5)

CLUTCH SHAFT

COUPLING SHIMS

(NOTE 2)

ENGINE SHAFT FIREWALL SEAL

OVERRUNNING CLUTCH

50−70 IN. LB

(5.65−7.91 NM)

REPLACEMENT OF COMPLETE CLUTCH

CLUTCH SUBASSEMBLY

369A5350−11

(NOTE 6)

ENGINE POWER AND AC−

CESSORY GEARBOX

RETAINING RING

(BEVEL SIDE OUTWARD)

ENGINE SHAFT FIRE−

WALL SEAL

NOTES:

CLUTCH HOUSING

DRAG TORQUE FOR BOLT (SELF−LOCKING) SERVICEABILITY

(NOTE 6)

IS 25 IN. LB (2.82 NM) MIN., 200 IN. LB (22.60 NM) MAX.

CORROSION RESISTANT STEEL SHIM; 0.002 IN. (0.0508 MM) LAMINATIONS.

USE FEELER GAGE TO CHECK GAP DIMENSION.

REPAIR BY REPLACEMENT OF

COAT COUPLING BOLT THREADS WITH ANTI−SEIZE COMPOUND

CLUTCH SUBASSEMBLY

(36, TABLE 2−4) BEFORE ASSEMBLY.

(NOTE 6)

COAT COUPLING−TO−CLUTCH SPLINES WITH GREASE (57).

THE CLUTCH SUBASSEMBLY SERIAL NUMBER IDENTIFIES THE COMPLETE

REPAIRED CLUTCH.

30−077J

Figure 9-12. Overrunning Clutch Repair or Replacement

Page 9-37

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

C. Overrunning Clutch Inspection

NOTE: The −11, −21 and −31 clutch assembly

capacity is 1.52 U.S. Oz (45cc).

Perform the following inspections anytime the

The −41 and −51 clutch assembly capac−

helicopter engine or overrunning clutch

ity is 1.01 U.S. Oz (30cc).

assembly is removed from the helicopter.

(6). Using care to avoid oil spillage, insert

NOTE: Overrunning clutch subassembly can

clutch sub−assembly into clutch

be replaced with engine installed.

housing and install retaining ring with

beveled side outward.

(1). Check clutch oil level (Ref. Sec. 2).

NOTE: On the identification plate on the clutch

(2). Remove grease and visually check

housing, obliterate the serial number and

clutch input shaft splines for wear. If

lubrication specification. Change part num−

wear is noted, refer to Part II, COM.

ber to read 369A5350−603. The serial num−

ber on the clutch sub−assembly identifica−

tion plate will now identify the complete

NOTE: Relubricate splines on clutch input

clutch.

shaft and splines inside engine power and

accessory gearbox with grease

(21,

Table 2−4) prior to reinstalling overrunning

(7). Install clutch.

clutch.

(8). Install main transmission drive shaft.

(3). Inspect overrunning clutch sub−assem−

bly and ball bearing.

F. Overrunning Clutch Repair/Overhaul

D. Overrunning Clutch Sub-Assembly and

Accomplish repair/overhaul of the overrunning

Ball Bearing Inspection

clutch according to applicable instructions in

CSP−H−5.

Accomplish inspection of overrunning clutch,

clutch sub−assembly and ball bearing accord−

9. Tail Rotor Transmission

ing to applicable instructions in CSP−H−5.

The tail rotor transmission is a right−angle,

E. Overrunning Clutch Sub-assembly

speed−increasing transmission (2045−3018

Replacement

rpm at 100% N₂) having a magnesium alloy

housing. The transmission drive consists of a

The overrunning clutch sub−assembly can be

pair of spiral−bevel gears that are splash

replaced while the engine installed as followed:

lubricated. An oil level sight plug and magnet−

ic chip detector are located on the aft end of

(1). Remove main transmission drive shaft.

the transmission and a breather−filler is

located on top. The breather−filler, on all

(2). Remove coupling bolt, clutch coupling

except early gearboxes, is threaded for

and shims.

attachment of a strobe light pickup of a tail

rotor balancing kit (31, Table 2−2) when tail

rotor balancing is required. Section 2 provides

(3). Remove retaining ring from clutch

servicing information.

housing. Then pull complete clutch

sub−assembly out of housing.

A. Tail Rotor Transmission Removal

(4). Remove shipping plug and O−ring from

end of shaft in replacement clutch

(Ref. Figure 9−13 and Figure 9−14)

sub−assembly .

(1). Remove tail rotor drive shaft and

(5). Drain preservative oil from clutch

transmission as a unit.

sub−assembly by inverting it several

times. Then add lubricating oil (5, Table

(2). Remove tail rotor from tail rotor

2−3).

transmission (Ref. Sec. 8).

Page 9-38

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

COUPLING SHIMS

(NOTE 4)

TRANSMISSION

OUTPUT GEARSHAFT

COUPLING

(NOTE 7)

TAIL ROTOR DRIVE

SHAFT DAMPER

COUPLING BOLT, 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

TAIL ROTOR

(NOTES 1, 9)

NOTE 6

DRIVE SHAFT

80−100 IN. LB

(9.04−1 1.30 NM)

80−100 IN. LB

COUPLING BOLT, 250−300 IN. LB

(28.25−33.90 NM) PLUS DRAG TORQUE

(9.04−1 1.30 NM)

(NOTES 1, 9)

SHAFT DAMPER

NOTE 6

SLEEVE

TAIL ROTOR

DRIVE SHAFT INSTALLATION

BREATHER/FILLER,

GEARBOX COUPLING

45−55 IN. LB (5.08−6.21 NM)

(NOTE 7)

(NOTE 5)

75−95 IN. LB

NOTE 2

(8.47−10.73 NM)

(NOTE 8)

OUTPUT BEVEL

PINION GEARSHAFT

LIQUID LEVEL PLUG,

50−60 IN. LB (5.65−6.78 NM)

COUPLING SHIMS

(NOTE 4)

INPUT BEVEL PINION

GEARSHAFT (NOTE 3)

SELF−CLOSING VALVE,

50−60 IN. LB (5.65−6.78 NM)

NOTES:

CHIP DETECTOR,

DRAG TORQUE FOR SELF−LOCKING BOLT SERVICEABILITY IS

40−50 IN. LB (4.52−5.65 NM)

25 IN. LB (2.82 NM) MIN., 200 IN. LB (22.60 NM) MAX.

LOCKWASHER

RUNOUT (TIR) NOT MORE THAN 0.003 IN. (0.0762 MM) AT SPLIT

12−15 IN. LB (1.36−1.58 NM)

RING GROOVE.

AXIAL PLAY NOT MORE THAN 0.005 IN. (0.127 MM) WHEN INPUT

STA. 282.00 BELLCRANK

SHAFT IS MOVED IN AND OUT.

ALUMINUM ALLOY; 0.002 IN. (0.0508 MM) LAMINATIONS.

THREADED INSERT TYPE BREATHER/FILLER FOR TAIL ROTOR

TRANSMISSION INSTALLATION

VIBRATION ANALYSIS.

REASSEMBLY USING CORROSION RESISTANT STEEL WASHER

IN PLACE OF AL ALY.

COAT COUPLING SPLINES WITH CORROSION PREVENTIVE

COMPOUND (70, TABLE 2−4).

USE ONLY NAS1304−24H OR −26H BOLTS. CHECK BOLT

HOLE DEPTH FOR PROPER BOLT INSTALLATION.

COAT COUPLING BOLT THREADS WITH ANTI−SEIZE

COMPOUND (36) BEFORE ASSEMBLY.

44-463C

Figure 9-13. Tail Rotor Transmission and Drive Shaft Installation with

Kamatic Couplings Installed (Sheet 1 of 2)

Page 9-39

Revision 20

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

MEASURED GAP

ALIGNMENT

BOLT OR PIN

1.370 IN. (34.798 MM) OD

(NOTE 11)

NOTE 10

COUPLING

SHIMS

BOLT

THIN WASHER

(3 PLCS)

TAIL ROTOR

AFT

GEARSHAFT

DRIVE SHAFT

COUPLING

INPUT SHAFT

MAIN

TRANSMISSION

OUTPUT PINION

FORWARD COUPLING

COUPLING

0.010 IN. (0.254 MM

BOLT

MINIMUM STEP

(NOTE 12)

SHIMS

AFT COUPLING

NOTES: (CONT)

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

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

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

SHOULDER OF FORWARD COUPLING.

44-460-3A

Figure 9-13. Tail Rotor Transmission and Drive Shaft Installation with

Kamatic Couplings Installed (Sheet 2 of 2)

Page 9-40

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

COUPLING SHIMS

(NOTE 4)

FAILSAFE COUPLING BOLT,

250−300 IN. LB (28.25−33.90 NM)

PLUS DRAG TORQUE

(NOTES 1, 9, 10)

DRIVE SHAFT INSTALLATION

TRANSMISSION OUTPUT

GEARSHAFT COUPLING

TAIL ROTOR DRIVE

(NOTE 7)

SHAFT DAMPER

FAILSAFE SOCKET

NOTE 6

(NOTE 10)

80−100 IN. LB

(9.04−1 1.30 NM)

TAIL ROTOR

DRIVE SHAFT

SHAFT DAMPER

TAIL ROTOR

SLEEVE

DRIVE SHAFT

TAIL ROTOR

80−100 IN. LB

GEARBOX COUPLING

NOTE 6

(9.04−1 1.30 NM)

(NOTE 7)

BREATHER/FILLER,

45−55 IN. LB

INPUT BEVEL

(5.08−6.21 NM)

PINION GEARSHAFT

OUTPUT BEVEL

(NOTE 5)

(NOTE 3)

PINION GEARSHAFT

75−95 IN. LB

(8.47−10.73 NM)

(NOTE 8)

NOTE 2

LIQUID LEVEL PLUG,

FAILSAFE

50−60 IN. LB (5.65−6.78 NM)

SOCKET

FAILSAFE

COUPLING BOLT

COUPLING SHIMS

(NOTE 4)

NOTES:

DRAG TORQUE FOR SELF−LOCKING BOLT

SERVICEABILITY IS 25 IN. LB (2.82 NM) MIN.,

SELF−CLOSING VALVE,

200 IN. LB (22.60 NM) MAX.

50−60 IN. LB (5.65−6.78 NM)

RUNOUT (TIR) NOT MORE THAN 0.003 IN.

(0.0762 MM) AT SPLIT RING GROOVE.

AXIAL PLAY NOT MORE THAN 0.005 IN. (0.127 MM)

LOCKWASHER

CHIP DETECTOR,

WHEN INPUT SHAFT IS MOVED IN AND OUT.

40−50 IN. LB (4.52−5.65 NM)

ALUMINUM ALLOY; 0.002 IN. (0.0508 MM)

12−15 IN. LB (1.36−1.58 NM)

LAMINATIONS.

THREADED INSERT TYPE BREATHER/FILLER FOR

STA. 282.00 BELLCRANK

TAIL ROTOR VIBRATION ANALYSIS.

TRANSMISSION INSTALLATION

REASSEMBLY USING CORROSION RESISTANT

STEEL WASHER IN PLACE OF AL ALY.

COAT COUPLING SPLINES WITH CORROSION

PREVENTIVE COMPOUND (70, TABLE 2−4).

USE ONLY NAS1304−24H OR −26H BOLTS. CHECK BOLT

HOLE DEPTH FOR PROPER BOLT INSTALLATION.

COAT COUPLING BOLT THREADS WITH ANTI−SEIZE

COMPOUND (36) BEFORE ASSEMBLY.

30-078L

10. FAILSAFE COUPLING AND FAILSAFE BOLT REQUIRED

ON BENDIX COUPLING INSTALLATION.

369A5000 / 369H5600

Figure 9-14. Tail Rotor Transmission and Drive Shaft Installation with

Bendix Couplings Installed (Sheet 1 of 2)

Page 9-41

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

MEASURED GAP

THIN

ALIGNMENT

WASHER

BOLT OR PIN

TAIL ROTOR

(3 PLCS)

MAIN

WASHER

GEARBOX INPUT

TRANSMISSION

(3 PLCS)

SHAFT

OUTPUT PINION

FAILSAFE

BOLT

AFT

TAIL ROTOR

COUPLING

DRIVE SHAFT

NOTE 11

1.370 IN.

FAILSAFE

(34.798 MM) OD

SOCKET

(NOTE 12)

SHIMS

FAILSAFE

BOLT

FORWARD COUPLING

AFT COUPLING

COUPLING

0.010 IN. (0.254 MM)

MINIMUM STEP

(NOTE 13)

FAILSAFE SOCKET

FAILSAFE

BOLT

VIEW D−D

NOTES: (CONT)

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

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

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

SHOULDER OF FORWARD COUPLING.

44-462-1A

Figure 9-14. Tail Rotor Transmission and Drive Shaft Installation with

Bendix Couplings Installed (Sheet 2 of 2)

Page 9-42

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Tail Rotor Transmission Installation

NOTE: Although not required, placing marks

on the end of the output shaft provides

Do not carry or otherwise sup−

guides for subsequent installation of the tail

CAUTION

port the gearbox by the cou−

rotor assembly in a manner that reduces

pling, as the coupling diagram will buckle if

chances of high frequency tail rotor vibra−

excessively deflected. During performance

tions and lessens possibility of requirement

of all maintenance on the gearbox, use extra

for tail rotor balancing.

care to keep contaminants such as paint,

(5). Inspect all scoring or scratching of the

dirt, etc. from the areas around the input

output shaft to determine if the marks

and output shaft seals.

penetrate through the cadmium plating

and into the steel shaft. Penetration of

(1). If gearbox is a replacement, perform

the steel shaft is allowable to a maxi−

buildup.

mum depth of 0.010 inch (0.254 mm).

(2). Install tail rotor on tail rotor transmis−

D. Tail Rotor Transmission Stripping

sion (Ref. Sec. 8).

(Ref. Figure 9−13 and Figure 9−14)

(3). Install tail rotor drive shaft and

transmission as a unit (Ref. Tail Rotor

(1). Remove coupling bolt, coupling, and

Drive Shaft Installation with Kamatic

coupling shims from input gearshaft.

Couplings or Tail Rotor Drive Shaft

Keep shims with coupling for reuse.

Installation with Bendix Coupling).

NOTE: Further stripping is not required, as a

replacement transmission is equipped with

(4). Drain any residual preservative oil and

all other accessories.

service transmission with lubricating

oil (1, Table 2−3).

(2). Drain oil from gearbox. The residual

operating lubricant is approved internal

C. Tail Rotor Transmission Inspection

preservative for shipping or storage.

(Ref. Figure 9−13 and Figure 9−14) If the

(3). Wrap gearbox in barrier material (44,

following inspections reveal damage, perform

Table 2−4) to protect shaft splines and

repair according to applicable instructions in

chip detector stud during handling,

CSP−H−5.

shipping or storage.

E. Tail Rotor Transmission Buildup

(1). Check the transmission for leaks,

cracks or corrosion. (Refer to Fluid

(Ref. Figure 9−13, Figure 9−14 and

Leak Analysis, Section 2, to evaluate oil

Figure 9−15) Replace the liquid level plug, chip

leakage.)

detector and breather−filler according to the

following information. Repair other compo−

(2). Check the input bevel gearshaft for

nents or replace tail rotor transmission oil

axial play by moving the input shaft in

seals according to applicable instructions in

and out. The gearbox must be cold.

CSP−H−5.

Axial play is limited to 0.005 inch

(0.127 mm) maximum.

(1). Replacement of Chip Detector, Liquid

Level Plug and Breather−Filler:

(3). Check tir in the split ring groove of the

Use the following torque values for

output bevel pinion gearshaft. Runout

accessories; lubricate with petrolatum

is limited to 0.003 inch (0.0762 mm) tir.

(34, Table 2−4) to prevent damage to

Check the gearshaft for axial play; no

O−rings.

play is permissible.

(a). Chip detector:

(4). Check for high and low runout at the

split ring groove on the output shaft;

Valve body − 50 − 60 inch−pounds

mark the high and low extremes on the

(5.65 − 6.78 Nm);

outer end of the shaft with grease

Detector − 40 − 50 inch−pounds

pencil.

(4.52 − 5.65 Nm).

Page 9-43

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Liquid Level Plug:

cover to housing; remove cover and

shim. Retain all hardware except safety

50 − 60 inch−pounds (5.65 − 6.78

wire for use at reassembly.

Nm).

(4). Using heat gun or blow dryer, heat

(c). Breather−Filler:

output housing bore to 275° ±25°F

(135° ±l2°C); remove gearshaft and

45 − 55 inch−pounds (5.08 − 6.21

contact pattern shim(s). Retain shim(s)

Nm). Locate the breather hole on

for use at reassembly.

threaded insert breather−filler. The

breather hole must be directed

(5). Install Speedi−Sleeve as follows:

rearward at final torque relative to

gearbox installation on helicopter

Do not allow any contaminants

CAUTION

(Ref. Figure 9−15). Locating the vent

to enter shaft bearings. Dust

at any angle aft of the output shaft

and other contaminants can damage or

centerline (viewed from above)

shorten the service life of the bearings.

adequately directs vent rearward.

One or two AN960PD1016L washers

(a). Set gearshaft on end, bearings down,

may be added between the O−ring

on hard, clean, level surface. Wipe

and breather flange, one washer

away dust and foreign particles from

changes orientation by approximately

gearshaft using a clean, lint free

100°.

cloth, dampened by solvent (1,

Table 2−4).

(2).

Install shim selection retained for reuse

at disassembly, 0.010 inch (0.254 mm)

NOTE: If shaft has been grooved from rubbing

minimum, on input gearshaft.Coat

against lip of output gearshaft cover seal,

coupling splines with corrosion preven−

and depth of groove exceeds 0.005 inch

tive compound (70) and coupling bolt

(0.127 mm), shaft must be replaced (Ref.

threads with anti−seize compound (36)

CSP−H−5). If groove does not exceed 0.005

before assembly. Install coupling and

inch (0.127 mm) depth, it may be repaired

bolt. Check that bolt self−locking drag

with plastic steel (135).

torque is not less than 25 inch−

(b). Apply light coat of plastic steel (135)

pounds (2.82 Nm) or more than 200

to shaft area to be covered by sleeve.

inch−pounds (22.60 Nm). Torque

coupling bolt to 250 − 300 inch−

(c). While plastic steel is wet, put sleeve

pounds (28.25 − 33.90 Nm) plus drag

on shaft, flange down, and press or

torque.

tap in place using 1.250 inch (3.175

cm) tube or pipe bottomed on flange

(3).

Install tail rotor drive shaft.

of sleeve. Unflanged end of sleeve

F. Protective Sleeve (Speedi-Sleeve)

must be even with outboard end of

Installation, Output Gearshaft

1.088−1.090 inch (2.76352−2.7686

cm) diameter portion of shaft. Tap

(Ref. Figure 9−16) Repair oil leaks at output

end of pipe with hammer or mallet as

gearshaft cover by installing a protective

necessary to correctly position sleeve

sleeve (Speedi−Sleeve PN 084957) on the

on shaft. Wipe any excess plastic

gearshaft area contacted by the oil seal lip.

steel from shaft using a clean, lint

Install the protective sleeve as follows;

free cloth.

(1). Remove tail rotor and pitch control

(d). Clip flange of sleeve to notch line and

assembly (Ref. Sec. 8).

peel from shaft.

(2). Drain lubricant from tail rotor trans−

(6). Reassemble tail rotor transmission.

mission (Ref. Sec. 2).

(a). Apply heavy coating of petroleum

(3). Remove safety wire, three bolts and

jelly (34) to bearings on gearshaft

washers attaching output gearshaft

end.

Page 9-45

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

1.088−1.090 IN.

(2.76352−2.7686 CM) DIA

SLEEVE

OUTBOARD END

FLANGE

NOTES:

REPAIRABLE

DAMAGED SHAFT

UNDAMAGED SHAFT

SLEEVE REPLACEMENT

FILL GROOVED AREA AND BOND

BOND SLEEVE TO SHAFT WITH

CUT EDGE OF DAMAGED SLEEVE WITH FILE

SLEEVE TO SHAFT WITH DEVCON A.

DEVCON A.

AND PEEL BACK.

CLIP FLANGE AND PEEL FLANGE OFF

CLIP FLANGE AND PEEL FLANGE

PEEL SLEEVE FROM SHAFT.

SHAFT AT NOTCH LINE.

OFF SHAFT AT NOTCH LINE.

CLEAN WITH KEROSENE; DRY WITH CLEAN,

LINT−FREE CLOTH.

BOND SLEEVE TO SHAFT WITH DEVCON A.

CLIP FLANGE AND PEEL FLANGE OFF SHAFT

AT NOTCH LINE.

44−230A

Figure 9-16. Protective Sleeve Installation/Replacement, Output Gearshaft

Page 9-46

Revision 17

CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 7