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

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

369H7352 PILOT’S COLLECTIVE

CONTROL STICK ASSEMBLY

INDEX MARK OR LINE ON

GAS PRODUCER

INTERCONNECT TORQUE

TUBE END FITTING FLUSH

WITH THE INBOARD END

OF THE PILOT’S

COLLECTIVE STICK

ASSEMBLY

MEASURE BETWEEN INDEX

MARK AND HEX END OF

GAS PRODUCER

INTERCONNECT TORQUE

GAS PRODUCER

TUBE

INTERCONNECT TORQUE

INDEX

TUBE FITTING

MARKING

HEX

END

INDEX

MARK

369H7355 GAS PRODUCER

INTERCONNECT TORQUE TUBE END

FITTING

GAS PRODUCER INTERCONNECT TORQUE TUBE MEASUREMENT

MEASUREMENT BETWEEN

INBOARD END OF PILOT’S

COLLECTIVE STICK HOUSING

AND END OF GEAR SHAFT IN

PILOT’S COLLECTIVE STICK

ASSEMBLY

PILOT’S COLLECTIVE

STICK HOUSING

ASSEMBLY

GEAR SHAFT IN PILOT’S

COLLECTIVE STICK

ASSEMBLY

GEAR SHAFT RECESSION

MEASUREMENT

TOTAL THICKNESS OF AN960C816 WASHERS

AND SNAP RING. EQUAL TO 0.750 MINUS

ENGAGEMENT LENGTH OF GAS PRODUCER

INTERCONNECT TORQUE TUBE INTO GEAR

SHAFT IN PILOT’S COLLECTIVE STICK ASSEMBLY

ADDED TO END OF GAS PRODUCER

INTERCONNECT TORQUE TUBE

ENGAGEMENT LENGTH OF GAS

PRODUCER INTERCONNECT TORQUE

TUBE INTO GEAR SHAFT OF PILOT’S

COLLECTIVE STICK ASSEMBLY

0.750 NOMINAL LENGTH OF HEX

END ON THE GAS PRODUCER

INTERCONNECT TORQUE TUBE

TORQUE TUBE

88-484

SHIMMING

Figure 7-36. Shimming of Gas Producer Interconnecting Torque Tube Assembly

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(3). Remove bolt securing bellcrank to

without changing the friction adjustment in

inboard gearshaft.

the event of a power failure.

There is no suitable check that the pilot can

(4). Position throttle midway between idle

stop and full open.

make, with helicopter on the ground, to

determine if maintenance adjustment of

(5). With assistant, tighten pipe plugs at

collective friction is correct. This is due to the

each and of torque tube simultaneously;

large force application necessary to overcome

maintain throttle as set in step (4).

the collective bungee and the blades resting on

Initial torque required to turn pipe

the droop stops.

plugs may be high because of dried

If stick friction is inadequate during flight, a

primer used at installation.

maintenance check should be performed.

NOTE: If the normally installed plug does not

Once friction adjustment is determined to be

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

correct at the low friction point, any further

pipe plug 0.380 inch (9.652 mm) long may be

mechanical adjustment to alter (increase)

substituted. Whichever plug is used, it must

friction at the low point can cause the mecha−

not protrude more than 0.030 inch (7.62

nism gear to be stripped when the grip is fully

mm) when tightened.

rotated for maximum friction.

(6). Reinstall bolt to secure bellcrank to

A. Collective Stick Friction Mechanism

inboard gearshaft.

Operational Check

(7). Reinstall snap plug in exterior skin.

(1).

Remove the two nylon straps that

secure guard to pitch stick and remove

(8). Reinstall pilot seat cover.

guard.

NOTE: If optional dual controls are installed,

(2).

Check that teeth of friction drive gear,

perform following rigging and deceleration

idler gear, and driven gear are not

check using co−pilot’s throttle.

stripped or otherwise damaged.

(9). Check engine gas producer control

(3).

Rotate the friction drive gear grip

rigging.

counter−clockwise to the maximum

friction stop; the gear train must rotate

(10). Perform deceleration check per Pilot’s

freely.

Flight Manual.

(4).

Check the position of the shaft assem−

54. Collective Pitch Stick Friction

bly pin. The pin should be at the

highest point of cam (Detail C).

(Ref. Figure 7−35) The pilot’s collective pitch

stick friction allows the pilot to vary the

(5).

If the pin is not at the approximate

amount of effort required to raise and lower

peak of the cam or has overridden the

the collective pitch stick as well as increasing

peak (Detail C), the friction mechanism

stick resistance to position change resulting

must be readjusted.

from sudden changes in main rotor collective

(6).

If the pin is in correct position, continue

forces. The grip is marked with arrows

with step (7). below.

indicating the direction of rotation for increas−

ing or decreasing the friction. Friction can be

(7).

Rotate the drive gear grip clockwise to

applied or released with one hand by rotating

the minimum friction position and

the friction adjustment grip.

release the grip; the gear train must

rotate freely. The pin should be at the

The collective stick friction mechanism is

approximate low point of the cam.

designed so that positive locking of the pitch

(Detail C) for the range of desired and

stick cannot be obtained at the maximum

acceptable minimum friction position

friction point.

positions for the pin.

Safety of flight considerations require that

(8).

With the pin in the low point of the

pilot be able to instantly overcome the

cam, hand−rotate the spring retainer

established collective pitch stick position,

housing.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(a). If there is drag on the retainer, there

(6). If the gear assembly does not correctly

is friction on the guide and collective

position the pin, reposition the idler

friction must be readjusted.

gear on the drive gear.

(b). If the retainer rotates freely, without

NOTE: The gear ratio of idler gear−to−gear as−

obvious looseness, the low point

sembly is 3:1 which permits fine adjust−

friction setting is correct.

ments. When repositioning the idler gear, be

sure to reinstall the same number of wash−

ers that were removed from between the cot−

B. Collective Stick Friction Mechanism

ter pin and idler. These washers limit gear

Adjustment

end play to a maximum of 0.010 inch (0.254

mm). When reassembled, the gear train

For the collective friction mechanism to be

must rotate freely.

correctly adjusted for maximum friction, three

actions must occur at the same time:

(7). Reinstall phenolic washer, teflon

washer, retainer assembly and nut.

D The drive gear must contact stick fitting

fixed stop (Detail B);

(8). With the drive gear still at the maxi−

mum friction position, tighten the

D The spring retainer housing washer must

retainer nut until it just bottoms on

contact the retainer internal stop (Detail A);

retainer stop.

D The gear assembly pin must be at the

(9). Rotate the friction drive gear clockwise

approximate peak of the cam (Detail C).

to the minimum friction stop position

and release the grip. Check the follow−

Do not overtighten the retainer

ing:

CAUTION

nut so that the retainer washer

contacts the retainer stop before the friction

(a). If the pin has overridden the low

drive gear reaches the stick fitting stop. Ad−

point of the cam (Detail C) (desired

justment that does not produce approxi−

minimum friction position), and

mately simultaneous contact will allow ex−

grip−to−stick friction prevents spring

cessive additional rotation of the drive gear

back of the pin to the cam low point,

grip and cause the composition nylon gear to

manually turn the grip and move pin

be stripped.

to low point.

NOTE: A drive gear that does not rotate freely

(1). Remove the friction mechanism guard.

(binds) on the collective stick tube should be

replaced.

(2). Rotate the friction drive gear counter−

clockwise to the maximum friction

(b). With pin in cam low point, manually

position.

rotate the retainer assembly; it

should turn freely on the shaft of the

(3). Remove cotter pin, nut, retainer

gear assembly with only light finger

assembly, teflon washer, and one

pressure. Adjust retainer nut to the

phenolic washer.

nearest castellation that produces

zero friction (no drag on the retainer

(4). Slide the gear assembly out far enough

assembly during rotation). Install

to disengage it from the idler gear. Use

new cotter pin.

care to keep other washer and spacer

from dropping.

NOTE: If undesirable collective forces (i.e.

light, heavy or creeping collective) are re−

(5). Remesh the gear assembly with the

ported to exist in the collective stick during

idler gear to position the pin on highest

flight, do not attempt to compensate by an

part of the cam gear (Detail C). Check

increase in collective friction. The reported

that the drive gear is still at the

condition should be corrected elsewhere in

maximum friction stop position.

the control system.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

PIPE PLUG

COLLECTIVE CONTROL

(NOTE 3)

INTERCONNECTING

TORQUE TUBE

SNAP PLUG

FUSELAGE

DROOP CONTROL

SKIN

OVERRIDE LINK

BRACKET

BUSHING

(NOTE 1)

CLIP (3 PLCS)

N_R DISABLE

(NOTE 5)

SWITCH AND

GAS PRODUCER

BRACKET

INTERCONNECT

(NOTE 5)

PIPE PLUG

0.20 IN. (5.08 MM)

TORQUE TUBE

(NOTE 3)

(NOTE 4)

SUPPORT BEARING

CONTROLS BRACKET

CRADLE INDEX GROOVE

BUNGEE SUPPORT BRACKET

ACTUATING

CAM

2.70 IN. (6.858 CM)

CONTROLS SUPPORT

(NOTE 4)

BRACKET

BUNGEE OVER−CENTER

THREADED INSERT

ADJUSTMENT BOLT

TORQUE TUBE

GAS PRODUCER

SUPPORT BEARING

CONTROL ROD

BUNGEE OVER−CENTER FITTING

INBOARD COLLECTIVE STICK

SOCKET ASSEMBLY

FITTING

MALE BEARING

RETAINER

SPRING

NOTES:

SLOTTED

EDGE OF BUSHING MUST PROTRUDE A MIN. OF

BUSHING

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

NOTE 2

(NOTE 1)

(2.032 MM) ABOVE OUTSIDE SURFACE OF PART

30−40 IN. LB

AFTER NUT IS TIGHTENED.

(3.39−4.52 NM)

LUBRICATE RETAINER CUPS AT EACH END OF

SPRING, FEMALE BEARING THREADS AND MALE

BEARING SHAFT WITH GREASE (26, TABLE 2−4).

INSTALL WITH WET PRIMER (4, TABLE 2−4).

BUNGEE INSTALLATION

TIGHTEN FOR ZERO BACKLASH BETWEEN

TOOL (369A9936)

TORQUE TUBE AND CONTROL GEARSHAFT AT

EACH END OF TUBE. PLUG MUST NOT PROTRUDE

MORE THAN 0.030 IN. (0.762 MM) INTERNAL

FEMALE BEARING

NOTE 2

WRENCHING PRESSURE PIPE PLUG 1/8−27 X 0.38 IN.

ASSEMBLY

(9.652 MM) LONG MAY BE USED AS ALTERNATE IF

AN932−2 PLUG DOES NOT EXPAND TUBE ENOUGH.

PRELIMINARY ADJUSTMENT ONLY.

USED ON HELICOPTERS WITH N₁/N_R ENGINE

POWER−OUT WARNING SYSTEM. REF. SEC. 17 FOR

RIGGING ADJUSTMENT.

COMPRESSION TOOL ROD

REINSTALL EXISTING WASHERS UNDER BOLT HEAD

AND CHANNEL (369A9985)

AND BETWEEN SPACER AND NUT.

30−052−1D

Figure 7-37. Collective Torque Tube, Gas Producer Torque Tube, Collective

Bungee (Sheet 1 of 2)

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

55. Collective Control Interconnect Torque

(7). Remove nuts, washers and bolts that

Tube

connect stick housing to torque tube.

(Ref. Figure 7−37) The collective interconnect

(8). Remove stick by sliding it outboard and

torque tube consist of the tube, a bungee

off torque tube.

bracket, bungee fitting, and a tube support

(9). Remove torque tube by sliding it a total

bearing. The torque tube interconnects the

of approximately 3 inches (7.62 cm)

pilot’s collective pitch stick and the inboard

toward the right side of the seat

collective stick socket assembly. The torque is

structure to disengage left end from

supported at the left end by a bearing installed

support bearing inside left torque tube

in the seat structure, and at the right end by

support. Provide support at seat

the controls support bracket.

structure lightening hole and carefully

withdraw torque tube from structure.

A. Collective Control Interconnect Torque

Tube Inspection

(10). Remove gas producer interconnect

torque tube by carefully sliding it out of

(1). Remove pilot’s seat cover, control access

collective torque tube.

door, and left side foot support fairing

(Ref. Sec. 2).

C. Collective Control Interconnect Torque

Tube Repair

(2). Inspect collective interconnect torque

tube for cracks, and bends or similar

(1). Replace loose or binding torque tube

distortions.

support bearing.

(3). Inspect bungee bracket, and bungee

(a). Drill out rivets securing retainer and

fitting for security and condition.

doubler to seat structure to replace

left support bearing.

(4). Inspect all accessible rivets for loose−

ness and support bearings for security,

(b). Drill out three rivets securing right

and evidence of binding.

end fitting to torque tube to replace

right support bearing.

(5). Reinstall pilot’s seat cover, control

(c). Pick up existing hole patterns and

access door and foot fairing.

install new bearings.

B. Collective Control Interconnect Torque

(2). Replace torque tube if it is cracked or

Tube Removal

has elongated holes.

(1). Remove collective bungee.

NOTE: The torque tube droop control bracket

(2). Remove inboard collective socket

may be either an aluminum or magnesium

assembly.

casting. Ref. Sec. 2 for corrosion control and

identification of magnesium alloy parts.

(3). Disconnect aft end of droop control

(3). Replace a bent or stripped bungee

override link from torque droop control

adjustment bolt. Torque nut to 30 − 40

bracket (Ref. Figure 7−30, Detail A).

inch−pounds (3.39 − 4.52 Nm) and

(4). Remove hardware securing reinforce−

install new cotter pin.

ment strap, bungee support bracket

(4). Replace scratched, nicked or damaged

and torque tube to controls support

reinforcement strap.

bracket.

D. Collective Control Interconnect Torque

(5). Slide bungee bracket to side and

Tube Installation

remove controls bracket cradle cap and

reinforcement strap.

(1). Install gas producer interconnect

torque tube by sliding it carefully into

(6). Slide the collective control torque tube

place in collective control interconnect

sufficiently towards the right side of the

torque tube.

seat structure to remove the pilot’s

collective pitch stick housing from end

(2). Insert torque tube into lightening hole

of tube.

in seat structure. Use care when

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

inserting tube into place to prevent

This unit attaches between the bungee

scraping on edge of hole; insert tube

over−center fitting and bungee bracket of the

only to a position that provides suffi−

collective interconnecting torque tube.

cient space between tube end and

The collective bungee is provided to help

fuselage skid for installation of pilot’s

maintain selected collective pitch stick position

stick housing on end of tube.

in flight by counter−acting forces that are fed

(3). Lubricate pilot’s stick housing with

back to the collective pitch sticks: blade

grease (26, Table 2−4).

pitching moments; rotor head strap pack

torsion when collective pitch stick is raised or

NOTE: Stick housing must be placed on torque

lowered from mid−position (strap pack neutral

tube before installing torque tube attaching

position); combined imbalance of forces in the

hardware.

control system.

(4). Slide Pilot’s Stick housing on collective

The flight characteristics of the helicopter are

control interconnect torque tube.

such that collective forces are relatively low

during most of stick travel from low pitch

(5). Complete insertion of tube and position

toward high pitch. At a point near full pitch

left end of tube in fixed bearing bore.

the stick forces reverse and become heavy. The

Rotate torque tube slowly back and

purpose of the adjustable bungee and the

forth until right end bearing rests

overcenter bracket attachment is to counteract

cradle of controls support bracket.

these forces so that collective stick loads are

relatively constant throughout the full range of

(a). Check that two slotted bushings are

travel.

in place in upper lugs of bungee

bracket. position torque tube, control

There are two adjustments available to

bracket cradle cap, reinforcement

establish or correct collective flight loads.

strap, and bungee bracket on control

Adjustment of the collective bungee spring will

support bracket.

correct a variation in collective load from low

pitch (level flight) to high pitch (climb). Setting

(b). Check that cap−to−cradle index

of overcenter bolt to raise or lower bungee

grooves are matched. Install attach−

fitting will cause an overall reduction or

ing hardware and ensure that

increase of collective forces in both low pitch

reinforcement strap is tight with

(level flight) and high pitch (climb).

bolts torqued, shim with washers as

required.

A. Collective Bungee Removal

(c). Apply a thin layer of grease to sliding

(1). Remove pilot’s seat cover from seat

surface of bungee overcenter fitting.

structure (Ref. Sec. 2).

(6). Install droop control override link to

(2). Raise the collective stick and use the

torque tube droop control bracket (Ref.

torque tube over−center action to

Figure 7−30, Detail B).

compress the bungee spring until

bungee installation tool (26, Table 2−2)

(7). Install inboard collective socket

will fit over the spring retainers. Secure

assembly.

tool halves in place with clamp.

(8). Complete installation of pilot’s collec−

(3). With stick in over−center position,

tive pitch stick.

remove cotter pin, nut, washer, and bolt

that secure male bearing to bungee

(9). Install collective bungee.

over−center fitting.

56. Collective Bungee

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

and bolt that attach female bearing end

(Ref. Figure 7−37) The collective bungee

of bungee to the bungee bracket.

installation consists of a male bearing assem−

bly, female bearing assembly, spring, and

(5). Remove collective bungee and installa−

retainer.

tion tool as a unit.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

Remove installation tool only as

(5). Compress spring by closing vise until

CAUTION

directed (Ref. Collective Bungee

the bungee clamp may be removed from

Disassembly).

bungee.

B. Collective Bungee Installation

(6). Slowly open vise until bungee spring is

fully extended.

(1). Position the collective bungee in

installation tool (26, Table 2−2) so that

(7). Remove retainer, spring and female

bearing assembly.

the female bearing assembly is forward

and aligns with mating hole in the

NOTE: Do not disassemble female bearing as−

bungee bracket (Detail A).

sembly. Replace as a unit if defective.

(2). Check that slotted bushing for bracket

D. Collective Bungee Inspection

lug is in place, install bolt, two washers,

nut and new cotter pin.

NOTE:

D The bungee support bracket may be ei−

(3). Position male bearing to align with

ther an aluminum or magnesium casting.

mating hole in bungee over−center

Ref. Sec. 2 for corrosion control and iden−

fitting.

tification of magnesium and aluminum

(4). Install bolt, washer, nut and new cotter

alloys.

pin.

D Replace any bungee parts having ques−

tionable condition.

Do not turn the female bearing

CAUTION

assembly spring retainer while

(1). Inspect spherical bearings in male

the bungee installation tool is under spring

bearing and female bearing assembly

load.

for evidence of binding, corrosion and

galling.

(5). Raise the collective stick and use the

torque tube over−center action to

(2). Inspect female bearing assembly

compress spring until bungee installa−

threads for damage.

tion tool can be removed.

(3). Inspect spring for evidence of deforma−

(6). With collective stick at full down

tion. Free length of spring must be 4.50

position, make preliminary adjustment

±0.060 inches (11.43 ±0.1524 cm).

of the bungee installation.

(4). Inspect male bearing rod for cracks,

evidence of binding, corrosion and

(7). Adjust bungee after flight evaluation,

deformation.

as required.

E. Collective Bungee Reassembly

C. Collective Bungee Disassembly

(1). Use a bench vise having jaws that are

(1). Remove male bearing from bungee

lined with a nonskid material.

clamped in compression by the installa−

tion tool.

(2). Lubricate cups of spring retainers and

threads and bore of female bearing

(2). Install bungee compression tool rod and

assembly with grease (26, Table 2−4).

channel (27) on compressed bungee.

Insert a 0.250 inch (6.35 mm) bolt

(3). Assemble retainer, spring, and female

through channel and female bearing

bearing assembly. Install compression

rod end (Detail A).

tool rod and channel (27, Table 2−2) in

position. Insert a 0.250 inch (6.35 mm)

(3). Line the jaws of a bench vise with

bolt through channel and female

masking tape or similar nonskid

bearing rod end (Detail A).

material.

(4). Position assembly in jaws of bench vise.

(4). Place compression tool and bungee in

the vise so that the vise jaws make

(5). Close the jaws to compress bungee

contact with tool rod and channel.

spring until bungee installation tool

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(26) will fit over the retainers. Secure

(a). This adjustment must also provide

tool halves in place with clamp.

absence of an excessive download or

upload while in hover and at 120

(6). Open bench vise jaws slowly, and

knots level cruise.

remove the bungee compression tool rod

and channel.

(b). Helicopter must be landed after each

flight check, before making corrective

(7). Install male bearing into place in

adjustment.

compressed bungee.

Use all necessary precau−

F. Collective Bungee Adjustment

WARNING

tions to prevent possible

entry of any foreign objects into con−

(Ref. Figure 7−31) Adjustment of the bungee

trols linkage exposed by removal of pi−

system is only permissible when the helicopter

lot’s seat cover to make adjustment of

is on the ground.

bungee system.

(1). Collective load forces are affected by

After each bungee adjustment is

any adjustment made in the main rotor

CAUTION

made, collective stick must be

system. Observe the following:

slowly moved through its full travel range to

assure that there is no binding or restriction

(a). Bungee adjustment should only be

of stick motion, and that spring does not bot−

made when the main rotor blades are

tom at overcenter position.

in track and autorotation rpm is

established.

NOTE: Do not turn female bearing assembly

retainer while bungee installation tool is

(b). Ensure that collective stick friction is

spring loaded.

correctly adjusted.

(c).

If an upload exists on ground at flat

(c). Perform flight evaluation of collective

pitch and normal rpm but a down−

forces with helicopter takeoff weight

load prevails during hover and at 120

at 2200 pounds (998 kg), N₂ at 103%

knots level cruise, turn bungee

and ZERO COLLECTIVE STICK

adjustment retainer nut clockwise to

FRICTION.

increase preload in bungee system.

(2). Prior to test flight, establish the

(d).

To correct a download on ground

half−way point of the collective friction

during flat pitch at normal rpm and

adjustment grip (drive gear) as follows.

an upload condition during hover and

120 knots level cruise, turn bungee

(a). Using a soft, colored pencil, index the

adjustment retainer nut counter−

collective friction adjustment grip at

clockwise to decrease preload in

zero friction.

bungee system.

(b). Roll on maximum friction (approxi−

mately 275 degrees rotation). Note

(e).

When a relatively constant upload

travel and reset friction grip half−

condition prevails during flat pitch at

way. Hold in this position.

normal rpm on the ground, at hover,

and at 120 knot level cruise, decrease

(c). Using a dot of white paint or similar

upload by turning bungee over−center

method, temporarily mark the top of

adjustment bolt clockwise.

the friction grip and the adjacent

exposed area of the collective stick.

(f).

When a relatively constant download

The friction half−way index mark

condition prevails during flat pitch

should be visible to the pilot.

normal rpm on the ground, at hover,

and at 120 knot level cruise, decrease

(3). While helicopter is on ground, adjust

download by turning bungee over−

bungee to extent necessary to avoid any

center adjustment bolt counterclock−

upload in flat pitch at normal rpm.

wise.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: Rotation of the adjustment bolt head is

NOTE: If disassembly is not intended, install

the only mechanical operation required to

four spacers and reinstall the washers and

adjust the over−center position of the bungee

nuts on the protruding bolts to keep the as−

fitting.

sembly intact.

(g). After minimum and balanced collec−

B. Inboard Collective Stick Socket Assembly

tive forces have been obtained, not

- Disassembly

more than one−half the available

(1). Disconnect the link from the idler.

collective stick friction (friction grip

at half−way index) must cancel

(2). Remove the idler from the socket

collective forces during flight test at

housing. Do not remove idler bearing

120 knots level flight.

unless replacement is necessary.

(h). If friction applied in step (g). above is

(3). Remove the four bolts and washers that

insufficient to cancel collective forces,

attach housing cap to socket housing.

repeat adjustment procedure just

(4). Rotate the shaft assembly until gear

concluded.

tooth cutout clears pinion (bellcrank

ears at approximately 195 degrees);

57. Inboard Collective Stick Socket Assembly

then separate the bellcrank, housing

cap and shaft assembly from the

(Ref. Figure 7−38) The inboard collective stick

housing.

socket assembly is a cast magnesium housing

that contains gas producer linkage and

(5). Remove the bellcrank from shaft

provisions for attachment of dual collective

assembly to separate housing cap from

controls.

shaft.

The internal gas producer drive gear linkage is

NOTE: Do not press bearings from cap or hous−

essentially the same as that in the pilot’s

ing unless replacement is necessary. Keep

collective stick housing with the addition of a

backlash shims with shaft assembly.

splined N₁ pinion gear for simplified installa−

(6). Remove link from bellcrank.

tion or removal of a pilot’s collective stick.

(7). Remove snap ring that retains the N₁

The lower end of the collective mixer tunnel−

pinion gear aft bearing in the housing.

routed control rod is attached to the socket

housing, and the exterior bellcrank, idler and

(8). Press the pinion gear and aft bearing,

link transfer movement of the pilot’s collective

as an assembly, out through the access

stick throttle to the gas producer controls

hole at the back of the housing.

routed through the fuselage to the engine.

NOTE: Disassemble pinion bearings from pin−

A. Inboard Collective Stick Socket Assembly

ion and housing only if replacement is nec−

Removal

essary.

(1). Remove the pilot’s seat cover and the

C. Inboard Collective Stick Socket Assembly

controls access door (Ref. Sec. 2).

Inspection

(1). Inspect all bearings for binding or

(2). Disconnect collective mixer tunnel−

looseness.

routed control rod.

(2). Inspect gears for cracks, and chipped or

(3). Disconnect gas producer control rod

broken teeth.

from idler (Ref. Figure 7−37).

(3). Inspect all components for cracks,

(4). Remove N_R disable switch if installed.

corrosion and deformation.

(5). Remove the four nuts and washers that

NOTE: The bellcrank and idler may be either

attach the socket assembly to the

an aluminum or magnesium casting. Ref.

collective torque tube and remove the

Sec. 2 for corrosion control an identification

assembly.

of magnesium and aluminum alloy parts.

Page 7-108

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SNAP RING

GAS PRODUCER INTERCONNECT

N₁ PINION GEAR

TORQUE TUBE

AFT BEARING

(NOTE 4)

PIPE PLUG

SNAP RING

SLOTTED

BUSHING

CLIP (3 PLCS)

(NOTE 5)

SOCKET HOUSING

SPACER

(NOTE 1)

BEARING

(NOTE 4)

BACKLASH SHIM

FORWARD BEARING

(NOTES 2, 4)

SHAFT ASSEMBLY

BACKLASH SHIM

BEARING

(NOTE 4)

LINK

N_R DISABLE SWITCH AND BRACKET

(NOTE 3)

(NOTE 5)

ACTUATING CAM

(NOTE 5)

HOUSING CAP

IDLER

BELLCRANK

IDLER BEARING

(NOTE 4)

NOTES:

FOUR SPACERS USED ONLY ON REMOVED SOCKET ASSEMBLY TO KEEP ASSEMBLY INTACT.

N₁ PINION FORWARD BEARING IS LIGHT PRESS FIT IN HOUSING BORE.

LINK MUST BE BOLTED TO BELLCRANK BEFORE BELLCRANK AND SHAFT ASSEMBLY ARE INSTALLED.

INSTALL BEARINGS WITH GRADE A LOCKING COMPOUND (29, TABLE 2−4). BOND THE TWO SHAFT ASSEMBLY

BEARINGS ONLY AFTER SHIMMING FOR BACKLASH.

USED ON HELICOPTERS WITH N₁/N_R ENGINE POWER−OUT WARNING SYSTEM. REF. SEC. 17 FOR RIGGING

AND ADJUSTMENT.

30−053

Figure 7-38. Inboard Collective Stick Socket Assembly

Page 7-109

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

D. Inboard Collective Stick Socket Assembly

(6). Establish N₁ pinion and shaft assembly

Repair

bevel gear backlash (Ref. Figure 7−39).

(1). Replace bearings if corroded, excessive−

(7). After backlash shimming is correct,

ly worn, or if the outer or inner races of

remove housing cap and gear shaft.

bearings rotate on mating surfaces and

(8). Install bellcrank on shaft assembly, and

locking compound is inadequate to

link to bellcrank.

prevent rotation.

NOTE: Bellcrank attachment bolt must be

(a). Install new bearings with grade A

installed with head slightly down and for−

locking compound (29, Table 2−4).

ward.

(b). Check that replacement bearing is

(9). Lubricate teeth of pinion gear and shaft

properly seated in its bore.

assembly bevel gear with grease (26).

(2). Replace any part that is cracked.

(10). Apply grade A locking compound to

gear shaft and ID of bearings.

(3). Replace entire link if bearings are

defective; link bearings are not replace−

(11). With the centerline (wide) toothspace of

able.

the N₁ pinion gear up (on top), install

shaft assembly gear at midtravel

(4). Replace a pinion gear or shaft assembly

position.

bevel gear when correct backlash

cannot be maintained because of tooth

NOTE: N₁ pinion gear side toothspace should

irregularities caused by wear or

be position up at approximately one o’clock

deformation.

position, as viewed looking aft into open end

of socket.

E. Inboard Collective Stick Socket Assembly

- Reassembly

(12). Install four bolts, eight washer, four

spacers and nuts to secure cap to

(1). Check gear shaft bearings in housing

housing.

cap and housing for security of outer

(13). Install idler to housing, and link to

races.

idler.

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

NOTE: As installed, idler to gas producer con−

Table 2−4) to install replacement

trol rod bolt holes should be in line with

bearings.

centerline of stick assembly housing cap

when gear shaft and pinion gears are posi−

(b). Use care to prevent compound from

tioned as outlined in step (11). above.

entering bearings, and make sure

that each bearing is seated against

F. Inboard Collective Stick Socket Assembly

its bore shoulder.

Installation

(2). Apply grade A locking compound (29) to

(1). Remove four nuts washers and spacers

pinion gear aft bearing OD, and

from socket assembly mounting bolts.

matching bore in socket housing.

(2). With throttle grip on pilot’s collective

(3). Install the assembled N₁ pinion gear

stick at midtravel (Ref. Figure 7−34),

and aft bearing; seat bearing firmly

rotate bellcrank back and forth slightly

against bore shoulder.

to engage socket assembly to gearshaft

on hexagonal end of gas producer

(4). Install snap ring that retains aft

interconnect torque tube.

bearing in housing bore.

(a). Bellcrank centerline, N₁ pinion gear

(5). Apply locking compound to bond pinion

centerline toothspace and pilot’s

shaft and forward bearing ID.

throttle must be as shown.

Page 7-110

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTE: With pilot’s throttle grip at midtravel,

(9). Reinstall pilot’s seat cover and the

two grip attach bolts should be approxi−

controls access door.

mately straight down. Simultaneously,

idler−to−gas producer control rod bolt holes

(10). Check that inboard collective pitch stick

should be in line with centerline of inboard

socket gears are at midtravel when

stick assembly housing cap. At midtravel,

pilot’s collective pitch stick throttle grip

inboard N₁ pinion gear spline wide tooth−

is set to midtravel. If not, adjust

space should be at approximately 1 o’clock

collective pitch stick(s) gas producer

as viewed looking aft into open end of sock−

control linkage.

et.

(11). Adjust N_R disable switch if installed.

(3). Install N_R disable switch if required,

and secure socket assembly housing to

collective torque tube.

58. Cyclic Controls

(4). Rotate pilot’s throttle and check for zero

The cyclic pitch control system is a fully

backlash between gas producer inter−

mechanical control system. Any combination of

connect torque tube and the hexagonal

lateral and longitudinal cyclic pitch stick

(ID) interior of drive gearshaft in socket

movement is mixed by cyclic lateral and

assembly housing.

longitudinal control mixers and transferred to

the main rotor swashplate, which applies the

(5). Eliminate backlash by removing

combined motion through pitch control rods to

housing cap and gearshaft, and then

the main rotor blades.

removing pipe plug in end of torque

tube (Ref. Figure 7−37).

Forward and rearward movement of the cyclic

pitch stick causes helicopter motion in a

(a). Coat pipe plug with wet primer (4,

longitudinal direction, while side−to−side

Table 2−4), reinstall and tighten it so

movement provides motion in a lateral

that there is no backlash between

direction. This action varies the lift developed

torque tube and control gearshaft at

by main rotor blades and thus serves as

each end of the tube.

primary control of horizontal flight.

NOTE: If the normally installed plug does not

The pilot’s compartment cyclic controls include

sufficiently expand tube, a 8− 27 internal−

the control stick, a lateral interconnecting rod,

wrenching pipe plug 0.380 inch (9.652 mm)

lateral cyclic bellcrank, longitudinal cyclic

long may be substituted.

control interconnecting torque tube and lateral

and longitudinal friction mechanisms.

(b). Whichever plug is used, it must not

protrude more than 0.030 inch (0.762

The one−way lock assembly, longitudinal cyclic

mm) when tightened.

trim actuator, lateral cyclic trim actuator,

longitudinal idler bellcrank and lateral idler

(c). Zero degree backlash is required at

bellcrank are located beneath the pilot’s seat

both ends of tube.

structure.

(d). After plug is tightened, reinstall

Tunnel−routed longitudinal and lateral control

gearshaft and housing cap.

rods connect the underseat idler bellcranks to

the main rotor lateral pitch mixer bellcrank

(6). Connect gas producer control rod to

and longitudinal pitch idler.

idler.

Dual control provisions are incorporated into

(7). Connect collective mixer tunnel−routed

the pilot’s compartment cyclic controls

control rod.

installation. Dual control information for the

helicopter is provided in CSP−018, CSP−H−3,

(8). Remove bungee installation tool.

or HMI Supplement M, as applicable.

Page 7-111

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

STEP 2

TOOTHSPACE ON SPLINE

STEP 1

LINK

BELLCRANK

GENERAL NOTE:

SELECT SHIMS AS REQUIRED. CRES SHIMS

TOP VIEW

PROVIDED IN 0.001, 0.002, 0.005, 0.012 AND

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

0.8128 MM) THICKNESS.

GRIP / N₁ PINION GEAR

MID−TRAVEL

N₁ CLOSED

N₁ OPEN

IDLE STOP

6°

15°

73° 30’

15°

70° 40’

2° 50’

LOF N1 PINION AND

LOF SHAFT ASSY

GEAR CUTOUT

STEP 3

RIGHT SIDE VIEW

STEP 1

STEP 3

POSITION C (WIDE) TOOTHSPACE OF N₁ PINION GEAR SPLINE UP AT

AFTER SHIMMING IS CORRECT, INSTALL SHAFT ASSY BEARINGS WITH

APPROX 1 O’CLOCK VIEWED FROM SOCKET END.

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

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

INSTALL SHAFT ASSY (WITH LINK ATTACHED TO BELLCRANK) SO THAT

STEP 2

POSITION OF BELLCRANK, C OF SHAFT ASSY GEAR CUTOUT AND C

(WIDE) TOOTHSPACE OF PINION SPLINE ARE AS SHOWN.

INSTALL BACKLASH SHIMS TO OBTAIN 0.003 IN. MAXIMUM BACKLASH.

NOTE: C OF SHAFT ASSY GEAR CENTER TOOTH IS 2° 50’ OFF THE

CAUTION: BEARINGS MUST BE SEATED AGAINST BORE SHOULDER

CUTOUT

AND GEARS MUST NOT BIND.

30−054B

Figure 7-39. Adjustment of Gas Producer Drive Backlash (Inboard Collective

Stick Socket Assembly)

Page 7-112

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

59. Pilot’s Cyclic Control Stick (Left Position)

(7). Connect electrical plug.

(Ref. Figure 7−40) The left position pilot’s

C. Pilot’s Cyclic Control Stick Grip Removal

cyclic control stick consists of a grip, and a

(1). Disconnect removable contacts from

anodized aluminum alloy tube riveted in a

electrical plug (Ref. Sec. 19).

magnesium or aluminum socket. The cyclic

grip contains a toggle−type switch for the

(2). Remove the nylon strap that secures

cyclic trim controls and a trigger−type switch

wiring to stick socket.

for radio/interphone communication. A blank

switch socket is provided to the left of the trim

NOTE: Remove strap mounting plate only if

switch for optional equipment switch installa−

unserviceable.

tion. Coiled and deadened wiring is provided in

the grip for connection to the optional switch.

(3). Remove screw from grip and separate

grip from tube.

A. Pilot’s Cyclic Control Stick Removal (Left

Position)

(4). Tie a ‘‘fish’’ string to each wire bundle

to aid reassembly.

(1). Disconnect control stick electrical plug.

(5). Push wire slack into wiring exit holes

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

in stick socket while pulling grip wiring

and bolt that secure the pilot’s lateral

from stick tube.

control rod to the stick socket.

(6). Remove grip and wiring; leave strings

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

in tube.

and bolt that attach the lateral friction

mechanism link to the cyclic torque

D. Pilot’s Cyclic Control Stick Grip

tube.

Installation

(1).

Separate grip wiring into approximate−

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

ly equal color−coded bundles, according

and bolt that attach the stick socket to

to the wiring diagram in Section 20.

the end of the cyclic torque tube.

Remove stick with lateral friction

(2).

Install an 8 inch (20.32 cm) length of

mechanism attached.

AWG Size No. 3 electrical insulation

sleeving (31, Table 2−4) on each bundle

B. Pilot’s Cyclic Control Stick Installation

and push sleeving into grip.

(Left Position)

(3).

Route wiring through stick tube and

(1). Position pilot’s cyclic control stick to

out wiring exit holes with the aid of

align with mating holes in torque tube

‘‘fish’’ strings.

(Ref. Figure 7−33).

(4).

Push wires at grip end while pulling

(2). Install bolt, two washers, nut, and new

slack out of socket.

cotter pin.

(5).

Install an additional 8 inch (20.32 cm)

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

length of insulation sleeving to protect

then align plot’s lateral control rod with

each wire bundle where routed through

stick socket.

exit holes in socket.

(4). Install bolt, two washers, nut and new

(6).

Position grip on stick tube and install

cotter pin.

screw.

(5). Position guide link to align with mating

(7).

Push as much wire slack as possible

hole in torque tube.

back into the stick.

(6). Install bolt, sleeve bushing, three

(8).

Secure wiring to socket with a new

washers, nut and new cotter pin.

nylon strap, or equivalent.

Page 7-113

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTES:

NOTE 2

ASTERISK IDENTIFIES SLOTTED BUSHING. EDGE OF

SLEEVE

BUSHING MUST PROTRUDE A MIN. OF 0.010 IN.

BUSHING

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

NOTE 2

OUTSIDE SURFACE OF PART AFTER NUT IS TIGHTENED.

TORQUE TUBE LINK

ARRANGE WASHERS TO LINE UP LINK WITH TORQUE

STUD

TUBE. SPACE LOOSELY WITH THREE WASHERS.

ADJUST CAP NUT TO STOP THE KNOB WITH SPRING

AT FREE LENGTH ±0.03125 INCH (0.79375 MM).

FRICTION MECHANISM ASSEMBLY IS THE SAME AT

THE LATERAL POSITION.

KNOB

INSTALL WITH GRADE A LOCKING COMPOUND

(NOTE 4)

(29, TABLE 2−4).

IF NUT CAN BE TURNED WITH FINGER PRESSURE,

THE NUT MUST BE REPLACED.

CAP NUT

(NOTES 3, 6)

SPRING

DISC

RETAINER

SCREW

NYLON STRAP AND

MOUNTING PLATE

PILOT’S LATERAL

CONTROL ROD

LATERAL IDLER

BELLCRANK

CSK

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

BEARING

CONTROL

DIM L

ANGLE

ASSY PART

(NOTE 5)

ROD ASSY

IN. (CM)

NUMBER

PILOT’S LATERAL

12.63

(32.0802)

42°

369A7102

STA 70 LATERAL

6.65

(16.891)

90°

369A7005

MS20470AD RIVET

MAX ALLOWABLE AXIAL

STA 70 LATERAL

(INBD END)

PLAY 0.040 IN. (1.016 MM)

CONTROL ROD

PILOT’S LATERAL

STA 67 LATERAL

CONTROL ROD

CYCLIC BELLCRANK

30−056C

Figure 7-40. Pilot’s Cyclic Stick, Control Linkage and Friction Controls

Page 7-114

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

E. Pilot’s Cyclic control Stick Inspection

(3). Assemble friction mechanism to stick

(Left Position)

socket or torque tube (Detail A).

(4). Adjust friction knob cap nut to stop the

(1). Inspect stick tube attachment to socket

knob when the spring reaches free

for evidence of loose rivets, distortion

length, no compression ±0.03125 inch

and corrosion.

(±0.79375 mm).

NOTE: The socket may be either an aluminum

60. Cyclic Stick Guard

or magnesium casting. Ref. Sec. 2 for corro−

sion control and identification of magne−

(Ref. Figure 7−41) The cyclic stick guard

sium and aluminum alloys.

installation protects passengers in the pilot’s

compartment from movement of the cyclic

(2). Inspect parts of friction mechanism for

linkage forward of the seat structure and also

physical damage. Free length of friction

blocks the entry of any large foreign objects

spring should be approximately 0.580

that might jam or foul the control linkage.

inch (14.732 mm).

The guard installation consists of three

(3). To check installation:

polycarbonate plastic guards and one alumi−

num alloy guard, attached to the floor and face

(a). Loosen lateral and longitudinal

of the seat structure. The small aluminum

friction knobs, move cyclic control

guard (second from left) forms the stationary

stick and check for binding or unusu−

half of its rotating counterpart that is riveted

al noises.

to the cyclic torque tube.

(b). Check that the rod end bearings of

A. Cyclic Stick Guard Replacement

the pilot’s lateral control do not jam

Remove and reinstall cyclic stick guards by

when the stick is full forward and full

removing the attaching screws and washers.

aft.

The right guard has two slip−fit locating pins

(rivets) that engage the large central guard to

F. Pilot’s Cyclic Control Stick Repair (Left

keep the two guards aligned.

Position)

NOTE: Riveted nutplates are provided at all

Disassemble cyclic control stick only as

screw locations except for the top left and

necessary to replace damaged or faulty parts.

two top center screws of the large (central)

guard; regular washers and nuts are

NOTE: The stick tube should not be removed

installed at these three places.

from the stick socket; the assembly should

only be replaced as a unit.

61. Pilot’s Compartment Lateral and

Longitudinal Cyclic Control Linkage

(1). Cut wiring to correct length and

reinstall replaceable contacts and

(Ref. Figure 7−40) The pilot’s compartment

electrical plug according to Sec. 19 and

lateral and longitudinal cyclic control linkage

wiring diagram in Sec. 20.

consists of the two control rods and bellcrank

that interconnect lateral control movement,

G. Pilot’s Friction Mechanism Replacement

and the cyclic torque tube and one−way lock

control system that interconnect longitudinal

(1). Remove cap nut from friction stud and

control movement of the pilot’s cyclic stick to

disassemble friction mechanism from

the tunnel−routed mixer control rods.

stick socket or torque tube (Detail A).

A. Lateral Control Rods and Station 67

(2). Replace a bent or stripped friction stud.

Bellcrank Removal

(a). Drill out rivet and press stud from

(Ref. Figure 7−41)

socket; install new stud and rivet in

(1). Remove the large (central) cyclic stick

place.

guard.

(b). Press a replacement spring pin into

(2). Remove the pilot’s seat cover, and

friction stud until one end of pin is

controls access door from Sta. 78.50

flush with surface of stud.

canted bulkhead (Ref. Sec. 2).

Page 7-115

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

CYCLIC PITCH INTERCONNECTING

PILOT’S CYCLIC

TORQUE TUBE

ONE−WAY

STICK ASSY

LOCK ASSY

LONGITUDINAL CONTROL

FRICTION MECHANISM

WASHER

LINK

SLOTTED

BUSHING

(NOTE 1)

STA 67

LATERAL

CYCLIC

BELLCRANK

CYCLIC STICK GUARD

INSTALLATION

LATERAL CONTROL

FRICTION MECHANISM

PILOT’S LATERAL

CONTROL ROD

(NOTE 2)

CYCLIC STICK GUARD

INSTALLATION

SLEEVE BUSHING

LOCATING PIN

(2 PLCS)

NOTES:

EDGE OF BUSHING MUST PROTRUDE A MIN. OF 0.010 IN. (0.254 MM)

TO A MAX. OF 0.080 IN. (2.032 MM) ABOVE OUTSIDE SURFACE OF

PART AFTER NUT IS TIGHTENED.

CONTROL ROD END BEARINGS MUST NOT JAM THROUGHOUT FULL

RANGE OF LONGITUDINAL TRAVEL (34°).

30−055A

Figure 7-41. Pilot’s Compartment Cyclic Control and Guard Installation

(3).

Remove the cotter pin, nut, two wash−

between rod end bearing centers for

ers and bolt from each end of the pilot’s

future reference; use the trammel

lateral control rod, or Sta. 70 lateral

method, or equivalent.

control rod, as applicable; remove rod

B. Lateral Control Rods and Station 67

assembly.

Bellcrank Installation

(4).

Remove the cotter pin, two washers and

(1). Check that slotted bushing is in upper

bolt that secure Sta. 67 lateral cyclic

web of seat structure fitting. Align Sta.

bellcrank to seat structure fitting;

67 lateral bellcrank and install bolt,

remove bellcrank.

two washers, nut and new cotter pin.

(5).

If rod or rod ends require replacement,

(2). Check that slotted bushings are in

accurately measure and record distance

place and install Sta. 70 lateral control

Page 7-116

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

rod and pilot’s lateral control rod at

(c). A dye−check for cracking shall

each end with bolt, two washers, nut

always be performed after cold−

and new cotter pin.

straightening; replace a cracked rod,

or cracked or bent rod end.

(3). Move cyclic stick full forward, then full

Use care when drilling to re−

aft and set pilot’s lateral control rod end

CAUTION

move or install riveted rod end;

bearing angularity so that the bearings

the rod end is steel and the rod is aluminum.

do not jam at the full throw positions;

Do not tighten adjustable rod end jam nut

hold rod end and tighten jam nut.

on pilot’s lateral control rod until rod is in−

(4). If a new control rod or rod ends were

stalled and cyclic stick longitudinal travel is

replaced, perform a cyclic control

checked.

rigging check.

(6). Replace a control rod end if bearing

axial play is more than 0.040 inch

(5). Install the large (central) cyclic stick

(1.016 mm). Set initial control rod

guard, pilot’s seat cover and controls

length and bearing angularity.

access door.

D. Cyclic Pitch Interconnect Torque Tube

C. Lateral Control Rods and Station 67

Removal

Bellcrank Repair

(Ref. Figure 7−40)

(1). Replace the Sta. 67 lateral bellcrank if

(1). Remove pilot’s seat cover (Ref. Sec. 2).

it has elongated holes or is cracked.

(2). Position pilot’s cyclic stick to align holes

(2). Replace the pivot bearing if it binds or

in one−way lock support links with the

is excessively worn; install with grade A

bolt that attaches forward end of

locking compound (29, Table 2−4).

one−way lock to torque tube; tighten

longitudinal friction.

(3). Check free play of a bellcrank having a

(3). Disconnect rod end from torque tube

newly installed pivot bearing by

arm.

applying light up and down pressure at

forward end of bellcrank with bearing

(4). Remove the pilot’s cyclic stick.

secured.

(5). Remove all of the cyclic stick guard

installation except the small guard next

(4). Bellcrank total play measured at

to the pilot’s cyclic stick.

centerline of bolt that attaches pilot’s

lateral control rod end must not be

(6). Remove the longitudinal control friction

more than ±0.024 inch (±0.6096 mm) for

mechanism (Detail A).

the bearing to be acceptable.

(7). Remove pilot’s lateral control rod from

Sta. 67 lateral bellcrank.

NOTE: The Sta. 67 lateral bellcrank may be ei−

ther an aluminum or magnesium machined

(8). Cut lockwire and remove the support

forging. Ref. Sec. 2 for corrosion and identifi−

nuts, support bolts and the two wide

cation of magnesium and aluminum alloys.

(left−hand) support spacers from the

seat structure fitting lugs and torque

(5). Perform a straightness check on a

tube.

control rod that appears bent or bowed.

NOTE: Use care to prevent the torque tube

(a). The total length of the rod (excluding

from dropping as the bolts are removed.

rod ends) must be straight within

(9). Remove the torque tube and two

0.010 inch (0.254 mm).

narrow (right−hand) support spacers.

(b). Cold−straightening of the rod is

E. Cyclic Pitch Interconnect Torque Tube

permissible provided there are no

Repair

nicks or sharp dents in the bend

(Ref. Figure 7−42)

length, and the rod ends are NOT

used to support the rod during the

(1). The cyclic torque tube may be either a

straightening process.

machined magnesium or aluminum

Page 7-117

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

casting. Ref. Sec. 2 for corrosion control

lock rod ends until there is no sideload

and identification of magnesium and

on the one−way lock control system.

aluminum alloys.

(5). Check that no structural interference

(2). Replace the torque tube if it is cracked,

results from the spacer interchange.

has elongated holes or deformed

(6). When there is no sideload on one−way

bearing supports.

lock, install and tighten the support

(3). Replace the main support bearings or

nuts.

cyclic stick pivot bearings if they bind

(7). Using 0.032 inch (0.8128 mm) lockwire

or are excessively worn.

(2, Table 2−4), safetywire each nut to

the hole in the threaded end of the

(a). Drill out the four rivets and remove

mating bolt.

bearing retainer to replace right

support bearing.

NOTE: Use care when installing lockwire as

both the nut and bolt are aluminum.

(b). Install cyclic stick pivot bearing and

the right support bearing with grade

(8). Install pilot’s lateral control rod (riveted

A locking compound (29, Table 2−4).

rod end) to Sta. 67 lateral bellcrank.

NOTE: The left support bearing is a slip−fit in

(9). Install the longitudinal control friction

the torque tube lug; coat OD of replacement

mechanism (Ref. Detail A).

bearing with grease (26).

(10). Install cyclic stick guards.

(4). Replace a bent or stripped friction stud.

(11). Install the pilot’s cyclic stick.

Drill out rivet; install new stud, pick up

predrilled hole in stud and rivet in

(12). Position pilot’s cyclic stick to align bolt

place.

holes in torque tube arm with holes in

one−way lock support links.

F. Cyclic Pitch Interconnect Torque Tube

Installation

(13). Install bolt, two washers, nut and new

cotter pin.

(Ref. Figure 7−40)

(14). Install pilot seat cover.

(1). Align cyclic torque tube support

bearings with holes in structure fitting

62. One-W ay Lock Control System

lugs.

(Ref. Figure 7−42) The cyclic control system

(2). Place a narrow support spacer on the

one−way lock (Uni−loc) is located in the

right side of each support bearing, and

longitudinal control linkage within the pilot’s

install the two wide support spacers

seat structure.

and support bolts.

The one−way lock control system is essentially

NOTE: The support bolts may be installed from

a self−contained closed−loop hydraulic unit

either direction, and the two narrowest

consisting of a check valve, relief valve and

(right−hand) support spacers may be inter−

pushrod mechanism.

changed to get best alignment of the torque

tube with the one−way lock.

The check valve is seated when longitudinal

control force (feed−back) originated by the

(3). Check that slotted bushing is in torque

main rotor tends to move the one−way lock

tube arm, and fit one−way lock rod end

(and cyclic stick) in an aft direction. Seating

against unbushed lug of arm.

the check valve prevents unwanted aft

movement of the cyclic stick and shunts the

(4). If tightening of the attachment bolt will

feed−back force into the helicopter structure.

apply sideload on the rod end, inter−

change the two narrowest (right−hand)

Normally, only very slight aft movement of the

support spacers, and/or adjust the

cyclic stick is required to unseat the check

lateral position shimming of the

valve. Should the check valve or pushrod shaft

longitudinal idler bellcrank or one−way

that unseats the valve gall and freeze in the

Page 7-118

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

valve−closed position, a force of approximately

Do not remove cotter pin from

CAUTION

30 pounds is necessary to open the relief valve

output shaft end bearing or

and bypass the check valve. This force will

make any adjustment on serrated end. Mal−

then be required for each subsequent move−

function of one−way lock will result. Over−

ment of the cyclic stick, either forward or aft.

haul replacement instructions are provided

CSP−H−5.

Conversely, should the check valve spring fail,

(3).

Replace one−way lock if output shaft

the one−way lock will not function to shunt

end bearing is binding.

longitudinal feed−back forces into the struc−

ture.

(4).

Replace protective boot if it is cracked,

torn or deteriorated.

The unit is mounted in two pivoting supports

(5).

Replace the one−way lock if the exposed

attached to the seat structure, and has an

portion of the piston has nicks,

unbreakable, transparent, vented reservoir

with a capacity of approximately 0.670 fluid

scratches or wear penetrating the

ounce (20 cc). The one−way lock control system

chrome plating.

is serviced through the filler as necessary with

(6).

Replace the one−way lock if the OD of

hydraulic oil (11, Table 2−3).

the external mounting bushing is less

than 0.4979 inch (12.64666 mm).

A. One-W ay Lock Removal

(7).

One−way lock must be replaced if nicks,

(1).

Remove pilot’s seat cover, and controls

dents and scratches to the body exceed

access door from Sta. 78.50 canted

0.040 inch (1.016 mm) after repair.

bulkhead (Ref. Sec. 2).

(8).

One−way lock must be replaced if end

play between rod ends exceeds 0.010

(2).

Remove the large (central) cyclic stick

inch (0.254 mm) measured at the input

guard.

end.

(3).

Position pilot’s cyclic stick to align holes

(9).

One−way lock must be replaced if it is

in one−way lock support links with the

leaking, except as noted for the reser−

bolt that attaches forward end of

voir in step (1). above.

one−way lock to cyclic torque tube;

C. One-W ay Lock Repair

tighten longitudinal friction. Disconnect

rod end from torque tube arm.

Refer to CSP−H−5 for overhaul information.

(4).

Disconnect one−way lock lower rod end

(1). Remove dents, nicks and scratches by

from longitudinal idler bellcrank.

using grade 400 abrasive paper (9,

Table 2−4) to remove rough edges.

(5).

Disconnect upper end of each support

Finish by polishing with crocus cloth

link from the seat structure and remove

(23). Maintain a smooth transition into

one−way lock with links attached.

the surrounding area. After repair treat

the area with chemical film (8).

(6).

Remove the two cotter pins, washers

(2). When replacing input shaft rod end

and links. Do not remove the pivot

bearing be sure that with the piston in

bushings from the links unless replace−

mid stroke the bearing center−to−center

ment is necessary.

distance is 8.58 ±0.030 inches (21.7932

±0.0762 cm). Adjust as required. After

B. One-W ay Lock Inspection

correct length has been obtained,

tighten and lockwire the lock nut.

(1). Replace reservoir if it is cracked,

leaking or has a loose or damaged filler

(3). Support links may be either forged

cap.

aluminum or magnesium castings. Ref.

Sec. 2 for corrosion control and identifi−

(2). Replace input end rod end bearing if

cation of magnesium and aluminum

bearing is binding.

parts.

Page 7-119

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

NOTES:

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

(0.254 MM) TO A MAX. OF 0.080 IN. (2.032 MM) ABOVE

CONTROLS SUPPORT

OUTSIDE SURFACE OF PART AFTER NUT IS TIGHTENED.

BRACKET

MAY BE INSTALLED IN EITHER DIRECTION.

MAY BE INTERCHANGED TO ALIGN ONE−WAY LOCK.

INSTALL WITH GREASE (26, TABLE 2−4) ON OD.

INSTALL WITH GRADE A LOCKING COMPOUND (29, TABLE 2−4).

CAUTION: DO NOT BUCK RETAINER RIVETS; SQUEEZE ONLY.

SHIM WASHERS, AS REQUIRED, TO ALIGN ONE−WAY LOCK

(REMOVE SIDELOAD).

LONGITUDINAL IDLER

BELLCRANK

CYCLIC

STICK

SHIM WASHER

PIVOT

ONE−WAY

(NOTE 7)

BEARING

LOCK ASSY

SLOTTED BUSHING

(NOTE 1)

SHIM WASHER

(NOTE 7)

SLOTTED BUSHING

CYCLIC PITCH

PIVOT BUSHING

(NOTE 1)

INTERCONNECTING

TORQUE TUBE

SUPPORT LINK

SUPPORT BEARING

(NOTE 5)

RETAINER

FLANGE

SUPPORT BOLT

BUSHING

(NOTE 2)

SLEEVE BUSHING

SUPPORT SPACER

CYCLIC STICK

0.20 IN. (5.08 MM)

PIVOT BEARING

WIDE (NOTE 3)

SUPPORT BEARING

(NOTE 4)

SUPPORT SPACER 0.430 IN.

(10.922 MM) WIDE

SUPPORT NUT

RIVET (MS20470B3)

SUPPORT BOLT

RIVET (MS20427M5C)

(NOTE 2)

(NOTE 6)

SUPPORT SPACER

FRICTION STUD

0.260 IN. (6.604 MM)

SUPPORT NUT

WIDE (NOTE 3)

SUPPORT SPACER

0.520 IN. (13.208 MM)

SPRING PIN

WIDE

30−057A

Figure 7-42. Cyclic Torque Tube and One-Way Lock Control System

Page 7-120

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

D. One-W ay Lock Installation

63. Installation of Fuselage Access Panels for

Cyclic Trim Actuator Assemblies

(1). Check that rod end bearing center−to−

center distance.

(Ref. Figure 7−43 and Figure 7−44)

(2). Install new pivot bushings in support

(1). Gain access to pilot’s underfloor

links if replacement is necessary

compartment.

(3). Attach lower ends of links to one−way

(2). Jack up helicopter to provide access to

lock; use new cotter pins.

work area at underside of fuselage

(4). Align upper ends of links with mating

structure (Ref. Sec. 2).

holes in seat structure fitting and

NOTE: If ADF or transponder antenna is in−

attach each link with bolt, sleeve

stalled, remove antenna (Ref. CSP−H−3).

bushing, washer, nut and new cotter

pin.

(3). Drill out rivets securing 369A2500−163

stiffener and 369A2500−169 doubler.

(5). Check that slotted bushing is in place

in longitudinal idler bellcrank; then fit

(4). Drill out rivets securing 369A2500−164

lower rod end bearing against un−

stiffener and 369A2500−169 doubler.

bushed lug of bellcrank to check if

sideloading will occur when attachment

(5). Drill out rivets securing 369A2500−165

bolt is tightened.

doubler.

NOTE: There must be no sideloading applied to

(6). Remove doublers and stiffeners; remove

the one−way lock mechanism.

any sealing compound residue.

(6). Arrange shim washers, as necessary, to

(7). Drill out rivets securing 369A2500−9

position longitudinal idler bellcrank

stiffener, 369A2500−10 stiffener, and

and/or lower rod end for no sideload

369A2524 center beam assembly to

alignment.

fuselage skin between Sta. 60.73 and

(7). Position pilot’s cyclic stick to align holes

Sta. 74.287.

in support links with hingeline for

upper end of one−way lock and cyclic

(8). Remove any sealing compound residue.

torque tube arm; tighten longitudinal

NOTE: Read step (26). below before drilling or

friction.

riveting per steps (9). thru (25). Number and

(8). Repeat the check for no sideload on the

placement of rivets may have to be altered

one−way lock, step (4). above, and

accordingly.

arrange shim washers, as necessary, to

position upper rod end for no−sideload

(9). Insert 369D22501−43 doubler (RH) in

alignment.

position between −10 stiffener and

369H2524 center beam assembly, and

NOTE: The two narrowest (right−hand) cyclic

fuselage skin.

torque tube support spacers may also be in−

terchanged to align the one−way lock.

(10). Mark rivet hole centers on doubler;

remove doubler and drill rivet holes.

(9). When there is no sideload on one−way

lock, secure each rod end bearing with

(11). Insert 369D22501−41 doubler (LH) in

bolt, two washers, nut and new cotter

position between −9 stiffener and

pin.

369H2524 center beam assembly, and

fuselage skin.

(10). Check the oil cup fluid level (Ref. Sec.

(12). Mark rivet hole centers on doubler; also

mark hole centers on doubler for two

(11). Install large (central) cyclic stick guard.

existing 0.311−0.318 inch

(12). Install pilot’s seat cover, and controls

(7.8994−8.0772 mm) diameter holes in

access door.

fuselage skin.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(13).

Remove −41 doubler; drill rivet holes

(25). Insert −41 doubler in place between −9

and two 0.311- 0.318 inch

stiffener and center beam assembly,

(7.8994−8.0772 mm) diameter holes in

and fuselage skin; secure with rivets 39

doubler.

places as shown; install additional

rivets 16 places around circumference

(14).

Position 369D22501−21 door on −43

of cutout.

doubler; mark and drill four

0.169−0.175 inch (4.2926−4.445 mm)

(26). Replace rivets removed in step (7). as

diameter holes and eight 0.096 inch

required to secure stiffeners and center

(2.4384 mm) diameter rivet holes in

beam assembly to fuselage skin

doubler for nutplates.

between Sta. 60.73 and Sta. 74.287.

(15).

Install four NAS697C08M nutplates on

(27). Install rivets (through both skin and

upper side of doubler as shown.

doubler) to plug any open rivet holes

that exist in skin due to step (3). thru

(16).

Drill fourteen 0.096 inch (2.4384 mm)

(5). above, meeting the following

diameter rivet holes in doubler around

criteria:

circumference of cutout as shown.

(a). Rivets reinstalled in existing holes

(17).

Position 369D22501−11 door on −41

must NOT be closer than 1.5 x

doubler; mark and drill four

diameter (edge distance) minimum

0.169−0.175 inch (4.2926−4.445 mm)

from edge of applicable parts in−

diameter, and 0.096 inch (2.4384 mm)

volved. If this criterion cannot be

diameter rivet holes for six nutplates.

met, leave rivet hole in skin blank

and fill in with ProSeal 890 sealant.

(18).

Install four NAS697C08M nutplates

and two MS21076L4 nutplates on

(b). Rivets reinstalled in existing holes

upper side of doubler as shown.

must NOT be closer than 3.0 x

diameter (rivet spacing) minimum

(19).

Drill sixteen 0.096 inch (2.4384 mm)

from location of any new rivet added

diameter rivet holes in doubler around

per this installation. If this criterion

circumference of cutout as shown.

cannot be met, install ONLY the rivet

through the existing hole in the

(20).

Using doublers as templates, mark and

structure and eliminate the new rivet

make cutouts in fuselage skin to match

intended for this location.

doublers as shown.

(28). Apply a 0.060 inch (1.524 mm) bead of

(21).

Drill four 0.169−0.175 inch

PR1221 sealant on inside skin surface

(4.2926−4.445 mm) diameter holes in

at stiffeners and center beam assembly;

skin to match nutplate holes in dou−

apply a 0.030 inch (0.762 mm) bead of

blers, as applicable.

sealant at doubler attachments.

(22).

Cut or drill 0.750 inch (19.05 mm)

NOTE: Perform step (29). below if ADF anten−

diameter hole through skin to match

na is not to be installed.

−41 doubler if transponder antenna is

to be installed.

(29). Install two NAS604−6P screws and

AN960C416L washers as plugs in

(23).

Drill 0.096 inch (2.4384 mm) diameter

MS21076L4 nutplates on LH side

rivet holes in skin to match rivet holes

installation as shown.

around circumference of each cutout as

shown.

(30). Install access door(s) using NAS602−7P

screws and AN960C8 washers. Elimi−

(24).

Insert −43 doubler in place between −10

nate 369D22501−11 door (LH) and its

stiffener and center beam assembly,

attaching hardware if antenna is to be

and fuselage skin; secure with rivets 34

installed.

places as shown; install additional

rivets 14 places around circumference

(31). Check installation of doublers and

of cutout.

access door for discrepancies.

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Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(32). As applicable, install ADF or trans−

NOTE: Lateral actuator upper hingeline has a

ponder antenna per CSP−H−3.

0.1875 inch (4.7625 mm) bolt hole; longitu−

dinal has a 0.250 inch (6.35 mm) bolt hole.

64. Cyclic Trim Actuators

(5). Disconnect lower end of trim actuator.

Access to the attaching nut is through a

Each of the two cyclic trim actuators consists

hole in the underfloor compartment aft

of an actuator, housing support, trim tube, and

bulkhead, near the centerline beam.

spring assembly.

(6). Remove trim actuator. Reinstall the

The actuator is a motor−driven shaft that

lower end attaching hardware to go

compresses a spring assembly, counteracting

with actuator if the actuator is being

feedback forces from the main rotor and

replaced; a new actuator includes this

compensating for imbalance conditions such as

hardware.

those imposed by crosswinds or unevenly

distributed cargo.

B. Cyclic Trim Actuator Installation

Cyclic trim is controlled by the cyclic trim

(Ref. Figure 7−30)

switch located on top of cyclic stick grip. The

(1).

Check the trim actuator spring assem−

cyclic trim switch has five positions: normally

bly for free play between the spring and

OFF in the center, and momentary FOR−

spring adapters. Tighten spring adapter

WARD, AFT, LEFT, and RIGHT. When the

screw until no play can be felt while

trim switch is moved off center to any of the

pushing and pulling on spring assem−

four trim directions, the electrical system

bly.

energizes one of the trim motors to apply trim

spring force in the desired direction. By

(2).

Remove the hardware supplied in

momentarily moving the switch, very small

housing end of a new trim actuator.

trim increments may be obtained.

(3).

Check that slotted bushings are in

Trim forces cannot be applied in two directions

place in actuator housing.

simultaneously; when both lateral and

(4).

Place one AN960−716L washer around

longitudinal trim corrections are required, it is

each side of the pivot bearing in the

necessary to apply first one, then the other.

center beam support lug and align the

actuator housing with the bearing.

The cyclic trim mechanism does not limit

travel of the cyclic pitch control stick trim

(5).

Install the bolt, two washers, nut and

spring tension can be overridden at any time.

new cotter pin (all new if actuator is a

replacement).

A. Cyclic Trim Actuator Removal

(6).

Align actuator with idler bellcrank.

(Ref. Figure 7−30)

(7).

Check that slotted bushing is in

(1). Jack up the helicopter until the landing

bellcrank lug; install actuator pivot

gear is fully extended and clears the

bushing if actuator is a replacement.

ground (Ref. Sec. 2).

NOTE: The pivot bushing must rotate freely in

the actuator.

(2). Remove foot fairing, controls access

door from Sta. 78.50 canted bulkhead,

(8). Install bolt, two washers, nut and new

and open or remove pilot’s compartment

cotter pin. After the bolt is tightened

floor access door, as applicable.

the pivot bushing must not rotate in the

idler bellcrank.

(3). Disconnect bonding jumper and

electrical connector from actuator

NOTE: Lateral actuator upper hingeline has a

housing.

0.1875 inch (4.7625 mm) bolt hole; longitu−

dinal has a 0.250 inch (6.35 mm) bolt hole.

(4). Disconnect upper end of trim actuator.

Keep pivot bushing with actuator

(9). Connect bonding jumper. Jumper

unless actuator is being replaced.

connected over actuator electrical

Page 7-125

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

receptacle should have an electrical flat

centers, set up test dial indicator and

washer installed under jumper termi−

measure the ram end play.

nal to keep nut from bottoming on

threads. Retaining nut torque must not

(a). The end play must not exceed 0.0075

exceed 50 inch−pounds (5.65 Nm).

inch (0.1905 mm).

(10). Connect electrical plug to actuator.

(b). Remove any spring free play in the

spring assembly by tightening the

(11). With main rotor blades lifted off the

spring adapter screw until no play

droop stops, perform a power−on

can be felt.

operational check of the cyclic trim

actuator. The actuator must not bind

(c). While tightening the screw, check

throughout the travel range in either

that there is thread−locking friction

direction, and must maintain at least

from the self−locking threaded insert.

0.015 inch (0.381 mm) minimum

(d). Replace actuator assembly if end

clearance with the center beam struc−

play is excessive.

ture.

(5). Position test switch to RETRACT and

(12). Lower the helicopter and remove the

allow the actuator ram to fully retract.

jacks.

(a). Using the end of the trim tube as a

C. Cyclic Trim Actuator Inspection

reference point, measure the portion

(Ref. Figure 7−45)

of the ram that remains out of the

tube to the nearest 0.015625 inch

(1). Inspect electrical connector for evidence

(0.396785 mm).

of damage, and broken or missing

contacts.

(b). Record this measurement for use in

step (7). below.

(2). Inspect exterior of trim actuator for

evidence of damage and deformation.

(6). Set the stopwatch to zero second.

(3). When actuator speed (response time) is

(a). Start the actuator and stopwatch at

questionable, perform the bench test

the same time.

(Ref. Cyclic Trim Actuator Bench

(b). Observe the time it takes the actua−

Testing).

tor ram to travel from fully retracted

D. Cyclic Trim Actuator Bench Testing

to fully extended.

(1). Connect cyclic trim actuator to test

(c). Check time interval for actuator

harness and equipment.

motor tested.

(2). Mount the actuator in a suitable fixture

Actuator Motor

Time Interval

that will allow vertical extension and

Part Number

(Seconds)

retraction.

369A7001

58.4

(3). Turn on direct−current power and

369A7014 (High Speed)

38.0

adjust output to 25.75−26.25 Vdc.

369A27001 (Super Fast)

15.5

During the following tests, do

CAUTION

not retract the spring assembly

(7). Measure the length of the extended

(ram) so that actuator length is less than

ram.

13.50 inches between attach bolt centers.

(a). Subtract the measured result of step

(4). With actuator spring assembly (ram)

(5). above from this value.

approximately halfway between travel

limits, actuator length at 14.46 inches

(b). The result must be 1.92 inches

(36.7284 cm) between attach bolt

(4.8768 cm) minimum.

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Revision 20

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

SPRING

ADAPTER

SPRING GUIDE

SPRING ADAPTER

SCREW

GROUND STUD

OR CLIP

ADAPTER

TEST LOAD

CONNECTION

ACTUATOR MOTOR

TRIM TUBE

(NOTE 1)

TRIM DECAL

SELF−LOCKING

THREAD INSERT

SPRING

WASHER

NOTE 2

ACTUATOR

MOTOR

TRIM

ACTUATOR

TUBE

NAS1398B4−3 RIVET

(4 PLCS)

SPRING

ACTUATOR

HOUSING

NOTES:

369A7001 AND 369A7014 ACTUATOR CAN BE USED

FOR LATERAL OR LONGITUDINAL TRIM. 369D2701

ADAPTER

ACTUATOR CAN BE USED FOR LONGITUDINAL

ACTUATOR

1.00 IN.

TRIM ONLY.

HOUSING

TUBE

INSTALLATION

REPLACEMENT PARTS HAVE NUTPLATE RIVETED IN

(25.4 MM)

HOLE

PLACE; WASHER, NUT AND COTTER PIN NOT REQUIRED.

ITEM

EQUIPMENT DESCRIPTION

NO.

SPDT SWITCH

STOPWATCH, CALIBRATED IN 1/10 SECOND INCREMENTS

(MINERVA OR EQUIVALENT).

EXTEND

6 IN. (15 CM) SCALE.

DC VOLTMETER, CALIBRATED 0−50 VOLTS (WESTON

OFF

MODEL 931 OR EQUIVALENT).

26 VDC

RETRACT

DC MILLIAMETER, CALIBRATED 0−5 AMPERES

V M2

POWER

(WESTON MODEL 931 OR EQUIVALENT).

VARIABLE DC POWER SUPPLY, 10−36 VOLTS (N. J. E.

−

MODEL SY 36−10 OR EQUIVALENT).

DIAL INDICATOR GAGE (BROWN AND SHARP

MODEL 740 OR EQUIVALENT).

SWITCH, SPDT, CENTER OFF.

TEST HOOKUP

30−059C

Figure 7-45. Cyclic Trim Actuator

Page 7-127

Revision 16

MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

In the following test, do not run

65. Cyclic Trim Actuator Repairs

CAUTION

actuator against extend limit

(Ref. Figure 7−45)

stop with the 163 pound (73.94 kg) weight

aiding actuation. The actuation thrust bear−

A. Cyclic Trim Actuator Drive Gear

ing may be damaged.

Retention Nut Field Repair

(8). Connect a 163 pound (73.94 kg) load to

Loosening of drive gear retention nut of the

the actuator.

cyclic trim actuator may occur. Whether the

actuator is inoperative because of a stalled

rather than an electrical failure can be

(a). Set test switch to RETRACT. Check

determined from this procedure to remove and

the time it takes the ram to travel

reinstall the retention nut with a Loctite

1.72−1.78 inches (4.3688−4.5212 cm)

sealant.

to the retract stop.

NOTE:

(b). Check retraction time for actuator

D Rework of operative trim actuators is rec−

motor tested.

ommended at major inspection period.

D Rework is NOT applicable to actuators

Actuator Motor

Time Interval

having letter ‘‘R" following vendor part

Part Number

(Seconds)

number on actuator housing.

369A7001

30-50

(1). Remove cyclic trim actuator from

369A7014 (High Speed)

15-25

helicopter.

369A27001 (Super Fast)

7-12

NOTE: If actuator is inoperative, bench test

unit. A reading of 0.00− 0.10 ampere indi−

cates electrical failure; replace actuator. Mo−

(9). The operating current under load

tor runs but output shaft does not move to

conditions must not exceed 1.2 amperes

indicate mechanical failure; replace actua−

running and 2.0 amperes stalled.

tor. An 0.070 ampere (approximately) read−

ing of actuator extends partway and stalls

NOTE: It is not necessary to extend or retract

indicates mechanical failure; rework actua−

the actuator ram more than 0.250 inch (6.35

tor per steps (2). thru (7). below.

mm) for the test in the next two steps.

(2). Remove lockwire and six screws

(10). Reduce the voltage input to 21 volts.

securing actuator cover to housing.

The actuator ram must retract and

When removing housing, note

extend. Overtravel is limited to 0.020

CAUTION

location and number of shims on

inch (0.508 mm) with an overriding

each gear for reassembly in proper location.

(aiding) load; otherwise there must be

no overtravel.

NOTE: Step (3). does not apply if actuator is op−

erative. Perform steps (4). thru (7). below.

(11). Increase the input voltage to 28 Vdc.

The actuator arm must retract and

(3). Using fingers only, check gear drive

extend. Overtravel is limited to 0.020

retention (hex) nut for looseness. If nut

inch (0.508 mm) maximum with an

is loose, rework per instructions below.

overriding (aiding) load; otherwise

If nut is NOT loose, replace actuator

there must be no overtravel.

assembly.

(4). Remove nut and clean threads. Rein−

(12). Remove 163 pound (73.94 kg) load and

stall nut using Loctite No. 290 on

repeat step (4). above.

threads. Torque nut to 30 − 40

inch−pounds (3.39 − 4.52 Nm).

(13). Run actuator until the arm is extended

1.750 inches (4.445 cm). Turn power off

(5). Reinstall actuator cover with existing

and disconnect the cyclic trim actuator.

screws; lockwire screws.

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MD Helicopters, Inc.

CSP−H−2

500 Series - Basic HMI

(6). Add letter ‘‘R" at end of vendor part

(4). Use the dimensions to assemble the

number on actuator housing.

replacement actuator housing and trim

tube. Pick up and drill, 0.098 inch

(7). As applicable, reinstall trim actuator.

(2.4892 mm), the four attaching rivet

B. Cyclic Trim Actuator Spring Assembly

holes, if required.

Replacement

(5). Coat the mating surfaces of the trim

(1). Insert a screwdriver into the open end

tube and actuator housing with primer

of the spring guide and remove the

(4, Table 2−4). Assemble while primer is

screw that connects the two spring

still wet.

adapters.

(6). Install the four mechanically expanding

NOTE: Identify the screw for lateral or longitu−

rivets (NAS1398B4−3).

dinal trim because the screws are no inter−

changeable. The lateral actuator screw is

(7). Reinstall the actuator.

2.875 inches (7.3025 cm) long; the longitudi−

nal screw 2.625 inches (6.6675 cm) long.

(8). Reinstall the actuator spring assembly.

(2). Slide spring assembly out of the trim

(9). Perform a bench test.

tube.

D. Cyclic Trim Actuator (Motor/ Gear Drive

(3). Clean the inside of the trim tube with

Mechanism) Replacement

solvent (1, Table 2−4).

(4). Coat the outside of the replacement

(1).

Remove actuator spring assembly.

spring assembly tube lightly with

(2).

Remove the trim tube.

grease (26).

(5). Slide replacement spring assembly into

(3).

Support the actuator tube and press out

the trim tube.

the spring pin.

(6). Install spring adapter screw in the open

(4).

Unscrew the adapter from the actuator

end of spring assembly and tighten

and remove the actuator from the

screw until no free play can be felt

housing.

while pushing and pulling on spring

assembly. While tightening the screw,

(5).

Screw the adapter into the replacement

check that there is thread−locking

actuator shaft until it bottoms. If the

friction from the self−locking threaded

spring pin hole drilled in the adapter

insert.

intersects the guide hole in the actua−

tor, the adapter must be replaced;

(7). Wipe off all excess grease.

otherwise, the adapter may be reused.

(8). Perform a bench test to check actuator

(6).

Use a 0.0625 inch (1.5875 mm) drill to

operation.

drill the spring pin hole through the

C. Cyclic Trim Actuator Housing or Trim

adapter and actuator. Deburr the hole.

Tube Replacement

(7).

Reassemble the actuator housing and

(1). Remove the actuator spring assembly.

trim tube.

(2). Carefully drill out the four trim tube

(8).

Install the actuator in the housing.

attaching rivets. Remove trim tube.

Screw the adapter onto the actuator.

(3). Remove actuator from actuator hous−

ing. Check housing for condition and

(9).

Support the actuator shaft. Press in the

evidence of corrosion.

spring pin. Be sure that the pin is flush

with the shaft.

NOTE: The housing may be either an alumi−

num or magnesium casting. Ref. Sec. 2 for

(10).

Install the actuator spring assembly.

corrosion control and identification of mag−

nesium and aluminum alloys.

(11).

Bench test the actuator assembly.

Page 7-129/(7-130 blank)

Revision 16

MD Helicopters, Inc.

CSP-H-2

500 Series - Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 8 Tail Rotor and Control System .

8−1

Tail Rotor and Control System

8−1

Tail Rotor and Control System TroubleShooting

8−1

Figure 8−1. Tail Rotor and Control System

8−2

Table 8−1. Troubleshooting Tail Rotor/Vibrations

8−3

Figure 8−2. Isolating Control System Troubles

8−4

Tail Rotor Controls Rigging

8−5

Figure 8−3. Tail Rotor Control System Rigging

8−6

Tail Rotor and Pitch Control Assembly

8−7

Tail Rotor and Pitch Control Assembly Replacement

8−7

A. Tail Rotor and Pitch Control Assembly Removal

8−7

B. Tail Rotor and Pitch Control Assembly Installation

8−8

Figure 8−4. Replacement of Tail Rotor and Pitch Control Assemblies

(Sheet 1 of 2)

8−9

Tail Rotor and Pitch Control Assembly Inspection

8−12

A. Pitch Control Assembly Inspection

8−12

B. Metal Blade Inspection

8−12

C. Fiberglass Blade Inspection

8−12

D. Tail Rotor Bearing Inspection

8−13

E. Remaining Components Inspection

8−14

Elastomeric Bearing Inspection

8−14

Figure 8−5. Tail Rotor and Pitch Control Assemblies − Inspection of,

and Handling Limits (Sheet 1 of 4)

8−15

Figure 8−6. Blade Flapping Resistance Measurement (Elastomeric

Bearings)

8−18

Elastomeric Bearing Care and Cleaning

8−19

Tail Rotor and Pitch Control Assembly Repair

8−19

10. Pitch Control Link Replacement

8−19

11. Leading Edge Tape Replacement (Fiberglass Blade)

8−20

12. Tail Rotor Assembly Bungee Initial Installation (Fiberglass−to−Metal Tail Rotor

Blade Conversion)

8−20

Figure 8−7. Tail Rotor Assembly Bungee Installation (Metal Blade) .

8−21

13. Tail Rotor Balance Adjustment (Without Balance Kit)

8−21

14. Tail Rotor Balance Adjustment (With Balancing Kit)

8−22

A. Tail Rotor Balance Preliminary Adjustment

8−22

Figure 8−8. Tail Rotor Vibration Analysis Equipment

8−23

B. Tail Rotor Vibration Analysis Kit Installation

8−24

C. Preparation for Balancing

8−24

Page 8-i

Revision 17

MD Helicopters, Inc.

CSP-H-2

500 Series - Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

Figure 8−9. Tail Rotor Balancing

8−25

D. Vibration analysis

8−26

E. Balance at Fiberglass Blade Tip

8−26

F. Balance at Metal Blade Tip

8−27

Table 8−2. Rotor Balance Weight Location Chart

8−28

Table 8−3. Tail Rotor Balance Weight Value Chart

8−29

15. Tail Rotor Blade Track Verification

8−30

16. Tail Rotor Blades

8−30

A. Fiberglass Blades

8−30

B. Metal Blades

8−30

C. Fiberglass Tail Rotor Blade Replacement

8−30

D. Metal Tail Rotor Blade Replacement

8−31

17. Tail Rotor Blade Replacement

8−31

18. Pitch Control Assembly

8−33

19. Pitch Control Assembly Replacement

8−33

20. Pitch Control Assembly Inspection

8−34

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

8−35

Figure 8−11. Assembled Tail Rotor and Blades − Cross Section View

(Elastomeric Bearings)

8−36

21. Tail Rotor Swashplate Regreasing

8−37

22. Tail Rotor Hub and Fork Assembly

8−37

23. Hub and Fork Assembly Maintenance

8−38

A. Inspection of Hub and Fork Assembly − Blades Removed .

8−38

B. Strap Pack Assembly Precautions

8−38

C. Parts Replacement Information

8−38

24. Tail Rotor Pedal Installation (Left Position)

8−38

25. Tail rotor Pedal Installation Replacement

8−38

A. Tail rotor Pedal Installation Removal (Left Position)

8−38

Figure 8−12. Tail Rotor Swashplate Bearing Regreasing . .

8−39

Figure 8−13. Tail Rotor Swashplate Bearing Regreasing Tool .

8−39

B. Installation of Tail Rotor Pedal Installation (Left Position) .

8−40

26. Disassembly of Tail Rotor Pedal Installation (Left Position) .

8−40

A. Reassembly of Tail Rotor Pedal Installation (Left Position) .

8−41

27. Tail Rotor Pedal Installation Inspection (Left Position)

8−41

A. Tail Rotor Pedal Installation Repair (Left Position)

8−41

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

8−42

28. Floor−and−tunnel−Routed Control Rods

8−43

Page 8-ii

Revision 17

MD Helicopters, Inc.

CSP-H-2

500 Series - Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

29. Floor−Routed Tail Rotor Control Rod Repair

8−43

30. Sta. 78.50 Tail Rotor (Tunnel−Routed) Control Rod

8−43

31. Tail Rotor Idler Bellcrank

8−43

32. Upper Fuselage and Boom Tail Rotor Control Linkage

8−43

33. Sta. 100 Control Rod Sta. 142 Bellcrank Replacement

8−44

A. Sta. 100 Control Rod Sta. 142 Bellcrank Removal

8−44

B. Sta. 100 Control Rod or Sta. 142 Bellcrank Installation .

8−44

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

8−45

34. Sta. 282.00 Bellcrank Replacement

8−46

A. Sta. 282.00 Bellcrank Removal

8−46

B. Sta. 282.00 Bellcrank Installation

8−46

35. Tailboom Control Rod Replacement

8−46

A. Tailboom Control Rod Removal

8−46

B. Tailboom Control Rod Installation

8−46

36. Sta. 95 Bellcrank and Support Replacement

8−47

A. Sta. 95 Bellcrank and Support Removal

8−47

B. Sta. 95 Bellcrank and Support Installation

8−47

37. Upper Fuselage and Boom Tail Rotor Control Linkage Inspection .

8−47

38. Upper Fuselage and Boom Tail Rotor Control Linkage Repair .

8−47

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

8−49

Page 8-iii/(8-iv blank)

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 8

TAIL ROTOR AND CONTROL SYSTEM

1. Tail Rotor and Control System

The control linkage on the helicopter with the

cambered metal−bladed tail rotor includes a

(Ref. Figure 8−1) The tail rotor, mounted on

bungee spring designed to relieve left forces in

the tail rotor transmission at the end of the

flight.

tail boom, counteracts main rotor torque and

When the helicopter is on the ground, the

controls the heading of the helicopter. The

pedal to seat distance is adjustable by remov−

rotor consists of two variable−pitch blades

ing quick−release pins on the pedal arms and

mounted on a teetering delta−type hub.

repositioning the pedals.

The tail rotor control system produces direc−

Dual control provisions are included with the

tional control by varying the pitch of the tail

pilot’s compartment tail rotor control installa−

rotor blades. Depressing the antitorque pedals

tion.

moves a system of bellcranks and push−rods

routed through the fuselage and tailboom to

2. Tail Rotor and Control System

the tail rotor.

TroubleShooting

Troubleshooting information is divided into:

Blade angle is controlled by a pitch control,

assembly consisting of links connecting pitch

(1). Investigation of operational vibration

controls arms to a swashplate that slides

problems originating with the tail rotor

axially on the tail rotor transmission output

assembly, or symptoms that can be

shaft. During flight, the pedal position and

recognized (Ref. Table 8−1).

pressure required to maintain a desire heading

will vary depending on main rotor torque

(2). Isolation of an unusual controls

variations, altitude and airspeed conditions.

malfunction (Ref. Figure 8−2).

Page 8-1

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 8-1. Troubleshooting Tail Rotor/Vibrations

Symptom

Probable Trouble

Corrective Action

Heavy medium-frequency vibration

Tail rotor out of balance.

Rebalance tail rotor assembly.

in tail rotor assembly vibration

Runout of tail rotor transmission

Replace gearbox if runout (TIR) of

sometimes felt in pedal as a

output shaft excessive.

shaft exceeds 0.003 in. (0.0762 mm)

buzzing sensation.

maximum.

High frequency vibration, primarily

Tail rotor blades slightly out of

Replace pitch control link bearings if

in pedals as a buzzing sensation.

balance.

they have a staking groove

(CSP-H-5). Replace link if bearing is

pressed-lip assembly.

NOTE: High frequency vibration in

Excessive wear of swashplate or

Replace double-row bearing or

the helicopter can also be

double-row bearing in housing of

swashplate (CSP-H-5) or pitch

caused by components of other

pitch control assembly.

control assembly.

systems (Ref. Sec. 5, 9 and 10).

Excessive looseness in tail rotor

Adjust bearing preload by

folk bearings.

reshimming hub or replace bearings

(CSP-H-5); or replace tail rotor

assembly.

Tail rotor hub-to-fork play.

Adjust bearing preload by resembling

hub or replace bearings CSP-H-5,

(HMI Appx C); or replace tail rotor

assembly.

Separation of leading edge

Replace blade(s) or tail rotor

abrasion strip (fiberglass blades

assembly (Ref. CSP-H-5 for dent

only) or excessive dents in leading

limits).

edge of metal blades.

Insufficient torque on stabilizer strut

Retorque bolts (Ref. Sec. 5) or

bolts or tail rotor assembly

retaining nuts.

retaining nut.

Leading edge abrasion tape worn

Replace leading edge abrasion tape.

away or lost from blade. (fiberglass

blades only)

Worn or deteriorated damped type

Replace damper snubber discs.

stabilizer strut snubber discs.

Excessive play in pitch control link

Worn pitch control link bearings.

Replace excessively worn bearings if

assemblies.

they have a staking groove

(CSP-H-5). Replace link if bearing is

pressed-lip staked.

High left pedal forces required in

Bungee spring (Sta. 63.00)

Reconnect or replace bungee spring

flight (metal blade tail rotor only).

disconnected, broken or stretched.

as required.

Page 8-3

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 8-1. Troubleshooting Tail Rotor/Vibrations (Cont.)

Symptom

Probable Trouble

Corrective Action

Pedals binding.

Excessive drag of pitch control

Clean swashplate bore and output

swashplate on gearbox

shaft splines; reduplicate splines if

outputshaft.

swashplate liner is oilite bronze.

Nylon liner loose in swashplate.

Replace swashplate (CSP-H-5).

Snapping noise heard in

No trouble - noise is normal action

None required - noise indicates pack

nonoperating tail rotor when pitch

of strap pack and caused by

straps are intact.

angle changed from one extreme

tension-torsion pack straps

to the other.

twisting and bending when blade is

feathered without centrifugal load

present.

Figure 8-2. Isolating Control System Troubles

Symptom

Isolating Step

Corrective Action

Binding, locking-up and erratic

Disconnect pitch control links from

If symptom gone, replace tail rotor

action of foot pedals (1).

pitch control assembly.

assembly.

Symptom remains

Disconnect Sta. 282 aft boom

If symptom gone, clean swashplate

bellcrank from pitch control

bore and output shaft splines.

assembly (Ref. Figure 8-4).

Lubricate splines if swashplate liner

is oilite bronze. Replace swashplate

if necessary. Check for elongation

of bolt hole in support arm portion of

main housing assembly of tail rotor

gearbox, caused by looseness of

bellcrank fulcrum bolt and nut. (2).

Symptom remains

Disconnect floor-routed tail rotor

If symptom gone, inspect tail rotor

control rod from foot pedal torque

control rods and bellcranks until

tube fitting (Ref. Figure 8-14).

defective part is located.

Symptom remains

Loosen foot pedal torque tube

If symptom gone, pedal torque tube

bracket mounted on front of floor

misaligned; shim for correct

structure.

alignment. If symptom remains,

disassemble and inspect tail rotor

foot pedal installation until defective

part is located (Ref. Figure 8-14).

Trouble corrected

NOTES:

(1) Never force controls.

(2) Binding of swashplate with nylon liners may be caused by extreme low temperatures. Check by running

helicopter until control system is warmed.

Page 8-4

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3. Tail Rotor Controls Rigging

(3). Remove hardware attaching tailboom

control rod to inboard end of Sta. 282.00

Rigging of the tail rotor control system must be

bellcrank on tail rotor transmission

accomplished immediately after replacement

(Ref. Figure 8−4).

of linkage that can not be accurately measured

(by trammeling, etc.) before it is installed in

(4). Tie back the tail rotor rotating boot.

the tail rotor control system or if helicopter

Place the midtravel portion of tail rotor

operation reveal a rigging deficiency.

swashplate rigging tool (28 or 29,

Table 2−2) between the swashplate and

Remove pilot’s pedals to prevent

CAUTION

the tail rotor fork split retaining ring

possible contact with the lower

(Detail B, Figure 8−3).

windshield during rigging sequence.

NOTE: Check that the rigging tool is in contact

NOTE: Control rod end bearing adjustment is

to be made to the nearest half turn that will

with the split ring and not on the fork.

produce correct rigging. When tightening

the jam nut at the adjustable end of a con−

(5).

Turn tailboom control rod at aft end.

trol rod, always hold the rod end with a

Adjust rod length to the nearest half

wrench to prevent jamming of the bearing.

turn of the rod end that will allow the

tool to just slide between the split ring

(1). Using two pieces of wood and a C−

and swashplate.

clamp or a rope, secure pilot’s foot pedal

arms so they are aligned (Detail A,

(6).

Recheck that centerline of tailboom

Figure 8−3). With the pilot’s foot pedals

control rod forward attach bolt is still

clamped in the neutral position and the

4.75−5.09 inches (12.065−12.9286 cm)

control rod lengths adjusted as shown

from aft face of Sta. 137.50 bulkhead.

in Figure 8−14 and Figure 8−15, the

Also check check forward rod end for

control system bellcrank positions may

not less than one and one−half exposed

be checked as follows:

threads with checknut snug against

rod. If either condition does not exist,

NOTE: On helicopters with cambered metal tail

disconnect forward end of Sta. 100

rotor blades, disconnect bungee spring at

control rod and readjust both control

connection to the aft end of the floor−routed

rods until Sta. 142 bellcrank position

control rod.

and exposed threads of both control

rods are within tolerance.

(a). Tail rotor idler bellcrank: Centerline

of aft arm should be at 90 ±2 degrees

to Sta. 78.50 bulkhead.

(7).

Ensure that slotted bushing is in place

in bottom ear of Sta. 282 bellcrank and

(b). Sta. 95 bellcrank: Centerline of

inboard ear of Sta. 95 bellcrank.

tunnel−routed control rod attach bolt

Connect control rods using hardware

should be 4.30 ±0.090 inches (10.922

removed and cotter pin.

±0.2286 cm) above the mast base

structure.

(8).

Check witness holes for proper thread

engagement. Align rod ends to get

(c). Sta. 142 bellcrank: Centerline of

approximately equal angular throw in

tailboom control rod attach bolt

bellcrank, and tighten checknuts.

should be 4.75−5.09 inches

(12.065−12.9286 cm) from the aft face

(9).

Remove clamping device from foot pedal

of the Sta. 137.50 bulkhead. Gain

arms.

access to bellcrank by removing the

tail rotor control bellcrank access

door.

(10).

If installed, loosen stop nuts on pedal

stop bolts (Detail A). Screw in the pedal

(2). Loosen rod end checknut at forward

stop bolts approximately 0.50 inch (12.7

end of tailboom control rod.

mm).

Page 8-5

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTES:

0.250 IN. (6.35 MM) MAX.

ROTATING BOOT NOT SHOWN FOR CLARITY;

MISALIGNMENT

NORMALLY TIED BACK TO LOCATE RIGGING TOOL.

BETWEEN PEDALS

TAILBOOM CONTROL ROD AND STA. 100 CONTROL

ROD ADJUSTED AS REQUIRED TO GET MIDTRAVEL

POSITION (REFER TO TEXT).

USE TOOL (28, TABLE 2−2) TO RIG FIBERGLASS BLADED

CLAMPING BLOCKS

TAIL ROTOR ONLY. BOTH TOOLS ARE DIMENSIONALLY

IDENTICAL FOR RIGGING PURPOSES (−3 IS IMPROVED

STOP NUT

VERSION).

(NOTE 5)

USE TOOL (29, TABLE 2−2) (COLORED YELLOW) TO RIG

METAL BLADED TAIL ROTOR ONLY. RIGHT PEDAL AND

RIGHT STOP BOLT

LEFT PEDAL DIMENSIONS ARE DIFFERENT THAN THOSE

LEFT STOP BOLT

OF ITEM 19 TOOLS.

ON CURRENT TYPE TAIL ROTOR PEDAL INSTALLATION.

PEDAL ARM ALIGNMENT AND STOP

BOLT ADJUSTMENT

NON−ROTATING

BOOT

NOTES 3, 4

TAIL BOOM

CONTROL ROD

TAIL ROTOR

(NOTE 2)

FORK

TAIL ROTOR CONTROL

BELLCRANK ACCESS DOOR

MIDTRAVEL RIGGING

STA. 100

CONTROL ROD

(NOTES 1, 2)

(NOTE 2)

LEFT

369A9931

RIGHT

MID RIG

PEDAL

LEFT PEDAL RIGGING

RIGHT PEDAL RIGGING

30−064E

Figure 8-3. Tail Rotor Control System Rigging

Page 8-6

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Use care when actuating pedals

(16). Reinstall Sta. 142 bellcrank access door.

CAUTION

to avoid the possibility of dam−

aging the tool or the windshield.

4. Tail Rotor and Pitch Control Assembly

The tail rotor and pitch control assembly

(11).

Adjust right pedal stop bolt (Detail A)

consists of a hub, drive fork and two blades

so that when pedal arm is held against

assembled to a pitch control assembly.

the stop the right pedal portion of

rigging tool will just slide between the

The two blades are telescoped over the hub

split ring and swashplate (Detail C).

and interconnected by a tension−torsion strap

The fit should be tight enough to

assembly inside the hub.

support the tool weight. Without

changing adjustment of bolt or tool fit,

The hub is bolted in the drive fork and two

tighten stop nut (if installed) on bolt.

pitch control links are attached between the

blade arms and the pitch control assembly.

(12).

Adjust left pedal stop bolt (Detail A) so

The metal−blade tail rotor assembly is

that when pedal arm is held against the

standard on current production helicopters

stop with 20 − 25 pounds (89 − 111 N)

and optional for earlier helicopters originally

pressure (or pull on right pedal) the

equipped with the fiberglass blade tail rotor

left pedal portion of rigging tool will

assembly. The metal−blade tail rotor assembly

just slide between the split ring and

is required on a helicopter with an Allison

swashplate (detail D). The fit should be

250−C20 Engine.

tight enough to support the tool weight.

Without changing adjustment of bolt or

All following information applies to both

tool fit, tighten stop nut (if installed) on

metal− and fiberglass−blade tail rotor assem−

bolt. Remove rigging tool and restore

blies, unless specifically indicated otherwise.

rotating boot to normal position.

Maintain both the metal− and fiberglass−blade

tail rotor assemblies as specified as follows.

(13).

Reinstall pedals. Slowly press the

outboard pedal to its full travel position

5. Tail Rotor and Pitch Control Assembly

against the stop bolt. With not more

Replacement

than 20 pounds (89 N) of pressure

(Ref. Figure 8−4)

applied, the upper and lower edges of

the pedal must clear the canopy glass

A. Tail Rotor and Pitch Control Assembly

by not less than 0.20 inch (5.08 mm).

Removal

(14).

Operate through full range of travel.

CAUTION

While the controls are being moved:

D Whenever the blades and hub are re−

(a). Check that there is never less than

moved as an assembly, or whenever the

0.060 inch (1.524 mm) clearance

pitch control links are disconnected, do

around the Sta. 100 control rod

not allow blade pitch to exceed 30 degrees

where it passes through the structure

from the neutral pitch position (Ref.

at Sta. 137.50.

Figure 8−5). This is equal to blade pitch

control arm movement of approximately 1

(b). Check that there is never less than

inch (25.4 mm) in either direction. Unre−

0.010 inch (0.254 mm) clearance

stricted rotation of blades on the hub can

around the tailboom control rod

excessively bend or stretch the internal

where it exits between the boom and

tension−torsion strap assembly and cause

tail rotor transmission.

undetected damage to the strap assembly

and an out−of−balance condition for the

(15). On helicopters with a cambered

tail rotor when reassembled.

metal−blade tail rotor, connect bungee

spring between aft end of floor−routed

D To prevent balance problems at reassemb−

control rod and Sta. 63.00 bracket. Note

ly of parts and hardware, note and mark

that pilot’s left pedal moves to its

the exact locations and positions of all

normal forward position.

items before removal to ensure reinstalla−

Page 8-7

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

tion at the same locations and positions

NOTE:

during reassembly. It is advisable to sepa−

D Placing a grease pencil mark on the drive

rate, tags and index all items as disas−

fork, to key it to the transmission output

sembled, for subsequent ease of reas−

shaft will enable subsequent installation

sembly in proper position.

of tail rotor assembly at same position.

Also, application of a small painted

D Do not remove the hub− to− drive fork

matchmark next to the centerline splined

hinge bolt to remove the tail rotor assem−

groove on both the pitch control assembly

bly. This bolt should be removed accord−

and tail rotor drive fork aids reassembly

ing to overhaul instructions (CSP−H−5).

at same position on the transmission

It is possible to damage the strap pack if

shaft.

any other procedure is used.

D One spline groove of the fork is located di−

rectly on the centerline passing through

(1). Perform one of the following, as

the centers of the two fork bearings while,

applicable.

at the opposite side of the spline bore, the

same centerline passes through a spline

(a). If only the tail rotor is to be removed:

tooth. A similar condition exists with re−

spect to the swashplate splines, except

1). Color code the pitch control arms,

that the reference centerline originates

links and attaching hardware (Ref.

between the swashplate arms. (Ref.

Figure 8−9).

CSP−H−5 for illustrations showing

matchmarks and additional information.)

2). Disconnect pitch control links from

(5). Slide tail rotor assembly (including

blade pitch control arms (Ref.

pitch control assembly if being re−

Figure 8−4) and retain attaching

moved) off shaft: catch or remove split

hardware.

rings from shaft.

NOTE: Two types of split ring consisting of two

(b). If the complete tail rotor assembly

half sections, are in service. Half sections of

including the pitch control assembly

different types must not be inter−mixed and

is to be removed:

should be retained as a matched set when

removed from the helicopter.

(Ref.

1). Remove Sta. 282 bellcrank from

Figure 8−4 for correct applicability.)

transmission at pivot points so

B. Tail Rotor and Pitch Control Assembly

that bellcrank pivot pin is disen−

Installation

gaged from self−aligning bearing

in pitch control housing (fig. 8−3).

(1). Pull beaded end of rotating boot from

groove of drive fork and position tail

(2). Cut lockwire and pull beaded end of

rotor assembly in line with transmis−

non−rotating boot out of inboard groove

sion output shaft.

of pitch control housing.

NOTE: Installing tail rotor blades at 90 degrees

to the high and low extremes of shaft run−

(3). Straighten tang of tang washer. Using

out, using reference marks placed on the

torque wrench adapter (30, Table 2−2),

shaft at time of inspection, reduces chances

loosen retaining nut and slide tail rotor

of high frequency vibrations and lessens

outward on shaft to remove blade stop

possibility of requirement for tail rotor bal−

and spacer (or stop support), then

ancing.

remove nut.

(2). If pitch control assembly is installed,

position complete tail rotor and pitch

Tail rotor tang washer must not

control assembly in line with transmis−

CAUTION

be reused.

sion output shaft and rotate tail rotor

back and forth slightly until splined

(4). Remove and discard tang washer.

swashplate engages splines of shaft.

Page 8-8

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TAIL ROTOR

TRANSMISSION

SPRING TENSION

WASHER

TAIL ROTOR

EXTENDED BALANCE

CONTROL ROD

BOLT 369A1606

SPECIAL WASHER

(NOTE 4)

(REDUCED OD)

PITCH CONTROL LINK

PITCH CONTROL ASSEMBLY

(HOUSING, BEARINGS,

STA. 282

SWASHPLATE) (NOTE 7)

BELLCRANK

NOTE 3

50−80 IN. LB

(5.65−9.04 NM)

(NOTE 7)

NOTE 1

HINGE

BOLT

50−80 IN. LB

DRIVE FORK

(5.65−9.04 NM)

TRANSMISSION OUTPUT SHAFT

SPLIT RING (NOTE 2)

ROTATING BOOT

NOTE 3

BLADE STOP

(NOTE 2)

FORK BEARING

TANG WASHER

(NOTE 5)

RETAINING NUT

SPACER OR

FIBERGLASS TAIL

RETAINING NUT

ROTOR BLADE

400−450 IN. LB

STOP SUPPORT

(45.19−50.84 NM)

(NOTE 2)

(NOTE 6)

FINAL TORQUE

(NOTE 6)

SPECIAL WRENCH OR TORQUE

WRENCH ADAPTER

NOTES:

CENTERLINE TOOTHSPACE MATCHMARK MUST MATE TO

AT REPLACEMENT, USE HS1551S290 STRAIGHT TANG WASHER OR

CENTERLINE TOOTHSPACE MARK ON DRIVE FORK WHEN

HS1551−290 CONED TANG WASHER. DIMENSION ACROSS INSIDE

ASSEMBLED ON OUTPUT SHAFT.

(BORE) DIAMETER FROM EDGE OF KEY TO OPPOSITE EDGE (ON

SEE BOXED DETAILS FOR INSTALLATION INFORMATION.

CENTERLINE) SHOULD BE 0.695−0.715 IN.(17.653−18.161 MM).

COAT WITH PRIMER (4, TABLE 2−4) AT INSTALLATION.

TORQUE NUT TO 550−600 IN. LB (62.14−67.79 NM) USING WRENCH

BALANCING WASHERS NOT SHOWN. IF ALTERNATE STANDARD

ADAPTER (30, TABLE 2−4), BACK OFF TO 50−250 IN. LB (5.65−28.25 NM),

BOLT NAS464P−( ) IS USED. REFER TO TEXT FOR INFORMATION

THEN RETORQUE TO 400−450 IN. LB (45.19−50.84 NM).

ON INSTALLATION AND ASSOCIATED HARDWARE USED.

LUBRICATE WITH GREASE (18, TABLE 2−4).

30−065−1B

Figure 8-4. Replacement of Tail Rotor and Pitch Control Assemblies (Sheet 1 of 2)

Page 8-9

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NUT 400−450 IN. LB

DOUBLE−ROW BEARING

(45.19−50.84 NM)

PITCH CONTROL ASSEMBLY

(CURRENT TYPE DISASSEMBLY,

REFER TO HMI FOR ALL OTHERS)

TANG WASHER

SWASHPLATE

HOUSING

SELF−ALIGNING

PIVOT BEARING

(NOTE 7)

30°

SPLIT RING APPLICABILITY

369A1722−3 SUPERSEDES AND IS

ONE−WAY INTERCHANGEABLE

WITH TWO 369A1720 SPLIT RING

0.120−0.123 IN.

HALF SECTIONS.

(3.048−3.1242 MM)

SPLIT RING 369A1720

0.120−0.123 IN.

(3.048−3.1242 MM)

0.040−0.060 IN.

(1.016−1.524 MM)

0.063 IN. (1.6002 MM)

(2 HOLES)

30°

* SPLIT RING 369A1722−3

* MATCHED SET OF TWO HALF SECTIONS

EARLY CONFIGURATION

0.15 IN. (3.81 MM)

0.75 IN. (19.05 MM)

0.52 IN.

* SPACER AVAILABLE IN

0.28 IN. (7.112 MM)

0.78 IN. (19.812 MM)

(13.208 MM)

0.15 IN. (3.81 MM) (369A1812−5) AND

0.19 IN. (4.826 MM) (369A1812−3) THICKNESS.

USE THICKNESS UNDER STOP THAT

1.50 IN.

1.56 IN. (39.624 MM)

PROVIDES MINIMUM BLADE−TO−BOOM

(38.1 MM)

CLEARANCE REQUIRED (REFER TO TEXT).

0.50 IN.

* INSTALL WITH RECESSED SIDE INBOARD

SPACER 369A1812−( ) (PHENOLIC)

(12.7 MM)

STOP 369A1809 (RUBBER)

CURRENT CONFIGURATION

0.312 IN.

0.310 IN.

(7.9248 MM)

(7.874 MM)

2.00 IN.

1.83 IN. (46.482 MM)

(50.8 MM)

STOP SUPPORT 369H5306 (ALUMINUM)

STOP 369H5307 (RUBBER)

30−065−2B

Figure 8-4. Replacement of Tail Rotor and Pitch Control Assemblies (Sheet 2 of 2)

Page 8-10

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

In next step do not force blade

CAUTION

stop into position with a screw−

driver; this can crack the stop.

D In next step, be sure that two spline bore

matchmarks (one on swashplate and one

(5). Refer to Figure 8−4, Sheet 2 and

on drive fork) are in direct alignment with

determine whether rubber stop and

each other. This assures that swashplate

phenolic spacer or aluminum stop

and drive fork will both be located on the

support is used for tail rotor installa−

same spline bore centerline and prevents

tion. Either combination is acceptable.

the possibility of an approximate 180 de−

Slide tail rotor assembly outboard

gree misalignment of the splines. Spline

against nut. Install phenolic spacer

misalignment will damage the pitch con−

(recessed side facing inboard) or

trol links when the tail rotor assembly is

aluminum stop and rubber stop.

installed.

NOTE:

The phenolic spacer comes in two thick−

D Arrangement of the hardware and bolt

nesses. Use only one spacer with the thick−

heads in direction of rotation must be as

ness, 0.10 or 0.15 inch (2.54 or 3.81 mm)

shown in Figure 8−4. An out−of−balance

that provides minimum blade− to− boom

tail rotor assembly will result if bolt, nut

clearance of 2 inches (5.08 cm) when control

and washer combinations is not main−

pedals are in neutral and 2 pounds (8.90 N)

tained.

plus the break− loose value of pressure is

applied at blade tip.

(3). Slide tail rotor assembly onto shaft,

(6). Fold back rotating boot to expose groove

keeping the drive fork−to−hub pivot

in shaft. Groove must be clean and free

bolt aligned with lugs of swashplate.

of paint and foreign material. Insert

Position tail rotor assembly on shaft so

split ring in groove of shaft with

that approximately two threads at end

beveled edges of split rings facing

of shaft are exposed outboard of drive

beveled seat in drive fork.

fork.

NOTE: Two types of split rings are in service.

It is possible for pitch control

Half sections of the different types should

CAUTION

swashplate to be misaligned by

not be intermixed because they are fabri−

one− half spline in relation to drive fork.

cated as matched sets. Installing split ring

Make sure drive fork, pitch links and swash−

with gaps centered on blade span line re−

plate are in exact alignment with transmis−

duces chances of high frequency vibrations,

sion shaft centerline. If incorrectly as−

and lessens possibility of requirement for

sembled, swashplate will be misaligned

tail rotor balancing.

approximately 10 degrees from drive fork.

To correct this condition, remove and rotate

(7). While holding split ring in place, slide

the tail rotor 180 degrees, and reinstall.

tail rotor assembly inboard. Be sure

that beveled ring faces remain com−

NOTE: Preassembly of tang washer, nut, phe−

pletely nested in beveled seat of drive

nolic spacer and rubber stop as a unit aids in

fork, and that the fork contacts both

their installation when performing steps (4).

split rings. Replace the split ring if a

and (5). below. Marking the outer tang that

gap of more than 0.002 inch (0.0508

is next to the inner key on tang washer, be−

mm) exists between the fork and one

fore assembly of the parts, simplifies align−

split ring half with the other ring half

ment with keyway on shaft. Teeter blades to

in contact.

start tang washer on the shaft.

(8). Visually align a tang on tang washer

with any convenient reference point.

(4). Slip new tang washer (Note 5,

Figure 8−4) over exposed threads of

(9). Using torque wrench adapter (30,

shaft; key tang must face inboard

Table 2−2), torque nut to 550 − 600

towards gearbox. Install nut approxi−

inch−pounds (62.14 − 67.79 Nm),

mately two full turns on shaft threads

back off to 50 − 200 inch−pounds (5.65

to verify threads engaged.

− 22.60 Nm), and then retorque to 400

Page 8-11

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

−

450 inch−pounds (45.19 − 50.84

(18). If conical bearing tail rotor hub has

Nm). Check blade−to−boom clearance

been disassembled, recheck fork bolt

at the maximum teetering position;

torque (CSP−H−5) after 50 hours of

refer to NOTE in (5). above.

operation.

(10). Check that tang has not moved more

6. Tail Rotor and Pitch Control Assembly

than one tang width in relation to

Inspection

reference point noted in step (8).

(Ref. Figure 8−5) Inspect an assembled tail

rotor and pitch control assembly as follows:

NOTE: Tang washer movement of more than

one tang width is an indication that the tang

A. Pitch Control Assembly Inspection

washer inner key has sheared. This condi−

(1). Excessive drag on gearbox output shaft

tion requires replacement of the washer and

if there is binding in the control system.

reassembly of parts according to the initial

installation procedure.

(2). Surface defects.

(11).

Bend tang on tang washer to lock the

(3). Wear on inner surfaces of swashplate

nut. When bending the tang, do not

clevis ears.

force−form tang to match nut contour;

(4). Evidence of contact between swashplate

maintain the natural bend radius that

and housing.

develops at the tang root.

(5). Evidence of slippage between double−

(12).

Insert beaded end of non−rotating boot

row bearing inner race and swashplate

(drain/vent holes down) into groove of

(early type swaged assembly).

pitch control housing and beaded end of

(6). Wobble on the gearbox output shaft.

rotating boot into groove of drive fork.

Secure with lockwire (2, Table 2−4).

B. Metal Blade Inspection

(13).

Make sure that pivot pin on Sta. 282.00

(1). Surface for cracks, scratches, nicks,

bellcrank and self−aligning bearing in

gouges, dents, pits or corrosion

underside of pitch control housing are

(2). Leading edges for erosion or dents.

lubricated with grease (18, Table 2−4).

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

(14).

If removed, position Sta. 282.00

and gouges. No cracks are allowable.

bellcrank so that pivot pin slips into

Scratches that do not exceed 0.020 inch

bearing of pitch control assembly.

(0.508 mm) depth are permissible with

Rotate bellcrank back and forth as

rework.

required to align bellcrank bearing with

gearbox arm and install bolt, two

(4). Presence and security of tip weights

washers, nut and cotter pin.

and attachment hardware.

(5). Clogged drain openings.

(15).

If disconnected, position pitch control

links and install hardware.

(6). All exposed edges for possible adhesive

separation.

(16).

Position tail rotor pedals in neutral and

NOTE: If any of these conditions are found, per−

recheck that drive fork, the pitch links

form appropriate detailed inspections and

and the swashplate are in exact

allowable repairs according to limits and

alignment with gearbox output shaft

procedures in CSP−H−5. Additionally, pre−

centerline.

form a balance check at the interval speci−

(17).

If fiberglass−blade tail rotor assembly

fied in CSP−H−4.

was replaced with metal−blade tail

C. Fiberglass Blade Inspection

rotor assembly, rig tail rotor controls.

Check rigging of tail rotor controls

(1). Presence of either a green or white dot

following installation of any removed or

located just outboard of the blade data

replaced parts.

plate.

Page 8-12

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(2). Evidence of collapsed airfoil.

(1). Maximum axial looseness for bearing in

pitch control link is 0.020 inch (0.508

If either or both of the blades show

mm).

signs of a collapsed airfoil, the blades or

NOTE: If bearings secured in link by staking of

the assembly should be replaced. Minor

the bearing (pressed−lip staked) the bearing

contour variation is allowed.

is not replaceable. However, since bearing

NOTE: Minor contour variations on tail rotor

wear will usually occur only at the blade

blades are not considered a safety of flight

pitch control arm because of greater dis−

condition. Affected tail rotor assemblies

placement during operation, the link can be

may be continued in service until a replace−

continued in service until either or both

ment is available or pedal position for cruise

bearings exceed the wear tolerance.

flight changes 1 inch (25.4 mm) or more.

(2). Inspect area of link around staked

bearings for cracks. Scrap link assem−

(3). Leading edge damage or separation.

bly if any cracks are found.

(4). Fiberglass skin damage.

(3). Inspect for excessive wear at both ends

of pitch links. Check that wear is

(5). Trailing edge separation and clogged

smooth and does not extend into inner

vent/drain holes.

race of bearing. Touch up wear area

If trailing edge is separated the blade

with primer (4, Table 2−4) and match−

must be replaced. No trailing edge

ing paint (6).

separation is allowable.

(4). Inspect staked groove in outer race of

bearings for cracks. No cracks are

(6). Loose or damaged tip caps.

allowed.

(7). Spar for cracks, scratches, nicks and

(5). Maximum allowable play for spherical

gouges. No cracks allowed.

drive fork bearings is 0.024 inch (0.6096

mm) axial, or 0.008 inch (0.2032 mm)

Scratches and nicks between attach−

radial, if vibration is not excessive. No

ment bolt hole and pitch control arm

axial or radial play is allowed for the

that do not exceed 0.050 inch (1.27 mm)

conical drive fork bearings. Refer to

depth are permissible with rework.

Figure 8−10 for configuration identifica−

tion.

NOTE: If any of the above conditions are found,

perform appropriate detailed inspection and

NOTE: A physical check for pitch bearing wear

allowable repair according to limits and pro−

(step (6). below), that causes spar looseness

cedures in CSP−H−5.

on the hub, can be made by holding one

blade firmly and measuring the flapping

(8). Stainless steel leading edge abrasion

play at the tip of the opposite blade. The

strip damage or starting to separate

measured play will indicate the combined

from blade.

wear of the pitch bearings. For fiberglass

blades, excessive tail rotor vibration will

(9). Loose, unserviceable or missing leading

usually result when play is approximately

edge abrasion tape. If any such condi−

0.250 inch (6.35 mm) or more.

tion exists, replace tape.

(6). Maximum allowable wear for the pitch

(10). Perform a balance check at the internal

(feathering) bearing in the spars is

specified in CSP−H−4.

limited only by the effect of the wear on

tail rotor vibration.

D. Tail Rotor Bearing Inspection

NOTE: If any of these conditions are found, re−

Inspect pitch control link bearings, drive fork

place the defective bearing or preload shim

bearings and pitch (feathering) bearings in

fork bearings as applicable (CSP−H−5).

blade spars (fiberglass blade) or root fittings

(metal blades) for excessive looseness or play

(7). Check for indications of rust and

from wear, as follows:

corrosion on hub fork bolt. If surface is

Page 8-13

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

not protected, clean and coat with

NOTE: For any questionable and all other

primer (4).

items, refer to the complete and detailed in−

spection, damage wear and repair limits

and requirements for the tail rotor assembly

E. Remaining Components Inspection

provided in CSP−H−5.

(1). Inspect for evidence of rotational

7. Elastomeric Bearing Inspection

binding by hand−turning the tail rotor

assembly a few turns while listening for

Visually inspect elastomeric bearings installed

unusual sounds. If condition is ques−

in fork assembly, at intervals specified in

tionable, perform Inspection of Pitch

CSP−H−4, for damage and debonding from

Control Assembly.

fork as follows:

NOTE: Change of blade pitch angle when the

Elastomeric material can be

tail rotor is static can produce an audible

CAUTION

damaged by solvents, grease or

snapping noise. The blade strap pack causes

oil. If cleaning is necessary, refer to Care

the noise as the laminations are twisted and

and Cleaning of Elastomeric Bearings.

bent without a centrifugal load imposed.

Such a noise is not harmful and of no con−

(1).

Apply teetering force by hand to rotor

cern.

blades (stop−to−stop). Check for

fork−to−bearing failure. Failure is

(2).

Teeter the blades back−and−forth and

indicated by any motion between outer

check for evidence of abnormal binding.

bearing cage and fork (bearing turns in

(Some stiffness is normal, especially

fork). If failure is noted, remove bearing

when the blade stop is newer.)

and rebind in fork according to instruc−

tions in CSP−H−5.

(3).

Check that hub−to−blade pitch arm

(2).

Teeter blades stop−to−stop as in step

clearance is within typical dimensions

(1). Observe four radial molded ridges

of 0.001−0.130 inch (0.0254−3.302 mm).

on each bearing as teetering takes

place. If ridges assume continue curved

(4).

Inspect fork and hub for scratches,

shape, bearing are intact. Discontinuity

nicks, dents, cracks, corrosion and

in molded ridges indicates bearing

similar surface defects. No cracks are

failure and bearing must be replaced

allowable. Scratches and nicks that do

according to instructions in CSP−H−5.

not exceed 0.005 inch (0.127 mm) depth

are permissible with rework.

(3).

Check bearing for general condition.

Replace bearing if damaged. Evidence

of light swelling, pock marks and

(5).

Inspect all bolts and nuts for security.

crumbs are surface conditions and are

not indications of bearing failure.

(6).

Inspect blade stop and boots for

deterioration. Be sure to check for

(4).

Elastomeric bearings are suspected of

cracking or splitting in the stem area of

being unserviceable, if visual inspection

the stop.

reveals rubber deterioration, separation

or a vibration is reported. Perform

following steps to check blade flapping

(7).

Check both halves of the split ring for

resistance measurement to determine if

damage and width conformity. (Ref.

suspect elastomeric bearing has failed.

Figure 8−4). Smooth out any roughness,

burrs or irregularities on the bevel

surfaces, using grade 400 abrasive

(5).

To perform the measurement, remove

paper or crocus cloth (9 or 23,

rubber blade stop between tail rotor

Table 2−4).

hub and fork on two bladed tail rotor.

Page 8-14

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

PITCH ARM

30°

NUT

PITCH CONTROL

TIP CAP

BOLT

MAX.

LINK

DRAIN HOLE

BLADE

(TYP)

PITCH ARM

VENT HOLES

(TYP)

BALANCE

WASHER(S)

ABRASION

BLADE SPAR

FIBERGLASS

STRIP

SPRING

SKIN

WASHER

SPECIAL (REDUCED OD)

WASHER

TAIL ROTOR BLADE

(NOTE 5)

OVERLAP ABRASION

HUB

STRIP BY 0.250 IN.

0.001−0.130 IN.

(6.35 MM)

(0.0254−3.302 MM)

(TYP)

1.18 IN.

(2.9972 CM)

HUB−TO−BLADE PITCH

ARM CLEARANCE

ABRASION STRIP

BLADE TRAVEL LIMITS WITH

(NOTE 1)

PITCH LINKS DISCONNECTED

NON−ROTATING BOOT

(NOTE 4)

(NOTE 3)

3.30 IN. (8.382 CM)

SPAR

PITCH CONTROL

BLADE SPAR

ASSEMBLY

BLADE PITCH ARM

FORK

ROTATING BOOT

HUB

0.020 IN. (0.508 MM)

SPAR

ABRASION TAPE

MAX.

(NOTE 1)

FORK BEARING

CENTER

1 IN.

LINK BEARING

SWASHPLATE

(2.54 CM)

MAX.

WHITE

ABRASION

LINK BEARING LOOSENESS

(NOTE 2)

STRIP

L OF

PITCH CONTROL

ARM BUSHING

NOTE 6

3 IN. (7.62 CM)

NOTES:

2 IN. (5.08 CM) WIDE TAPE (32, TABLE 2−4) MAY BE APPLIED AS SHOWN TO

RED

PREVENT LEADING EDGE EROSION.

EARLY TYPE BLADES ARE PAINTED WITH A 6 IN. (15.24 CM) BLACK BAND

3 IN. (7.62 CM)

INBOARD OF RED.

WHITE

TWO DRAIN VENT HOLES IN FOLDS AT BOTTOM.

CAUTION: DO NOT ALLOW BLADE PITCH TRAVEL TO EXCEED LIMITS

SHOWN. ROTATING THE BLADES TO EXCESSIVE PITCH ANGLES MAY

3 IN. (7.62 CM)

RESULT IN UNDETECTED DAMAGE TO TENSION−TORSION STRAP ASSY.

RED

FIBERGLASS BLADE SHOWN. (FOR METAL BLADES, SEE SHEET 2.)

FOR PAINT SPECIFICATIONS, SEE APPLICABLE 500 S/E OR M SUPPLEMENT.

30−134−1B

Figure 8-5. Tail Rotor and Pitch Control Assemblies - Inspection of,

and Handling Limits (Sheet 1 of 4)

Page 8-15

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

DIRECTION OF PITCH CONTROL

ASSY WOBBLE ON OUTPUT SHAFT

0.020 IN. (0.508 MM) MAX.

FOR SERVICE

BOLT HOLE

CENTERLINE

PITCH CONTROL ASSY

0−10 LB. (0−50 N)

SPRING SCALE

(NOTE 8)

TWINE

WASHER

PIVOT PIN

(NOTE 9)

PITCH CONTROL LINK

NOTES: (CONT)

FORCE REQUIRED TO SLIDE PITCH CONTROL ASSY

STA. 282 BELLCRANK

INWARD OF OUTWARD ON OUTPUT SHAFT MUST NOT

EXCEED 3 POUNDS WITH PITCH LINKS, BELLCRANK AND

RUBBER BOOTS DETACHED FROM PITCH CONTROL ASSY.

WOBBLE CHECK

ADD ONE OR TWO WASHERS AS REQUIRED FOR CLEARANCE

VIEW X−X

OF BELLCRANK THRU PEDAL TRAVEL.

10. TORQUE SCREWS TO 21 − 24 INCH−POUNDS (2.37 − 2.71 NM).

30−134−3C

Figure 8-5. Tail Rotor and Pitch Control Assemblies - Inspection of,

and Handling Limits (Sheet 3 of 4)

WEAR AREA SMOOTH AND DOES NOT

EXTEND INTO BEARING OUTER RACE

BEARING O.D.

PITCH LINK (NO CRACKS ALLOWED

AROUND STAKED BEARING)

OUTER BEARING RACE STAKED GROVE

(NO CRACKS ALLOWED)

0.070 IN. (1.778 MM) MAX. WEAR

(2 PLCS EACH END)

0.231−0.269 IN.

(5.8674−6.8326 MM)

30−214A

Figure 8-5. Tail Rotor and Pitch Control Assemblies - Inspection of,

and Handling Limits (Sheet 4 of 4)

Page 8-17

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Do not remove hub− to− drive

9. Tail Rotor and Pitch Control Assembly

CAUTION

forkhinge bolt to remove tail ro−

Repair

tor assembly. This bolt should only be re−

(1). Repair of allowable surface defects on

moved according to instructions in

fork and hub that may be reworked by

CSP−H−5. Damage to strap pack may occur

using grade 320 abrasive paper (20,

if any other procedure is used.

Table 2−4) to round out and blend

defect.

(6). Measure flapping resistance of blade

using spring scale attached within 1.00

(2). Apply exterior surface touchup treat−

inch (25.4 mm) inboard of blade tip

ment and paint touchup (Ref. Sec. 2)

(Ref. Figure 8−6).

(Repairable damage limits are defined

in CSP−H−5).

(a). Block or hold tail rotor pedal in

(3). Repair both halves of split ring by

neutral position, record spring scale

rounding out or blending any rough−

value when blade tip is 3.00 inches

ness, burrs or irregularities on the

(7.62 cm) inboard and outboard from

beveled surfaces, using grade 400

no load position.

emery paper or crocus cloth (23).

(b). Scale must indicate 1.5−5.0 pounds

10. Pitch Control Link Replacement

(6.67−22.24 N). If load is not within

specified limit, replace bearing Ref.

CAUTION

CSP−H−5).

D Prior to removal of pitch control links, col−

(7). Reinstall rubber blade stop.

or code pitch control arm, bolt and all

washers used at each arm

(Ref.

Figure 8−10) . The bolt, or an identical

NOTE: When reinstalling tail rotor fork assem−

one, and same combination of washers

bly a new tang washer must be used.

must be reassembled at locations from

which removed or tail rotor balance can

8. Elastomeric Bearing Care and Cleaning

be seriously affected.

D Do not allow blade pitch angles to exceed

Elastomeric bearings are not inherently

30 degrees, approximately one inch (25.4

resistant to greases, oils, or solvents if

mm) in each direction (Ref. Figure 8−5).

immersed. They are however, somewhat

Undetected damage to the internal ten−

resistant to occasional splash or spillage of

sion torsion strap pack may occur.

these materials if exposed on an occasional

basis. If elastomeric material do come in

(1). Disconnect ends of pitch control link

contact with these fluids, the elastomeric

from clevis ear of swashplate and from

surface should be immediately cleaned. If

blade pitch control arm (Ref.

cleaning is accomplished properly, the effect of

Figure 8−4).

greases, oils, or solvents on the performance of

(2). Insert either end of repaired or replace−

the elastomeric material will be minimal.

ment pitch control link between clevis

ears of swashplate.

(1). If greases, oils or solvents come in

contact with the elastomeric damper

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

material, wipe immediately with a

torque nut to 50 − 60 inch−pounds

clean dry rag.

(5.65 − 6.78 Nm); install cotter pin.

(4). Pull pitch control assembly inboard or

(2). If wiping is not sufficient (oil or grease

outboard as required to align pitch

is too thick) clean the affected area of

control link bearing with pitch control

the elastomer with a soft bristle brush

arm bushing.

and a solution of pure soap and water.

(5). Check or apply color code for correct

(3). Rinse with tap water.

match. Place special (reduced outside

Page 8-19

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

diameter) washer and large diameter

(b). Spar outboard length is 1.18 inches

spring tension washer on extended

(2.9972 cm).

balance bolt so that concave (dished)

surface of spring washer is against bolt

(c). Tape length at blade root is to

head. With washers in place on bolt,

overlap metal abrasion strip by 0.250

insert bolt through bearing of pitch

inch (6.35 mm).

control link and bushing in pitch

control arm.

(3). Apply tape on leading edge centerline of

blade and spar; press down firmly to

NOTE: If alternate (standard NAS 464P − )

eliminate all air pockets.

bolts are used instead of extended balance

bolts, first install balance washers(s) of

12. Tail Rotor Assembly Bungee Initial

same color code as pitch control arm and

Installation (Fiberglass-to-Metal Tail

bolt, then install an AN 960−416 washer un−

Rotor Blade Conversion)

der bolt head before installing bolt. Insert

bolt shank through spring washer, reduced

(Ref. Figure 8−7) Installation of new metal tail

OD washer, bearing of link and bushing of

rotor assembly is preceded by removal of the

blade pitch arm. The AN 960−416 washer

existing fiberglass−bladed tail rotor assembly

prevents balance washer contact with

and inspection of split rings. Existing tail rotor

spring washer.

pitch control sub−assembly is to be used. Tail

rotor controls must be rerigged using a

(6). Install washer(s) of same color code as

different rigging tool (29, Table 2−2).

pitch control arm and bolt, install nut,

Section 8, torque nut to 50 − 60 inch−

(1). Remove access cover between pilot’s

pounds (5.65 − 6.78 Nm) and install

seat and left passenger’s footwell on aft

cotter pin with wet primer (4,

side of canted bulkhead.

Table 2−4) (Ref. Figure 8−4).

NOTE: If the riveted bearing is installed at aft

(7). If removed from extended balance bolt,

end of floor−routed control rod, the control

install balance washer(s) of same color

rod must be removed from helicopter.

code as pitch control arm on extended

balance bolt and secure with nut.

(2).

Removal the nonriveted bearing

installed at one end of control rod;

11. Leading Edge Tape Replacement

discard bearing. Do not remove riveted

(Fiberglass Blade)

bearing.

(Ref. Figure 8−5)

(3).

Place locknut and fitting on new

bearing and install on end of rod

Do not allow solvent to soak into

assembly. Adjust rod assembly to 30.06

CAUTION

blade crevices as it may cause

inches (76.3524 cm) as shown.

damage to bonding adhesive.

(4).

Drill 0.190−0.194 inch (4.826−4.9276

(1). Remove old adhesive tape from three

mm) hole through bracket and touchup

locations on leading edge of blade and

with primer (4, Table 2−4).

spar; clean areas from which removed

with solvent (1, Table 2−4).

(5).

Install eyebolt on bracket.

Do not cut tape after it has been

(6).

Install eyebolt on fitting at new

CAUTION

installed on blade.

bearing.

(2). Measure and cut 2 inch (5.08 cm) wide

(7).

Install floor−routed control rod, with

tape (32) to lengths indicated for

new bearing and fitting at aft end.

locations as follow:

(8).

Install bungee spring as shown.

(a). Spar inboard length is 3.30 inches

(8.382 cm).

(9).

Reinstall footwell.

Page 8-20

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

369A2541 BRACKET

L HELICOPTER

3.25 IN. (8.255 CM)

0.190−0.194 IN. (4.826−4.9276 MM)

HOLE THRU BRACKET

AN42B−C3A EYE BOLT

AN960−10L WASHER

MS21042−3 NUT

STA 63.00

STA 74.875

AN42B−C3A EYE BOLT

369A7521

AN960−10L WASHER (2 REQD)

SPRING

MS21−42−3 NUT

369A7006−3

ROD ASSEMBLY

WL 16.92

1.75 IN. (4.445 CM)

369A7305 BELLCRANK

369A2541 BRACKET

369A7522 FITTING

369A7961−51 BEARING

AN315−6R NUT

30.06 IN.

(76.3524 CM)

30−227A

Figure 8-7. Tail Rotor Assembly Bungee Installation (Metal Blade)

13. Tail Rotor Balance Adjustment (Without

NOTE: Blurry appearance of lower vertical or

Balance Kit)

horizontal stabilizer, at 100−103% N2 with

tail rotor pedals in neutral position, is a typ−

The following procedure

ical vibrations.

WARNING

should only be used if a

(a). With tail rotor operating at normal

slight out−of−balance condition is

rpm, feel the control pedals for the

noted on a operating tail rotor and a

presence of high frequency vibration

tail rotor balance kit is not available.

(buzz).

Tail balance should normally be accom−

plished using the balancing kit equip−

(b). If vibration is noticeable, observe the

ment described in paragraph 8−15.

outboard tip of the horizontal stabi−

Damage can occur with an excessively

lizer. Determine if stabilizer buzz is

out−of−balance tail rotor.

in excess of 0.0625 inch (1.5875 mm).

NOTE: High frequency vibrations in the heli−

(c). If stabilizer buzz appears excessive

copter can also be produced by other compo−

(cannot be damped easily by holding

nents besides the tail rotor (Ref. Sec. 5, 9

tip with one hand) or pedal buzz feels

and 10). Be sure that any excessive high fre−

excessive, tail rotor balance should be

quency vibrations are tail rotor induced. be−

improved by performing the actions

fore readjusting tail rotor balance.

outlined in steps (2). thru (5). below.

(1). Evaluate tail rotor high frequency

(2). Attempt imbalance correction by

vibration

repositioning tail rotor on driveshaft:

Page 8-21

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(a). Remove tail rotor and pitch control

14. Tail Rotor Balance Adjustment (With

assembly, rotate 45 degrees from

Balancing Kit)

original index position and reinstall.

(Ref. Figure 8−8) Tail rotor balancing may be

accomplished by strobe light observation of the

(b). With rotor operating at normal rpm,

tail rotor during ground run.

determine if the vibration is im−

proved to an acceptable level.

A vibration pick−up (accelerometer), mounted

on the tail rotor gearbox, causes the strobe

(c). If vibration level is increased,

light to flash in each vibration cycle. The

reposition tail rotor 45 degrees in the

flashing light stops the rotating blade image,

opposite direction from the original

as viewed by the operator.

index position.

The vibrations, measured in mils on an

(d). If vibration level is still unacceptable,

analyzer dial, and the tail rotor angle, mea−

return tail rotor to the original index

sured with a protractor mounted on the strobe

position and proceed with step (3).

light, are recorded by the operator. This data is

below.

applied to tables showing location and weight

required to restore tail rotor balance.

(3). Attempt rebalancing of the tail rotor by

Complete instructions for tail rotor balancing

addition of tape as follows:

are contained in the Chadwick−Helmuth

Strobex Blade Tracker Manual. This handbook

(a). Select either blade. Assuming that it

is a component of balancing kit (59, Table 2−2).

is the light blade, wrap two layers of

2 inch (5.08 cm) width pressure−sen−

A. Tail Rotor Balance Preliminary

sitive abrasion tape (32, Table 2−4)

Adjustment

around the shank of the blade.

To prevent damage from an excessively

out−of−balance tail rotor, the following check

(b). Operate the tail rotor at normal

should be accomplished prior to use of the

flight rpm and evaluate the vibration

above kit, at each 100 hour tail rotor balance

level.

inspection, and whenever new or rebuilt tail

rotor assembly is installed. Use the equipment

(c). If vibration level has decreased,

cited for the above−noted manuals.

continue to add tape until the

vibration level is acceptable.

(1). Install tail rotor vibration analyzer kit.

(d). If vibration level has increased,

(2). Ground run engine with main rotor

remove the tape and evaluate the

blades at flat pitch, tail rotor pedals in

opposite blade in the same manner.

neutral, and engine at ground idle

speed.

(4). If an acceptable vibration level can be

(3). With utility switch on, adjust analyzer

produced according to above, continue

and strobe per Chadwick−Helmuth

tail rotor in service with tape installed.

handbook of instructions.

(5). If vibration level is unacceptable after

(4). Set RPM tune dial to 229 (2289 tail

attempt correction (steps (2). or (3).

rotor rpm with engine at ground idle).

above):

(5). Set rpm range dial to X10.

(a). Obtain the special tail rotor balance

(6). Direct strobe light at tail rotor and

analyzer kit (31, Table 2−2) that is

observe Clock Angle of grip target.

used to balance installed tail rotors.

(7). Press Verify Tune Button and adjust

(b). Alternately, remove the complete tail

RPM Tune Dial while button is pushed,

rotor assembly and send to overhaul

to return target to angle observed

for balancing.

before button was pushed.

Page 8-22

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ZERO ANGLE LINE

ANGLE VIEWED ON

PROTRACTOR

UTILITY

RECEPTACLE

(FOR 24 VDC

ELECTRICAL

VIBRATION ANALYZER

POWER)

BLUE BLADE

SCALE #2 BUTTON

FILTER

POWER SWITCH

POWER OUT **

CONNECT TO HELICOPTER

UTILITY RECEPTACLE

PROTRACTOR

VIBRATION ANALYZER

STABILIZER

369A9801 (NOTE 2)

PROTRACTOR ASSY

369A9979 (NOTE 1)

SIGNAL

OUT *

CONNECT TO TAIL

ROTOR GEARBOX

ATTACH

PICKUP

MOUNTING

CONNECT TO

SPRING AROUND

STROBE LIGHT

ANALYZER

FACE LUGS

CASE UNIT

SIGNAL OUT *

(NOTE 1)

PROTRACTOR ON

STROBE LIGHT

GAIN

(NOTE 1)

CONTROL

STROBE LIGHT

CABLE

NOTES:

STROBE LIGHT AND CASE UNIT

FORM STROBE LIGHT 369A9925

CONNECT TO

(CHADWICK−HELMUTH MODEL 135M−( )

ANALYZER

STROBEX). (PART OF BLADE TRACKING

POWER OUT **

KIT 369A9926−5 OR −7, (16, TABLE 2−2).)

CHADWICK−HELMUTH MODEL 170.

(PART OF TAIL ROTOR BALANCE ANALYZER

KIT 369A9999, (31, TABLE 2−2).)

30−145B

Figure 8-8. Tail Rotor Vibration Analysis Equipment

Page 8-23

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(8). Release button, observe angle, press

(2). On tail rotor gearbox having a breath−

and adjust again to match new ‘‘un−

er−filler with a threaded hole, install

pushed’’ angle.

pickup on breather (finger−tight).

(9). Repeat until there is no change wheth−

(3). Connect vibration pickup cable to

er button is pushed or released.

pickup. Route cable forward along right

side of tailboom. Secure with tape (32,

NOTE: Adjust RPM Tune Dial only when but−

Table 2−4).

ton is pushed.

Place weights on cable on

(10). Read Clock Angle with button released,

CAUTION

ground to prevent possible foul−

and IPS without strobe flashing.

ing of tail rotor.

If IPS meter reading is 0.5 or

CAUTION

(4). Connect components of the vibration

greater, do not increase rpm.

analyzer kit (369A9999) (31, Table 2−2)

and blade tracking kit (369A9926−5 or

(11). If IPS meter reading is 0.5 or greater,

−7) (16) as shown in Figure 8−8.

proceed with preliminary adjustment as

follows:

(5). Attach protractor assembly 369A9979

to strobe light.

(a). Plot the low rpm IPS and Clock

Angle on chart.

(6). If not already marked, identify blue

(b). Use four times the indicated weight

blade with paint provided in analyzer

and re−run the helicopter at ground

kit.

idle.

(7). Set strobe light ON−OFF switch to ON.

(c). Correct Clock Angle, if necessary,

using Chart Corrector.

(8). Adjust analyzer indicator needle to

zero, if necessary.

(d). Repeat until IPS meter reading less

than 0.5 (preferably 0.2).

Always perform first run in a

CAUTION

cautious manner so that vibra−

(12). Accomplish final balancing with engine

tions from an out−of−balance tail rotor will

speed 103% N2 and RPM Tune Dial set

not cause damage.

at 310 (X10 3100 tail rotor rpm at 103%

N2). Reduce IPS to 0.2 or less.

C. Preparation for Balancing

B. Tail Rotor Vibration Analysis Kit

(Ref. Figure 8−8) Ground run engine with

Installation

main rotor blades in flat pitch and tail rotor

pedal in neutral. Slowly increase engine speed

NOTE: Equipment required: Main rotor blade

to 103% N2. With Utility switch ON, adjust

tracking kit

369A9926−5 or

−7

(16,

analyzer and strobe as follows:

Table 2−2) ; tail rotor balancing kit

369A9999 (31). (Ref. Figure 8−8) The de−

(1). Adjust analyzer kit filter TUNE until

tailed balancing instructions outlined in ad−

the needle reads maximum.

justment steps (1). thru (6). below supercede

those instructions contained in both the

analyzer and the tracking kit.

(2). In blade blade tracking kit, adjust

GAIN control counterclockwise until

(1). On tail rotor gearbox without breather−

strobe light flashes; then rotate 1/8 turn

filler threaded for vibration pickup,

more.

install pickup mounting bracket

assembly 369A9920 as shown in Detail

NOTE: Do not operate the strobe light with the

C, Figure 8−9; then install vibration

Gain too high as this may cause the light to

pickup on mounting bracket.

flash erratically and indicate false angles.

Page 8-24

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SCREW

(NOTES 2, 5)

BLADE TIP BALANCE

WASHER NAS620−10L

(NOTE 5)

FIBERGLASS TYPE

NAS464P4−( ) BOLT

BLADES SHOWN

(NOTE 2)

AN960−416

BLADE PITCH ARM

PICKUP

WASHER

BALANCE WASHER

CABLE

(NOTE 3)

(NOTE 4)

TAPE

SPRING

SPECIAL WASHER

WASHER

(REDUCED OD)

ALTERNATE ASSEMBLY

WITH NAS BOLT

VIBRATION PICKUP

(ACCELEROMETER)

PITCH

CONTROL

LINK

BREATHER

PITCH ARM

50−60 IN. LB (5.65−6.78 NM)

RETAINING NUT

BALANCE WASHER

(NOTE 4)

BLUE BLADE

WHITE MARK

STANDARD ASSEMBLY WITH

369A1606 BOLT

EXTENDED BALANCE BOLT

369A1606

PITCH

SPRING WASHER

CONTROL

LINK

PITCH ARM

50−60 IN. LB

VIBRATION PICKUP

(5.65−6.78 NM)

(NOTES 1, 7)

PICKUP ON TAIL ROTOR

TRANSMISSION

NOTES:

INSTALL FINGER−TIGHT.

REFER TO TABLE 8−4 FOR LENGTH, WEIGHT VALUES

AND GRAM WEIGHTS.

ONE −416 WASHER MUST BE INSTALLED AT THIS POINT

TO PREVENT WASHER CONTACT WITH SPRING WASHER.

MOUNTING

MAXIMUM WASHER WEIGHT ALLOWED AT EITHER PITCH

BRACKET

ARM IS 32 GRAMS (OR 27 HS306−227L WASHERS).

369A9920

MAXIMUM COMBINED WEIGHT ALLOWABLE AT TIP:

(NOTE 6)

SCREW/WASHERS ON FIBERGLASS BLADE − 8 GRAMS;

SCREW/WEIGHTS ON METAL BLADE − 24 GRAMS.

PART OF TAIL ROTOR BALANCE ANALYZER KIT 369A9999

(3, TABLE 2−2).

PART OF VIBRATION ANALYZER 369A9801 (PART OF

BALANCE ANALYZER KIT 369A9999).

30−146A

Figure

8-9. Tail Rotor Balancing

Page 8-25

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

D. Vibration analysis

NOTE: Tail rotor fork bearings that are im−

properly seated or that have excessive loose−

ness between races can cause tail rotor

(Ref. Figure 8−8)

vibration. Such bearings must be replaced

(Ref. Tail Rotor and Pitch Control Assembly

(1). Stand approximately 10 feet (3 m) away

Replacement). If bearings are serviceable,

from the tail rotor and 90 degrees to the

continue with the following inspections.

axis of rotation.

(a). Remove tail rotor assembly and

(2). Direct the strobe light toward the

inspect split ring (Ref. Figure 8−4).

rotating tail rotor and align the leading

Replace damaged or mismatched.

edge of the protractor stabilizer with

(b). With tail rotor removed, check tir in

the leading edge of the upper vertical

split ring groove of gearbox output

stabilizer: read the angle on the

shaft. Run−out is limited to 0.003

protractor between the blue blade

inch (0.0762 mm) tir.

leading edge and zero degree centerline.

Record reading.

(c). Check that there is no axial play in

output shaft; none is allowed.

NOTE: Erratic strobe light flashing is expected

at a meter reading of 1.50 mils or lower and

(d). Replace tail rotor gearbox if output

is an indication of a good balance.

shaft condition is beyond limits. (Ref.

Sec. 9 for gearbox replacement.)

(3). Read the value on analyzer upper dial.

(e). After any required replacement,

If analyzer meter needle reads above

reinstall tail rotor and pitch control

10, depress SCALE #2 button and read

assembly.

the lower dial.

(f). Repeat vibration analysis. If meter

(4). If meter reading is 2 or less (strobe

reading is still more than 20, replace

light flashing erratic), balance is

tail rotor blade(s) or assembly.

acceptable.

Balance at Fiberglass Blade Tip

(5). If meter reading is more than 2, record

(Ref. Figure 8−9) A weight increase at a light

reading, shut down engine and proceed

blade tip may be obtained by removal of

with steps (6). or (7). below, as appropri−

equipment washer weight from the opposite

ate.

blade tip. Always remove washers from

opposite tip, if installed, and subtract from the

(6). When meter reading is more than 2,

weight added before adding more weight.

but less than 20:

(1). Remove blade tip screw and any

existing balance washers.

(a). Use Table 8−2 and Table 8−3 to

determine number and location of

(2). Select the new washer and screw

balance washers required.

combination by using Table 8−2 and

Table 8−3 and by observing the follow−

(b). Install or remove washers or weight

ing.

on the specified blade tip and/or pitch

arm bolt.

(a). Screw used at tip must be

NAS1351−3−(

)P. A selection of these

NAS screws is provided in the

(c). Repeat vibration analysis until

vibration analyzer kit.

balance is acceptable.

(b). Thread length for engagement must

(7). When meter reading is more than 20,

not exceed 0.750 inch (19.05 mm) nor

inspect tail rotor installation on the

be less than 0.3125 inch (7.9375 mm),

gearbox as follows:

with or without washers installed.

Page 8-26

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE:

(7.9375 mm) minimum thread engage−

ment. Do not use longer than the

D Each blade tip must have a screw

original 0.8125 inch (20.6375 mm)

installed; however, no minimum number

screws.

of washers is required.

(4). Balance at Blade Pitch Arm

D Screw head protrusion beyond blade tip

after installation is not desirable but is al−

(Ref. Figure 8−9). A weight increase at a light

lowable provided the weight limit for the

pitch arm may be obtained by removal of

tip is not exceeded.

equivalent washer weight from the opposite

pitch arm. Always remove washers from

(c). Screw length may be changed to

opposite pitch arm, if installed and subtract

increase or decrease tip weight

from the weight to be added before adding

and/or maintain minimum screw

more weight. Adjust pitch are weight as

engagement. A longer or shorter

follows:

screw also can replace washers.

(5). On a standard tail rotor assembly with

Combined weight of screw/

extended balance bolts, remove balance

CAUTION

washer selection must not ex−

washer retaining nut (Detail B) and

ceed 8 grams at either tip.

install or remove washers as deter−

mined by use of Table 8−2 and

(3). Install selected screw and washer

Table 8−3. Maximum washer weight

combination.

allowed at either pitch arm bolt is 32

grams (27 ‘‘standard size’’ washers).

F. Balance at Metal Blade Tip

(6). On a tail rotor assembly with alternate

When balancing indicates that a weight

NAS bolts, remove cotter pin, nut,

increase at a light tip is required, it is always

washers and bolt (Detail A) and install

best to remove equivalent weight from the

or remove washers next to bolt head as

opposite tip if possible. The blade weight can

determined by use of Table 8−2 and

thus be kept as near the manufactured

Table 8−3.

(prebalanced) weight as possible. Adjust tip

weight as follows:

NOTE: The alternate bolt used at pitch arm

must be NAS465P−( ). A selection of these

NOTE: The two tip screws may be used without

NAS bolts is provided in the vibration ana−

tip weights if required.

lyzer kit. NAS bolt length may be changed to

increase or decrease blade pitch arm weight

(1). Remove the blade tip screws and

and/or provide for washers. A longer or

weights. Select proper weights to add or

shorter bolt also can replace washers.

remove as determined using Table 8−2

and Table 8−3.

(7). Assemble washers and bolt as shown in

Details A & B, as appropriate. Be sure

NOTE: The screws (NAS602−13P installed the

that washer weight distribution is

tips during manufacture and original bal−

within limits.

ance are long enough to accommodate the

maximum thickness of tip weights that may

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

be used while maintaining thread engage−

(5.65 − 9.04 Nm) for either type of bolt.

ment of 0.3125 inch (7.9375 mm) minimum.

NOTE: There is a possibility of slight weight

variation between pitch control links after

(2). Install the combination of weights

forging and machining.

required, using the two screws. The

maximum weight is 24 grams (approxi−

(9). If a tail rotor has the maximum balance

mately 11 thick weights (washers)

washer weight allowed on one pitch

369A1622−5 and two NAS602−13P

arm, compare the two links.

screws). Torque screws to 21 − 24

(10). If the pitch link opposite the weight

inch−pounds (2.37 − 2.71 Nm).

requirement appears larger, exchange

(3). If shorter than normal tip screws have

one link for the other and repeat

been used, check for 0.3125 inch

vibration analysis.

Page 8-27

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 8-2. Rotor Balance Weight Location Chart

Angle (degrees)

Meter reading (mils)

Fiber−

Metal

glass

340

Blue Tip

355

Green Pitch Arm

Blue Tip

Only

105

120

100

135

115

150

130

Blue Tip

Blue Pitch Arm

165

145

180

160

Green Tip

Blue Pitch Arm

195

175

210

190

225

205

240

220

Green Tip

255

235

Only

270

250

285

265

300

280

315

295

330

310

Green Tip

Green Pitch Arm

345

325

USE OF DIAGONAL LINE NUMBERS:

The numbers in the Meter reading (mils) columns indicate the number of ‘‘standard size’’ washers and weights with a

weight value of ‘‘1’’ (table 8−4) to be added at the blade tip or pitch arm. The number above the diagonal line is for the tip

and the number below is for the pitch arm.

EXAMPLE OF CHART APPLICATION:

Angle viewed on protractor − 195° (fiberglass blades) − 175° (metal blades)

Analyzer meter reading − 4

Read down the angle (degrees) column to 195 or 175, as applicable; then read to the right to Meter reading (mils)

column 4. At this point, the numbers 1/4 are to be found indicating the need for one tip washer or weight, as appropriate,

having a weight value of ‘‘1’’ and four pitch arm washers each of which has a weight value of ‘‘1’’. If an equivalent

number of ‘‘standard size’’ washers or weights already exist on the opposite blade, remove them rather than installing

the additional weight. Also check whether appropriate bolt or screw substitution on one blade might not eliminate the

need for adding weight to the other. If washer sizes used at pitch arm are not the ‘‘standard sizes’’ listed in table 8−4, the

numbers on location chart 8−3 will be invalid unless there is gram weight equivalence.

30−147

Page 8-28

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 8-3. Tail Rotor Balance Weight Value Chart

At Fiberglass Blade Tip (7)

Screws (2)(8)

Length inch (mm)

Weight (Grams)

Weight Value (4)

NAS1351-3-6P

(1)

0.375

(9.525)

2.17 minus

4-1/2

NAS1351-3-12P

0.750

(19.05)

2.17

NAS1351-3-14P

0.875

(22.225)

3.86

1-1/2

NAS1351-3-16P

1.00

(25.4)

4.26

Standard Size Washer - Steel

Thickness inch (mm)

Weight (Grams)

Weight Value

NAS620-10L

0.032

(0.8128)

0.272

At Metal Blade Tip

Screws

Length inch (mm)

Weight (Grams)

Weight Valve

NAS602-13P

0.8125

(2.06375)

2.44

Weights

Thickness inch (mm)

Weight (Grams)

Weight Valve

369A1622-3

0.016

(0.4064)

0.29

369A1622-5

0.036

(0.9144)

1.76

At Any Blade Pitch Arm (10)

Bolts (5)

Length inch (cm)

Weight (Grams)

Weight Value (4)

NAS464P4-18

1.46875

(3.730625)

12.17

NAS464P4-19

1.0

(2.54)

12.56

1/2

NAS464P4-20

1.59375

(4.048125)

12.94

NAS464P4-21

1.65625

(4.206875)

13.34

NAS464P4-22

1.71875

(4.365625)

13.73

1-1/2

NAS464P4-23

1.78125

(4.524375)

14.12

Standard Size Washers (Steel) (6)(9)

OD inch (mm)

Weight (Grams)

Weight Value

Thickness in. (mm)

AN960-416 (3)

0.063

(1.6002)

0.50

(12.7)

1.45

HS306-227L

0.016

(0.4064)

0.80

(20.32)

1.17

NOTES:

(1) If necessary, a -6P screw may be used without washer.

(2) Screw threads for engagement in blade insert (with or without washers): 0.3125 in. (7.9375 mm) minimum,

0.750 in. (19.05 mm) maximum.

(3) One -416 washer required next to spring washer on alternate NAS bolt. Not required on extended bolt.

(4) Weight Value - Example: A change from NAS 464P4-18 to a -23 bolt has a weight value of ‘‘2”; that is the

change in length is equal to two ‘‘standard size” washers in Table 8-3. Measure installed screw or bolt

length and compare with this chart to determine weight value.

(5) Extended balance bolt 369A1606 used on standard assembly. NAS bolts used on alternate assembly. NAS

bolt values not applicable to extended bolt.

(6) Used on either extended bolt or alternate NAS bolt.

(7) Maximum combined screw and washer weight limited to 8 grams a tip.

(8) Protrusion of screw head beyond tip cap is undesirable but allowed.

(9) Maximum of 27 washers with 0.432 in. (10.9728 mm) total thickness on extended balance bolt.

(10) Minimum of two threads must extend past locknut securing balance washers on extended balance bolt.

Page 8-29

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(11). If maximum allowable weight at one

Helmuth Blade Tracker Manual. This hand−

pitch arm will not correct the assembly

book is a component of balancing kit.

balance, the tail rotor hub may be

shifted in the fork and hub−to−fork

16. Tail Rotor Blades

shimming adjusted, if maximum

Either metal or fiberglass tail rotor may be

allowable play in the fork bearings is

installed. The basic differences between metal

not exceeded.

and fiberglass blades are as follows:

(a). This is done by transferring fork−to−

A. Fiberglass Blades

hub spacing shims from the balance

weighted side to the opposite side of

(1). Fiberglass blades are used for normal

the hub, according to hub and fork

performance requirements.

reassembly procedures in CSP−H−5.

(2). Each consists of a tapered−wall, steel

NOTE: Span wise balance will probably be af−

alloy spar with a fiberglass skin bonded

fected by any chordwise shift of the fork.

to form the airfoil.

(12). The cordwise weight shift resulting

(3). The outer fiberglass ply is painted as

from each 0.001 inch (0.0254 mm) of

shown in Figure 8−5.

spacing shim thickness transferred will

(4). Corrosion−resistant steel abrasion

reduce the requirement at the weighted

strips form the leading edges of the

pitch arm by one ‘‘standard size"

blades.

(HS307−227L) balance washer.

(5). Fiberglass blades are either painted, or

Example: Transferring one

on early type paper−covered blades,

369A1717−53 spacing shim, 0.010 inch

have a layer of colored paper directly

(0.254 mm), would allow initial removal

bonded to the outer ply of the fiberglass

of 10 thin washers from the pitch arm.

skin.

NOTE: A tail rotor out− of− balance condition

(6). The position and width of the stripes for

that cannot be corrected by standard bal−

either blade is shown in Figure 8−5.

ancing procedures may be an indication of

excessive play in tail rotor hub components.

NOTE: The stripes on paper− covered blades

are overlaid and bonded on a red base layer

(13). If maximum allowable play in the fork

of paper that covers the outboard 15 inches

bearings is exceeded, the bearings must

(38 cm) of skin.

be replaced.

B. Metal Blades

(14). Replacement or adjustment of parts

requires balancing of the tail rotor

(1). Metal blades are cambered for high

following reassembly.

thrust to provide increased directional

control at high altitude.

15. Tail Rotor Blade Track Verification

(2). Each consists of an aluminum honey−

comb spar, aluminum skin, riveted

Blade track cannot be adjusted, but it can be

aluminum blade fittings and a alumi−

verified by use of the tracking equipment

num tip cap, all structurally bonded

contained in balance kit (59, Table 2−2). If this

together.

kit is available, it is recommended that track

verification be accomplished before attempting

(3). The blades are painted as shown in

to balance tail rotor, to avoid performing

Figure 8−5.

balancing procedures that are ineffective due

to an out−of−track condition that can only be

C. Fiberglass Tail Rotor Blade Replacement

remedied by blade replacement.

Ensure that replacement fiberglass blades are

Completed instructions for the blade track

serviceable and blade static balancing mo−

verification are contained in the Chadwick−

ments are within required limitations.

Page 8-30

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

A balancing check and/or ad−

brought within plus or minus 40

CAUTION

justment is required after blade

gram−inches of each other in either of

removal, at subsequent replacement or rein−

the two categories by use of a special

stallation of blade.

balancing fixture and prebalancing

with tip weights.

(1). One or both blades may be replaced;

however, fiberglass blades must be

(3). Erosion or allowable repairs may cause

matched.

minor balance moment changes for

metal blades. Such changes are consid−

(2). Static balancing moments of fiberglass

ered negligible enough to allow direct

blades must be within 80 grams−inches

replacement of any used blade with a

of each other.

new one and interchangeable use of

blades with remaining service life.

(3). When both are being replaced with

fiberglass blades, a matched set of

(4). In any case of blade selection or use,

blades should be ordered.

the inspection, repair and serviceability

requirements specified in CSP−H−5

(4). When replacing a single fiberglass

must be complied with for metal blades.

blade, it is necessary to find the static

balancing moment of the used blade

(5). The retirement schedule and remaining

being retained in serviced, as well as

service life of a used blade should

that of the replacement blade.

always be considered when making the

decision to replace a single blade.

NOTE: For additional information on and de−

termination of the static balancing moment

for fiberglass blades, refer to CSP−H−5.

17. Tail Rotor Blade Replacement

(5). The retirement schedule and remaining

Before blade replacement, refer to Fiberglass

service life of a used blade should be

Tail Rotor Blade Replacement and Metal Tail

considered when making the decision to

Rotor Blade Replacement for fiberglass or

replace a single blade.

metal tail rotor blade replacement matching

criteria.

NOTE: If fiberglass blades are replaced with

metal blades, installation of a bungee spring

NOTE: Always record the number and location

and rerigging of tail rotor controls is re−

of balance washers when installing a new

quired.

blade. This record will assist dynamic bal−

ance troubleshooting.

D. Metal Tail Rotor Blade Replacement

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

(1). For replacement, metal blades are

pitch arm bolt from outboard end of

divided into two categories. These are

pitch control link (Ref. Figure 8−4).

category ‘‘A’’ and category ‘‘B’’.

Bushings and crush washers in−

(a). Category ‘‘A’’ blades, identified by the

CAUTION

stalled on current model blades

letter ‘‘A’’ following the serial num−

can be reused, but must be installed on the

ber, must be installed in a set with

same blade and strap assembly in the exact

another ‘‘A’’ blade.

location from which they were removed.

(b). Category ‘‘B’’ blades, so identified,

NOTE: If same blade is to be reinstalled, retain

must be installed in a set with a ‘‘B’’

intact for reuse (or note and record number

blade.

and type of) balance washers and attach−

NOTE: The blade categories are not inter−

ment hardware used on bolt at blade pitch

changeable within a set.

arm.

(2). As manufactured, the static balancing

(2). For fiberglass blades or early configura−

moments of all metal blades are

tion metal blades:

Page 8-31

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(a). Remove nut, bolt, and countersunk

D If either the blade or strap pack assembly

washer, special (flat aluminum)

from which they were removed is re−

washer for a metal blade and sleeve

placed, replace crush washers and bush−

bushing attaching blade to the

ing.

tension−torsion strap (Ref.

D Bushings must be free of nicks and burrs.

Figure 8−10).

D Comply with special inspection and in−

stallation requirements described in

(3). For current configuration metal blades:

CSP−H−5.

(a). Remove nut, bolt, shoulder bushing

(8). Install O−ring on hub trunnion.

and crush washer attaching blade to

(9). Slide blade on hub with blade leading

the tension−torsion strap.

edge facing in a counterclockwise

direction. Use care to keep blade

(4). Withdraw blade from hub trunnion.

properly aligned so that hub trunnion

slides into blade pitch (feathering)

bearings. Do not use force.

CAUTION

(10). Align bolt holes in blade with hole

D Do not disassemble outboard shoes from

through bushing in outboard shoes of

end of tension− torsion strap assembly

tension−torsion strap assembly.

protruding from trunnion. Strap assem−

bly parts are not individually replaceable

(11). Coat bolt with primer (4, Table 2−4).

and must remain assembled.

(12). For fiberglass blades or early configura−

D Avoid damaging strap assembly.

tion metal blades:

Scratches or nicks on strap laminates

(a). Install special countersunk washer

may make strap assembly unserviceable.

on bolt with chamfered edge of

washer next to bolt head.

(5). If strap assembly is to remain exposed

for any length of time, wrap exposed

(b). Install special (flat aluminum)

end of strap assembly with wax paper

washer on the bolt against the

or other similar non−abrasive material

countersunk washer for a metal

to protect from damage.

blade.

(13). For current configuration metal blades:

(6). If blade being removed is to be rein−

stalled, do not remove blade tip screw,

(a). Install shoulder bushing on bolt with

any balance washers or weight from

crush washer.

blade.

(14). Insert attaching bolt through leading

(7). Remove any protective covering from

edge of blade, shoe of strap assembly

tension−torsion strap assembly extend−

and trailing edge of blade (both threads

ing from hub trunnion.

at trailing edge).

(15). For fiberglass blades or early configura−

NOTE: Remove old primer from mating sur−

tion metal blades:

faces and attaching hardware prior to reas−

sembly.

(a). Slide sleeve bushing over end of bolt

and into blade until bushing end

contacts outboard shoe on strap

CAUTION

assembly.

D Bolt, nut, washers and bushings may be

(16). For current configuration metal blades:

reinstalled if serviceable.

(a). Slide shoulder bushing, with crush

D If bushing and crush washers are to be re−

washer, over end of bolt and into

used, they must be installed in the exact

blade until bushing end contacts

location from which they were removed.

outboard shoe on strap assembly.

Page 8-32

Revision 17

CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 6