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

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Install contact pattern shim(s)

on the transmission. A damper located near

removed at disassembly, and gear−

the center of the shaft maintains a minimum

shaft in housing. Heat output hous−

vibrations level in the tail rotor drive system.

ing bore using heat gun or blow dryer

until gearshaft bearing retainer

A. Tail Rotor Drive Shaft Removal

assembly fits easily into housing.

(Ref. Figure 9−13 and Figure 9−14)

(c). Install clamp−up shim removed at

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

disassembly and output gearshaft

access doors.

cover assembly ( Ref. CSP−H−5).

(2). Remove three bolts and washers that

(7). Install tail rotor and pitch control

secure shaft to output gearshaft

assembly (Ref. Sec. 8).

coupling on main transmission.

(8). Fill tail rotor transmission with

approved lubricant (Ref. Sec. 2).

(3). Disconnect chip detector wiring from

tail rotor transmission.

G. Protective Sleeve (Speedi-Sleeve)

Replacement, Output Gearshaft

(4). Detach Sta. 282 bellcrank from tail

rotor transmission.

(Ref. Figure 9−16) Replace a worn protective

sleeve (Speedi−Sleeve PN 084957) on the

(5). Remove lockwire, bolts and washers

output gearshaft as follows:

that attach tail rotor transmission to

tailboom.

Use care not to cut into or dam−

CAUTION

age gearshaft when removing

To prevent damage to the gear−

CAUTION

damaged sleeve. Do not allow filings or oth−

box coupling during and after

er contaminants to enter shaft bearings.

removal, provide good level support for both

the transmission and tail rotor, as the

(1). Remove output gearshaft from tail rotor

weight of these items might buckle the cou−

transmission.

pling.

(2). Use file or other suitable instrument to

(6). With help from an assistant in guiding

cut through edge of sleeve; carefully pry

the shaft through the damper, remove

cut edge away from shaft.

tail rotor driveshaft as an assembly.

(3). Grasp raised edge with pliers and peel

Slowly and carefully slide the assembly

damaged sleeve off shaft.

aft until drive shaft clears the tailboom.

(4). Remove any plastic steel residue from

(7). Support assembly along its entire

shaft using dry cleaning solvent (1,

length, remove the three gearbox

Table 2−4); dry shaft with clean, lint

coupling bolts and washers, and remove

free cloth.

drive shaft from gearbox.

(5). Install replacement sleeve on shaft

Do not carry or otherwise sup−

CAUTION

(Ref. Protective Sleeve (Speedi−Sleeve)

port the gearbox by use of the

Installation, Output Gearshaft.

coupling. Use care with removal tools to pre−

vent scratching coupling.

10. Tail Rotor Drive Shaft

B. Tail Rotor Drive Shaft Installation with

(Ref. Figure 9−13 and Figure 9−14) The tail

Kamatics Couplings

rotor drive shaft interconnects the main

transmission and the tail rotor transmission.

(Ref. Figure 9−13) Whenever main transmis−

The shaft is a dynamically balanced and

sion, tail rotor transmission, transmission

positively dampened aluminum alloy tube,

couplings, coupling shims, tail rotor drive shaft

approximately 13 feet (4 M) long, that rotates

or tailboom assembly have been replaced, start

at 2,045 rpm. Identical mounting flanges,

installation with step (1). If none of these

riveted to each tapered end of the tube,

components has been replaced, and only

connect the shaft to the flexible joint couplings

installation is involved, start with step (5).

Page 9-47

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE:

inch−pounds (8.47 − 10.73 Nm) plus

drag torque.

D Kamatic coupling to not require failsafe

bolts and sockets.

(7). Align forward end of drive shaft with

D When installing 369D25501− 9 Kamatic

coupling on main transmission output

coupling, install SKCP2554−15 or

gearshaft. Partially install two bolts as

369D25503−1 coupling bolt supplied with

an alignment aid but do not tighten.

the Kamatic coupling.

Align drive shaft inspection markings.

If any of four white stripes is indistinct

D If tail rotor drive shaft is replaced for tor−

or does not exist, paint replacement

sional buckling, replace and discard main

stripes.

transmission output gearshaft coupling,

tail rotor gearbox coupling and both cou−

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

pling bolts.

mm) gap between forward flange of tail

rotor drive shaft and flange of forward

(1).

Coat coupling splines with grease (21,

coupling using using the following

Table 2−4) and coupling bolt threads

procedure:

with anti−seize compound (36) before

assembly. Install coupling onto tail

(a).

Ensure alignment bolts in previous

rotor gearbox and torque coupling bolt

step are backed off between

to 250 − 300 inch−pounds (28.25 −

0.050−0.100 inch (1.27−2.54 mm).

33.90 Nm) plus drag torque. Check

coupling bolt for drag torque service−

(b).

Remove end play in tail rotor trans−

ability of 25 inch−pounds (2.82 Nm)

mission by applying force to tail rotor

minimum, 200 inch−pounds (22.60

blades in opposite direction of

Nm) maximum.

operation rotation while holding

forward coupling of tail rotor drive

(2).

Coat forward coupling splines with

shaft on main transmission to

grease (21) and coupling bolt threads

prevent rotation. Do not push tail

with anti−seize compound (36) before

rotor drive shaft fore or aft.

assembly. Install coupling onto tail

rotor gearbox and torque coupling bolt

(c).

Using feeler gage, measure gap

to 250 − 300 inch−pounds (28.25 −

between forward coupling flange and

33.90 Nm) plus drag torque. Check

flange of tail rotor drive shaft. Record

coupling bolt for drag torque service−

the gap.

ability of 25 inch−pounds (2.82 Nm)

(d).

With assistance, remove tail rotor

minimum, 200 inch−pounds (22.60

transmission and driveshaft in line

Nm) maximum.

for minimum deflection of coupling.

(3).

Support entire length of tail rotor drive

(e).

Using measured gap from step (c).

shaft and position end stamped AFT to

above, add or remove required

align with tail rotor transmission

number of shims at main transmis−

coupling.

sion between output pinion shaft and

forward coupling to obtain specified

(4).

Install three bolts and washers to

gap of 0.010−0.020 inch (0.254−0.508

connect tail rotor gearbox coupling to

mm).

shaft; torque bolts to 80 − 100 inch−

pounds (9.04 − 11.30 Nm) plus drag

(9). Coat forward coupling splines with

torque.

grease (21) and coupling bolt threads

with antiseize compound (36) before

(5).

With assistance, support transmission

assembly. Install coupling and torque

and shaft in line, for minimum deflec−

coupling bolt to 250 − 300 inch−

tion of coupling, and guide drive shaft

pounds (28.25 − 33.90 Nm) plus drag

carefully through tailboom and damper

torque. Check coupling bolt for drag

into position.

torque serviceability of 25 inch−

(6).

Install four tail rotor mounting bolts

pounds (2.82 Nm) minimum, 200

with washers and torque to 75 − 95

inch−pounds (22.60 Nm) maximum.

Page 9-48

Revision 17

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(10). With assistance, support transmission

(16). Check transmission oil level and service

and shaft in line for minimum deflec−

as required (Ref. Sec. 2).

tion of coupling and guide drive shaft

carefully through tailboom and damper

(17). Slowly rotate drive shaft and check for

into position.

not less than 0.250 inch (6.35 mm)

clearance between shaft and fairing

NOTE: If in use, four AN174H−17A bolts are to

tube at Sta. 137.50. In addition, check

be replaced with either NAS1304− 24H or

for minimum clearance of 0.190 inch

− 26H bolts to provide increased tail rotor

(4.826 mm) between shaft and cooling

transmission to tailboom mounting frame

blower scroll.

attachment strength (check bolt hole depth

for proper bolt installation). The gearbox

(18). Install all access doors and covers.

mounting bolt washers are 5052 aluminum

alloy (NAS1197−416) and are used specifi−

C. Tail Rotor Drive Shaft Installation with

cally for corrosion protection. When new, the

Bendix Couplings

outside edge is painted orange for identifica−

tion.

(Ref. Figure 9−14) Whenever main transmis−

sion, tail rotor transmission, transmission

(11). Measure bolt holes for proper bolt

couplings, coupling shims, tail rotor drive shaft

installation as follows:

or tailboom assembly have been replaced, start

installation with step (1). If none of these

(a). Fabricate a tool for measuring bolt

components has been replaced, and only

hole depth.

installation is involved, start with step (7).

(b). Install three gearbox mounting bolts

NOTE: If tail rotor drive shaft is replaced for

and lightly tighten bolts.

torsional buckling, replace and discard

main transmission output gear shaft cou−

(c). Measure depth of remaining bolt hole

pling and tail rotor gearbox coupling.

to determine proper bolt length.

(1). Remove existing shims and install one

(d). Remove bolts and proceed with

0.010 inch (0.254 mm) shim on tail

following steps.

rotor transmission input shaft. Coat

coupling splines with grease (21,

(12).

Apply primer (4) to the four gearbox

Table 2−4) and coupling failsafe bolt

mounting bolts. Install bolts and

threads with anti−seize compound (36)

aluminum washers while primer is still

before assembly. Install coupling and

wet: torque evenly to 75 − 95 inch−

torque failsafe coupling bolt to 250 −

pounds (8.47 − 10.73 Nm) plus drag

300 inch−pounds (28.25 − 33.90 Nm)

torque.

plus drag torque. Check coupling bolt

for drag torque serviceability of 25

(13).

Install three bolts and washers at

inch−pounds (2.82 Nm) minimum,

forward coupling; torque bolts to 80 −

200 inch−pounds (22.60 Nm) maxi−

100 inch−pounds (9.04 − 11.30 Nm)

mum.

plus drag torque.

(14).

Connect electrical wire to tail rotor

(2). Determine shim thickness required at

transmission chip detector. Torque nut

forward flexible coupling:

to 12 − 15 inch−pounds (1.36 − 1.69

Nm).

Bottom the flexible coupling by

CAUTION

holding at the

1.370 inch

(15).

Coat pin of Sta. 284.00 bellcrank with

(3.4798 cm) OD of coupling. Do not bottom

grease (18) and insert it into bearing in

coupling by pushing on drive shaft attach

tail rotor pitch control. Pivot bellcrank

flange; doing so may damage coupling.

to align with mating hole in tail rotor

transmission and install bolt, washers

(a). Bottom forward coupling on main

and nut and cotter pin (Ref. Sec. 8).

transmission output shaft.

Page 9-49

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Measure gap between end of flexible

tion of coupling, and guide drive shaft

coupling and shoulder of output

carefully through tailboom and damper

shaft. Add 0.005 inch (0.127 mm) to

into position.

gap measured. This is the minimum

shim thickness required at the

(8). Install four tail rotor gearbox mounting

forward coupling, to prevent coupling

bolts with washers and; torque to 75 −

from bottoming on output shaft.

95 inch−pounds (8.47 − 10.73 Nm)

plus drag torque.

(c). Install minimum shim thickness on

main transmission output shaft.

(9). Align forward end of drive shaft with

coupling on main transmission output

(d). Measure step between aft end of

gearshaft. Partially install two bolts as

output shaft and shoulder of cou−

an alignment aid but do not tighten.

pling, by bottoming coupling against

Align drive shaft inspection markings.

shims. (Ref. CAUTION above)

If any of four white stripes is indistinct

or does not exist, paint replacement

NOTE: Maintain minimum 0.010 inch (0.254

stripes.

mm) step between aft end of output shaft

and coupling shoulder to prevent coupling

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

bolt from bottoming on output shaft.

mm) gap between forward flange of tail

rotor drive shaft and aft end of failsafe

(e). Install additional shims to maintain

socket using the following procedure:

0.010 inch (0.254 mm) minimum step

as required.

(a).

Ensure alignment bolts in previous

step are backed off between

(3).

Position failsafe socket on aft face of

0.050−0.100 inch (1.27−2.54 mm).

forward coupling so that three of the

nine holes are indexed to the three

(b).

Remove end play in tail rotor trans−

nutplates of the coupling in such a way

mission by applying force to tail rotor

that maximum clearance is obtained

blades in opposite direction of

between the bolt key and socket.

operational rotation (while holding

Visually verify proper clearance before

forward coupling of tail rotor drive−

in stalling tail rotor drive shaft.

shaft on main transmission output

shaft to prevent rotation). Do not

(4).

Repeat previous step to install failsafe

push tail rotor drive shaft fore or aft.

socket on input coupling of tail rotor

transmission.

(c).

Using feeler gage, measure gap

between socket flange and flange of

(5).

Support entire length of tail rotor drive

tail rotor drive shaft. Socket flange

shaft and position end stamped AFT to

must be in full contact with flange of

align with tail rotor transmission

forward flexible coupling. Record the

coupling.

gap.

(6).

Install three bolts and washers to

(d).

With assistance, remove tail rotor

connect tail rotor transmission coupling

transmission and driveshaft, sup−

to shaft; torque bolts to 80 − 100

porting transmission and driveshaft

inch−pounds (9.04 − 11.30 Nm) plus

in line for minimum deflection of

drag torque.

coupling.

When reinstalling tail rotor

(e).

Using measured gap from step (c).

CAUTION

transmission and drive shaft, do

above, add or remove required

not compress the forward or aft couplings as

number of shims at main transmis−

damage to the couplings could result.

sion between output shaft and

forward coupling to obtain specified

(7). With assistance, support transmission

gap of 0.010−0.020 inch (0.254−0.508

and shaft in line, for minimum deflec−

mm).

Page 9-50

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE:

(b). Install three gearbox mounting bolts

and lightly tighten bolts.

D Maintain minimum 0.010 inch (0.254

mm) step between coupling shoulder and

(c). Measure depth of remaining bolt hole

output shaft (step (2).).

to determine proper bolt length.

D Shim, 0.010 inch (0.254 mm), installed in

(d). Remove bolts and proceed with

step (1). may be removed from aft cou−

following steps.

pling if necessary. If less than specified

gap, 0.010−0.020 inch (0.254−0.508 mm),

(14).

Apply primer (4) to the four gearbox

exists under minimum shim require−

mounting bolts. Install bolts and

ments, install a maximum of one

aluminum washers while primer is still

NAS1197− 416 washer between gearbox

wet; torque evenly to 75 − 95 inch−

housing and boom fitting. Apply zinc

pounds (8.47 − 10.73 Nm) plus drag

chromate primer (4) to both sides of wash−

torque.

er at installation. After washer installa−

(15).

Install three bolts and washers at

tion, repeat steps (10). (a). thru (e).

forward end of tail rotor drive shaft to

D If adding a washer between gearbox and

connect to forward coupling; torque

boom fitting, it may be necessary to

bolts to 80 − 100 inch−pounds (9.04 −

install a longer bolt. Ensure proper bolt

11.30 Nm) plus drag torque.

thread engagement while ensuring that

(16).

Connect electrical wire to tail rotor

bolt does not shank out.

transmission chip detector. Torque nut

to 12 − 15 inch−pounds (1.36 − 1.69

(11). Coat forward coupling splines with

grease (21) and coupling bolt threads

Nm).

with anti−seize compound (36) before

(17).

Coat pin of Sta. 284.00 bellcrank with

assembly. Install coupling and torque

grease (18) and insert it into bearing in

failsafe coupling bolt to 250 − 300

tail rotor pitch control. Pivot bellcrank

inch−pounds (28.25 − 33.90 Nm) plus

to align with mating hole in tail rotor

drag torque. Check coupling bolt for

transmission and install bolt, washers,

drag torque serviceability of 25 inch−

nut and cotter pin (Ref. Sec. 8).

pounds (2.82 Nm) minimum, 200

inch−pounds (22.60 Nm) maximum.

(18).

Check transmission oil level and service

as required (Ref. Sec. 2).

(12). With assistance, support tail rotor

(19).

Slowly rotate drive shaft and visually

transmission and shaft in line for

check to ensure shaft is not bent and for

minimum deflection of coupling and

not less than 0.250 inch (6.35 mm)

guide drive shaft carefully through

clearance between shaft and fairing

tailboom and damper into position.

tube at Sta. 137.50. In addition, check

NOTE: If in use, four AN174H−17A bolts are to

for minimum clearance of 0.190 inch

be replaced with either NAS1304− 24H or

(4.826 MM) between shaft and cooling

− 26H bolts to provide increased tail rotor

blower scroll.

transmission to tailboom mounting frame

(20).

Install all access doors and covers.

attachment strength (check bolt hole depth

for proper bolt installation). The gearbox

D. Tail Rotor Drive Shaft Twist Inspection

mounting bolt washers are 5052 aluminum

(Ref. Figure 9−17) The following inspection

alloy (NAS1197−416) and are used specifi−

determines if the drive shaft has been torsion−

cally for corrosion protection. When new, the

ally strained to the extent that permanent

outside edge is painted orange for identifica−

twist exists.

tion.

(1). Remove left side aft fairing access door;

(13). Measure bolt holes for proper bolt

then hand turn main rotor until two

installation as follows:

white stripes (View A) are aligned.

(a). Fabricate a tool for measuring bolt

(2). At tail rotor transmission, look inboard

hole depth.

from tail rotor side of helicopter and

Page 9-51

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

locate two white stripes (View B). Stripe

(9). Apply white index stripe 0.120 inch

on input shaft bearing retainer flange

(3.048 mm) wide and 0.50 inch (12.7

of tail rotor transmission is located at

mm) long on boom fairing bulkhead

approximately 2 O’clock, looking aft.

doubler (Sta. 137.50) at approximately

Stripe on coupling should be approxi−

6−8 O’clock position looking forward.

mately 10 O’clock, looking forward.

(10). Apply a corresponding joining index

Both stripes should be aligned.

stripe on the tail rotor drive shaft at

NOTE: Any time the associated tail rotor drive

Sta. 137.50. approximately 0.120 inch

shaft units are removed or replaced, an in−

(3.048 mm) wide and 0.50 inch (12.7

dexing check and reapplication of index

mm) long.

marks is required.

NOTE: Any time the associated tail rotor drive

E. Tail Rotor Drive Shaft Index Stripe

shaft units are removed or replaced, an in−

Application

dexing check and re− application of index

marks is required.

(Ref. Figure 9−17) If any of four white stripes

used for inspection of tail rotor drive shaft

(11). Install all access doors and covers.

twist are indistinct or do not exist, paint

replacement aligning index stripes (128,

F. Tail Rotor Drive Shaft Inspection

Table 2−4) as follows:

(1). Inspect a removed shaft by the follow−

(1). Remove tail rotor drive shaft, tail rotor

ing indications:

transmission as an assembly.

(a). Scratches in the shaft section that

To prevent damage to the gear−

CAUTION

passes through the plenum chamber

box coupling during and after

fairing tube. Such scratches indicate

shaft removal, provide good level support for

possible contact with the tube edges

both the tail rotor transmission and shaft,

at the bulkhead openings.

as the weight of these items might buckle

the coupling.

(b). Evidence of torsional buckling or

(2).

Inspect tail rotor drive shaft for

shaft bending as a result of blade

evidence of torsional twist or buckling.

strike or hard ground contact by the

lower stabilizer (tail low, hard

(3).

Remove any old index stripes.

landing).

(4).

Apply white index stripe 0.120 inch

(c). Corrosion.

(3.048 mm) wide and approximately

0.250 inch (6.35 mm) long on the tail

(d). Evidence of shaft damper sleeve bond

rotor transmission input shaft bearing

failure (sleeve shifting) from exces−

retainer flange at approximately 10

sive heat or loads.

O’clock position looking forward, so it

will be seen when standing on the left

(2). Take the following action with shafts

of tail rotor.

having the above indications:

(5).

Apply white index stripe 0.120 inch

(a). Replace shafts for bending, or for

(3.048 mm) wide and any length on the

scratches that exceed limits.

coupling inline with the index stripe on

tail rotor gearbox retainer.

(b). Repair corrosion.

(6).

Install tail rotor drive shaft.

(3). If there is abnormal shaft vibration,

check damper friction and shaft

(7).

Align index stripes on tail rotor gearbox

straightness or runout. When rotated

bearing retainer and aft coupling.

between centers, or with ends plugged

(8).

Remove tail rotor bellcrank access door

and rolled over rollers, the runout of

fairing and observe the area where tail

the large diameter must not exceed

rotor drive shaft passes through the

0.060 inch (1.524 mm) tir (permissible

fairing forward bulkhead.

dents exclude).

Page 9-52

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

G. Tail Rotor Drive Shaft Repair

spring−loaded against a structural support

bracket mounted on the aft section tailboom

(1). Nicks and scratches no deeper than

fairing. Maximum possible shaft deflection in

0.0015 inch (0.0381 mm) are allowable

one direction is limited to less than 1.50 inch

without rework but require finish

(3.81 cm) at the extreme throw positions of the

protection with chemical film (8,

damper.

Table 2−4).

A. Tail Rotor Drive Shaft Damper Inspection

(2). Other surface damage shall be eva−

luated and repaired according to the

(Ref. Figure 9−18) If there is excessive drive

limits specified below. Use grade 400

shaft vibration as shaft passes through the

abrasive paper (9) to smooth out and

first critical rpm range, the probable cause is a

blend the repair area into the surround−

defective or loose damper.

ing material until the damage is

(1). Inspect the damper for correct drag

completely removed; then polish with

friction adjustment (Ref. Tail Rotor

crocus cloth (23) to equal the original

Drive Shaft Damper Friction Adjust−

finish. Apply finish protection with

ment).

chemical film (8) and two coats of

primer (4).

(2). Inspect the damper for shaft clearance

as follows:

Any section of the shaft that ap−

CAUTION

pears to be scratched, nicked or

(a). Remove boom−bolts access doors.

corroded in a previously reworked area

must not be repaired a second time. Remove

(b). Inspect the tail rotor drive shaft

such a shaft from further service. Replace

damper and support structure for

any shaft that has damage in excess of the

broken, cracked or bent parts.

specified limits.

(c). Displace the damper so that it

(a). Scratches 0.007 inch (0.1778 mm)

touches the tail rotor drive shaft.

deep to a maximum length of 1.00

inch (2.54 cm), at any random angle.

(d). Use a wire gage to measure the

damper to shaft clearance 180° from

(b). Scratches 0.007 inch (0.1778 mm)

the contact point. Minimum accept−

deep to a maximum length of 0.250

able clearance is 0.020 inch (0.508

inch (6.35 mm), at any random angle.

mm).

(c). Circumferential scratches 0.004 inch

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

(0.1016 mm) deep.

intervals from the initial check point

until clearance on each side (360°) of

(3). Smoothly contoured dents are allowable

damper has been checked.

when the ratio of dent diameter to dent

depth is at least 15:1; for example,

(f). Dampers not meeting the minimum

when the depth is 0.040 inch (1.016

clearance of 0.020 inch (0.508 mm) on

mm), the minimum acceptable diameter

each side are to be replaced.

would be 0.60 inch (1.524 mm). The

(3). Inspect the inside diameter of the

maximum acceptable depth of a dent is

damper for excessive wear. If the

0.040 inch (1.016 mm). Dents that raise

diameter is more than 3.035 inches

material require that the shaft be

(7.7089 cm), damper must be replaced.

replaced.

B. Tail Rotor Drive Shaft Damper

11. Tail Rotor Drive Shaft Damper

Replacement

(Ref. Figure 9−18) Tail rotor drive shaft

(Ref. Figure 9−18)

damper is a graphite−filled teflon plate that

controls and limits deflection of the tail rotor

(1). Remove boom−bolts access doors.

drive shaft about its approximate mid−point at

all drive system speeds. The damper is

(2). Remove tail rotor drive shaft.

Page 9-54

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

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

B. Tail Rotor Drive Shaft Coupling

shim washers, plate and spacers, and

Inspection (Bendix)

damper.

(Ref. Figure 9−14)

(4). Position new damper over mounting

(1). Inspect coupling diaphragms for dents,

holes in support bracket. Install plate

cracks, nicks, rust spots and joint

and spacers with bolts, washers,

separation at the weld junction. If any

springs and spacer washers.

such defect is evident, the coupling

must be replaced.

Make certain that the two bolts

CAUTION

and washers under the bol−

(2). Inspect coupling ends for scratches,

theads are seated against the spacers when

nicks, dents, cracks and corrosion pits.

tightened. The bolts will wear rapidly if the

No cracks are allowed. Maximum depth

clamp−up is not solid.

of other defects allowed before rework is

0.005 inch (0.127 mm).

C. Tail Rotor Drive Shaft Damper Friction

Adjustment

(3). Measure the overall length of the

couplings at three different points. If

(Ref. Figure 9−18)

average of the readings exceeds 2.541

inches (6.45414 cm), the coupling must

(1). Remove tail rotor drive shaft.

be replaced.

(2). Using a 0−10 lb. (0−5 kg) spring scale,

C. Tail Rotor Drive Shaft Coupling

measure the force required to move the

Inspection (Kamatic)

damper radially on bulkhead. Pressure

friction must be adjusted so that a pull

(Ref. Figure 9−13)

of 2 ±0.25 lb. (0.91 ±0.11 kg) is required

to slide the damper between the plate

(1). Inspect coupling springs for dents,

and support bracket.

cracks, nicks and rust spots.

(2). Inspect coupling splined section and

(3). To increase friction, add spacer washers

flange for scratches, nicks, dents,

between the springs and the plate. To

cracks and corrosion pits. No cracks are

decrease friction, remove washers. (Add

allowed. Maximum depth of other

or remove the same number of washers

defects allowed before rework is 0.005

at each pressure point.)

inch (0.127 mm).

NOTE: A minimum of one washer must always

(3). Measure overall length of coupling at

remain between each spring and the plate.

three different points. If average of

readings exceed 2.630 inches (6.6802

(4). Install tail rotor drive shaft.

cm), coupling must be replaced.

12. Tail Rotor Drive Shaft Couplings

(4). Inspect drive shaft flange for signs of

contact. If signs of contact are noted,

A. Tail Rotor Drive Shaft Coupling Removal

remove and reinstall coupling bolt.

(Ref. Figure 9−13 and Figure 9−14)

D. Tail Rotor Drive Shaft Coupling Repair

(Bendix)

(1). Remove tail rotor drive shaft.

(Ref. Figure 9−14)

(2). Remove rear coupling from tail rotor

transmission by removing attaching

(1). Repairs to flexible web areas of dia−

coupling. Retain shims with coupling

phragms are not allowed.

for reinstallation.

(2). Repair damage to splined section and

(3). Remove front coupling from main rotor

flange of coupling that is no deeper

transmission by removing attaching

than 0.005 inch (0.127 mm). Use

bolt. Retain shims with coupling for

abrasive paper grade 400 − 600 (9,

reinstallation.

Table 2−4) and crocus cloth (23) to

Page 9-56

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

completely remove and polish out

abrasive paper grade 320 grit or finer

defect. Maximum depth after rework is

(9, Table 2−4) and crocus cloth (23) to

0.010 inch (0.254 mm). Apply primer (4)

completely remove and polish out

to repaired area.

defect. Maximum depth after rework is

0.007 inch (0.1778 mm). Apply primer

(3). Repair damage to outer welded portion

(4) to repaired area.

of diaphragm halves as in step (2).

above, except that maximum thickness

NOTE: Flange may be hand lapped using a

of material removed shall be not more

sheet of #440 emery cloth (49), placed on a

than 10 percent of original material

surface table. A figure ‘‘8’’ motion should be

thickness.

used while lapping the coupling, using care

not to let part ‘‘rock’’.

E. Tail Rotor Drive Shaft Coupling Repair

(Kamatic)

(3). Minimum flange thickness after

cleanup is 0.10 inch (0.254 mm).

(Ref. Figure 9−13)

F. Tail Rotor Drive Shaft Coupling

(1). Repairs to coupling spring areas are not

Installation

allowed.

(Ref. Figure 9−13 and Figure 9−14, Tail Rotor

(2). Repair damage to splined section and

Drive Shaft Installation with Kamatics

flange of coupling that is no deeper

Couplings or Tail Rotor Drive Shaft Installa−

than 0.005 inch (0.127 mm). Use

tion with Bendix Couplings).

Page 9-57

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 10 Engine Installation and Cooling System .

10−1

Engine

10−1

Engine Installation Troubleshooting

10−1

Table 10−1. Engine Installation Troubleshooting

10−1

Engine Removal

10−2

A. Engine Disconnecting for Removal

10−2

B. Removal of Disconnected Engine

10−2

Engine Installation

10−3

A. Engine Installation in Mounts

10−3

B. Connecting an Installed Engine

10−3

Figure 10−1. 250−C18 Engine Removal and Installation (Sheet 1 of 2) .

10−4

Figure 10−2. 250−C20 Engine Removal and Installation (Sheet 1 of 2) .

10−6

Engine Stripping

10−8

Engine Build−Up

10−9

Figure 10−3. 250−C18 Engine Stripping and Buildup (Sheet 1 of 2) .

10−10

Figure 10−4. 250−C20 Engine Stripping and Buildup (Sheet 1 of 2) .

10−12

Installation of 369H8144−3 Engine Fuel Pump Pressure Switch Assembly .

10−15

Engine Mounts and Fittings

10−15

Lower Engine Mount Replacement

10−16

A. Lower Engine Mount Removal

10−16

B. Lower Engine Mount Installation

10−16

10. Upper Engine Mount Replacement

10−16

A. Upper Engine Mount Removal

10−16

Figure 10−5. Engine Mounts and Fittings

10−17

B. Upper Engine Mount Installation

10−18

C. Engine Mounts and Fittings Inspection

10−18

D. Engine Mounts and Fittings Repair

10−18

E. Engine−to−Transmission Alignment Check

10−18

Figure 10−6. Adjustable Engine Mounts

10−19

11. Engine Cooling System

10−19

A. Engine Cooling System Inspection

10−20

B. Cooling System Repair or Replacement

10−20

12. Engine Shaft Firewall Seal

10−20

A. Engine Shaft Firewall Seal Replacement

10−20

B. Engine Shaft Firewall Seal Inspection

10−20

C. Engine Shaft Firewall Seal Repair

10−20

Figure 10−7. Engine Cooling (Sheet 1 of 2)

10−21

Page 10−i

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 10

ENGINE INSTALLATION AND COOLING SYSTEM

1. Engine

temperatures (TOT) and consequently higher

output power, particularly at higher altitudes.

The helicopter may be equipped with either

Refer to the applicable engine operation and

the Allison 250−C18A, 250−C18C or 250−C20

maintenance manual for detailed maintenance

engine.

information and theory of engine operation.

The free turbine, turboshaft engine is mounted

Starter limitations for engine compressor

in the helicopter on centerline at a 43−degree

cleaning are given in Section 2. A daily water

angle from horizontal. It consists of a multi−

rinse that is accomplished without disconnect−

stage axial−centrifugal compressor, a single

ing the compressor discharge pressure (P_c)

combustion chamber, a two−stage gas producer

sensing tube is recommended for helicopters

turbine and a two−stage power turbine which

operating in a corrosive environment to

provides the output power of the engine.

remove any contaminants and corrosive air

particles. A periodic (200 to 300 hours)

The engines are basically identical in external

compressor waterwash using cleaning solvents

appearance except for variations in fuel control

to remove dirt buildup is recommended for

system components on the 250−C20 engine. In

helicopters that operate in smoggy areas. The

addition, a start (cycle) counter is included as

Pc tube must be disconnected and the opening

part of the 250−C20 engine electrical system.

capped to prevent introduction of chemical

agents into the controls system Pc connection

When engine automatic reignition is installed,

during the wash operation.

the counter is modified to prevent counter

NOTE: Engine conversion information that mo−

operation when automatic reignition occurs.

difies the helicopter for 250− C20 engine

Section 14 of this manual provides basic

installation is provided in CSP−H−3.

ignition troubleshooting information.

2. Engine Installation Troubleshooting

Internal differences in the 250−C20 engine

allow for operation at higher turbine outlet

(Ref. Table 10−1)

Table 10-1. Engine Installation Troubleshooting

Symptom

Probable trouble

Corrective action

NOTE: Refer to the engine operation and maintenance manual for troubleshooting information on the engine

assembly. Verify that the associated helicopter system is functioning correctly (i.e. chip detectors, instruments, fuel

supply system, etc.) before troubleshooting the engine.

High frequency vibration

Loose engine mount bolts

Retorque engine mount bolts to 100

-140 in.-lb. (11.30 - 15.82 Nm)

NOTE: High frequency vibrations may also be caused by components in other systems. (Ref. Sec. 5, 8 and 9.)

Page 10-1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3. Engine Removal

(12). Disconnect N₂ control rod from idler

bellcrank. Tie or tape control rod out of

(Ref. Figure 10−1 and Figure 10−2)

the way against the firewall.

NOTE: Removal of the engine does not require

(13). If cable−actuated anti−icing control

removal of the engine mounts.

valve lever is installed, disconnect by

removing cotter pin, loosening nut on

A. Engine Disconnecting for Removal

adapter and detaching control cable. If

anti−icing valve electrical actuator is

(1). Turn all switches OFF and disconnect

installed, remove two clamps at forward

external power.

firewall.

(2). Remove main transmission drive shaft

(14). Disconnect N₁ control rod from gas

(Ref. Sec. 9).

producer lever. Tape or tie control rod

out of the way against the firewall.

(3). Remove engine tailpipes (Ref. Sec. 15).

(15). Disconnect accessory drive overboard

Cap all disconnected lines and

vent.

CAUTION

fittings. Do not use tape to cover

fuel and oil openings. Tape adhesive is solu−

(16). Disconnect oil line from engine oil

ble in fuel or oil and can cause contamina−

pressure reducer fitting.

tion.

(17). On 250−C20 engine, disconnect drain

NOTE: As an aid to reassembly, attach identify−

line from fuel control.

ing tags to all electrical wires and fuel and

oil hoses prior to disconnection.

Remove the oil inlet and outlet

CAUTION

lines only at the engine. Remov−

(4).

Remove lockwire and engine electrical

al at the oil cooler end will damage the cool−

harness plug from the receptacle

er frame if the frame oil port boss is not sup−

mounted on the right side oleo structur−

ported with a wrench. For the same reason,

al fitting.

do not apply extreme bending loads on the

oil cooler lines after they are disconnected

(5).

Disconnect thermocouple leads from

from the engine.

terminal studs and leads from termi−

nals E, C and B of starter−generator.

(18). Disconnect engine oil inlet line.

Disconnect bond jumper at center

firewall stud.

(19). Disconnect engine oil outlet line.

(6).

Remove clamp on right engine mount to

(20). Disconnect engine oil vent line.

release engine harness.

B. Removal of Disconnected Engine

(7).

Remove combustion chamber drain line

from burner drain valve.

(1). Install engine hoist (39, Table 2−2)

between hoisting eye fitting (located on

(8).

Disconnect fuel inlet line at pump and

intercostal above engine) and the hoist

seal drain line.

fitting provided on engine.

(9).

Disconnect cabin air outlet tube at

(2). Station an assistant on engine hoist

firewall fitting.

and apply tension on hoist line.

(10).

Loosen compressor cooling air duct

(3). Remove bolt and washer from bottom

clamp at firewall coupling, disconnect

engine mount. Maintain slight down−

support bracket at hoisting eye and

ward pressure at rear of engine during

remove duct from engine compartment.

removal of engine mount bolts.

(11).

Disconnect oil line from torquemeter

(4). Remove two bolts and washers from the

fitting.

left and right engine mounts.

Page 10-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Do not use fuel or oil lines to

handle. Shift engine toward side of

CAUTION

handle engine during removal.

stand with disconnected shaft to

Take care not to contact adjoining structure

disengage the fixed shaft. Roll stand

or compartments while lowering engine.

away from engine.

Use particular care to prevent damage to

Do not grasp fuel or oil lines

the N₁ bearing oil return line on the under−

CAUTION

during engine installation. Use

side of the compressor, and to avoid cracking

particular care not to contact adjoining

or breaking the engine air inlet bell on the

structure or components and to avoid crack−

compressor.

ing or breaking engine air inlet bell on com−

pressor.

(5).

Remove detent pin and unscrew the

adjustable support shaft in engine

(3). Have assistant slowly raise the engine

stand (38) for clearance.

while necessary pressure is applied

downward at rear of engine.

(6).

Align the engine stand under the

engine so that the adjustable support

(4). Align left and right engine mounts with

shaft will engage the left engine mount

mount fittings and install bolts and

fitting.

washers. Torque bolts to 100 − 140

inch−pounds (11.30 − 15.82 Nm).

(7).

Slowly lower engine from the helicopter.

Align hole in lower engine mount with

Align engine side mount fittings

mount fitting and install bolt and

between the fixed and the adjustable

washer. Torque bolt to 100 − 140

support shaft.

inch−pounds (11.30 − 15.82 Nm).

Safety bolts with lockwire (2,

(8).

Screw the adjustable support shaft

Table 2−4).

inward until engine mount bosses are

securely engaged with the support shaft

(5). Check to ensure that the engine air

sockets.

inlet firewall seal ring contacts the

firewall seal all the way around.

(9).

Insert detent pin through the adjust−

(6). Remove engine hoist from helicopter.

able support shaft.

B. Connecting an Installed Engine

(10).

If engine is to be stored or transported,

(1). Connect engine oil vent line; torque the

engage the engine stand transport and

line nut to 120 − 140 inch−pounds

storage bar in the engine lifting eye

(13.56 − 15.82 Nm).

fitting.

Do not overtorque engine oil in−

4. Engine Installation

CAUTION

let or outlet couplings; damage

to the coupling orself− closing valve, if

(Ref. Figure 10−1 and Figure 10−2)

installed, may result. Do not apply extreme

bending loads on the oil outlet line. Such

A. Engine Installation in Mounts

loads will be transferred to the oil cooler in−

(1). Position engine stand as close as

let port boss and can cause the cooler frame

possible to helicopter with engine

to fracture.

access doors open. Remove detent pin

(2). Connect engine oil outlet and inlet

from the adjustable support shaft on

lines. Hand−tighten until snug; then

engine stand. Detach transport and

wrench−tighten approximately 1/4 turn

storage bar from engine lifting eye

or until definite resistance is felt.

fitting.

(3). Connect engine oil pressure line.

(2). Install engine hoist (39, Table 2−2)

(4). Position accessories drive overboard

between engine hoist fitting on struc−

vent elbow and torque to 150 − 250

ture above engine and on engine hoist

inch−pounds (16.95 − 28.25 Nm).

fitting on engine. Have assistant apply

and hold tension on the hoist. With

(5). Connect accessories drive overboard

engine supported manually, unscrew

vent. Torque tube nut to 20 − 30

the adjustable support shaft with

inch−pounds (2.26 − 3.39 Nm).

Page 10-3

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ANTI−ICING VALVE CONTROL CABLE

(NOTE 1)

OR ELECTRICAL ACTUATOR HARNESS

(NOTE 2)

COMPRESSOR COOLING AIR

DUCT AND SUPPORT BKT

TAIL PIPES

CABIN AIR OUTLET TUBE

LH ENGINE MOUNT BOLT

350 IN. LB (39.54 NM)

100−140 IN. LB (11.30−15.82 NM)

MAIN TRANSMISSION

DRIVE SHAFT

N2 CONTROL ROD

TORQUEMETER

OIL LINE

HARNESS CLAMP

FUEL INLET LINE

120−140 IN. LB

(13.56−15.82 NM)

BOND JUMPER

FUEL PUMP SEAL DRAIN LINE

20−30 IN. LB (2.26−3.39 NM)

COMBUSTION CHAMBER

DRAIN LINE

GENERATOR LEADS

(E, C, B ONLY) AND

BOND JUMPER

ENGINE HARNESS PLUG

NOTES:

USED ON HELICOPTERS WITH MANUALLY

OPERATED ANTI−ICING VALVE INSTALLATION.

ON ELECTRICALLY OPERATED ANTI−ICING

VALVE INSTALLATION, REMOVE TWO WIRE

HARNESS CLAMPS ON FIREWALL.

30-081-1D

Figure 10-1.

250-C18 Engine Removal and Installation (Sheet 1 of 2)

Page 10-4

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(6).

On 250−C20 engine, connect drain line

NOTE: Check that the burner drain valve and

to fuel control. Torque nut to 20 − 30

plug are correctly installed in the combus−

inch−pounds (2.26 − 3.39 Nm).

tion chamber. Each part must be installed

with a packing. The drain valve is installed

(7).

Connect N₁ control rod to lever with

in the aft (lowest) position.

bolt, two washers, nut and new cotter

(16).

Secure engine harness to engine mount

pin. Install the bolt with head outboard,

with cushioned loop clamp. Connect oil

one washer (standard OD) under the

pressure sender lead if the electrical

nut and one large OD, 0.80 inch (20.32

indicating system is used.

mm) washer under the head. Torque

nut to 40 − 45 inch−pounds (4.52 −

(17).

Install E, C, B generator leads on

5.08 Nm) and install new cotter pin.

starter/generator and secure with

washers and nuts.

(8).

If anti−icing valve is manually con−

trolled, install control cable in lever

(18).

Connect thermocouple leads to terminal

adapter. If valve is electrically con−

block studs and secure with chromel

trolled, install wire harness clamps at

and alumel nuts provided. Install clamp

firewall. Make an operational check of

on door frame.

either installation (Ref. Sec. 11).

(19).

Connect engine harness plug to recep−

tacle and safety with 0.032 inch (0.8128

(9).

Connect short N₂ control rod to gover−

mm) lockwire (2, Table 2−4). Install

nor lever with bolt (head up), one

bond jumper terminal to lower engine

washer (standard OD) under head, one

attach fitting. Torque bolt to 140 − 160

large OD, 0.80 inch (20.32 mm) washer

inch−pounds (15.82 − 18.08 Nm).

under the nut and a new cotter pin.

Safety bolt with 0.032 inch (0.8128 mm)

Connect long N₂ control rod with

lockwire.

bolt−head forward), two washers, nuts

and new cotter pin.

(20).

Install engine exhaust tailpipes (Ref.

Sec. 15).

(10).

Connect oil line to torquemeter fitting

(21).

Install main transmission drive shaft

below N₂ tach generator.

(Ref. Sec. 9).

(11).

Install compressor cooling air duct

(22).

Remove all identifying tags from

support bracket on hoisting eye above

electrical wires and fuel and oil lines.

engine. Connect and tighten flexible

duct on firewall coupling.

(23).

Check rigging of gas producer (N_l) and

power turbine (N₂) engine power

controls (Ref. Sec. 17).

(12).

Connect cabin air outlet tube (or hose)

to firewall fitting. Make sure no

(24).

Check overall condition of engine

interference exists between compressor

installation and connections.

bleed air tube and 3/8 inch diameter

engine bleed air tube. Tighten both tube

5. Engine Stripping

nuts to 350 inch−pounds (39.54 Nm).

(Ref. Figure 10−3 and Figure 10−4)

(13).

Connect engine fuel pump seal drain

(1). Disconnect A and D leads from starter−

line. Torque tube nut to 20 − 30 inch−

generator. Loosen mounting clamp that

pounds (2.26 − 3.39 Nm).

secures starter−generator to mounting

flange and remove starter−generator.

(14).

Connect fuel inlet line to fuel pump.

Remove four nuts and washers; then

Torque line nut to 120 − 140 inch−

remove mounting flange and gasket.

pounds (13.56 − 15.82 Nm).

Install pad cover on engine.

(15).

Install combustion chamber drain line

(2). Disconnect electrical connectors from

on drain valve.

both chip detectors.

Page 10-8

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(3).

Disconnect both tachometer generator

(19).

Remove governor control idler support,

connectors, anti−icing valve actuator

bellcrank and short N₂ control rod as

connector (if installed), ignition exciter

an assembly. Install vacuum/hydraulic

lead, fuel filter pressure switch and

pump pad cover.

start counter leads (if installed).

(20).

Remove torque pressure snubber,

(4).

Remove bracket or clamp at overrun−

reducer and two O−rings.

ning clutch and lower engine mount

(21).

Remove three bolts, washers and nuts

fitting; then remove entire wire har−

attaching firewall seal to overrunning

ness.

clutch and remove seal.

(5).

Remove fuel inlet reducer and O−ring.

(22).

Remove the overrunning clutch (Ref.

Sec. 9), install pad cover.

(6).

Remove oil inlet and outlet couplings

with O−rings.

(23).

On 250−C20 engine, remove fuel control

vent elbow fitting, nut and O−ring.

(7).

Remove accessory drive overboard vent

elbow, nut and O−ring.

(24).

On engines with a Bendix fuel system

installed, remove the three cubic inch

(8).

Loosen both ends of the compressor

accumulator from fuel line in accor−

bleed air tube and detach from engine.

dance with the engine manufacturer’s

applicable installation bulletin.

(9).

Remove elbow, nut and gasket from the

compressor scroll.

(25).

With engine supported manually,

unscrew the adjustable support shaft

(10).

Remove tee, nut and gasket from

with handle.

compressor scroll.

(26).

Switch engine toward side of stand with

(11).

Remove oil pressure reducer, snubber

disconnected shaft to disengage the

and two O−rings.

fixed shaft.

(12).

Remove both tachometer generators by

(27).

Keep engine in vertical position and

removing four nuts and washers and

remove carefully from stand.

lifting directly off mounting pad; then

remove gasket.

(28).

Position engine on a stable surface.

Remove bolts, washers, bond jumper

(13).

Remove tube or hose assembly, reducer,

and three mount fittings from engine.

fuel filter pressure switch and two

O−rings from fuel pump assembly.

6. Engine Build-Up

(14).

Remove engine air inlet bell and

(Ref. Figure 10−3 and Figure 10−4)

engine−to−firewall seal (Ref. Sec. 16).

(1). Support replacement engine in position

(15).

On helicopter equipped with electrically

for access to engine mount fitting

actuated anti−icing valve, remove

locations.

actuator and controls (Ref. Sec. 11).

(2). Install the three engine mount fittings,

(16).

On helicopter equipped with manually

using washers and bolts. Torque to 140

actuated anti−icing valve, remove

− 160 inch−pounds (15.82 − 18.08

anti−icing valve lever assembly from

Nm) and safety with lockwire. Do not

poppet guide.

safety lower engine mount fitting at

this time.

(17).

Remove three bolts, washers and

engine hoist fitting, and actuator

(3). Install engine in engine stand (38,

bracket, if installed.

Table 2−2).

(18).

Remove elbow, nut and O−ring from the

(4). Install O−ring, nut and special tee in

fuel pump seal drain port.

compressor scroll. Do not tighten.

Page 10-9

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ELBOW

O−RING

(NOTE 1)

O−RING

NUT

FUEL INLET

GASKET

COUPLING

OVERBOARD VENT ELBOW

(NOTE 1)

OIL PRESSURE

N2 TACH / GEN

REDUCER

CONNECTION

COMPRESSOR BLEED

AIR TUBE (OR HOSE)

O−RING

150−200 IN. LB

(16.95−28.25 NM)

OIL PRESSURE

N1 TACH / GEN

SNUBBER

CONNECTION

IGNITION

EXCITER LEAD

O−RING

OIL TANK VENT

UNION AND O−RING

CHIP DETECTOR

CONNECTORS

FUEL FILTER

SWITCH KNIFE

ENGINE STAND

SPLICE

369A9948

(NOTE 2)

D" LEAD

A" LEAD

OIL PRESSURE

SENDER LEAD

(ELECTRICAL

START / GEN CLAMP

GAUGE ONLY)

ENGINE HARNESS

OIL INLET

OIL OUTLET

COUPLING

O−RING

NOTES:

OBSERVE POSITION OF FITTING BEFORE

REMOVING TO AID REASSEMBLY AT

CORRECT ANGLE.

INSULATE WITH FIBERGLASS SLEEVING

(87, TABLE 2−4.).

30-082-1G

Figure 10-3.

250-C18 Engine Stripping and Buildup (Sheet 1 of 2)

Page 10-10

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

HOSE ASSY

ELECTRICAL CONNECTION

(NOTE 3)

(NOTE 2)

3/8 IN. DIA. BOLT

FUEL PRESSURE

REDUCER

ANTI−ICING ACTUATOR BRACKET

160−190 IN. LB

SWITCH 40−50 IN. LB

(NOTE 4)

(18.08−21.47 NM)

(4.52−5.65 NM)

O−RING

ENGINE AIR

O−RING

INLET BELL

AFTER FILTER

PORT

ENGINE−TO−FIREWALL

BEFORE FILTER

SEAL

PORT

LIFT

ENGINE SHAFT

FITTING

FIREWALL SEAL

5/16 IN. DIA. BOLT (TYP)

140−160 IN. LB (15.82−18.08 NM)

BLEED AIR TUBE OR HOSE

OVERRUNNING

150−250 IN. LB (16.95−28.25 NM)

ENGINE MOUNT

CLUTCH

FITTING

CABIN AIR OUTLET TUBE

350 IN. LB (39.54 NM)

ANGLE

DETENT PIN AND LANYARD

BOND JUMPER

SUPPORT SHAFT

ADJUSTMENT HANDLE

STORAGE AND

TRANSPORT BAR

140−160 IN. LB

(15.82−18.08 NM)

RPM GOVERNOR

CONTROL IDLER

SUPPORT BELLCRANK,

N2 CONTROL ROD

TEE

(NOTE 1)

NUT

GASKET

REDUCER

PUMP SEAL DRAIN ELBOW

(NOTE 1)

NUT

O−RING

TORQUEMETER

OIL PRESSURE

SNUBBER

O−RING

NOTES: (CONT)

HOSE ASSEMBLY IS ONE−WAY

INTERCHANGEABLE WITH TUBE ASSEMBLY.

INSTALLED ON ENGINES EQUIPPED

WITH ELECTRICALLY OPERATED

ANTI−ICING VALVE.

30-082-2G

Figure 10-3.

250-C18 Engine Stripping and Buildup (Sheet 2 of 2)

Page 10-11

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

O−RING

ENGINE MOUNT

FITTING

NUT

ANGLE

OVERBOARD VENT

(NOTE 1)

ELBOW

BOND JUMPER

(NOTE 1)

140−160 IN. LB

ACCESSORIES DRIVE VENT

(15.82−18.08 NM)

ELBOW INSTALLATION

ENGINE MOUNT FITTING

INSTALLATION (TYP)

N2 TACHOMETER GENERATOR

N1 TACHOMETER

GENERATOR

OIL PRESSURE

REDUCER FITTING

IGNITION EXCITER LEAD

(NOTE 2)

OIL INLET COUPLING

WITH O−RING

START COUNTER

KNIFE SPLICE

OIL OUTLET COUPLING

(NOTE 2)

WITH O−RING

CHIP DETECTOR

CONNECTOR

ENGINE ELECTRICAL

CHIP DETECTOR

HARNESS

CONNECTOR

FUEL INLET REDUCER

WITH O−RING

FUEL INLET SWITCH

KNIFE SPLICE

(NOTE 2)

D" WIRE LEAD

STARTER/GENERATOR

A" WIRE LEAD

ENGINE STAND

NOTES:

APPLIES ONLY TO LOWER MOUNT.

INSULATE WITH FIBERGLASS SLEEVING

(87, TABLE 2−4).

CHECK THAT LEVER ARM IS INSTALLED

PARALLEL WITH TOP OF ENGINE.

30-207-1C

Figure 10-4.

250-C20 Engine Stripping and Buildup (Sheet 1 of 2)

Page 10-12

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

AFTER FILTER

COMPRESSOR BLEED AIR HOSE

PORT (AF)

FUEL PUMP SEAL ELBOW,

NUT AND O−RING

BEFORE FILTER PORT (BF)

SPECIAL TEE FITTING

O−RING

NUT

O−RING

ELBOW 20−25 IN. LB (2.26−2.82 NM)

REDUCER 40−50 IN. LB (4.52−5.65 NM)

O−RING

ENGINE AIR

O−RING

FITTING 40−50 IN. LB

CABIN AIR FITTING

INLET BELL

(4.52−5.65 NM)

INSTALLATION

ENGINE−TO−FIREWALL

O−RING

SEAL RING

FUEL PRESSURE SWITCH

40−50 IN. LB (4.52−5.65 NM)

BUSHING 40−50 IN. LB (4.52−5.65 NM)

HOSE ASSEMBLY 20−25 IN. LB 2.26−2.82 NM)

ANTI−ICE VALVE

FUEL PRESSURE SWITCH

LEVER

INSTALLATION

(NOTE 3)

OVERRUNNING CLUTCH−

TO−FIREWALL SEAL

OVERRUNNING

CLUTCH

3/8 IN. DIA. BOLT

TORQUEMETER REDUCER

COMPRESSOR

160−190 IN. LB

FITTING WITH O−RING

BLEED AIR HOSE

(18.08−21.47 NM)

DETENT PIN

LIFT FITTING

5/16 IN. DIA. BOLT (2 PLCS)

140−160 IN. LB (15.82−18.08 NM)

ADJUSTABLE

ENGINE LIFT FITTING

SUPPORT

INSTALLATION

SHAFT

GOVERNOR CONTROL IDLER

SUPPORT, BELLCRANK AND

N2 CONTROL ROD ASSEMBLY

ACCUMULATOR

30-207-2D

Figure 10-4.

250-C20 Engine Stripping and Buildup (Sheet 2 of 2)

Page 10-13

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(5). Connect compressor bleed air hose

(14).

Install anti−icing valve lever with

between special tee and compressor

attaching hardware on poppet guide

elbow. Tighten special tee nut; then

(Ref. Sec. 11). If required, reposition

torque hose nut to 150 − 250 inch−

poppet guide so that lever is parallel

pounds (16.95 − 28.25 Nm).

with top of engine.

(15).

On helicopters equipped with electrical−

(6). Install overrunning clutch (Ref. Sec. 9).

ly actuated anti−icing valve, install

actuator and controls (Ref. Sec. 11).

(7). Install engine firewall seal on overrun−

ning clutch and secure with three bolts,

(16).

Install engine−to−firewall seal and

six washers and three nuts.

engine inlet bell (Ref. Sec. 16).

(8). Install torquemeter oil pressure reducer

(17).

On 250−C18, install O−ring and fuel

and snubber with O−rings.

filter pressure switch in the before−filt−

er port of the pump. Torque switch to 40

The engine spark igniter lead on

− 50 inch−pounds (4.52 − 5.65 Nm).

CAUTION

a new or overhauled engine is

Install O−ring and reducer in the

routed above the N₂ governor causing inter−

after−filter port. Install tube assembly.

ference with and possible obstruction of the

(18).

On 250−C20, install fuel pressure

governor arm. During installation of the

switch fitting with O−ring in after (AF)

governor idler support, check that the en−

port of the fuel pump; then install fuel

gine spark igniter lead is routed as shown in

filter pressure switch an O−ring and

Figure 10−3 and Figure 10−4. Also, check

torque to 40 − 50 inch−pounds (4.52 −

that only cushioned clamps are used to at−

5.65 Nm). Install bushing in switch.

tach the igniter lead and replace if required.

Install reducer fitting with O−ring in

If not as shown, re−route the lead below the

before filter (BF) port; then install hose

governor as shown using existing hardware

between (AF) and (BF) fittings.

and additional cushioned clamps as neces−

sary.

(19).

Install tachometer generators (Ref. Sec.

17).

(9). Install governor control idler support,

bellcrank and short N₂ control rod as

(20).

Install O−ring, nut and elbow for

an assembly.

accessories drive overboard vent. DO

NOT tighten until final installation in

NOTE: Only high temperature all metal nuts

helicopter.

(not the fiber insert type) are to be used for

anchoring governor control idler support

(21).

Install oil inlet and outlet couplings

bracket to engine accessory pad.

with O−rings.

(22).

Install starter−generator (Ref. Sec. 19).

(10). Install oil pressure reducer fitting,

snubber and O−rings.

(23).

Install engine harness. Connect ignition

exciter lead, starter−generator A and D

(11). Install fuel inlet reducer coupling and

leads, fuel pressure switch splice and

O−ring.

start counter splice. Install fiber glass

sleeving (87, Table 2−4) over knife

(12). Install O−ring, nut and elbow fitting in

splice and secure with high tempera−

fuel pump seal drain port.

ture lacing cord (37). Install electrical

connectors to tach generators and chip

(13). Position anti−icing valve actuator

detectors. Safety the connectors with

bracket, if so equipped, and install

lockwire.

engine hoist fitting using three washers

and bolts. Torque the 3/8 inch−diameter

(24).

On engines with Bendix fuel system

bolt to 160 − 190 inch−pounds (18.08

installed, install the three cubic inch

− 21.47 Nm). Torque the two 5/16

accumulator in fuel line according to

inch−diameter bolts to 140 − 160

the engine manufacturer’s applicable

inch−pounds (15.82 − 18.08 Nm).

installation instructions.

Page 10-14

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

7. Installation of 369H8144-3 Engine Fuel

(c). Have assistant hold switch clear;

Pump Pressure Switch Assembly

connect battery and electrical power

and actuate start pump. Filter

This procedure is for replacement of the

by−pass warning light should actu−

existing 369H8144 engine fuel pump fuel

ate, indicating proper operation of

pressure switch assembly with new

filter by−pass switch.

369H8144−3 switch assembly to be accom−

(d). Shut off electrical power, start pump,

plished in conjunction with installation of 5

battery switch; disconnect battery

micron filter replacement kit (Allison PN

and jumper wire.

6895028). The −3 switch assembly accommo−

dates the 5 micron filter element to preclude

(e). Disconnect bushing at by−pass hose;

premature actuation of the fuel filter warning

cap hose assembly.

light on the instrument console.

(9). Remove plug from after filter port;

install 369H8020 adapter fitting with

(1).

Check that all electrical power is OFF;

new MS29512−03 packing at the after

disconnect battery.

filter port.

(10). Remove cap from by−pass hose; recon−

(2).

Gain access to engine accessory section;

nect bushing at by−pass hose.

locate fuel filter pressure (by−pass)

switch on front of engine driven fuel

(11). Check fuel filter pressure switch

pump (Ref. Figure 10−4).

installation for discrepancies.

(12). Run up engine and perform operational

(3).

Remove protective sleeving and

check of engine and fuel system; check

disconnect knife splice on by−pass

for leaks and non−actuation of fuel

switch wiring.

filter by−pass light when start pump is

actuated.

(4).

Disconnect and cap by−pass hose

assembly at AN894−3−2 bushing.

8. Engine Mounts and Fittings

(Ref. Figure 10−5) The engine mount installa−

(5).

Remove 369H8020 adapter fitting (with

tion consists of one lower and two upper

switch and bushing intact) from after

engine mounts, six structural attach fittings,

filter port. Plug after filter port.

three engine mount fittings and associated

attaching hardware.

(6).

Remove bushing and adapter from

switch, discard switch and packing.

Each of the three engine mounts is a tubular

steel, V−shaped, welded assembly.

(7).

Install bushing with new MS29512−03

The lower engine mount is bolted to the two

packing on new 369H8144−3 switch;

bulkhead splice fittings and an engine mount

install switch with new MS29512−02

fitting located on the underside mounting pad

packing on adapter; torque switch and

of the power and accessories gearbox.

bushing 40 − 50 inch pounds (4.52 −

5.65 Nm).

The two upper engine mounts are symmetri−

cally opposite assemblies; the longer end is

bolted to an upper engine attach fitting on the

(8).

Perform function test of new

firewall; the shorter end to the oleo support

369H8144−3 switch as follows:

fitting and the aft end to an engine attach

fitting on the side mounting pad of the power

(a). Remove cap from by−pass hose and

and accessory gearbox.

reconnect bushing (with switch and

adapter fitting intact) in hose fitting.

On current configuration helicopters, the left

and right upper engine mounts may be

(b). Connect knife splice on switch

adjustable for engine−to−transmission

wiring; connect jumper wire to

alignment. Adjustment is accomplished by

ground by−pass switch to airframe

turning a left and right threaded fitting that is

ground (E−12).

part of each upper engine mount leg.

Page 10-15

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

The three engine mount fittings, bolted to the

(4). Disconnect the left and right forward

power and accessory gearbox are machined

ends of the lower engine mount; discard

aluminum alloy forgings, each having a

the two nuts.

self−locking, steel−thread insert.

(5). Disconnect lower engine attach fitting.

The engine lift fitting (hoisting eye) is an

B. Lower Engine Mount Installation

anodized machined aluminum alloy forging,

mounted on top of the power and accessory

gearbox just aft of the air inlet scroll.

CAUTION

D Do not tighten bolts until the engine at−

CAUTION

tach bolt is tightened.

D If engine mount adjustment fittings are

D Retorque the engine attach bolt after 3 to

disturbed or if new or replacement upper

5 hours of flight if the engine mount will

be attached to a previously unused mount

engine mounts (either fixed or adjustable)

fitting.

are installed, realignment of the engine is

required.

NOTE: All engine mount fitting bolts, washers

D To avoid disturbing security of the engine

and nuts are corrosion resistant steel.

installation or alignment of the engine, do

(1). Place ends of lower engine mount

not loosen and/or remove more than one

against bulkhead fittings. Install two

engine mount at any one time.

bolts, four washers and two new nuts at

D Do not readjust adjustable engine mount

bulkhead attach points. Torque nuts to

fittings unless an engine− to− transmis−

30 − 40 inch−pounds (3.39 − 4.52 Nm)

sion alignment check is performed.

plus drag torque.

D Do not use open end wrenches when re−

(2). Install engine attach bolt and washer

moving engine attach fittings and attach−

securing mount to fitting on engine.

ing hardware. Use box end and socket

Torque bolt to 100 − 140 inch−pounds

wrenches to avoid tool damage to hard−

(11.30 − 15.82 Nm); safety with 0.032

ware and engine mount fittings.

inch (0.8128 mm) lockwire.

9. Lower Engine Mount Replacement

(3). Tighten bulkhead fitting bolts and nuts.

A. Lower Engine Mount Removal

10. Upper Engine Mount Replacement

(1). Remove the bolt and nut attaching the

A. Upper Engine Mount Removal

compressor air duct support bracket to

the overhead engine hoist fitting.

(1). Remove engine oil pressure sender

clamps, if installed, and engine harness

(2). Install engine hoist (39, Table 2−2).

clamp from right side engine mount.

Apply enough tension with hoist to

remove weight from lower mount.

(2). Disconnect forward attach points of

Engine load will be neutral when the

upper engine mount at upper mount

attaching bolts turn freely with nuts

fitting and oleo support; discard the

backed off one−half turn.

nuts.

(3). Release cargo compartment upholstery

(3). Remove aft end of mount from mount

enough to gain access to the bulkhead

fitting on pad of power and accessory

fitting boltheads.

gearbox.

Page 10-16

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

OVERHEAD ENGINE

LOWER ENGINE

HOIST FITTING

ATTACH FITTING

BULKHEAD

SPLICE FITTING

LOWER ENGINE

STA. 124 FIREWALL

MOUNT

BULKHEAD

100−140 IN. LB

ANGLE

(11.30−15.82 NM)

140−160 IN. LB

BONDING

(15.82−18.08 NM)

JUMPER

160−190 IN. LB

(18.08−21.47 NM)

ENGINE LEFT

FITTING

140−160 IN. LB

(15.82−18.08 NM)

ADJUSTABLE UPPER

SIDE ENGINE MOUNT

(NOTE 4)

ENGINE SIDE

0.3122−0.3132 IN.

ATTACH FITTING

(7.92988−7.95528 MM)

NON−ADJUSTABLE

(NOTE 2)

UPPER SIDE ENGINE

MOUNT

UPPER ENGINE

MOUNT FITTING

100−140 IN. LB

140−160 IN. LB

(11.30−15.82 NM)

(15.82−18.08 NM)

BONDING JUMPER

(NOTE 3)

NOTES:

ALL BOLTS, NUTS AND WASHERS MUST BE

CRES. USE THIN WASHERS IN ALL

OLEO SUPPORT

APPLICATIONS EXCEPT THOSE MARKED

FITTING

WITH AN ASTERISK ( * ).

ON UPPER ENGINE MOUNT−TO−FITTING BOLT

HOLES ONLY. HOLES WITH THREAD DAMAGE

MAY BE ENLARGED TO 0.3170 IN. DIAMETER

PROVIDED ENGINE ALIGNMENT IS NOT AFFECTED.

NOT USED ON ALL HELICOPTER MOUNTS.

REFER TO TEXT FOR ADJUSTMENT AND

30−084E

ENGINE ALIGNMENT CHECK.

Figure 10-5. Engine Mounts and Fittings

Page 10-17

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Upper Engine Mount Installation

corrosion. Magnetic−particle inspect

suspected engine mount assemblies. If

cracks are evident, the mount is

CAUTION

unserviceable.

D Do not tighten bolts until the engine at−

(5). Inspect flanges and bosses of engine

tach bolt is tightened.

mount fittings and lifting eye for

D Retorque the engine attach bolt after 3 to

flatness, cracks and corrosion. Replace

5 hours of flight if the engine mount will

defective fittings.

be attached to a previously unused mount

fitting.

(6). Inspect threaded steel insert for

damaged threads, corrosion and for full

NOTE: All engine mount fitting bolts, washers

bottoming to seat of insert hole.

and nuts are corrosion resistant steel.

D. Engine Mounts and Fittings Repair

(1). Place short end of upper engine mount

against oleo support fitting and long

No straightening or weld repair of the engine

end against firewall attach fitting.

mounts is authorized. Thread damage to either

Install bolt, two washers and new nut

upper engine mount, at the engine attach

to fasten mount to structure.

point, can be repaired by re−drilling the hole

(2). Install bolt and washer that attach

up to a maximum diameter of 0.3170 inch

mount to fitting on engine. Torque bolt

(8.0518 mm), provided that re−drilling does

to 100 − 140 inch−pounds (11.30 −

not permit engine−to−main transmission drive

15.82 Nm).

shaft misalignment and resulting clutch or

main transmission to drive shaft coupling gaps

(3). Torque upper mount fitting and oleo

in excess of that specified in Section 9.

support nuts to 30 − 40 inch−pounds

Otherwise, replace defective mounts and

(3.39 − 4.52 Nm) plus drag torque.

fittings.

(4). Remove engine hoist and reinstall the

NOTE: Re− drilling (opening) the hole on one

compressor air duct support bracket in

mount usually will not cause misalignment

the overhead hoist fitting.

beyond permitted tolerance. However, if

both mounts are reworked, engine to drive

(5). Reinstall engine oil pressure sender

shaft alignment must be checked.

clamps (if used) and engine harness

clamp on right engine mount.

E. Engine-to-T ransmission Alignment

Check

C. Engine Mounts and Fittings Inspection

(Ref. Figure 10−6) Adjustable upper left and

(1). Inspect all engine mount assemblies for

right engine mounts should normally not be

good condition of painted surface.

disassembled except for spares replacement or

magniflux inspection. In this event, a realign−

(2). Inspect all engine mount tubes for

ment check of the engine is required. Realign−

straightness. Hold a steel straight−edge

ment of the engine is also required if adjust−

against the surface of tubes to reveal

able mounts are interchanged between

any warps or bends in the tubes.

helicopters.

(3). Check that jam nuts and lockwire on

mounts with adjustable fittings are

(1). If only one adjustable upper mount is

secure and have not been disturbed. If

replaced or readjusted, check and

not secure or adjustment has been

readjust engine−to−transmission

disturbed, a check of engine−to−trans−

alignment using engine−to−transmis−

mission alignment is required.

sion aligning tool 369A50000−40101

according to instructions in CSP−H−6.

(4). Visually inspect all the tubes and

Following adjustment, proceed with

welded joints for cracks and evidence of

steps (3). and (4).

Page 10-18

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

0.032 IN. (8.128 MM) CRES

LOCKWIRE (BOTH LEGS)

UPPER ENGINE MOUNT

SLIPPAGE MARK

(RIGHT−HAND THREAD)

(BOTH LEGS)

JAM NUT

SCREW FITTING

JAM NUT

CAUTION:

DO NOT RE−ADJUST OR DISASSEMBLE UPPER ENGINE

UPPER END FITTING

(LEFT−HAND THREAD)

MOUNTS UNLESS AN ENGINE−TO−TRANSMISSION

ALIGNMENT CHECK IS PERFORMED FOLLOWING ANY

ADJUSTMENT.

30−213A

Figure 10-6. Adjustable Engine Mounts

(2). If both adjustable upper engine mounts

The oil cooler blower is belt−driven on the

are replaced or readjusted, install

current configuration helicopter and shaft−

engine and tailboom check fixture

driven on the early configuration.

369A9900−80906 (Ref. CSP−H−6) and

adjust mounts as required. Following

Air enters the ram air scoops, flows into the

adjustment proceed with steps (3). and

transmission cover around the transmission

(4).

and through ducts to the oil cooler blower. The

transmission cover is equipped with special

(3). Adjust mount(s) to bring engine into

baffles on helicopters with a 250−C20 engine.

alignment with transmission; then

tighten jam nuts and recheck align−

ment.

Air from the oil cooler blower is directed to and

through the engine oil cooler by the oil cooler

(4). Secure jam nuts with 0.032 inch

duct and into the engine compartment. The oil

(0.8128 mm) lockwire; then paint a

cooler blower also supplies a constant air flow

slippage mark across both jam nuts at

through the engine gearcase and compressor

each mount leg.

cooling ducts into the lower and upper areas of

the engine compartment.

11. Engine Cooling System

Two duct outlets direct the air upon the engine

(Ref. Figure 10−7) The engine cooling system

gearcase and the compressor section. Engine

consists of two ram air scoops integral with the

differences require variations in air flow

air inlet fairing, an oil cooler blower driven by

direction. All cooling air then exhausts from

the main transmission input gear shaft, an oil

the engine compartment through a gap

cooler duct and engine gearcase and compres−

provided around and between the exhaust

sor cooling ducts.

pipes and the engine access doors.

Page 10-19

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

A. Engine Cooling System Inspection

A. Engine Shaft Firewall Seal Replacement

(1). Remove engine.

Visually inspect for general condition, security

of clamps and for fraying or tears in the

(2). Remove three bolts, six washers and

flexible tubing.

three nuts that attach engine shaft

firewall seal to overrunning clutch.

B. Cooling System Repair or Replacement

(3). Position replacement engine shaft

firewall seal assembly on flange of

Repair damaged hose with tape (32,

clutch and secure with attaching

Table 2−4). Remove attaching clamps to

remove hose. Install clamps on each end of

hardware.

replacement hose; position hose and tighten

B. Engine Shaft Firewall Seal Inspection

clamps.

Inspect the firewall seal and backing for

cracks, breaks, corrosion or other damage that

12. Engine Shaft Firewall Seal

would prevent complete sealing of the firewall

opening.

(Ref. Figure 10−1 or Figure 10−2) The engine

shaft firewall seal assembly consists of a

C. Engine Shaft Firewall Seal Repair

stamped steel backing and a seal that is

bonded to the cupped diameter of the backing.

Replace engine shaft firewall seal by bonding

A slightly larger seal is used on helicopters

new seal to backing with adhesive (19,

equipped with the 250−C20 engine.

Table 2−4).

Page 10-20

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SCREW, WASHERS AND NUT

(5 OR 6 PLCS)

DUCT COUPLING

CLAMP

RESTRICTOR

(NOTE 1)

STA. 124.00 CANTED

FIREWALL

CLAMP

STA. 124.00 CANTED

FIREWALL

DUCT COUPLING

CLAMP

ENGINE HOISTING

EYEBOLT

FWD

STA. 124.00

CLAMP

CLIP

SUPPORT BRACKET

DUCT SUPPORT RING

(INSIDE DUCT) CLAMP

CHANNEL ASSY

GASKET

(NOTE 3)

SCREW, WASHER AND NUT

COOL AIR

(5 PLCS)

MANIFOLD DUCT

BLOWER SECONDARY

OUTLET

NOTE 4

FIREWALL BULKHEAD

STA. 124.00

DUCT SUPPORT RING (INSIDE

DUCT), BOLT, CLAMP,

CLAMP OR O−RING

0.250 IN. (6.35 MM) SPACER ( * ),

0.28125 IN. (7.14375 MM) SPACER,

WASHER AND NUT

DUCT CONNECTOR

NOTES: (CONT)

BOND TO STRUCTURE WITH ADHESIVE

(19, TABLE 2−4) ACCORDING TO

CONTAINER INSTRUCTIONS.

ADJUST AT 45 DEGREES FOR 250−C18 ENGINE

AND 30 DEGREES FOR 250−C20 ENGINE.

30−083−2E

Figure

10-7. Engine Cooling (Sheet 1 of 2)

Page 10-22

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 11 Engine Control System .

11−1

Power Control System

11−1

Power Controls Troubleshooting

11−1

Table 11−1. Power Controls Troubleshooting

11−1

Figure 11−1. Engine Power Controls System

11−2

Power Control System Rigging

11−3

A. Bendix Gas Producer Controls Rigging

11−3

Figure 11−2. Bendix Gas Producer Controls Rigging

11−4

Figure 11−3. Bendix Gas Procedure Fuel Control Adjustments .

11−5

B. CECO Gas Producer Fuel Control Rigging

11−6

Figure 11−4. CECO Gas Producer Control Rigging

11−7

Figure 11−5. Gas Producer Fuel Control Adjustment CECO .

11−8

C. Power Turbine Governor Controls Rigging (Bendix or CECO) .

11−9

Figure 11−6. Bendix Power Turbine Governor Controls Rigging (Sheet 1 of 2) .

11−10

Figure 11−7. CECO Power Turbine Governor Controls Rigging .

11−12

Gas Producer Controls

11−15

A. Gas Producer Linkage Replacement

11−15

B. Gas Producer Control Linkage Inspection

11−16

Figure 11−8. Gas Producer Control Linkage Disassembly .

11−17

C. Gas Producer Control Linkage Repair

11−18

D. Gas Producer Throttle Linkage

11−18

Power Turbine Governor Controls

11−18

A. Power Turbine Governor Linkage Replacement

11−18

Figure 11−9. Governor Control Linkage Disassembly (Forward of Engine

Compartment)

11−19

Figure 11−10. Governor Control Linkage Disassembly (Engine Compartment) .

11−20

B. Governor Control Linkage Inspection

11−21

C. Governor Control Rods and Bellcranks Repair

11−21

D. Relocation of Locknut and Installation of Spacer

11−22

E. Droop Control Override Link Assembly Repair

11−22

Figure 11−11. Relocation of Locknut − Sta. 68.00 Bellcrank Assembly .

11−23

RPM Governor (N2) Trim Actuator

11−24

A. N2 Trim Actuator Replacement

11−24

B. N2 Trim Actuator Repair

11−24

C. N2 Trim Actuator Testing

11−24

Figure 11−12. N2 Trim Actuator Test hookup

11−24

Anti−Icing System

11−25

Page 11−i

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

Anti−Icing System Troubleshooting

11−25

Table 11−2. Anti−Icing System Troubleshooting

11−25

Anti−Icing Controls (Electrically Operated System)

11−26

A. Anti−Icing Controls Operational Check (Electrically Operated0

11−26

B. Electrically Operated Anti−Icing Valve Rigging

11−26

C. Anti−Icing Valve Actuator and Linkage Replacement

11−26

Figure 11−13. Engine Anti−Icing Valve Electrically Actuated Equipment .

11−27

10. Anti−Icing Valve Control Cable (Manually Operated)

11−28

A. Anti−Icing Valve Control Operational Check (Manually Operated) .

11−29

B. Anti−Icing Valve Control Cable Inspection (Manually Operated) .

11−29

C. Anti−Icing Valve Control Cable Replacement (Manually Operated) .

11−29

Figure 11−14. Engine Anti−Icing Valve Manual Control Installation .

11−30

D. Anti−Icing Control Cable Repair (Manually Operated) .

11−31

Page 11−ii

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 11

ENGINE CONTROL SYSTEM

1. Power Control System

engine operation and maintenance manual for

fuel system theory of operation and other

detailed information.

(Ref. Figure 11−1) The power controls system

consists of the gas producer (N₁) controls and

NOTE: The Bendix system may be used on

the power turbine (N₂) governor controls. The

250−C18 Series engines converted to

mechanically operated gas producer controls

250− C20 configuration provided that Alli−

actuate the gas producer control lever that

son Commercial Engine Bulletin 250

schedules the quantity of fuel metered to the

CEB−126 and 250−C20 Installation Bulle−

engine. The electrically operated trim actuator

tin 1005 are complied with, and provided

and the mechanically operated droop compen−

that only the special ignition exciter Allison

PN 6870885 (GLA PN 43754) is used if auto−

sator change the position of the power turbine

matic reignition equipment is installed. Re−

governor control lever that regulates the

fer to CSP−H−3 for information on auto−re−

operating rpm of the engine. Bendix fuel

ignition equipment and the Model 250−C18

control system components are standard on

to 250−C20 engine conversion.

Allison 250−C18 engines and may also be

installed on the 250−C20 engine. Current

configuration helicopters equipped with the

2. Power Controls Troubleshooting

250−C20 engine use Chandler Evans (CECO)

fuel control system components. Refer to the

(Ref. Table 11−1)

Table 11-1. Power Controls Troubleshooting

Symptom

Probable Trouble

Corrective Action

Movement of control results in

Lost motion in linkage; gas

Tighten pipe plugs in torque tube for

springy feeling; response lags

producer interconnect torque tube

zero backlash (Ref. Sec. 7).

behind control movement

loose in collective stick gearshafts

Worn rod ends; worn bellcrank

Replace worn parts.

bearings

Control action stiff

Rod ends binding in fitting

Realign rod end bearings to

eliminate jamming.

Low power; improper idling speed;

Incorrectly adjusted gas producer

Adjust gas producer or power turbine

improper acceleration; variable

or power turbine governor controls

governor controls for correct

power output at constant setting

operation.

Defective gas producer control

Replace faulty unit (Ref. Engine

assembly or power turbine

Operation and Maintenance Manual).

governor

Stagnated or hot engine starts

Fuel control derichment

Adjust derichment valve (BENDIX).

misadjusted (BENDIX)

Fuel control light off and start

Adjust variable start and derichment

derichment controls misadjusted

control (CECO).

(CECO)

Excessive TOT readings during

Incorrectly adjusted engine power

Adjust engine power controls for

engine shutdown

controls

correct operation.

Page 11-1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

GOVERNOR LEVER

CONTROL ROD

N2 CONTROL

IDLER BELLCRANK

RPM GOVERNOR CONTROL

GAS PRODUCER INTERCONNECT

N2 IDLER BELLCRANK

IDLER SUPPORT

TORQUE TUBE

CONTROL ROD

THROTTLE AND GAS

STA 124 CONTROL SUPPORT

PRODUCER TUBE

FUSELAGE−ROUTED CONTROL ROD

STA 124 BELLCRANK

(POWER TURBINE GOVERNOR)

N2 TRIM

GAS PRODUCER LEVER

INBD COLLECTIVE STICK

SWITCH

CONTROL ROD

SOCKET ASSY

STA 129 BELLCRANK

GAS PRODUCER CON−

TROL SUPPORT

FIRE SCREEN

(2 PLCS)

DROOP CONTROL

OVERRIDE LINK

FUSELAGE−ROUTED CON−

TROL ROD

(GAS PRODUCER)

STA 73 GAS PRODUCER

CONTROL ROD

SPACER (TYP 10 PLCS)

STA 70 BELLCRANK

STA 68 BELLCRANK

STA 72 BELLCRANK

N2 TRIM ACTUATOR

30−085

Figure 11-1. Engine Power Controls System

Page 11-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3. Power Control System Rigging

When repositioning the gas pro−

CAUTION

ducer lever in d below, do not ex−

ceed the lever nut torque limit of 40 − 50

Rigging of the engine power controls system

inch−pounds (4.52 − 5.65 Nm). Overtorqu−

must be accomplished:

ing will cause binding of the lever.

(1). Immediately after replacement of

(4). With the engine compartment gas

linkage that cannot be accurately

producer control rod length set to 16.56

measured (by trammeling, etc.) before it

inches (420.624 mm), re−establish the

is installed in either the gas producer

gas producer lever mid−position so that

control system or the power governor

lever centerline is half way between the

control system; or

‘‘closed" and ‘‘maximum" travel stops;

lever serrations have 15 degree spacing.

(The ‘‘closed" stop position is parallel to

(2). If engine operation reveals a rigging

the engine compartment door frame

deficiency.

within ±5 degrees.)

When tightening a jam nut to

If any interference exists at the

CAUTION

secure a control end, always

gas producer lever, check that

hold the rod end with a wrench to prevent

the correct lever is installed.

jamming of the bearing against the fitting.

Check that all misalignment is divided

(5). Lower collective stick to full down.

equally between bearings of each control rod

(6). Rotate pilot’s throttle counterclockwise

assembly.

to maximum rpm, then clockwise to

idle.

A. Bendix Gas Producer Controls Rigging

(7). With pilot’s throttle held at idle, adjust

upper rod end of gas producer lever rod

(Ref. Figure 11−2) The following rigging

until gas producer pointer is positioned

instructions apply to all 250−C18 engines and

at 30−31 degrees on quadrant (detail

250−C20 engines with a Bendix fuel control

A). Mark pointer position on quadrant

system.

with grease pencil.

NOTE: Adjustment steps (1). thru (4). of this

Do not alter gas producer lever

CAUTION

procedure are necessary only when the pi−

position or control linkage to ad−

lot’s compartment linkage or the fuselage−

just idle speed. Idle speed will be checked

routed control rod have been removed and

during flight test and, if necessary, adjusted

reinstalled or replaced, or if there is insuffi−

by the fuel control idle screw, not by the

cient clearance between the lower firewall

linkage. Check extreme travel position of

bellcrank and its support. Otherwise, per−

the linkage to ensure that gas producer le−

form adjustment of gas producer controls

ver hits the fuel control stops before the

starting with step (5).

throttle grip stops make contact. There

must be no interference or binding in the

linkage. Ensure linkage clears engine tub−

(1). Position the collective stick and throttle

ing.

at mid−travel.

(8). Rotate pilot’s throttle counterclockwise

(2). Adjust the length of the Sta. 73 control

to maximum rpm.

rod so that the long arm of Sta. 70

bellcrank is vertical.

(9). Observe gas producer lever to ensure it

strikes the maximum travel stop.

(3). Adjust the length of the fuselage−

(10). Raise collective stick to full up.

routed gas producer control rod so that

the bolt center in the lower arm of Sta.

(11). If gas producer lever does not strike

129 bellcrank is 5.00 ±0.03 inch (127

maximum travel stop, check gas

±0.762 mm) from the firewall.

producer controls for binding.

Page 11-3

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

40−50 IN. LB

(4.52−5.65 NM) MAX.

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

CONTROL

DIMENSION L

ANGLE

ASSY PART

GAS PRODUCER

ROD ASSY

IN. (CM)

NUMBER

LEVER

FWD

FUSELAGE−ROUTED

58.67

(149.0218)

IN LINE

369A7008−5

STA. 73

7.11

(18.0594)

IN LINE

369A7334

GAS PRODUCER LEVER

16.56

(42.0624)

IN LINE

369A7705−5

L OF CON−

LEVER CONTROL

TROL ROD

ROD

0.040 IN. (1.016 MM) MAX. AL−

LOWABLE AXIAL PLAY

MS20470AD RIVET

LEVER POSITION

NOTE 2

QUADRANT

GAS PRODUCER LEVER CENTERLINE

SHOULD BE HALF−WAY BETWEEN

CLOSED AND MAXIMUM TRAVEL STOPS

(NOTE 1)

GAS PRODUCER CON−

GAS PRODUCER LE−

TROL SUPPORT

VER CONTROL ROD

STA 74.87

(L OF COLLECTIVE

STA 129 BELL−

PITCH TORQUE TUBE)

CRANK

VERTICAL CENTERLINES

SHOULD COINCIDE

(NOTE 1)

STA 73 CONTROL ROD

5 IN. (12.7 CM)

STA 124

STA 70 BELL−

CRANK

FUSELAGE−ROUTED

CONTROL ROD

NOTES:

WITH COLLECTIVE STICK AND THROTTLE AT MID−TRAVEL.

NORMAL SETTING IS 30−31 DEGREES.

IF THROTTLE TUBE IN COLLECTIVE STICK NOT MODIFIED,

CENTERLINE SHOULD

SETTING IS 30−35 DEGREES.

BE VERTICAL

(NOTE 1)

30−086F

Figure 11-2. Bendix Gas Producer Controls Rigging

Page 11-4

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(12). Rotate pilot’s throttle fully clockwise to

speed stabilizes at 62−67 percent.

fuel off. Observe gas producer lever to

Adjust N₁ speed with the fuel control

ensure it strikes minimum travel stop

idle speed adjustment screw (Ref.

(closed position).

Figure 11−3).

(13). Lower collective stick to full down.

(17). If idle rpm does not stabilize within

Observe gas producer lever to ensure it

limits in step (16)., proceed with engine

does not move from the minimum travel

troubleshooting in engine operation and

stop.

maintenance manual.

(14). At the full closed and full open posi−

NOTE: Bendix gas producer fuel controls

tions of the throttle, check all the

equipped with a variable derichment valve

movable linkage for clearance with

may be adjusted to eliminate stagnated or

supporting or adjacent parts. Check

hot starts (Ref. Allison Operation and Main−

that control rod bearings are not

tenance Manual).

jammed when the linkage is in the

extreme control positions.

The following check must be

WARNING

made to ensure that engine

NOTE: Before operating an engine in 250−C20

shutdown will not occur due to throttle

configuration with a Bendix gas producer

chop. Refer to NOTE: after step (17).

fuel control, check that the maximum fuel

flow adjusting screw is fixed in position

(18). Rotate pilot’s throttle control counter−

shown in Figure 11−3.

clockwise to normal engine operating

rpm; then clockwise to idle in a manner

(15). Start and operate engine at idle with

simulating a pilot training throttle

main rotor blades in flat pitch according

chop. Repeat this check using the

to the Owner’s Manual.

copilot’s throttle if optional dual

(16). With pilot’s throttle at idle, observe N₁

controls are installed. If shutdown

tachometer indicator to ensure N₁

occurs, perform steps (19). and (20).

IDLE SPEED ADJUSTING SCREW

LOCKNUT

(NOTE 1)

MINIMUM SPEED

START DERICHMENT

STOP

ADJUSTING SCREW

LOCKNUT

DIAL

(NOTE 2)

CLAMP

MAXIMUM FLOW

ADJUSTING SCREW

SCRIBE LINE (TYP)

POINTER

(NOTE 2)

MAXIMUM SPEED

REFERENCE DOTS AT

STOP SCREW

FWD

10 DEGREE INTERVALS

REAR VIEW

SIDE VIEW

(AS INSTALLED)

NOTES:

TURN CLOCKWISE TO INCREASE, COUNTERCLOCKWISE TO DECREASE

N1 SPEED. ENGINE SPEED CHANGES APPROXIMATELY 5% PER 1/8 TURN

(USE ALLISON TOOL P/N 6798292.)

USED ONLY WITH 250−C20 ENGINE WITH BENDIX FUEL CONTROL. INDEX

LINE ON FACE OF DIAL TO ALIGN WITH SCRIBE MARK ON SIDE OF DRIVE BODY.

30−155B

Figure 11-3. Bendix Gas Procedure Fuel Control Adjustments

Page 11-5

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(19). Adjust upper rod end of gas producer

129 bellcrank is 5.00 ±0.03 inch (127

lever rod to increase rod length by one

±0.762 mm) from the firewall.

or two rod turns to obtain slightly

higher setting (31 degrees maximum)

(4). Set gas producer lever control rod

on lever position quadrant. Be sure

length to 16.56 inches (420.624 mm).

maximum control rod length is not

When reinstalling control lever

exceeded by checking at the control rod

CAUTION

on fuel control shaft in next

witness hole.

step, do not exceed nut torque of 40 − 50

inch−pounds (4.52 − 5.65 Nm). Overtorqu−

(20). Repeat procedures in (5). thru (19).

ing will cause binding of the lever.

until engine shutdown does not occur

from a throttle chop.

(5). Remove control lever from gas producer

fuel control, rotate quadrant pointer to

NOTE: After rigging and testing of Bendix or

0° and then reinstall control lever so

CECO gas producer controls, perform a de−

that it is approximately parallel to

celeration check in accordance with proce−

engine compartment door frame.

dures found in the pilot’s flight manual, If

confirmed deceleration time is less than the

NOTE: Control lever serrations have a 15°

allowable minimum, refer to the applicable

spacing.

Allison Operation and Maintenance Manu−

al.

(6). Rotate pilot’s throttle to cutoff position

and connect gas producer rod to control

B. CECO Gas Producer Fuel Control Rigging

lever.

(Ref. Figure 11−4) The following rigging

If any interference exists at the

CAUTION

instructions apply to 250−C20 engines with a

gas producer lever, check that

CECO fuel control system.

the correctlever is installed.

(7). Rotate pilot’s throttle to fully open

NOTE: For all new fuel control unit installa−

position and check that fuel control

tions, check that the maximum fuel flow

quadrant pointer is on 90° and that

stop adjustment screw (Figure 11−5) is set

maximum stop on fuel control is

at the minus (−) mark, 235 PPH (107 kgPH).

contacted before throttle grip stop is

Use a 3/32 inch Allen wrench to reset the

contacted.

screw if required.

(8). Rotate pilot’s throttle to idle position

NOTE: Adjustment steps (1). thru (4). of this

and check that fuel control pointer is at

procedure are necessary only when the pi−

the 30° mark and that rigging pin holes

lot’s compartment linkage or the fuselage−

are aligned. Make small adjustments in

routed control rod have been removed and

length of gas producer control rod, at

reinstalled or replaced, or if there is insuffi−

the control lever end, if required.

cient clearance between the lower firewall

bellcrank and its support. Otherwise, per−

NOTE: The maximum allowable rigging error

form adjustment of gas producer controls

at idle position (pointer position not at 30°)

starting with step (5).

is 0.078 inch (1.984 mm) below the 30°

mark. However, the higher setting (30°) is

(1). Position the collective stick and throttle

required to prevent inadvertent over− con−

at midtravel.

trol and shutdown when dual controls are

installed.

(2). Adjust the length of the Sta. 73 control

rod (Figure 11−4) so that the long arm

(9). Rotate pilot’s throttle to cutoff position

of Sta. 70 bellcrank is vertical.

and check that quadrant pointer is at 0°

to minus 2° and that stop is in contact.

(3). Adjust the length of the fuselage−

The minimum stop on the fuel control

routed gas producer control rod so that

should be in contact before the throttle

the bolt center in the lower arm of Sta.

grip stop is contacted.

Page 11-6

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

CONTROL

DIMENSION L

ANGLE

ASSY PART

ROD ASSY

IN. (CM)

NUMBER

FUSELAGE−ROUTED

58.67

(149.0218)

IN LINE

369A7008−5

STA. 73

7.11

(18.0594)

IN LINE

369A7334

GAS PRODUCER LEVER

16.56

(42.0624)

IN LINE

369A7705−5

0.040 IN. (1.016 MM) MAX.

ALLOWABLE AXIAL PLAY

MS20470AD RIVET

CONTROL LEVER

(NOTES 2, 3)

CECO FUEL CONTROL

NOTES:

WITH COLLECTIVE STICK AND THROTTLE AT MID−TRAVEL.

GAS PRODUCER

LVER SRRATIONS HAVE 15 DEGREE SPACING.

GAS PRODUCER

CONTROL SUPPORT

INSTALL LEVER ON FUEL CONTROL SHAFT WITH POINTER

LEVER CONTROL ROD

AT 0° MARK ON QUADRANT AND WITH LEVER PARRALLEL

TO ENGINE COMPARTMENT DOOR FRAME.

STA 129

BELLCRANK

STA 74.87

(L OF COLLECTIVE

PITCH TORQUE TUBE)

VERTICAL CENTERLINES

SHOULD COINCIDE

(NOTE 1)

5 IN. (12.7 CM)

STA 73 CONTROL ROD

STA 124

IDLE

POSITION

CECO FUEL CONTROL

0.078125 IN. (1.984375 MM)

STA 70

MAX. ALLOWABLE POSITION

QUADRANT

BELLCRANK

ERROR FROM ALL CAUSES

FUSELAGE−ROUTED

TORQUE NUT TO

CONTROL ROD

40−50 IN. LB

POINTER

(NOTE 3)

(4.52−5.65 NM)

RIGGING PIN

PROVISIONS

CENTERLINE SHOULD

BE VERTICAL

(NOTE 1)

30−21 1A

Figure 11-4. CECO Gas Producer Control Rigging

Page 11-7

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

The minus 2° pointer position is

The following check must be

CAUTION

WARNING

desired for positive fuel cut−off.

made to ensure that engine

One−half turn on the minimum stop screw

shutdown will not occur due to throttle

equals 2° of pointer travel.

chop.

(10).

Rotate pilot’s throttle to fully open

(19). Rotate pilot’s throttle control counter−

position and check that fuel control

clockwise to normal engine operating

pointer is at 90° and in contact with the

rpm; then clockwise to idle in a manner

maximum stop.

simulating a pilot’s training throttle

(11).

Raise collective stick to full up position

chop. If optional dual controls are

and check that fuel control pointer

installed, repeat this check using the

remains in contact with the maximum

copilot’s throttle. If shutdown occurs

stop.

perform steps (20). and (21).

(12).

Rotate pilot’s throttle to cutoff position

(20). Recheck rigging and adjust rod length

and check that fuel control pointer

at upper rod end of gas producer lever

contacts the minimum stop.

rod, as required, until neither the pilot’s

(13).

Lower the collective stick to full down

or copilot’s throttle will move quadrant

position and check that fuel control

pointer below 30° at idle. Be sure

pointer remains on the minimum stop.

maximum control rod length is not

(14).

Recheck idle position rigging by

exceeded by checking at the control rod

rotating pilot’s throttle from cutoff

witness hole.

position to idle and from full open

position to idle. The fuel control pointer

(21). Recheck engine operation to determine

should indicate 30° with rigging pin

that shutdown does not occur at

holes aligned in both cases.

throttle chop, using both the pilot’s and

copilot’s throttles.

(15).

While operating the throttle through its

complete range, check all movable

C. Power Turbine Governor Controls

linkage for clearance from supporting

Rigging (Bendix or CECO)

and adjacent parts and check that

control rod bearings are not jammed at

Before rigging the power turbine governor

extremes of travel.

controls, determine the type governor installed

(16).

Start and operate engine at idle with

(either BENDIX or CECO).

main rotor blades in flat pitch according

to the Owner’s Manual.

(Ref. Figure 11−6 for the BENDIX installation.

(17).

With pilot’s throttle at idle, observe N₁

(Ref. Figure 11−7 for the CECO installation.

tachometer indicator to ensure N_l speed

stabilizes at 61−65 percent. Adjust N₁

speed with the fuel control idle speed

(1). Bendix Rigging Adjustments:

adjustment screw (Figure 11−5) using

5/16 inch Allen wrench. A 1/8 turn

NOTE: Adjustment steps (a). thru (d). of this

equals approximately 1% N₁. Turn the

procedure are necessary only when: the un−

screw clockwise to increase N₁ idle

derseat linkage or the fuselage−routed con−

speed.

trol rod has been removed and reinstalled or

replaced; or with Bendix governors prior to

(18).

If idle rpm does not stabilize within

Allison PN 6873450 installed, if there is less

limits in step (17)., proceed with engine

than 0.030 inch (0.762 mm) clearance be−

troubleshooting in engine operation and

tween the lower firewall bellcrank and its

maintenance manual.

support when the governor lever is at the

NOTE: The CECO fuel control is equipped with

maximum stop. (If governor nameplate does

lightoff and start derichment controls which

not have an Allison part number, the gover−

may be adjusted to eliminate stagnated or

nor is prior to PN 6873450.) Otherwise, per−

hot starts. (Ref. Allison Operation and

form adjustment of power turbine governor

Maintenance Manual)

controls starting with step (e).

Page 11-9

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

CONTROL

DIMENSION L

ANGLE

ASSY PART

NOTES:

ROD ASSY

IN. (CM)

NUMBER

INITIAL DIMENSION: SHORTEN TO INCR

FUSELAGE−ROUTED

56.13

(142.5702)

IN LINE

369A7008−3

COMPENSATION. LENGTHEN TO DECREASE.

N2 IDLER BELLCRANK

14.38

(36.5252)

90°

369A7705

DROOP CONTROL OVERRIDE LINK SPRING

GOVERNOR LEVER

3.94

(10.0076)

90°

369A7706

STARTS TO COMPRESS, GOV LEVER AT

APPROX. 78° AND STA 124.00 BELLCRANK

BOTTOMED.

0.040 IN. (1.016 MM) MAX. AL−

MS20470AD3

LOWABLE AXIAL PLAY

RIVET

GOVERNOR LEVER

CONTROL ROD

CONTROL IDLER

SUPPORT

COLLECTIVE TORQUE TUBE

IDLER BELLCRANK

CONTROL ROD

DROOP COMPENSATION

ADJUSTMENT FORK

DROOP CONTROL

OVERRIDE LINK

STRUCTURE RIB

STA 124.00

(REF)

N₂ TRIM

ACTUATOR

1.60 IN. (4.064 CM)

STA 68.00 BELLCRANK

(NOTE 1)

3.63 IN.

STA 124.00 BELLCRANK

(NOTE 2)

STA 124.00 CONTROL

SUPPORT

FUSELAGE−ROUTED

STA 72.00

CONTROL ROD

BELLCRANK

30−087−1B

Figure 11-6. Bendix Power Turbine Governor Controls Rigging (Sheet 1 of 2)

Page 11-10

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

RIGGING BENDIX GOVERNOR (PRIOR TO ALLISON PN 6873450)

FWD

TRIM ACTUATOR RETRACTED

TO MINIMUM N₂, COLLECTIVE

PARALLEL TO

NOTE 8

STICK DOWN

ENGINE

MINIMUM N₂ STOP

(UNUSED)

GOVERNOR LEVER CONTROL ROD

ADJUSTED TO POSITION LEVER 80°

(UNUSED TRAVEL)

FROM MINIMUM STOP (NOTE 3)

MAXIMUM N₂ STOP

40−50 IN. LB

(NOTE 7)

(4.52−5.65 NM) MAX.

GOVERNOR LEVER

GOVERNOR POINTER

(NOTE 5)

(NOTE 4)

RIGGING BENDIX GOVERNOR (ALLISON PN 6873450 OR LATER)

NOTE 8

TRIM ACTUATOR RETRACTED

GOVERNOR LEVER CONTROL ROD ADJUSTED

TO MINIMUM N₂, COLLECTIVE

TO POSITION LEVER 68° FROM MINIMUM STOP

STICK DOWN

(NOTE 3)

MINIMUM N₂ STOP

(UNUSED)

(UNUSED TRAVEL)

MAXIMUM N₂ STOP RANGE

(NOTE 7)

GOVERNOR LEVER

GOVERNOR POINTER

(NOTE 5)

(NOTE 6)

40−50 IN. LB

(4.52−5.65 NM) MAX.

MAXIMUM SPEED

POSITION

ONE SERRATION 15°

NOTES: (CONT)

WITH TRIM ACTUATOR EXTENDED TO MAXIMUM N₂, COLLECTIVE STICK DOWN.

POINTER SHOULD ALIGN WITH GOVERNOR LEVER CENTERLINE.

LEVER SERRATIONS HAVE 15° SPACING.

WITH POINTER ONE SERRATION CLOCKWISE (AWAY FROM ENGINE) FROM LEVER

CENTERLINE, TIP SHOULD ALIGN BETWEEN LETTERS P & E OF WORD SPEED.

DROOP CONTROL OVERRIDE LINK SPRING STARTS TO COMPRESS, ARM IS NOT

REQUIRED TO HIT MAXIMUM STOP WITH FULL COLLECTIVE AND ACTUATOR EXTENDED.

TRAVEL LIMIT OF TRIM ACTUATOR IS 32°.

30−087−2D

Figure 11-6. Bendix Power Turbine Governor Controls Rigging (Sheet 2 of 2)

Page 11-1 1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

INITIAL ROD ASSY LENGTH AND BEARING ANGULARITY (BEFORE RIG)

NOTES:

CONTROL

DIMENSION L

ANGLE

ASSY PART

INITIAL DIMENSION: SHORTEN TO INCREASE

ROD ASSY

IN. (CM)

NUMBER

COMPENSATION, LENGTHEN TO DECREASE.

FUSELAGE−ROUTED

56.13

(142.5702)

IN LINE

369A7008−3

WITH PILOT’S COLLECTIVE STICK AT FULL DOWN

N2 IDLER BELLCRANK

14.28

(36.2712)

90°

369A7705

AND N₂ TRIM ACTUATOR AT FULL INCREASE.

GOVERNOR LEVER

4.15

(10.541)

90°

369A7706

0.040 IN. (1.016 MM) MAX. AL−

MS20470AD3

LOWABLE AXIAL PLAY

RIVET

GOVERNOR LEVER

CONTROL ROD

CONTROL LEVER

CONTROL IDLER

SUPPORT

MAX

MIN

STOP

CECO GOVERNOR

QUADRANT

POINTER

IDLER BELLCRANK

PARTING LINE OF

IDLER BELLCRANK

GOVERNOR OUTER

CONTROL ROD

COVER PARALLEL

COLLECTIVE

TO LEVER

TORQUE TUBE

DROOP COMPENSATION

ADJUSTMENT FORK

369A7717−3

DROOP CONTROL

OVERRIDE LINK

STRUCTURE

RIB

STA 124.00

N₂ TRIM

ACTUATOR

2.30 IN. (5.842 CM)

3.60 IN.

STA 124.00 BELLCRANK

(NOTE 1)

STA 68.00 BELLCRANK

(NOTE 2)

STA 124.00 CONTROL

SUPPORT

FUSELAGE−ROUTED

STA 72.00

CONTROL ROD

BELLCRANK

30−212B

Figure 11-7. CECO Power Turbine Governor Controls Rigging

Page 11-12

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(a).

Check that droop control override

NOTE: Do not exceed the lever nut torque limit

link total end play does not exceed

of 40 − 50 inch−pounds (4.52 − 5.65 Nm) or

0.015 inch (0.381 mm).

the lever will bind.

NOTE: The pointer−to−lever positions specified

(b).

Check that the correct droop com−

above are standard production settings. Oc−

pensation adjustment fork is

casionally, slight variation in pointer−to−le−

installed. Fork must measure

ver position may be required to obtain prop−

2.50−2.75 inches (63.50−69.85 mm)

er travel and satisfactory engine operation.

from center of link hole to end of

Such variation is acceptable provided all

threaded shaft. Adjusted so that the

other rigging and engine performance re−

installed dimension between the

quirements are met. Governor lever travel

centerlines of the Sta. 68 bellcrank

produced by trim actuator operation, from

pivot bolt and the fork bolt is 1.60

forward travel point (trim actuator re−

±0.03 inches (40.64 ±0.762 mm).

tracted, collective stick down) to the aft

travel point (trim actuator extended − col−

(c).

Connect and turn on external power.

lective stick down), is 32°. Approximately

Check that the N₂ trim actuator is

48° degrees of governor lever travel from the

adjusted so that the dimension

minimum N₂ stop is unused on governors

between attach bolt centers is 5.47

prior to Allison PN 6873450; 36 degrees is

±0.03 inches (138.938 ±0.762 mm)

unused on governors with Allison PN

with actuator at maximum extension.

6873450 or later.

(d).

With the pilot’s collective stick full

(g). Adjust governor lever control rod

down and the N₂ trim actuator at

length until the governor pointer is

maximum extension, adjust the

at the center of the letter D in the

length of the fuselage−routed gover−

word SPEED embossed on the power

nor control rod so that the bolt center

turbine governor (detail A) or be−

in the lower arm of Sta. 124 bell−

tween the letters P and E in the word

crank is 3.63 ±0.03 inches (92.202

SPEED (detail B), as applicable.

±0.762 mm) from the firewall.

(h). Raise the pilot’s collective stick

(e).

Check that the engine compartment

approximately one−third to one−half

N₂ idler bellcrank control rod length

of full up travel and note the follow−

is set to 14.38 ±0.03 inches (365.252

ing with the N₂ trim actuator fully

±0.762 mm).

extended:

(f).

Check position of governor lever and

1). With governor shown in detail A

pointer.

installed, the governor lever may

shift to the maximum travel stop.

1). On Bendix governors prior to

NOTE: As the stick is raised above this position

Allison PN 6873450, the lever

and until it reaches full up travel the droop

pointer should align with the lever

control override spring compression contin−

centerline (detail A).

ues to increase.

2). On Bendix governors with Allison

2). With governor shown in detail B

PN 6873450 or later, the lever

installed, check that the governor

pointer should be positioned one

lever shifts to between the E and D

serration clockwise (away from

in the word SPEED before the

engine) from lever centerline

linkage (lower arm of Sta. 124

(detail B).

bellcrank) bottoms out.

3). Reposition lever and pointer, if

(i). Lower collective stick to full down

necessary, starting with both the

and decrease N₂ trim to minimum.

lever and governor shaft at the

Check that the governor lever shifts

minimum stop; lever serrations

back to approximately over the N of

have 15 degree spacing.

N₂ embossed on the governor.

Page 11-13

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

If any interference exists at the

(h). Install governor lever control rod and

CAUTION

governor lever, check that the

check rigging as indicated by gover−

correct lever is installed.

nor quadrant and pointer.

(2). CECO Rigging Adjustments:

1). With pilot’s collective stick full

down and with full increase trim,

(a).

Check that droop control override

read 75° ±2°. Operate N₂ trim to

Link total end play does not exceed

full decrease and read 45° ±2°.

0.015 inch (0.381 mm).

2). With pilot’s collective stick full up

(b).

Check that correct droop compensa−

and with full decrease trim read

tion adjustment fork is installed.

64° ±2°. Operate N₂ trim to full

Fork must measure 3.00 inches (76.2

increase and read 90° (quadrant

mm) from center of the link hole to

contacting maximum stop screw).

end of threaded shaft. Adjusted so

that the installed dimension between

NOTE: Use a mirror to view quadrant and

the centerlines of the Sta. 68 bell−

pointer squarely when taking readings.

crank pivot bolt and the fork bolts is

2.30 ±0.02 inches (58.42 ±0.508 mm).

(i). Adjust length of governor lever

control rod as required to achieve

(c).

Connect and turn on external power.

travel within the limits of steps (h).

Check that the N₂ trim actuator is

1). and 2).

adjusted so that the dimension

between attach bolt centers is 5.47

If any interference exists at the

CAUTION

±0.02 inches (138.938 ±0.508 mm)

governor lever, check that the

with actuator at maximum extension.

correct lever is installed.

(d).

With the pilot’s collective stick full

(3). Final Check and Adjustment (Bendix or

down and the N₂ trim actuator at

CECO):

maximum extension, adjust the

length of the fuselage−routed gover−

(a).

At the full up and full down positions

nor control rod so that the bolt center

of the collective stick, check all

in the lower arm of Sta. 124 bell−

movable linkage for clearance with

crank is 3.60 ±0.02 inches (91.44

supporting or adjacent parts. Check

±0.508 mm) from the firewall.

that the control rod, N₂ actuator and

override link bearings are not

(e).

Check that the engine compartment

jammed when the linkage is in the

N₂ idler bellcrank control rod length

extreme control positions.

is set to 14.28 ±0.03 inches (362.712

±0.762 mm).

(b).

Start and operate engine at idle with

main rotor blades in flat pitch

(f).

Adjust governor lever control rod

according to Pilot’s Flight Manual.

length to 4.15 inches (105.41 mm)

between attaching bolt centers.

(c).

Rotate pilot’s throttle counterclock−

wise to maximum rpm.

(g).

Remove control lever from turbine

governor. Rotate control quadrant

(d).

Decrease N₂ trim to minimum.

until 60° mark aligns with pointer on

housing and then reinstall control

(e).

Observe N₂ tachometer pointer for 98

lever so that it is approximately

percent or less (250−C18); 100

parallel to the governor outer cover

percent or less (250−C20) when rotor

parting line.

rpm pointer is superimposed on N₂

pointer and N_l

tachometer pointer is

NOTE: Lever and quadrant serrations have 15°

stabilized.

spacing. Do not exceed 40 − 50 inch−

pounds (4.52 − 5.65 Nm) torque when

(f).

With collective stick down, increase

tightening the lever nut.

N₂ trim to maximum.

Page 11-14

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(g). Observe N₂ tachometer pointer for

a). Shorten droop compensation

103 percent minimum (250−C18),

adjustment fork to increase

104 percent minimum (250−C20);

compensation.

104 percent maximum (250−C18),

b). Lengthen fork extension to

105 percent maximum (250−C20)

decrease compensation.

when rotor rpm pointer is superim−

posed on N₂ pointer and N₁ tachome−

c). Align fork with override link rod

ter pointer is stabilized.

end before tightening fork jam

nut.

Make all engine compartment

CAUTION

control rod adjustments with

d). Three to five turns of droop

engine shut down.

compensation fork may be

necessary to change droop

(h). Stop the engine. Adjust the length of

compensation approximately 0.5

the governor lever control rod until

percent.

N₂ trim is within limits given in

(m).

If high operating range for N₁ and

steps (e). and (g). Adjust one rod end

TOT cannot be reached when full

not more than one turn at a time.

power is demanded in flight, the gas

producer fuel control maximum

(i). Restart the engine, actuate N₂ trim

throttle stop may require adjustment.

for 102 percent with main rotor

(Refer to Allison Operation and

blades in flat pitch, lift off and hover.

Maintenance Manual.)

(j). Observe N₂ tachometer pointer when

NOTE: After rigging and test of Bendix or

pointer of N_l tachometer is stabilized.

CECO power turbine governor controls, per−

N₂ pointer indication (droop compen−

form deceleration check in accordance with

sation) should be 1 to 2 percent

procedure found in the pilot’s flight manual.

(250−C18) 0.50 to 1 percent

If confirmed deceleration time is less than

(250−C20) above N₂ setting in step

the allowable minimum, refer to the appli−

(i).

cable Allison Operation and Maintenance

Manual.

(k). Land and shut down engine.

4. Gas Producer Controls

(l). If droop compensation does not occur

as required in step (k)., perform the

(Ref. Figure 11−1) The gas producer controls

following:

include the throttle and its associated linkage

in the collective controls system (Ref. Sec. 7), a

1). Recheck entire power turbine

fuselage−routed control rod and engine

governor (N₂ rpm) control linkage

compartment linkage. The control rod assem−

rigging.

blies consist of aluminum alloy tubes or solid

rods with spherical bearing rod ends. Bell−

2). Check gas producer (N_l fuel con−

cranks and supports are either cast aluminum

trol) linkage adjustment.

or magnesium, each bellcrank containing a

roller bearing. Refer to Section 2 for corrosion

Any change to initial droop com−

control and identification of magnesium and

CAUTION

pensation fork length may re−

aluminum alloy parts.

sult in interference between N₂ trim actua−

A. Gas Producer Linkage Replacement

tor case and fork threaded end. Move

collective through full travel after adjust−

(Ref. Figure 11−8) Disassemble linkage only to

ment and check for clearance between mov−

extent necessary to replace worn or damaged

able linkage and adjacent parts.

parts, or to perform repairs.

3). If N_l and N₂ linkage are correctly

(1). Remove cotter pins, nuts, washers and

adjusted, an additional adjustment

bolts as necessary to disconnect the

may be made at droop compensa−

appropriate control rod, bellcrank or

tion adjustment fork.

support.

Page 11-15

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(2). Remove the control support from the

the collar swaging is questionable, use

firewall by removing the three standard

a Cherry or Huck inspection (strip)

bolts, washers and nuts from the

gage (#HG85−10) or an equivalent

vertical stiffener; then remove the

inspection gage per NAS1563 to check

pull−type lockbolt from the firewall as

for proper installation. Replace an

follows:

incorrectly installed lockbolt.

(6). Tighten the three nuts that attach the

(a). Locate the lockbolt installation at the

control support to the firewall.

floorline of the cargo compartment.

Split the collar axially with a sharp

NOTE: Before installing any control rod, mea−

cold chisel. Use a backup bar on the

sure the rod assembly for correct length

collar opposite to the side being split,

(Ref. Figure 11−2 or Figure 11−4).

to prevent deformation or breakout of

the hole.

When tightening a jam nut to

CAUTION

secure a control rod end, always

(b). Drive the lockbolt pin out with a

hold the rod end with a wrench to prevent

drift.

jamming of the bearing against the fitting.

Check that all misalignment is divided

NOTE: If lockbolt is carefully removed, another

equally between the bearings of each control

lockbolt of same diameter may be used as re−

rod assembly.

placement. If hole is enlarged to more than

0.1870 inch (4.7498 mm), an oversized lock−

(7). Install replacement control rod or

bolt must be installed.

bellcrank with bolt, washers, nut, and

new cotter pin (Ref. Figure 11−8).

(3). Fit replacement control support on the

(8). Rig the gas producer control system.

firewall. Align the three standard bolt

holes and the lockbolt hole with the

B. Gas Producer Control Linkage Inspection

matching holes. Install, but do not

tighten the three standard bolts,

washers, and nuts.

(1). Inspect rod end bearings for binding

and excessive wear, 0.040 inch (1.016

mm) maximum axial play.

NOTE: If locknut hole diameter in the firewall

does not exceed 0.1870 inch (4.7498 mm), a

(2). Inspect control rod for surface damage

standard diameter pin can be used. If the

and evidence of bending.

hole is oversize and can be cleaned up with a

#7 drill, 0.2015 inch (5.1181 mm) maximum,

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

use an oversize 3/16 inch nominal diameter

(lower end).

pin (Cherry or Huck part #R3007− T, or

equivalent).

(4). Inspect bearings in bellcranks for

binding.

(4). Install the replacement lockbolt pin and

collar; best fit results when the com−

(5). Perform a fluorescent dye penetrant

pressed air line pressure to the pulling

inspection on any suspected part.

gun is 90−125 psi (621−862 kPa). Use

up to three AN960PD10 washers under

NOTE: After replacement and inspection of gas

the pin head, if necessary, to obtain

producer controls linkage, perform decelera−

correct lockbolt grip.

tion check in accordance with the proce−

dures found in the pilot’s flight manual. If

(5). Visually inspect the lockbolt installa−

confirmed deceleration time is less than the

tion. No measurable gap is permissible

allowable minimum, refer to the applicable

under either the pin head or collar. If

Allison Operation and Maintenance Manu−

the pin grip length or completeness of

al.

Page 11-16

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

GAS PRODUCER IDLER

(NOTE 2)

GAS PRODUCER

LEVER

NOTE 3

GAS PRODUCER LEVER

CONTROL ROD, JAM NUTS

AND ROD ENDS

COUNTERSUNK

MS20470AD3 RIVET

STA. 73 CONTROL

ROD, JAM NUTS

AND ROD ENDS

* STA. 129

* GAS PRODUCER

BELLCRANK

CONTROL SUPPORT

BEARING

(NOTE 4)

NOTE 1

STA. 70

STA. 129

THIN SPACER

WASHERS

STA. 124

PULL−TYPE LOCKBOLT

PIN AND COLLAR

BEARING

(NOTE 4)

* STA. 70

NOTES:

BELLCRANK

AN960PD10 WASHER(S) USED UNDER HEAD ONLY

IF REQUIRED TO OBTAIN CORRECT GRIP.

PART OF INBD COLLECTIVE STICK SOCKET ASSY.

SPECIAL AL ALY WASHER, 0.25 IN. (6.35 MM) ID X

0.80 IN. (20.32 MM) OD.

INSTALL BEARING WITH GRADE A LOCKING

COMPOUND (29, TABLE 2−4).

FUSELAGE−ROUTED

ASTERISK ( * ) INDICATES PARTS MAY BE EITHER

CONTROL ROD, JAM

MAGNESIUM OR ALUMINUM ALLOY. REFER TO

NUTS AND ROD ENDS

SECTION 2 FOR ALLOY IDENTIFICATION AND

CORROSION CONTROL.

30−088D

Figure 11-8. Gas Producer Control Linkage Disassembly

Page 11-17

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

C. Gas Producer Control Linkage Repair

control tube, interconnect torque tube and

associated linkage.

(1). Perform a straightness check on a

control rod that appears bent or bowed.

5. Power Turbine Governor Controls

The total length of gas producer

controls rods (excluding rod ends) must

(Ref. Figure 11−1) The power turbine governor

be straight within the following

controls include the N₂ trim actuator and/con−

tolerances, with straightness variation

trol (beeper) switch on the collective stick, the

limited to a maximum of 0.010 inch

governor trim, droop control and override

(0.254 mm) in each 12 inches (304.8

linkage within the pilot’s seat structure, a

mm) of length.

fuselage routed control rod, and the engine

(a). Fuselage−routed control rod: 0.050

compartment linkage. The control rod assem−

inch (1.27 mm).

blies consist of aluminum alloy tubes or solid

rods with spherical bearing rod ends. The

(b). Sta. 73 control rod: 0.010 inch (0.254

bellcranks and supports may be either

mm).

aluminum or magnesium castings, each

(c). Gas producer lever control rod: 0.020

bellcrank containing a roller bearing. The N₂

inch (0.508 mm).

trim actuator consists of a reversible continu−

ous duty 26 Vdc motor that drives a gear train

A dye−check for cracking

having non−jamming mechanical stops. Refer

WARNING

shall always be performed

to Section 2 for corrosion control and identifi−

after cold−straightening. Replace a

cation of magnesium and aluminum alloy

cracked rod, or a cracked or bent rod

parts.

end.

A. Power Turbine Governor Linkage

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

Replacement

within tolerance (Ref. step (1).) pro−

vided there are no nicks or sharp dents

Replace control rods, bellcranks or supports

in the bend length. DO NOT use the rod

according to Gas Producer Linkage Replace−

ends to support the rod during the

ment, and Figure 11−9 and Figure 11−10, with

straightening process.

the following exceptions: the trim actuator and

Use care when drilling to re−

Sta. 72 bellcrank which must be removed as a

CAUTION

move or install a riveted rod

unit, and the droop control override link

end; the rod end is steel and the rod is alu−

assembly.

minum. Tighten the jam nut before drilling

and riveting.

NOTE: Only high temperature all metal nuts

(not fiber insert type) are to be used for an−

(3). Replace a control rod end if bearing

choring control idler support (Figure 11−10)

axial play is more than 0.040 inch

to engine gear case accessory pad.

(1.016 mm). Set initial control rod

length and bearing agularity as shown

(1). Remove the droop control override link

in Figure 11−2 or Figure 11−4.

by disconnecting the link housing end

fitting from the collective torque tube,

(4). Replace unserviceable bellcrank

and the rod end from the droop com−

bearings. Install a new bearing of the

pensation fork.

correct type with surface primer and

grade A locking compound (28 and 29,

Table 2−4), according to container

(2). Remove the N₂ trim actuator and Sta.

72 bellcrank as a unit:

instructions.

(5). Replace bellcranks or control supports

(a). Disconnect the bonding jumper and

for distortion, cracks or elongated holes.

electrical connector from the actua−

tor.

D. Gas Producer Throttle Linkage

Refer to Collective Controls in Section 7 for

(b). Disconnect the actuator from Sta. 68

information on the throttle gas producer

bellcrank.

Page 11-18

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTES:

NOTES: (CONT)

BUSHINGS MUST ROTATE FREELY AFTER

TAB ON CURRENT TYPE; STRAP ON

COLLECTIVE

ASSEMBLY.

EARLY TYPE.

TORQUE TUBE

INSTALL BEARINGS WITH GRADE A LOCKING

ASTERISK ( * ) INDICATES CORROSION

COMPOUND (29, TABLE 2−4).

RESISTANT STEEL.

LUBRICATE SPRING, RETAINERS, PLUNGER

DOUBLE ASTERISK ( * * ) INDICATES THAT

AND INSIDE OF HOUSING WITH GREASE (26)

PARTS MAY BE EITHER MAGNESIUM OR

BEFORE INSTALLATION OF RIVETS.

SPECIAL

ALUMINUM ALLOY. REFER TO SECTION 2

PLUNGER HEX FLATS ALIGN AT 90 DEGREES

WASHER

FOR ALLOY IDENTIFICATION AND

WITH ROD END VERTICAL. PLUNGER HEAD

CORROSION CONTROL.

MUST HAVE FREE TRAVEL TO END OF OBLONG

SLOT IN HOUSING END FITTING.

JAM NUT TIGHTENED FOR MINIMUM FREE

PLAY IN SPRING.

BONDING JUMPER

STRUCTURE RIB

DROOP

COMPENSATION

FORK

* * STA. 68 BELLCRANK

N2 TRIM ACTUATOR

BEARING

(NOTE 2)

NOTE 6

LOCKED

SLEEVE BUSHING

THREAD

CONTROLS SUPPORT

(NOTE 1)

INSERT

BRACKET

STRUCTURE

RIB

FLANGE

BUSHING

SLEEVE BUSHING

(NOTE 1)

STA. 64 SEAT

STRUCTURE

STA. 124

BRACKET

BEARING

BELLCRANK

(NOTE 2)

FUSELAGE−ROUTED

CONTROL ROD, JAM

NUTS AND ROD ENDS

* * STA. 72 BELLCRANK

SPECIAL

MS20604AD4K1

WASHER

(OR AD4W1) RIVET

MS20470A2 RIVET

PLUNGER (NOTE 4)

(NOTE 3)

RETAINER

ROD END

BEARING

(NOTE 4)

RETAINER

SPRING

(NOTE 2)

LINK HOUSING

DROOP CONTROL

JAM NUT

(NOTE 3)

OVERRIDE LINK

(NOTE 5)

30−089D

Figure 11-9. Governor Control Linkage Disassembly (Forward of Engine Compartment)

Page 11-19

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE 3

ENGINE ACCESSORY

GEARCASE PAD

* CONTROL IDLER

GOVERNOR LEVER

SUPPORT

GOVERNOR LEVER CONTROL ROD,

JAM NUTS AND ROD ENDS

AN4045−1 GASKET

* IDLER BELLCRANK

NOTE 4

BEARING

(NOTE 2)

MS20470AD3 RIVET

IDLER BELLCRANK CONTROL ROD,

JAM NUTS AND ROD ENDS

* STA. 124 CONTROL SUPPORT

* STA. 124 BELLCRANK

NOTE 1

PULL−TYPE

LOCK BOLT PIN

AND COLLAR

BEARING

(NOTE 2)

FUSELAGE−ROUTED CONTROL ROD

NOTES:

AN960PD10 WASHERS USED UNDER HEAD ONLY IF REQD TO OBTAIN CORRECT GRIP.

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

SPECIAL ALUMINUM ALLOY WASHER; 0.25 IN. (6.35 MM) ID X 0.80 IN. (20.32 MM) OD.

USE HIGH TEMPERATURE ALL−METAL NUTS ONLY.

ASTERISK ( * ) INDICATES THAT PARTS MAY BE EITHER MAGNESIUM OR ALUMINUM ALLOY.

REFER TO SECTION 2 FOR ALLOY IDENTIFICATION AND CORROSION CONTROL.

30−090F

Figure 11-10. Governor Control Linkage Disassembly (Engine Compartment)

Page 11-20

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(c). Disconnect Sta. 72 bellcrank from the

B. Governor Control Linkage Inspection

fuselage−routed control rod end.

(1). Inspect rod end bearings for binding

and excessive wear, 0.040 inch (1.016

(d). Remove the pivot bolt that attaches

mm) maximum axial play.

Sta. 72 bellcrank to structure rib and

controls support bracket; remove

(2). Inspect control rod for surface damage

actuator and bellcrank.

and evidence of bending.

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

(3).

Disconnect the trim actuator from Sta.

(lower end).

72 bellcrank. Use care to keep sleeve

bushings with bellcrank.

(4). Inspect bearings in bellcranks for

binding.

(4).

Check a replacement trim actuator for

(5). Perform a fluorescent dye penetrant

correct maximum extended length of

inspection on any suspected part.

5.47 ±0.03 inches (138.938 ±0.762 mm)

between attach bolt centers. If dimen−

NOTE: After replacement and inspection of the

sion is not correct, test actuator for

power turbine governor controls linkage,

proper operation.

perform deceleration check in accordance

with procedures found in the pilot’s flight

manual. If confirmed deceleration time is

(5).

Assemble original or replacement trim

less than the allowable minimum, refer to

actuator to original or replacement Sta.

the applicable Allison Operation and Main−

72 bellcrank with a bolt, two washers,

tenance Manual.

nut and new cotter pin. Check that both

sleeve bushings are in place in Sta. 68

C. Governor Control Rods and Bellcranks

bellcrank arm before connecting the

Repair

actuator; then install assembled unit in

controls support bracket and connect

(1). Perform a straightness check on a

linkage as shown in Figure 11−9. The

control rod that appears bent or bowed.

sleeve bushings in Sta. 68 bellcrank

The total length of governor control

arm must rotate freely, without any

rods (excluding rod ends) must be

binding, after the actuator is attached

straight within the following tolerances,

and the connecting hardware is tight−

with straightness variation limited to a

ened.

maximum of 0.010 inch (0.254 mm) in

each 12 inches (304.8 mm) of length.

(6).

Connect replacement droop control

(a). Fuselage−routed control rod: 0.050

override link to collective torque tube.

inch (1.27 mm).

Push on rod end and check that the link

assembly plunger head is free to slide

(b). Governor lever control rod: 0.010

back and forth in the link housing end

inch (0.254 mm).

fitting. Connect rod end to droop

compensation fork; the rod end should

(c). N₂ idler bellcrank control rod: 0.020

align with the fork.

inch (0.508 mm).

A dye−check for cracking

(7).

Connect the bonding jumper and

WARNING

shall always be performed

electrical connector to the actuator.

after cold−straightening. Replace a

cracked rod, or a cracked or bent rod

end.

NOTE: Replacement trim actuator may have a

tab or use a bonding strap/clamp for connec−

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

tion of the bonding jumper.

within tolerance (step (1).) provided

there are no nicks or sharp dents in the

(8). Rig the control system.

bend length. DO NOT use the rod ends

Page 11-21

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

to support the rod during the straight−

Apply primer (4, Table 2−4) to reworked

ening process.

area.

Use care when drilling to re−

(5). Install existing locknut and new

CAUTION

move or install a riveted rod

NAS42DD1010 spacer on −3 extension;

end; the rod end is steel and the rod is alu−

reinstall extension (Ref. Figure 11−1 1).

minum. Tighten the jam nut before drilling

(6). Perform rigging of power turbine

and riveting.

governor controls.

(3). Replace a control rod end if bearing

(7). Reinstall control covers and floor access

axial play is more than 0.040 inch

panels.

(1.016 mm). Set initial control rod

length and bearing angularity as shown

E. Droop Control Override Link Assembly

in Figure 11−6 or Figure 11−7.

Repair

(4). Replace unserviceable bellcrank

(Ref. Figure 11−9)

bearings. Install a new bearing of the

(1). Replace an unserviceable link housing

correct type with surface primer and

end fitting bearing (detail A). Install a

grade A locking compound (28 and 29,

new bearing of the correct type with

Table 2−4), according to container

surface primer and grade A locking

instructions.

compound (28 and 29, Table 2−4),

(5). Replace bellcranks or control supports

according to container instructions.

for distortion, cracks or elongated holes.

(2). Replace an unserviceable rod end or

broken spring:

D. Relocation of Locknut and Installation of

Spacer

(a). Remove the four rivets from rod end

of housing.

The following procedure to relocate the

existing droop compensation adjustment

(b). Drill out rod end rivet and disas−

locknut on the PN 369A7717−3 extension to a

semble spring assembly. Discard rod

new location above the arm assembly is to

end and plunger.

preclude loosening and/or loss of the locknut

during helicopter operation. This procedure

(c). Assemble new plunger, retainers,

affects PN 369H7825 droop control bellcrank

spring and jam nut. Screw down the

assembly (Sta. 68.00); it does NOT affect PN

jam nut on plunger threads until

369H7825−1 1 droop control bellcrank assem−

there is minimum free play of the

blies.

spring.

(1). Remove pilot’s floor access panels and

(d). Install replacement rod end to point

control covers to gain access to under−

of contact with jam nut. Check

seat linkage for power turbine governor

alignment of the flats on the plunger

controls.

head and the rod end; with rod end

vertical, two of the flats must be

(2). Remove PN 369A7717−3 extension from

perpendicular at 90 degrees (detail

droop control override link and Sta.

A). Tighten jam nut against rod end.

68.00 bellcrank.

NOTE: When the override link assembly is

NOTE: Spotface through radius of arm only.

installed between the droop compensation

DO NOT spotface below flat surface of arm

fork and the collective torque tube, the

around circumference of insert in arm.

plunger must be free to travel to the end of

the oblong slot in the link housing end fit−

(3). Spotface PN 369A7716 or 369N2606

ting without binding.

arm assembly, as shown in

(e). Using a #50 drill, drill through rod

Figure 11−1 1.

end and plunger at the witness hole

(4). Touch up reworked surface of arm with

of the rod end. Install an MS20470A2

Dow 7 or Dow 17 chemical treatment.

rivet of correct length.

Page 11-22

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(f). Lubricate the interior of the housing,

MS3106−10SL−3S

the spring retainers and plunger

SPDT

CONNECTOR

EXTEND

SWITCH

with grease (26). Install the spring

RETRACT

assembly in the housing so that

26 VDC

plunger hex enters end fitting slot

V M2

POWER

and rod end aligns vertically with

−

30−091

housing bearing (detail A).

(g). Complete the link assembly by

ITEM

EQUIPMENT DESCRIPTION

installing the four retention rivets

NO.

(MS20604AD4K1 or W1) in the

6 in. (152.4 mm) scale.

housing (detail A).

Dc voltmeter, calibrated 0-50 volts (Weston

6. RPM Governor (N₂) Trim Actuator

Model 931 or equivalent).

Dc miliiammeter, calibrated 0-5 amperes

The N₂ trim actuator (a linear electro−me−

(Weston Model 931 or equivalent).

chanical actuator that is operated by a

‘‘beeper" switch on the collective pitch stick)

Variable dc power supply, 10-36 volts

allows N₂ speed to be varied over a range of

(N.J.E. Model SY36-10 or equivalent).

approximately 94−105 percent. Any change in

Dial indicator gauge (Brown and Sharp

actuator length or in collective pitch actuates

Model 740 or equivalent).

the governor linkage and establishes a new

power output demand on the engine. For all

Switch, SPDT, center off.

practical purposes, the main rotor speed is

held constant. Operating stroke of the actuator

Figure 11-12. N₂ Trim Actuator Test hookup

ram is approximately 1.00 inch (25.4 mm), and

linear speed is 0.15 inch (3.81 mm) per second;

(3).

With actuator ram approximately

full travel from full retraction to full extension

halfway between stops, set up dial test

is approximately 7 seconds. The actuator is

indicator and measure the ram end

lubricated by the manufacturer and no further

play. The end play must not exceed

0.005 inch (0.127 mm) tir when mea−

lubrication is required for the life of the

sured under a 10 lb. (4.5 kg) reversing

actuator.

load.

A. N₂ Trim Actuator Replacement

(4).

Position test switch to RETRACT and

allow the actuator ram to fully retract.

Refer to Power Turbine Governor Linkage

Using the end of the ram sleeve as a

Replacement.

reference point, measure the portion of

ram that remains out of the sleeve to

B. N₂ Trim Actuator Repair

the nearest 0.015625 inch (0.396785

Repair of the N₂ trim actuator, other than that

mm). Record this measurement for use

performed by an authorized overhaul agency

in step (5).

or the manufacturer, is limited to replacement

(5).

Position test switch to EXTEND and

of an unserviceable rod end in the actuator

run ram to the extend stop. Measure

ram. With the ram at full extension, set the

the length of the extended ram, Sub−

distance between attach bolt centers to 5.47

tract the measured result of step (4).

inches (138.938 mm) before reinstalling the

from this value. The result should be

actuator.

0.97−1.03 inches (24.638−26.162 mm).

C. N₂ Trim Actuator Testing

(6).

The operating current under no−load

conditions, at 26.0 Vdc input should be

(1). Connect the N₂ trim actuator to test

between 0.60−1.25 amperes when

harness and equipment shown in

running and 2.0 amperes maximum

Figure 11−12.

when stalled.

(2). Turn on dc power and adjust output to

(7).

Operate the actuator motor in both

25.75−26.25 volts.

extend and retract direction. Overtravel

Page 11-24

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

must not exceed 0.020 inch (0.508 mm)

(10). Run the actuator to the fully extended

maximum when power is turned off.

position. The overall length of the

extended actuator should be 5.47 inches

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

(138.938 mm) between attach bolt

The actuator ram must retract and

centers. Turn power off and disconnect

extend to the stops without binding on

the actuator.

the stops or between the stops.

7. Anti-Icing System

(9). Increase the input voltage to 28 volts.

The actuator ram must retract and

8. Anti-Icing System Troubleshooting

extend to the stops without binding on

the stops or between stops.

(Ref. Table 11−2)

Table 11-2. Anti-Icing System Troubleshooting

Symptom

Probable Trouble

Corrective Action

NOTE: Refer to Section 19 for interconnection wiring and circuit information for the electrically operated anti-icing

system.

Actuation of anti-ice system does

Inoperative or defective actuator.

Replace actuator.

not restore normal engine

Defective N₂ GOV circuit breaker

Ref. Sec. 19.

operation when compressor icing

or electrical circuits.

occurs.

Actuator not rigged properly.

Check rigging.

Lack of anti-icing air.

Check engine air lines for leaks.

Defective or stuck anti air valve.

Replace anti-icing valve.

*Cable wire loose in anti-icing air

*Tighten or replace adapter with

valve lever adapter or adapter stud

cable and valve in correct position.

sheared or stripped.

De-actuation of anti-ice system

Same as troubles above.

Same as actions above.

does not return anti-icing valve

lever to forward position. (Inflight

*Cable to control lever piston

Replace damaged parts.

symptom is continuation of

retaining pin sheared (inside lever

approximately 10% reduction in

housing).

available power or torque.)

*Adapter nut over-tightened.

*Loosen adapter nut and retorque to

not more than 10 inch-pounds

(1.13 Nm).

Movement of anti-icing valve

**Control cable sleeve kinked or

**Check cable operation with cable

control lever very difficult.

one or more routing bend radii less

wire detached from shutoff valve

than a 3 inch (76.2 mm) minimum.

lever adapter (early system) or cable

clevis detached from shutoff valve

lever (current system). Replace

kinked cable or remove sharp bends

in cable routing.

NOTE:

* Indicates early manually operated anti-icing system only.

* * Indicates early and current manually operated anti-icing systems.

Page 11-25

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

9. Anti-Icing Controls (Electrically Operated

(4). If anti−icing valve lever has insufficient

System)

travel or linkage binds, re−rig (Ref.

Electrically Operated Anti−Icing Valve

(Ref. Figure 11−13) Anti−icing valve electrical

Rigging).

control equipment consists of an anti−icing

B. Electrically Operated Anti-Icing Valve

valve control switch, an electrical actuator and

Rigging

associated electrical wiring and miscellaneous

hardware.

(1). Disconnect the aft end of the engine

ant−ice rod (if connected).

The actuator is attached to a bracket mounted

under the engine hoist fitting behind the

(2). Manually position the engine anti−ice

anti−icing valve.

lever to the full OFF (forward) position.

Rigging adjustment is made by

An adjustable rod connects the anti−icing lever

CAUTION

changing anti− ice rod length.

to the actuator crank arm.

Do not reposition the actuator arm on the

A three−position anti−icing control valve

shaft. Also, do not force the actuator arm in

switch located overhead in the pilot’s compart−

either direction. Use the DE−ICE switch to

ment controls actuator operation in either a

position the actuator arm.

clockwise or counterclockwise direction.

(3). Turn power ON. Set DE−ICE switch to

OFF (aft) position.

Actuator circuits are protected by the N₂ GOV

circuit breaker on the instrument panel (Ref.

(4). For the spring−loaded anti−ice rod,

Section 19). When the switch is moved to the

loosen jam nut on engine anti−ice rod.

full aft (OFF) position the actuator shaft

Adjust the rod end until the forward

rotates counterclockwise (viewed from the

terminal slide pin is centered in the slot

shaft end) closing the anti−icing valve.

with aft terminal attached to the

Stop−to−stop actuator shaft rotation normally

actuator arm.

requires a minimum of 20 seconds.

(5). For the non−spring−loaded double end

adjustable engine anti−ice rod, loosen

A. Anti-Icing Controls Operational Check

jamnut and adjust disconnected aft rod

(Electrically Operated0

end until rod length is proper for

NOTE: The N₂ GOV circuit breaker on the

connection of rod to actuator crank arm;

instrument panel must be set (pushed in)

then tighten jamnut.

for the anti−icing actuator to operate.

(6). Secure the aft rod end to the actuator

arm with a clevis pin, washer and

(1). Set the DE−ICE switch to the OFF (aft)

cotter pin.

position.

(7). Perform an operational check of the

(2). Observe that the anti−icing valve lever

installed electrical actuator.

moves to the forward (OFF) position.

C. Anti-Icing Valve Actuator and Linkage

NOTE: If the installation is equipped with a

Replacement

spring−loaded anti−icing rod, carefully ob−

(Ref. Figure 11−13)

serve the pin position in the forward termi−

nal slot. The pin must be in the center of the

(1). Check that all electrical power is OFF.

slot (Figure 11−13). If the pin is not centered

NOTE: Although not mandatory, removal of the

in the slot, re−rig the anti−icing rod.

tailpipe assembly provides best access to

(3). Alternately set the DE−ICE switch to

components.

the ON and OFF positions. Make sure

(2). Disconnect the electrical connector from

the actuator operates the anti−icing

the actuator.

valve from the OFF (forward) to ON

(aft) position. Allow a minimum of 20

(3). Remove cotter pins, washer and pins to

seconds for the crank arm to travel

disconnect anti−icing rod from actuat−

between full throw positions.

ing levers.

Page 11-26

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(4). Disassemble rod only to the extent

10. Anti-Icing Valve Control Cable (Manually

necessary to replace worn or damaged

Operated)

parts.

(Ref. Figure 11−14) There are two types of

manually operated anti−icing valve control

(5). Release setscrew tension on actuator

cable installations.

crank arm and remove crank from

actuator.

The early type anti−icing valve control consists

of a flexible, enclosed wire−type cable assem−

(6). Remove the actuator, gasket and shield

bly bonded to a control housing.

by removing the lockwire, four attach−

ing screws and washers from the

The control housing with cable actuating knob,

support bracket.

is attached to the left side of the overhead

canopy frame in the pilot’s compartment.

NOTE: Refer to Section 10 for actuator bracket

Movement of the control lever rearward to the

assembly replacement.

latch notch opens the anti−icing valve com−

pletely. Releasing the control lever from the

(7). Install replacement actuator with

latch notch results in spring−loaded return of

gasket and shield on bracket assembly

the lever to the forward (OFF) position.

with four screws and washers. Safety

screwheads with lockwire.

Control lever piston travel in the housing is

approximately 1.50 inches (38.1 mm), from the

open to closed positions.

(8). Connect the electrical connector to

actuator.

The current type anti−icing valve control has a

control handle and the push−pull wire and

(9). Turn power ON and set DE−ICE switch

conduit assembly incorporated at the right side

to OFF (aft) position.

of a heat duct attached to the overhead canopy

structure.

(10). Install actuator crank arm on serrated

Movement of the cable actuating control

actuator shaft at 23 degree angle aft of

handle forward opens the anti−icing valve

shaft vertical centerline. (Vertical

completely. A spring−type detent holds the

centerline is parallel to forward edge of

handle in the forward (on) position. The

anti−ice actuator.) Alignment of missing

control handle must be manually returned to

tooth in arm and shaft (with arm

the rearward (off) position.

positioned down and aft) indicates

correct arm−to−shaft alignment. Be

Minimum travel for the control handle is 1.44

sure that shaft clears actuator scre−

inches (36.576 mm), from the open to the

wheads. Tighten the setscrew.

closed positions.

NOTE: If the engine anti−ice rod has a spring−

Cable routing for the early type installation is

loaded slide terminal and an adjustable ter−

on the left side of the main rotor mast support

minal jamnut, the slide terminal end must

structure alongside the torquemeter oil

be installed on the engine anti−ice lever.

pressure line as far as the plenum chamber; at

this point the anti−ice cable is routed down−

ward through the firewall into the engine

(11). Connect the slide (forward) terminal

compartment.

end of engine anti−ice rod to the engine

anti−ice lever with clevis pin, washer

Cable routing for the current type installation

and cotter pin.

is similar but along the right side of the mast

support structure and back to the plenum

(12). Refer to Electrically Operated Anti−Ic−

chamber.

ing Valve Rigging for instructions on

connection of the adjustable end of the

No electrical switching is used in the manually

anti−ice rod and proper rigging.

controlled anti−icing valve control systems.

Page 11-28

Revision 18

CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 8