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

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE: Hughes Notice HN− 151 provides

and checking for binding during full

instructions for replacing existing cabinet

movement of control lever knob or lever

heat duct assemblies with new fiberglass−

from ON to OFF positions. Manually

type duct assemblies. The new configuration

actuate the anti−icing valve lever to

for the optional cabin heating system is de−

check freedom of movement. Early

signed to provide greater resistance against

system: Reinstall cable wire and torque

heat, deformation, and wear. A procedure

adapter nut to 10 inch−pounds (1.13

for rework of the control cable assemblies to

Nm) maximum. Secure nut with new

make them compatible with the new fiber−

cotter pin. Current system: Reinstall

glass duct installation also is provided by

clevis to valve lever with clevis pin,

HN−151.

washer and cotter pin.

A. Anti-Icing Valve Control Operational

B. Anti-Icing Valve Control Cable Inspection

Check (Manually Operated)

(Manually Operated)

(1). Inspect cable for kinks, crushed sleeve

(1).

Move control lever knob to full aft

and corrosion.

position (early system) or control

handle to full forward position (current

(2). Early system: Inspect piston for wear or

system) to open anti−icing air valve.

elongation of knob shaft or lock pin

Control knob or handle should not creep

holes; inspect control spring for kinks

away from anti−icing valve full open

or breaks.

position.

(3). Inspect valve lever or valve lever

(2).

In engine compartment, check that

adapter for excessive wear.

anti−icing air valve lever is positioned

at aft travel limit and that cable wire

C. Anti-Icing Valve Control Cable

does not appear to be distorted by

Replacement (Manually Operated)

overtravel.

(Ref. Figure 11−14)

(3).

Early system: Release control lever

(1).

Unlatch or remove plenum chamber

knob from housing notch; lever piston

access door, and left or right half of

return spring should return lever knob

engine air inlet forward fairing, as

to housing forward stop without

appropriate, for access to cable.

manual assistance. If valve does not

return, the valve lever adapter nut may

(2).

Remove two screws, washers, and nuts

be over−tightened; refer to step (6).

and spacers that attach cable housing

Current system: Manually return

to structure (early system); or remove

control handle to full aft (of position.

seven screws attaching heat duct outer

box to heat duct and canopy frame

(4).

Recheck position of anti−icing valve

(current system)

lever; lever should be positioned at

forward travel limit.

(3).

Remove clamps and straps that attach

cable to structure along its full length.

(5).

If anti−icing valve lever does not have

sufficient travel or the cable appears to

(4).

Loosen the nut of adapter at the

distort when actuated, adjust cable wire

anti−icing valve on the engine (early

(early system) or cable clevis (current

system); or remove clevis pin, washer

system) for correct lever stroke,

and cotter pin attaching clevis to valve

lever (current system).

NOTE: On current system, check that pop−

petguide and arm are positioned as shown

(5).

Remove control cable.

in engine build−up illustration.

(6).

Route the replacement cable assembly

(6). When control cable operation is stiff,

into position. Check that grommets

isolate the trouble by removing the

(two on early type, one on current type

cable wire or clevis from the valve lever

cable) are in place on the cable.

Page 11-29

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

PISTON HOUSING

FLEXIBLE CASING

TEFLON PISTON

HOUSING SPACER

CABLE SPLICE

MOUNTING SPACER

CLAMP

0.34375 IN. (8.73125 MM)

LONG

CONTROL KNOB

NYLON STRAPS

(TYP EITHER SIDE)

RETURN SPRING

GROMMET (TYP)

LOCK PIN

EARLY SYSTEM

(LEFT SIDE)

MOUNTING SPACER

0.453125 IN. (11.509375 MM)

LONG

NOTES:

SEAL HOLE, ON ENGINE SIDE OF PAN,

CABLE ASSY

WITH ADHESIVE (102, TABLE 2−4).

FORWARD BLOCK AND CLAMP MATING

SURFACES FACED WITH TAPE (112).

GROMMET

HANDLE SHAFT SLIDES AGAINST THESE

RIGID TUBING

SURFACES.

2 PLCS

ADAPTER

PLENUM CHAMBER

AIR INLET PAN

1 PLC

SETSCREW

LEVER

ANTI−ICING VALVE

(EARLY SYSTEM)

POPPET GUIDE

CONTROL HANDLE

ANTI−ICING SYSTEM

(CURRENT SYSTEM)

CANOPY

FRAME

HANDLE DETENT

SPRING

FLEXIBLE CASING

CABLE SPLICE

CABLE SUPPORT BLOCK

(3 PLCS) (NOTE 2)

RIGID TUBING

PLENUM CHAMBER

CURRENT SYSTEM

OUTER BOX

AIR INLET PAN

HEAT DUCT

6 PLCS

MOUNTING

SCREW

OPEN

NOTE 1

CLEVIS ATTACH POINT

CABLE

ANTI−ICING VALVE

CLOSED

CLEVIS

INLET AIR

SCREEN

30°

LEVER ASSY

FIREWALL

SEAL

VERTICAL CENTERLINE

POPPET GUIDE

OF ENGINE

(LOOKING AFT)

30-092B

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

Page 11-30

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(7). Early system only: Attach control

D. Anti-Icing Control Cable Repair

housing to canopy structure bracket

(Manually Operated)

with two screws, the housing spacer,

(Ref. Figure 11−14) Early system only: The

mounting spacers (0.34375 inch

control assembly is normally replaced as a

(8.73125 mm) length inboard), washers

unit. However, disassembly to the extent

and nuts.

shown in Figure 11−14 can be accomplished for

inspection purposes No repairs are recom−

(8). Install clamps and straps that attach

mended except for replacement of lever

cable to structure. Seal hole at engine

mechanism parts.

side of plenum pan where current type

cable passes through, using adhesive

(1).

Move control knob to full extent of

(102, Table 2−4).

forward travel.

NOTE: The clamp nearest to the valveshould

(2).

Pull control knob shaft out of piston.

not be aligned until after travel is checked.

(3).

Pull piston out of housing.

(9). Current system only: Attach heat duct

(4).

Remove lock pin from piston to free

outer box to heat duct and canopy

cable and piston.

frame with seven screws.

(5).

Inspect and replace worn lever mecha−

nism parts as required.

(10). Adjust cable wire in valve lever adapter

(early system) or cable clevis at valve

(6).

Extend cable rod through housing so

lever (current system).

parts can be assembled.

(11). When assured that control will operate

(7).

Apply a thin film of grease (26,

the valve through full range of travel,

Table 2−4) on a serviceable spring.

tighten the clamp nearest the valve.

(8).

Fit serviceable piston on cable rod and

secure with lockpin.

(12). Latch or reinstall plenum chamber

access door and removed half of engine

(9).

Push piston into housing until large

air inlet forward fairing.

hole in piston is aligned with large hole

in end of housing slot.

(13). Current system only: After installation,

adjust handle to be parallel with

(10).

Insert control knob through housing

windshield glass.

slot and into piston.

Page 11-31

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 12 Engine Fuel System .

12−1

Engine Fuel System

12−1

Troubleshooting the Fuel System

12−1

Fuel System Inspection

12−1

Table 12−1. Troubleshooting the Fuel Supply System

12−1

Fuel Cells

12−2

Fuel Cell Replacement

12−2

A. Left Fuel Cell Removal

12−2

B. Right Fuel Cell Removal

12−2

C. Fuel Cell Installation

12−2

Fuel Cell Cover Replacement

12−3

A. Left Fuel Cell Cover Removal

12−3

B. Right Fuel Cell Cover Removal

12−3

C. Left Fuel Cell Cover Installation

12−3

Figure 12−1. Fuel Cell Installation (Sheet

1 of 2)

12−4

D. Right Fuel Cell Cover Installation

12−5

Fuel Cell Repair

12−6

A. Preparing Fuel Cell for Repairs

12−6

B. Fuel Cell Cleaning

12−6

C. Repair of Fuel Cell

12−6

Fuel Cell Pressure Test

12−8

Fuel Filler Shield

12−8

A. Fuel Filler Shield Replacement

12−8

B. Fuel Filler Shield Inspection

12−8

C. Fuel Filler Shield Repair

12−8

10. Fuel Filler Cap

12−9

11. Fuel Filler Cap Replacement

12−9

12. Fuel Filler Cap Inspection

12−9

13. Fuel Filler Cap Repair

12−9

14. Fuel Cell Vents

12−9

15. Fuel Cell Vent System Replacement

12−9

A. Forward Fuel Cell Vent System Removal

12−9

B. Aft Fuel Cell Vent System Removal

12−10

C. Forward Fuel Cell Vent System Installation

12−10

D. Aft Fuel Cell Vent System Installation

12−10

16. Fuel Cell Vent System Inspection

12−10

Page 12−i

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

Figure 12−2. Forward Vent − Fuel Cell

12−11

17. Fuel Shutoff Valve Control Assembly

12−12

18. Fuel Shutoff Valve Control Assembly Replacement

12−12

A. Fuel Shutoff Valve Control Assembly Removal

12−12

B. Fuel Shutoff Valve Control Assembly Installation

12−12

19. Fuel Shutoff Valve Control Assembly Inspection

12−13

20. Fuel Shutoff Valve Control Assembly Adjustment

12−13

21. Fuel Shutoff Valve Control Assembly Repair

12−13

Figure 12−3. Fuel Shutoff Valve (Sheet 1 of 2)

12−14

22. Fuel Shutoff Valve

12−16

23. Fuel Shutoff Valve Replacement

12−16

A. Fuel Shutoff Valve Removal

12−16

B. Fuel Shutoff Valve Installation

12−16

24. Fuel Shutoff Valve Inspection

12−16

25. Fuel Supply Drain Valves

12−16

26. Fuel Supply Drain Valve Replacement

12−16

A. Fuel Supply Drain Valve Removal

12−16

B. Fuel Supply Drain Valve Installation

12−17

27. Fuel Supply Drain Valve Inspection

12−17

28. Engine Fuel Supply System

12−17

29. Engine Fuel Supply System Replacement

12−17

A. Engine Fuel Supply System Removal

12−17

B. Engine Fuel Supply System Installation

12−18

30. Engine Fuel Supply System Inspection

12−18

31. Start Pump

12−18

32. Start Pump Replacement

12−18

A. Start Pump Removal

12−18

B. Start Pump Installation

12−19

33. Fuel System Bleeding

12−19

Figure 12−4. Fuel Start Pump Installation (Sheet

1 0f

12−20

Page 12−ii

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 12

ENGINE FUEL SYSTEM

1. Engine Fuel System

2. Troubleshooting the Fuel System

(Ref. Table 12−1 and Sec. 17)

The fuel system is a suction type (non−gravity

feed) system that consists of two flexible

3. Fuel System Inspection

interconnected fuel cells,located in separate

compartments beneath the cargo/passenger

(1).

Inspect the fuselage skin beneath the

compartment.

fuel cells for indications of fuel leakage.

Both fuel cells are vented to the atmosphere

(2).

Inspect the fuel cell drain valve for

through a venting system to the lower side of

leaks and lockwire for security.

the fuselage.

(3).

Inspect fuel lines, fittings, fuel cell

Additional components of the fuel system

covers and tank unit for leakage,

include forward and aft vents, two drainvalves,

damage and security.

starting fuel pump, shutoff valve, tank unit,

(4).

Inspect electrical wiring for damage

filler neck (with an extended range tank

and security.

fuelline connection) various interconnecting

fuel lines and associated electrical wiring.

(5).

Inspect fuel shutoff valve for operation,

leaks, damage and security.

The fuel cells are serviced through a filler neck

on the rightside of the fuselage.

(6).

Inspect fuel inlet line, engine pump

drain valve and fuel line connections at

Once the engine is started, fuel is drawn from

pump and bulkhead fittings for leaks,

the cells through the shut−off valve by the

damage and security. Inspect fire sleeve

engine−driven fuel pump.

for cuts, tears and punctures.

The engine operation and maintenance

(7).

Check that vent fairing opening (and

manual provides detailed information and

alternate opening, if installed) is free of

theory of operation for the engine fuel system.

obstructions such as ice, mud or other

foreign matter that may have come in

Refer to Section 17 for fuel filter switch and

contact with underside of helicopter.

fuel quantity tank unit information.

Inspect for damage and security.

Table 12-1. Troubleshooting the Fuel Supply System

Symptom

Probable Trouble

Corrective Action

Engine fails to start (starting pump

Starting fuel pump defective.

Replace starting fuel pump.

in operation).

No fuel flow or insufficient fuel flow

Disconnected, ruptured or broken

Check all fuel lines for security;

to engine-driven fuel pump

fuel line.

replace damaged fuel line.

(starting pump operating properly).

Defective fuel shutoff valve or fuel

Replace fuel shutoff valve; repair

shutoff control disconnected or

control installation as necessary.

loose at valve.

Clogged fuel line.

Clean or replace defective fuel line.

Twisted fuel inlet hose.

Remove and correctly install inletline.

FUEL FILTER warning light ON.

Clogged fuel filters.

Remove and clean engine-driven

fuel pump and gas producer fuel

control filters. (Refer to engine

operation and maintenance manual.

Page 12-1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

4. Fuel Cells

(detail A). Remove baffle support rod

from nipple and tabs in baffle.

The two fuel cells are interconnected, bladder

type cells enclosed within the lower fuselage

(9). Remove the two aluminum washers

section, directly under the cargo compartment

that are installed between crossover

floor.

fitting flange and the cell.

(10). Fold the fuel cell lengthwise and

Fuel is delivered to the engine from the left

remove through floor access opening.

fuel cell, which contains the fuel quantity tank

unit, engine starting fuel pump, an access

B. Right Fuel Cell Removal

cover and a forward and aft vent crossover

connection.

(1). Remove fuel filler shield (Ref. Sec. 2).

Remove clamp and disconnect filler

The mechanically actuated fuel shutoff valve is

from fuel cell neck.

located adjacent to the fuel quantity tank unit

(2). Remove nylon lacing.

on the access cover of the left fuel cell.

(3). Remove two bolts and washers from

The right fuel cell contains an access cover, a

forward fuel vent crossover fitting:

filler neck, and a forward and aft vent cross−

remove the two aluminum washers

over connection.

between the fitting and cell.

The fuel cells are supported by a fiberglass

(4). Remove nut and seal washer from aft

liner on the fuselage frames and secured by

vent fitting.

nylon lacing strung through non−metallic

hangers on the cells and supporting eyelets on

(5). Release two baffle support hooks by

the structure.

lifting tank upward at each end of

baffle support rod (detail A).

5. Fuel Cell Replacement

(6). Remove baffle support rod from nipple

and tabs of baffle.

(Ref. Figure 12−1)

(7). Fold the fuel cell lengthwise and

A. Left Fuel Cell Removal

remove through floor access opening.

(1).

Remove fuel cell covers.

C. Fuel Cell Installation

(2).

Using a spanner wrench to hold the

(1). Check that all electrical power is OFF

crossover fitting in the right cell,

and disconnect battery and external

remove nut and O−ring from fitting in

power. Check that helicopter is electri−

left cell.

cally grounded and left and right fuel

cell compartments are clean and free of

(3).

Remove lacing from left cell.

obstructions.

(4).

Remove starting pump.

(2). Fold fuel cells lengthwise and insert the

fuel cells into their respective compart−

(5).

Remove four bolts and washers that

ment. Align openings in the fuel cells

secure mounting pad to structure.

with associated openings in the struc−

ture.

(6).

Remove the fuel vent cover (Ref. Sec. 2).

Remove two bolts and washers from

(3). Install starting pump.

forward vent crossover fitting.

(4). Install the baffle support rods through

(7).

Remove nut and seal washer from rear

the tank baffle tabs and insert ends of

vent tube fitting. Disconnect clamp and

rod into the mating nipples inside the

remove powerplant supply tube from

fuel cells. Connect the four baffle

the union in Sta. 124.00 bulkhead.

support hooks to the structure (detail

A).

(8).

Release two baffle support hooks from

structure by lifting tank upward at

(5). Coat O−ring with petrolatum (34,

each end of the baffle support rod

Table 2−4) and install O−ring and cell

Page 12-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

interconnect fitting nut. Hold the fitting

leaks. Repair cause of any leakage as

in the right cell with a spanner wrench

necessary. Check fuel quantity indicator

and tighten nut. After nut has been

for correct indication.

tightened, end face of cell fitting must

(17). Install left and right access plates in

not be located more than 0.005 inch

cargo compartment floor.

(0.127 mm) inside exposed face of nut;

protrusion through nut is acceptable

6. Fuel Cell Cover Replacement

(detail B).

(Ref. Figure 12−1)

(6).

Install right fuel cell cover with twelve

A. Left Fuel Cell Cover Removal

washers and bolts; torque bolts to 50 −

(1).

Check that all electrical power is OFF

70 inch−pounds (5.65 − 7.91 Nm).

and disconnect battery and external

power.

(7).

Connect forward fuel vent crossover

fitting with four steel washers, four

(2).

Check that helicopter is electrically

aluminum washers between crossover

grounded.

fitting and fuel cell, and bolts. Torque

(3).

Drain all fuel from the fuel cells.

bolts to 20 − 25 inch−pounds (2.26 −

2.82 Nm).

(4).

Purge the fuel cells with dry filtered

compressed air.

(8).

Install nylon lacing (details C, D, and

(5).

Remove lockwire and disconnect

E). Draw lacing taut and tie each end

electrical connections from tank unit

with a bowline (detail D).

and from fuel pump receptacle.

(9).

Place clamp on filler and connect filler

(6).

Loosen nut and disconnect control cable

to fuel cell neck; tighten clamp. Install

wire from swivel in lever of fuel shutoff

fuel filler shield.

valve. Disconnect powerplant supply

(10).

Install new seal washers and aft vent

tube at fuel shutoff valve.

tube nuts. Torque nuts to 40 − 60

(7).

Remove tank unit (fuel quantity

inch−pounds .

transmitter) (Ref. Sec. 17).

(11).

Install four washers and bolts to secure

(8).

Remove bolts and washers from left fuel

fuel inlet mounting pad; torque bolts to

cell cover. (A headless setscrew is

20 − 25 inch−pounds. Install fuel cell

installed in place of the most inboard

drain valve in fuel inlet mounting pad

bolt and washer.)

and safety with 0.032 inch (0.8128 mm)

(9).

Remove the six attaching screws that

lockwire (2).

secure the three left fuel cell cover

support brackets. Remove the brackets

(12).

Install lacing (details C and E). Draw

and the three washers that are

lacing taut and tie each end with a

installed between the brackets and the

bowline (detail D).

cover.

(13).

Install left fuel cell cover.

(10).

Move left fuel cell cover sufficiently to

gain access to the starting pump supply

(14).

Install tank unit (Ref. Sec. 17)

hose and electrical connector. Discon−

(15).

Connect powerplant supply tube at fuel

nect hose and connector from cover:

shutoff valve and torque tube nut to

then remove cover.

150 − 250 inch−pounds (16.95 − 28.25

B. Right Fuel Cell Cover Removal

Nm). Connect control cable wire to

shutoff valve lever and rig the control.

Perform steps (1). thru (4). for removal of Left

Connect electrical plug to tank unit and

Fuel Cell Cover Removal. Remove right fuel

starting fuel pump plug to receptacle.

cell cover attaching hardware; remove cover.

C. Left Fuel Cell Cover Installation

(16).

Fill the fuel cells. Connect the battery

and external power. Operate fuel pump

(1). Check that all electrical power is OFF

and make fuel leak check. Inspect fuel

and disconnect battery and external

cells and associated plumbing for fuel

power.

Page 12-3

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ACFT

NOTE 3

O−RING

CELLS

50−70 IN. LB

(5.65−7.91 NM) FUEL FILLER SHIELD

RIGHT FUEL CELL COVER

GROMMET

SUPPORT BRACKET

BAFFLE SUPPORT ROD

SUPPORT

BRACKET

TANK UNIT

CAP

FILLER

50−70 IN. LB

CLAMP

(5.65−7.91 NM)

AFT VENT

NOTE 1

CLAMP

POWER PLANT

SUPPLY TUBE

FWD VENT

TORQUE TUBE

NUTS 150−250 IN.

SYSTEM

LB (16.95−28.25 NM)

TANK BAFFLE

SHUT−OFF

SEAL WASHER

VALVE

STA. 124.00

40−60 IN. LB

FUEL INLET

(4.52−6.78 NM)

HOSE

TANK

COVER

BAFFLE

START PUMP

ANTI−CHAFING TAPE

(NOTE 4)

RIGHT FUEL

BAFFLE SUPPORT ROD

CELL

BAFFLE SUPPORT HOOK

(NOTE 2)

BAFFLE

SUPPORT HOOK

O−RING

(NOTE 2)

CELL INTERCONNECT NUT

MOUNTING

(NOTE 3)

PAD

LEFT FUEL CELL

NOTES:

LOCATION FOR HEADLESS SET SCREW.

OUTBOARD CLIP TYPICAL OF INBOARD CLIP.

AFTER NUT HAS BEEN TIGHTENED, END FACE OF CELL FITTING MUST NOT

BE LOCATED MORE THAN 0.005 IN. (0.127 MM) INSIDE OF EXPOSED FACE OF

NUT; FITTING PROTRUSION THROUGH NUT IS ACCEPTABLE.

USE TAPE (42 OR 56, TABLE 2−4).

30−119−1F

Figure 12-1. Fuel Cell Installation (Sheet 1 of 2)

Page 12-4

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

BOWLINE KNOT

TOP OF TANK

START LACING WITH

BOWLINE KNOT

(FOLLOW ARROWS)

END LACING WITH

NYLON LACE

BOWLINE KNOT

NYLON LACE

LOOP

START LACING WITH

BOWLINE KNOT

(FOLLOW ARROWS)

END LACING WITH

BOWLINE KNOT

30−119−2C

Figure 12-1. Fuel Cell Installation (Sheet 2 of 2)

(2).

Check that helicopter is electrically

(8). Install washers and bolts to attach

grounded.

support brackets to left cell cover, and

cover to cell. (Substitute a headless

(3).

Install fuel pump electrical receptacle

setscrew for the most inboard bolt and

in fuel cell cover with nut; secure with

washer if the hex−head bolt contacts

lockwire.

the cargo floor structure.) Torque bolts

to 50 − 70 inch−pounds (5.65 − 7.91

(4).

Check condition of anti−chafing tape on

Nm).

powerplant supply tube. If worn,

replace with new tape (42 or 56,

(9). Install tank unit (fuel quantity trans−

Table 2−4).

mitter) (Ref. Sec. 17).

(5).

Position cover over cell opening.

(10). Connect powerplant supply tube at fuel

shutoff valve and torque tube nut to

(6).

Place clamp on powerplant supply tube

150 − 250 inch−pounds (16.95 − 28.25

and connect tube to union at Sta.

Nm). Connect control cable wire to

124.00 bulkhead; torque to 150 − 250

shutoff valve control. Connect electrical

inch−pounds (16.95 − 28.25 Nm).

plug to tank unit and starting fuel

Secure clamp to cargo floor with screw,

pump plug to receptacle.

washer and nut.

D. Right Fuel Cell Cover Installation

(7).

Install the three left fuel cell cover

support brackets and secure with six

Perform steps (1). and (2). for installation of

screws. Install one washer between

Left Fuel Cell Cover Installation. Install right

each of the bracket legs and the cover.

fuel cell cover with twelve washers and bolts;

Page 12-5

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

torque bolts to 50 − 70 inch−pounds (5.65 −

Do not use soaps or strong de−

CAUTION

7.91 Nm).

tergents when cleaning fuel

cells. Certain powerful detergents can react

with fuel to form a compound that may block

7. Fuel Cell Repair

fuel filters.

NOTE: The fuel cells are susceptible to fungus

The time and effort required for making

growth after contact with contaminated

temporary repairs to fuel cells is as great as

fuel. Fungus in a fuel cell is usually caused

that necessary for permanent repairs and the

by improper servicing and storage of jet

results are not satisfactory: therefore, the

fuels. Suitable filters and water traps

repair procedures provided are for permanent

should always be used in fuel storage tanks

cold type repairs.

and servicing equipment. If evidence of fun−

gus is present in the fuel cells, contamina−

tion is usually present in the helicopter fuel

The repairs are made with a cold type repair

filters which should be cleaned or replaced.

kit (84, Table 2−4) which contains consumable

materials listed in Table 2−4.

(1). Use hot water not exceeding 160°F

(71°C) and clean fuel cells by hand or

with a soft brush.

Either side of the fuel cell can be patched:

however, repair of a hole or tear larger than 2

(2). Use a solution of acetic acid (10% max.)

inches should not be attempted using the cold

for fuel cell cleaning. Vinegar may also

repair procedure. In such a case. contact the

be used as vinegar contains a 4−5

fuel cell manufacturer for information on

percent acetic acid concentration that

factory type repairs.

will clean and inhibit airborne fungus

growth.

A. Preparing Fuel Cell for Repairs

(3). Use jet fuels for fuel cell cleaning. The

oil content in the jet fuel will assist in

protecting the fuel cell during storage.

(1). Accomplish repair work on fuel cells in

a warm, dry place, 60° to 80°F (16° to

(4). Do NOT use MEK or similar solvents,

27°C) with a 50 percent humidity. High

alcohol, or soap for fuel cell cleaning.

humidity, especially in combination

with low temperature, will cause

NOTE: To prevent formation of bacteria, an

condensation to form on cemented

FAA approved fuel additive is recommended

surfaces and make adhesion of repair

for routine addition to the helicopter fuel

patches difficult.

cells while refueling. This is the same as the

anti−icing additive recommended in the fuel

servicing section of the Owner’s Manual.

(2). Drain cell and dry thoroughly as soon

Usually one treatment will kill the bacteria

as possible after damage. Drying may

and prevent re−growth in the fuel cells for

be speeded up by keeping cell in a

some time. Use Owner’s Manual instruc−

warm place, 80° F (27°C) and by using

tions for blending additive with fuel during

an air hose on the inside. Do not keep

servicing.

cells warm for long periods at a time.

C. Repair of Fuel Cell

(3). Thoroughly clean the cell.

(1). Remove the fuel cell.

(2). Collapse the cell and expose the

B. Fuel Cell Cleaning

damaged area on a flat working

surface.

Any one of three methods outlined in steps (1).

(3). Wipe the damaged area and surround−

thru (3). is recommended for cleaning the fuel

ing surface with a piece of cheesecloth

cells.

(53, Table 2−4) dampened with solvent

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(55) to remove any foreign material.

across at a time, so that air is not

The surface must be absolutely clean

trapped between the patch and the fuel

and dry to apply the patch.

cell material.

(4). Select and prepare a patch of synthetic

NOTE: Buffing and cementing of patch and cell

rubber−coated repair fabric:

is normally down at the same time. A clamp−

inside material (50) or

ing device consisting of two pieces of board

outside material (51) as follows:

or metal, one on each side of the seal, should

be placed over the patch and held in place by

(a). Select a patch 2 inches (5.08 cm)

two C−clamps under pressure for 8 hours. If

larger in all directions than the

such equipment is not available, a 25 pound

damaged area.

(12 kg) shot bag may be used. Oiled paper or

polyethylene should be placed between the

(b). Hand buff the material lightly and

equipment and the patch to prevent stick−

thoroughly with fine emery cloth

ing.

(49).

(c). Remove buffing dust by wiping patch

(8). Allow repair to remain undisturbed for

with slightly dampened cheesecloth

at least 8 hours; fuel cell is not to be

dipped in cement solvent.

returned to service for a minimum of 24

hours.

(d). Apply two thin, even coats of fuel cell

cement (54) to buffed side of patch,

NOTE: Twenty−four hours at temperatures of

allowing first coat to dry 15 minutes

60° to 80° F (16° to 27°C) is the minimum

before application of second coat;

time required forthe cement to fully cure for

allow second coat to dry 15 minutes.

the cold patch.

NOTE: Cement is to be used sparingly. Two

(9). Make additional minor repairs as

thin, even coats provide better adhesion

follows:

than thick uneven coats.

(a). Loose reinforcement edges, hangers

(5). Prepare damaged area of cell as follows:

or lap splices are to be lifted, buffed,

cemented thoroughly and looseness

(a). Hand−buff damaged area of cell

remedied, using procedures in steps

lightly and thoroughly with fine

(6). thru (8).

emery cloth: buffed area is to be

slightly larger in size than the patch.

(b). Scuffed areas where fabric is exposed

are to be buffed and cemented, and

(b). Remove buffing dust and apply two

allowed to air−dry for 8 hours as

thin coats of fuel cell cement to the

instructed in preceding steps. No

buffed area as described in steps

patch is required unless the fabric is

(4).(c). and (d).

torn

(6). Wipe the cemented area of the patch

and the fuel cell with cheesecloth

(10). Repairing Blisters:

moistened with solvent to make the

An inner blister is caused by trapped

surface of the cement tacky.

air between the liner and sealant.

NOTE: Application of the solvent to the cement

Blisters under 1 inch (2.54 cm) in

freshens the surface of the cement after it

diameter are not injurious and need not

has become dry to the touch.

be repaired.

(7). While still tacky, center and apply

To repair a blister:

patch to cemented area on the fuel cell

over the damaged area. Using a steel

(a). Buff surface of blister and an area

roller, or the smooth, round handle of a

extending 2 inches (5.08 cm) in all

screwdriver, roll the patch down on the

directions from its edge. Slit blister

cemented area. Roll the patch down

with a knife and buff underside of

from one edge, a half−inch to an inch

loose edges.

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(b). Thoroughly clean buffed area and

(g). Loose patches may also be repaired

apply two coats of cement to inside

by buffing, washing and cementing

surfaces, allowing proper time

separation unless it is obviously

between coats.

better to replace patch with a new

one.

(c). Roll down blister to remove all

trapped air.

8. Fuel Cell Pressure Test

(1). Plug the forward vent system.

(d). After blister has dried completely,

apply a patch of repair material (50)

(2). Install a manometer and air pressure

extending 1.50 inches (3.81 cm) in all

equipment.

directions from edge of blister, and

(3). Apply and hold 2 psi (14 kPa) of air

complete the repair in same manner

pressure for 10 minutes as a precondi−

as for inside repair.

tioning measure. This will force trapped

(11). Repairing Loose Seams and Patches:

air out from between the fuel cells and

helicopter structure. Repeat if neces−

Loose lap seams must be repaired as

sary until the cells are adjusted to the

soon as possible.

contour of the cell bay.

(4). Apply 2 psi (14 kPa) air pressure and

To repair loose seams and patches:

hold for 15 minutes with no visible, less

(a).

Buff both surfaces inside separation.

than 0.250 inch (6.35 mm), drop on

Buff an area on top of loose seam

manometer. If a pressure drop occurs,

extending 2 inches (5.08 cm) in all

check all fittings and retest the cells.

directions from edges of separation,

After careful testing, repair or replace

continuing measurement on next cell

parts as necessary to eliminate the

wall if necessary

pressure drop.

(5). Remove plug(s) from forward vent

(b).

Clean area inside separation with a

system, the manometer, and air

rag moistened with solvent (1). Allow

pressure equipment after completion of

area to dry. Apply two coats of

pressure test and or repairs.

cement (54). Allow proper drying

time between coats.

9. Fuel Filler Shield

(c).

Roll separation down firmly to

A. Fuel Filler Shield Replacement

remove trapped air and allow to dry

(Ref. Sec. 2, Fuel Filler Shield)

before proceeding.

B. Fuel Filler Shield Inspection

(d).

Cut a patch of repair material (50)

extending 1.50 inches (3.81 cm) in all

Inspect shield for cracks, crazing, and radius of

directions from edge of separation.

flanges for chipping and cracking. Inspect the

Round corners slightly and slice one

fuel inlet shield seals and grommet on side (if

edge of patch at an angle by tilting

installed) for security and deterioration.

shears instead of cutting square. Buff

C. Fuel Filler Shield Repair

patch on flat side.

(1). Repair polycarbonate fuel inlet shield

(e).

Clean buffed surface of patch and

body cracks by bonding a patch accord−

apply patch and complete the repair

ing to the criteria and methods speci−

in the same manner as for inside

fied for acrylic plastic in FAA AC 43.

repair.

13−1, Aircraft Inspection and Repair.

Use dichloromethane (38, Table 2−4) or

(f).

Loose lap seams on outside of cell

ethylene dichloride (39) as the bonding

are repaired in the same manner as

agent.

inside repair except that material

comparable to outside material of cell

(2). Repair small areas of seam separation

is used.

by injecting ethylene dichloride into the

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

void area and clamping together under

The vent tube is routed downward through the

light pressure.

control rod tunnel to a vent fairing mounted on

the bottom of the fuselage.

(3). Replace damaged or deteriorate

grommet (if installed).

An alternate venting source is provided on

current helicopters. Hughes Notice HN−8l

provides instructions for modifying early

10. Fuel Filler Cap

helicopters for the second vent provision.

(Ref. Figure 12−1) The fuel filler cap is located

A fuel cell vent line emergency shutoff valve, if

flush with the fuselage skin aft of the right

installed, connects the forward and aft vent

cargo door. The filler cap is attached to the

line hoses. The valve remains open as long as

filler neck by a safety chain.

the helicopter is within 45 degrees of normal

attitude in any direction. If this limit is

11. Fuel Filler Cap Replacement

exceeded, the vent valve closes to prevent fuel

spillage.

(1). Removal. Remove the filler cap from

filler neck by raising the spring−loaded

15. Fuel Cell Vent System Replacement

lever and rotating it counterclockwise

to OPEN. Remove the filler cap and

(Ref. Figure 12−1 and Figure 12−2)

disconnect the wire clip.

A. Forward Fuel Cell Vent System Removal

(2). Installation. Verify that the safety

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

chain is securely attached to filler neck

Disconnect external power and battery.

in fuselage and connect the safety chain

to the replacement filler cap with a wire

(2). Drain all fuel from the fuel cells into

clip. Insert cap in filler neck and rotate

suitable containers.

clockwise to CLOSE. Check that filler

cap is tight and firmly seated in filler

(3). Remove right foot support fairing,

neck.

controls access door, and fuel vent cover

(Ref. Sec. 2), Remove lockwire from

12. Fuel Filler Cap Inspection

connector hoses; remove hoses as

required.

Inspect the filler cap gasket for deterioration.

(4). Remove forward fuel vent line attach−

Inspect the cap body for damage and the

ing hardware; remove fuel vent line. On

condition of the spring that keeps the lever

helicopters equipped with a vent line

flush.

emergency shutoff valve, remove the

right pilot’s seat for access to the third

13. Fuel Filler Cap Repair

attachment bolt.

Replace an unserviceable filler cap gasket or

(5). On helicopters with an alternate

cap. Smooth scratches and nicks by filing.

venting air source, remove lockwire and

disconnect necessary tubing and

14. Fuel Cell Vents

connector at lower tee to release lower

vent tube.

(Ref. Figure 12−1) Fuel cell vents are located

in the forward and aft end of each fuel cell.

NOTE: After disconnecting the vent system

tubing and attaching hardware, removal is

The aft vent is a short, U−shaped tube that

best accomplished with the collective pitch

interconnects the top aft end of each fuel cell;

stick in the full down position. Then rotate

the vent line is routed forward and connected

the vent valve assembly inboard and slide

to the forward vent tube.

down over landing gear structure. This posi−

tions the assembly for removal through the

The forward end of each fuel cell is intercon−

controls access door opening.

nected by a vent crossover fitting (Ref.

Figure 12−2) that is routed into the control rod

(6). Carefully pull vent tube inboard, to

tunnel in the canted bulkhead.

release from clip, and upward to

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

withdraw from flared tubing riser of

(7). Secure controls access cover, right foot

plastic vent fairing; remove vent tube.

support fairing, fuel vent cover and

right pilot’s seat, if removed.

(7). Remove crossover fitting attaching

D. Aft Fuel Cell Vent System Installation

hardware; remove crossover fitting with

two clamps and two seals attached.

(1). Position aft vent over center beam at

aft end of the fuel cell compartments

(8). Provide suitable covers or plugs for fuel

and install new seal washers.

vent holes in fuel cells and aft vent line

tube to prevent contamination.

(2). Secure aft vent to each fuel cell with

nuts: torque nuts to 40 − 60 inch−

B. Aft Fuel Cell Vent System Removal

pounds (4.52 − 6.78 Nm).

(1). Remove fuel cell covers.

(3). Connect hose from forward vent line

and install clamp.

(2). Remove two nuts to disconnect aft vent

(4). Install fuel cell covers.

from left and right fuel cells.

16. Fuel Cell Vent System Inspection

(3). Remove the hose that connects the aft

vent to the forward vent; remove aft

(Ref. Figure 12−1 and Figure 12−2)

vent and discard two seal washers.

(1). Check fuel cell vent fairing(s) for

C. Forward Fuel Cell Vent System

freedom of obstruction and undamaged

Installation

condition.

(2). Inspect vent tube for dents, cracks,

(1).

Remove protective covers or plugs from

deformation or corrosion. Minor (or

fuel vent holes in fuel cells and aft vent

smooth) dents are permissible except at

line tube.

the lower end which must fit flush with

inner diameter of lower plastic vent

(2).

Install two clamps and seals on cross−

fairing flared riser.

over fitting and position fitting in fuel

cell vent openings. Install attaching

(3). Inspect hoses, tubes, and connectors for

hardware (steel washers on top of

cracks, deterioration or obstructions.

fitting flange).

(4). Inspect crossover fitting for cracks,

(3).

Assemble lower vent tube as shown in

dents, or corrosion. Minor (or smooth)

Figure 12−2 and place lower end into

dents are permissible. Check that the

vent fairing tube and press outboard to

two anti−syphon vent holes are open

snap upper end of vent tube into clip.

and that the hole diameter, 0.025−0.030

inch (0.635−0.762 mm) is not decreased

(4).

Install upper vent tube with two

by residue.

washers, bolt, nut and clamp.

(5). Inspect the vent line emergency shutoff

valve (detail A, Figure 12−2) as follows.

(5).

Install fuel vent hoses (if removed) and

alternate vent tube (if installed);

(a). Inspect for condition outlined in steps

protect vent tube against chaffing by

(1). and (2).

wrapping with tape (42, Table 2−4) as it

passes through landing gear brace.

(b). Valve should remain open when

Secure all hoses with a double wrap of

tilted in any direction up to 45

0. 032 inch (0.8128 mm) lockwire (2)

degrees off vertical.

that ends in at least five full twists.

(c). Gently blow in valve and check that

(6).

Check that complete installation does

valve is closed at any angle in excess

not interfere with free movement of

of 45 degrees from vertical in any

flight controls.

direction.

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

EMERGENCY SHUTOFF VALVE

(CROSS−SECTION VIEW)

VALVE CLOSED WHEN

PAN

TILT EXCEEDS 45°

FROM VERTICAL

FORWARD DRAIN TUBE

OVERBOARD

(NOTE 4)

LOCKWIRE

CLIP (2 PLCS)

FUEL VENT OUT

LACING CORD (TYP)

FUEL VENT

CLAMP

UPPER VENT TUBE

FORWARD−TO−AFT

LOCKWIRE (TYP)

VENT HOSE

SIDE VENT

FAIRING

CONNECTOR HOSE

(NOTE 5)

(NOTE 3)

STEEL WASHER

TUBE

CLIP

(NOTE 1)

CLAMPS

LOWER VENT

TUBE

ANTI−SYPHON

FUEL VENT COVER

LOCKWIRE

VENT HOLES

TUBING

SEAL

CROSSOVER FITTING

(NOTE 2)

ALUMINUM WASHER

LOCKWIRE

SEAL

LOWER VENT FAIRING

(NOTE 3)

NOTES:

BONDED TO FAIRING WITH ADHESIVE (121, TABLE 2−4).

ROUTED THRU LANDING GEAR BRACE.

NOT TO BE PAINTED.

FOR ADDITIONAL INFORMATION, REFER TO SECTION 9.

DO NOT PAINT FAIRINGS MADE FROM LEXON (TRANSPARENT).

O.K. TO PAINT FAIRINGS MADE FROM FIBERGALSS (NON−TRANSPARENT).

44−028C

Figure 12-2. Forward Vent - Fuel Cell

Page 12-11

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

17. Fuel Shutoff Valve Control Assembly

helicopter, and that hole in lever arm

aligns with holes in cam and stem.

(Ref. Figure 12−3) The fuel shutoff valve

control assembly consists of a flexible sheathed

(6). Secure valve lever arm and cam to

control wire actuated by a red PULL TO

valve stem with cotter pin.

CLOSE knob mounted on the instrument

(7). Check operation of fuel shutoff valve

panel.

assembly; full throw of valve lever arm

Pulling the control knob will close the fuel

is 90 degrees, stop−to−stop.

shutoff valve attached through a swivel to the

18. Fuel Shutoff Valve Control Assembly

control wire.

Replacement

On early configuration helicopters, the control

(Ref. Figure 12−3)

wire is routed aft near the helicopter center−

line to the shutoff valve located under the

A. Fuel Shutoff Valve Control Assembly

cargo compartment floor. On current configu−

Removal

ration helicopters, the control wire is routed

aft through the outboard left side of the

(1). Remove left fuel cell access door.

helicopter floor structure.

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

swivel at valve.

Due to control wire routing, the respective

valves close in opposite directions when

(3). Remove control wire end clamp or

actuated.

strap.

Optional modification of early helicopters to

(4). Remove clamps or straps from flexible

the current fuel shutoff control configuration,

sheath.

i.e., PN 369A8104−3 to 369A8104−5, may be

accomplished as follows:

(5). Remove instrument panel left fairing

and lower cover panels.

(1). Check that existing 369A8104−3 fuel

shutoff control valve is in CLOSED

(6). Loosen control assembly nut at instru−

position, with valve lever arm pointing

ment panel and run nut off threaded

towards C/L of helicopter.

portion of plunger housing.

(7). Pull fuel shutoff control through

NOTE:

instrument panel mounting hole. Catch

D Use care in removing valve lever arm and

the lockwasher and nut when control

cam, to prevent loss of two detentballs

wire end passes through mounting hole.

seated in detent cavities in valve boss.

(8). Remove any unserviceable hardware.

D Note existing position of cam valve stem

to facilitate repositioning (Ref. view F).

B. Fuel Shutoff Valve Control Assembly

Installation

(2). Remove cotter pin securing valve lever

arm and cam to valve stem; remove

(1). Determine fuel shutoff control configu−

valve lever arm.

ration.

(3). Remove cam and detent balls; reposi−

(2). Install bracket (if used) and new

tion cam on valve stem 90 degrees

grommets if required.

clockwise from original position, with

holes in cam and valve stem aligned.

(3). Place control wire end of fuel shutoff

control assembly through mounting

(4). Insert detent balls in holes in top of

hole in instrument panel and place

cam; check that ball bearings are

lockwasher and nut over end of control

seated properly in detent cavities in

wire.

valve boss.

(4). Thread fuel shutoff control assembly

(5). Install valve lever on cam and valve

through mounting hole in panel,

stem; check that lever arm bends

through grommets back to fuel shutoff

downward and points away from C/L of

valve.

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(5). Tighten nut to secure forward end of

NOTE: Shutoff valves on early configuration

control.

helicopters move clockwise to OPEN as

viewed from above. Current configuration

shutoff valves and shutoff systems so modi−

(6). Install clamps and/or straps as shown

fied move counterclockwise to OPEN. If in

in Figure 12−3.

doubt, blow gently through valve to deter−

mine open and closed positions or verify cor−

(7). Install valve arm swivel and washer.

rect part number.

Insert control wire through hole in

swivel and draw taut. Install and

(2). Watch fuel shutoff valve lever to check

tighten nut. Install cotter pin.

that lever has moved to closed position.

(3). Remove cotter pin and loosen nut on

(8). Adjust control assembly.

valve lever. Press lever arm against

open stop. Position control knob to

provide a 0.090−0.150 inch (2.286−3.81

19. Fuel Shutoff Valve Control Assembly

Inspection

mm) gap between the bottom of the

operating knob and the surface of the

fixed housing. Tighten nut on swivel to

(Ref. Figure 12−3)

secure.

(1). Remove left fuel cell access door.

(4). Operate control to close fuel shutoff

valve.

(2). Inspect the fuel shutoff control assem−

(5). Check that fuel shutoff valve lever arm

bly, nylon grommets and attachments

is in the closed position against stop.

for security.

NOTE: Full throw of valve lever is 90 degrees,

stop to stop. If both stops are not contacted,

(3). Inspect control bracket, if installed, for

check valve for angular installation of 90 de−

deformation and security.

grees to fuel tank cover.

(4). Inspect valve lever for corrosion,

(6). Operate control to open the fuel shutoff

damage, and freedom of movement.

valve. Recheck for proper gap under

Operate control and check for binding.

control knob when control lever is

Minimum bend radius of cable at any

against the open stop.

point must not be less than 2.75 inches

(6.985 cm). Push knob in and check for

21. Fuel Shutoff Valve Control Assembly

0.090−0.150 inch (2.286−3.81 mm) gap

Repair

between the bottom of the operating

(Ref. Figure 12−3) If the fuel shutoff valve

hand knob and the surface of the fixed

control assembly is pulled out more than 2

housing.

inches (5.08 cm) and the ball bearing moves

out of place, accomplish the following.

20. Fuel Shutoff Valve Control Assembly

(1). Loosen the swivel that secures control

Adjustment

wire to the valve arm and establish free

movement of the wire.

(Ref. Figure 12−3)

(2). Pull plunger of control assembly

outward until small hole in side of

NOTE: If the wire end of the control cable is

plunger is slightly beyond the plunger

disconnected or loose in the swivel, avoid

housing. Insert release rod into mating

pulling the control plunger more than 2 in−

opening of the plunger. Use care to

ches (5.08 cm) from the open position to pre−

align the notch in the release rod with

vent the ball bearing from moving out of

the hole in the plunger.

place.

(3). Apply grease (18, Table 2−4) between

(1). Pull control to close fuel shutoff valve.

the plunger and plunger housing.

Page 12-13

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

STEEL BALL

RELEASE ROD

CLOSED

VALVE LEVER ARM

PLUNGER

90°

SPRING

ACFT C/L

PLUNGER

OPEN

LOCKWASHER

CAM

HOUSING

INSTRUMENT PANEL

FUEL SHUTOFF VALVE (369A8104−3)

HEXNUT

NYLON

GROMMET

INSTRUMENT PANEL

CARGO FLOOR

CLAMP

(NOTE)

PITOT PRESSURE

STA. 84.79

TUBE

PILOT’S

CLAMP

FLOOR

STA. 78.50

(NOTE)

FUEL SHUTOFF

CONTROL CABLE

NYLON

CLAMP

GROMMET

(NOTE)

NYLON

POWER PLANT SUPPLY TUBE

GROMMET

VALVE LEVER AND

150−250 IN. LB (16.95−28.25NM)

STUD

SWIVEL

STRAPS, SCREWS,

CUP

WASHERS, NUTS

FLEXIBLE SHEATH

STAINLESS STEEL

LEFT FUEL

CONTROL WIRE

CELL COVER

BRACKET

FUEL

SHUTOFF

VALVE

SEAL

FUEL INLET

HOSE

150−250 IN. LB

(16.95−28.25NM)

270−325 IN. LB

(30.51−36.72 NM)

EARLY CONFIGURATION

NOTE: SCREW, WASHER AND NUT

INSTALLATION

TYPICAL HARDWARE

30−118−1A

Figure

12-3. Fuel Shutoff Valve (Sheet 1 of 2)

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(4). Install ball bearing into hole of plunger

(6). Fill the fuel tanks. Connect the battery

and push both release rod and plunger

and external power. Operate fuel pump

inward to full open position.

and make fuel leak check. Inspect fuel

cells and associated plumbing for fuel

Use care to hold ball bearing in

leaks. Repair cause of any leakage as

CAUTION

thehole until it goes into the

necessary. Check fuel quantity indicator

plunger housing.

for correct indication.

(5). Adjust control assembly.

(7). Install left access door in cargo

compartment floor.

22. Fuel Shutoff Valve

24. Fuel Shutoff Valve Inspection

The fuel shutoff valve is located on the left fuel

(Ref. Figure 12−3)

cell cover. A lever arm, mounted on top of the

(1). Inspect the fuel shutoff valve for

fuel shutoff valve, is actuated through an arc

obvious damage

of 90 degrees by push−pull control action from

the FUEL VALVE control on the instrument

(2). Check that the control lever arm

panel. The lever arm is detented in the open

operates through a 90 degree arc of

and closed positions. One of two part number

rotation with a pull of 2.5 ±1.0 lb. (1.13

valves are used. The respective valves close in

±0.454 kg) and seats firmly in detent at

opposite directions when actuated. Refer to

the full open and closed positions.

Figure 12−3 for valve identification.

Replace a defective shutoff valve.

23. Fuel Shutoff Valve Replacement

25. Fuel Supply Drain Valves

(Ref. Figure 12−4) Two drain valves are

(Ref. Figure 12−3)

provided in the fuel supply system.

A. Fuel Shutoff Valve Removal

The main drain valve is installed in the start

pump mounting pad and is accessible from the

(1). Disconnect the powerplant supply tube

underside of the helicopter. The engine fuel

assembly and swivel assembly; remove

drain valve is installed in the engine compart−

the left fuel cell cover.

ment as part of the engine fuel supply system.

(2). Remove nut and seal to disconnect fuel

The main drain valve and early configuration

shutoff valve from fuel cell cover.

engine compartment valves are identical.

These valves consist of a spring loaded plunger

B. Fuel Shutoff Valve Installation

which is depressed and rotated clockwise or

counterclockwise to the open−stop position

(1). Install fuel shutoff valve with washer

with a screwdriver.

(if installed) and seal on left fuel cell

cover.

Depress the plunger to release it from the

open−stop position, turn and allow valve

(2). Install nut; torque nut to 150 − 250

spring tension to return it to the closed

inch−pounds (16.95 − 28.25 Nm).

position. Current configuration engine

compartment drain valves are attached to the

(3). Install fuel cell cover).

engine compartment firewall fuel fitting and

drain overboard through a flexible tube. The

(4). Install tank unit (Ref. Sec. 17).

valve is actuated by depressing the plunger at

(5). Connect powerplant supply tube at fuel

the tube attachment.

shutoff valve and torque tube nut to

26. Fuel Supply Drain Valve Replacement

150 − 250 inch−pounds (16.95 − 28.25

Nm). Connect control cable wire to

(Ref. Figure 12−4)

shutoff valve lever. Refer to Fuel

A. Fuel Supply Drain Valve Removal

Shutoff Valve Control Assembly

Adjustment for rigging instructions.

(1). Check that all electrical power is OFF

Connect electrical plug to tank unit and

and disconnect battery and external

starting fuel pump lug to receptacle.

power.

Page 12-16

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(2). Drain all fuel from the fuel cells if

compartment. The fuel hose−to−engine pump

removing the fuel cell sump drain

connection is a self closing coupling. The Sta.

valve. Drain only the supply line and

124.00−to−Sta. 137.50 supply tube is only used

engine−driven pump if removing the

on early fuel systems. Hughes Notice HN−49

supply tube drain valve.

provides instructions for optional modification

and relocation of engine fuel hose and supply

NOTE: Current supply tube drain valve is

tube to the current routing, to preclude chafing

theneedle and seat type and is recom−

and damage to the fuel line in event of a hard

mended re−placement for early type valve.

landing or a collapsed landing gear damper.

(3). Remove lockwire, disconnect drain tube

29. Engine Fuel Supply System Replacement

on firewall mounted valve; then

unscrew drain valve and remove

(Ref. Figure 12−4)

O−ring. Discard O−ring if it is unser−

viceable.

A. Engine Fuel Supply System Removal

B. Fuel Supply Drain Valve Installation

(1). Check that all electrical power is OFF

and disconnect battery and external

(1). Install O−ring (new, if necessary) on

power.

drain valve. Install and tighten drain

valve in mounting pad or firewall

(2). Close the fuel shutoff valve by pulling

fitting as applicable.

outward on the fuel control knob.

(2). Safety fuel cell drain valve to adjacent

(3). Drain fuel from engine supply system.

bolthead and/or fuel line drain valve to

(4). Remove current configuration engine

body of firewall fitting (supply tube)

fuel supply system as follows:

with lockwire (2, Table 2−4).

(a). Loosen hose nuts and remove engine

(3). On firewall mounted drain valve,

fuel hose.

connect drain line and secure with

lockwire. Check that drain tube is

(b). Remove lockwire and overboard

routed through grommet in underside

drain line from firewall drain valve.

of fuselage.

(c). Release nuts and remove firewall

(4). Check that drain valves are closed.

fitting drain valve and elbow with

Refill fuel tanks and check drain valves

O−ring as required.

for leakage. Open fuel shutoff valve and

operate pump to pressurize the system

(5). Remove early configuration engine

during the leak check.

pump fuel hose and supply tube as

follows:

27. Fuel Supply Drain Valve Inspection

(a). Loosen or remove clamps; then slide

(Ref. Figure 12−4)

fire sleeve down away from the

engine pump and unscrew the

(1). Inspect drain valve for obvious damage.

coupling halves.

Check for positive shutoff in the closed

position.

(b). Slide fire sleeve upward and discon−

nect the hose coupling assembly at

(2). On firewall mounted drain valves,

the structural ring tee fitting; cap

check that drain tube is secure and is

open fittings.

routed through the grommet in under−

side of the fuselage. Check that slack is

(c). Loosen tube nut on supply tube at

provided in the drain tube to allow for

Sta. 137.50 structural ring and at

depression of the drain valve.

Sta. 124.00 bulkhead.

(d). Spring structural ring slight aft until

28. Engine Fuel Supply System

flare on supply tube clears lip on tee

(Ref. Figure 12−4) The engine pump fuel hose

fitting. Remove supply tube; cap ends

is located at the lower left side of the engine

of tube.

Page 12-17

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

B. Engine Fuel Supply System Installation

A twisted line will result in a

CAUTION

partial blockage in the line,

(1). Install current configuration engine

causing flame−out at high power settings.

fuel supply system as follows:

(d). Slide fire sleeve over coupling

assembly at pump and tee fitting and

(a). Assemble Sta. 124.00 firewall fitting,

secure with clamps.

elbow and drain valve with O−ring as

shown in Figure 12−4. Position the

(e). Secure split end of fire sleeve with a

fitting so that the drain valve tilts

double wrap of lockwire (2,

down from the horizontal plane

Table 2−4) at a point just above the

12−16 degrees.

fitting drain valve.

30. Engine Fuel Supply System Inspection

(b). Install the engine fuel hose between

the fitting elbow and the engine fuel

(Ref. Figure 12−4)

pump.

(1). Inspect self−closing coupling halves and

bulkhead fitting for obvious damage.

(c). On the 250−C18 series engine, torque

both hose ends to 120 − 140 inch−

(2). Inspect fire sleeve for serviceable

pounds (13.56 − 15.82 Nm).

condition (no cuts, tears, ect.).

(d). On the 250−C20 engine, torque the

(3). Inspect hose for damage and signs of

fuel hose−to−pump connection to 120

leakage.

− 140 inch−pounds (13.56 − 15.82

(4). If installed, inspect Sta. 124.00−to−Sta.

Nm) and the firewall connection to

137.50 supply tube for obvious damage.

150 − 250 inch−pounds (16.95 −

28.25 Nm).

31. Start Pump

(Ref. Figure 12−4) The start pump is a

(2). Install early configuration engine pump

submerged type installed in the left fuel cell.

fuel hose and supply tube as follows:

The pump operates on 24 Vdc power and is

controlled by a 7.5 ampere circuit breaker type

NOTE: A washer should be installed under Sta.

switch on the instrument panel.

124.00 bulkhead union jamnut. When not

present, install AN960PD1216 washers if

Do not operate start pump if

CAUTION

union loosens or when left fuel cell is re−

fuel is not present. Without fuel,

moved. Jamnut torque is 400 − 420 inch−

pump rpm is to high resulting in failure of

pounds (45.19 − 47.45 Nm).

the pump motor.

32. Start Pump Replacement

(a). Spring structural ring slightly aft so

that supply tubes flares will fit over

After each opening, removal

lip of fittings at Sta. 124.00 and Sta.

WARNING

or replacement of any part

137.50.

of the engine and/or aircraft fuel sys−

tem between the aircraft fuel tank and

(b). torque supply tube nuts to 250 − 300

the engine fuel nozzle, the fuel system

inch−pounds (28.25 − 33.90 Nm).

must be bled to remove trapped air.

Failure to comply with this procedure

(c). Position engine fuel hose and cou−

can result in engine flameout or power

pling assembly between fuel supply

loss.

line fitting in structural ring and the

A. Start Pump Removal

engine fuel pump. Torque fuel pump

coupling nut to 120 − 140 inch−

(1). Remove left fuel cell cover.

pounds (13.56 − 15.82 Nm). Torque

the nuts at the fuel drain valve ends

(2). Remove the three bolts and washers

to 150 − 250 inch−pounds (16.95 −

that attach the electrical pump to the

28.25 Nm).

mounting pad; remove pump.

Page 12-18

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(3). Remove fuel inlet hose and fitting from

(6). Connect inlet hose to shut off valve

pump and retain for re−use on replace−

fitting. With fuel cell cover correctly

ment pump.

oriented, torque hose nut to 270 − 325

inch−pounds (30.51 − 36.72 Nm).

B. Start Pump Installation

(7). Install fuel cell cover.

(1). Check that all electrical power is OFF

33. Fuel System Bleeding

and disconnect battery and external

power. Check that helicopter is electri−

Fuel/air vapor discharged

cally grounded.

WARNING

during bleeding procedure

is highly flammable. Ensure helicopter

(2). Check that fuel cell is clean and free of

is electrically grounded and is not en−

foreign material.

closed in a space (i.e.. hanger) where

fuel fumes can accumulate. Do not al−

(3). Install O−ring and fitting in pump

low fuel/air mixture to get into eyes as

outlet port.

irritation or injury may result.

Proper tightening of engine

(1). Ground helicopter per general mainte−

WARNING

tubing connections is criti−

nance instructions.

cal to flight safety. Correct torque val−

(2). Set helicopter master switch to battery

ues must be used at all times. Excessive

and start pump switch to on (up)

torque on fuel or pneumatic sensing

system connections can result in crack−

position.

ing of the flare causing an air leak

(3). Place an empty container under

which can cause flameout, power loss,

overboard drain line on underside of

or overspeed.

fuselage at Sta. 124.00.

Ensure start pump wire lead is

NOTE: On helicopter with optional drain kit in−

CAUTION

wrapped around or tie−wrapped

stalled, drain valve will be located on fire−

(using only MS3367 Ty−Raps) to fuel supply

wall fitting.

hose so that there is no possibility of its in−

terfering with fuel quantity transmitter

(4). Open drain valve and allow fuel to flow

float mechanism. Ensure electrical connec−

until a steady stream flow uninter−

tions will not be strained by G−induced hose

rupted without air bubbles. Close drain

movements.

valve.

(5). Purge air from engine fuel system

(4). Install fuel inlet hose of fuel pump

(Refer to applicable Allison engine

fitting and torque to 270 − 325 inch−

operation and maintenance manuals.

pounds (30.51 − 36.72 Nm).

(6). Set start pump and master switches to

(5). Install pump assembly on mounting

OFF position.

pad with three bolts and washers.

Torque bolts to 20 − 25 inch−pounds

(7). Replace any safety wire removed during

(2.26 − 2.82 Nm).

this procedure.

Page 12-19

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

FIRE SLEEVE

(NOTE 1)

COUPLING HALVES

120−140 IN. LB (13.56−15.82 NM)

CLAMP

ENGINE FUEL

TO ENGINE−DRIVE

HOSE

FUEL PUMP

150−250 IN. LB

(16.95−28.25 NM)

STA. 137.50

STRUCTURAL RING

SUPPLY TUBE

400−420 IN. LB

(45.19−47.45 NM)

START PUMP

CLAMP

O−RING

HOSE NUT, TORQUE TO

230−260 IN LB

BOLT TORQUE TO

(25.99−29.38 NM)

250−300 IN. LB

36−46 IN LB (4.07−5.20 NM)

(28.25−33.90 NM)

UNION, TORQUE TO

FUEL LINE

280−305 IN LB

WASHER

DRAIN VALVE

STA. 124.00

(31.64−34.46 NM)

O−RING

EARLY CONFIGURATION

150−250 IN. LB

SUMP PLATE

(16.95−28.25 NM)

TO ENGINE

DRIVEN

FUEL PUMP

ENGINE FUEL HOSE

O−RING

WITH FIRE SLEEVE

WASHER

BOLT, TORQUE TO

36−46 IN LB (4.07−5.20 NM)

TANK SUMP DRAIN VALVE

150−250 IN. LB

(TORQUE 95−105 IN LB)

(16.95−28.25 NM)

START PUMP INSTALLATION

ELBOW

STA. 124.00

150−250 IN. LB

(16.95−28.25 NM)

NOTES:

NOT IN ALL HELICOPTERS. INSTALL AT FIRST OPPORTUNITY.

LOCKWIRE TO DRAIN VALVE. ALLOW SLACK IN LINE FOR

CURRENT CONFIGURATION

ACTUATION OF DRAIN VALVE.

ENSURE ELECTRICAL HARNESS IS WRAPPED AROUND FUEL

INLET HOSE TO PREVENT ANY INTERFERENCE WITH THE

FUEL TANK FLOAT.

30−120J

Figure 12-4. Fuel Start Pump Installation (Sheet 1 0f 4)

Page 12-20

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 13 Engine Oil System .

13−1

Engine Oil Supply System

13−1

Troubleshooting the Oil Supply System

13−1

Table 13−1. Troubleshooting the Oil Supply System

13−1

Figure 13−1. Engine Oil System Schematic

13−3

Engine Oil Tank

13−4

Engine Oil Tank Replacement

13−4

A. Engine Oil Tank Removal

13−4

B. Engine Oil Tank Installation

13−4

Engine Oil Tank Inspection

13−4

Engine Oil Tank Repair

13−4

Figure 13−2. Engine Oil Tank

13−5

Liquid Level (Sight) Plug Replacement

13−6

Engine Oil Cooler

13−6

Engine Oil Cooler Replacement

13−6

A. Engine Oil Cooler Removal

13−6

B. Engine Oil Cooler Installation

13−6

Figure 13−3. Engine Oil Cooler and Duct

13−7

10. Oil Cooler Inspection

13−8

11. Oil Cooler Flushing

13−8

Figure 13−4. Oil Cooler Cleaning Setup

13−8

12. Engine Oil Cooler Repair

13−9

13. Upper Flanges, Oil Cooler Duct and Engine Oil Cooler Assembly Attachment .

13−9

Figure 13−5. Nutplate Installation − Oil Cooler Duct Attachment .

13−9

14. Oil Cooler Duct Assembly

13−9

15. Oil Cooler Duct Assembly Replacement

13−9

A. Oil Cooler Duct Assembly Removal

13−9

B. Oil Cooler Duct Assembly Installation

13−9

16. Oil Cooler Duct Assembly Inspection

13−9

17. Oil Cooler Duct Assembly Repair

13−10

18. Engine Oil Supply System Drain Valve and Check Valve . .

13−10

19. Oil Supply System Drain Valve and Check Valve Replacement .

13−10

A. Oil Supply System Drain Valve and Check Valve Removal .

13−10

B. Oil Supply System Drain Valve and Check Valve Installation .

13−10

20. Oil Supply System Drain Valve and Check Valve Inspection .

13−10

21. Oil Supply System Hoses, Fittings and Tubing

13−11

22. Oil Supply System Hoses, Fittings and Tubing Replacement .

13−11

Page 13−i

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 13

ENGINE OIL SYSTEM

1. Engine Oil Supply System

a pressure relief by−pass valve. Oil then flows

from the cooler into the spherical oil tank from

(Ref. Figure 13−1) The engine oil system is a

which the oil is pumped backed to the engine

circulating dry sump−type system that

internal lubrication system.

includes the engine internal lubrication

Section 17 provides information on the engine

system, oil tank and cooler, oil cooler duct, oil

oil temperature and oil pressure indicating

temperature and pressure senders, drain and

systems.

check valves and associated interconnecting

pressure and drain hoses and tubes.

The Engine Operation and Maintenance

Manual provides detailed information and

Oil flows from the engine through a check

theory of operation for the engine.

valve at the inlet port of the oil cooler. The

circulating oil is cooled to approximately 185°F

Refer to CSP−H−3 for information on optional

(85°C) by air blown through the cooler by the

armor installation engine oil system and an

cooler blower that is driven by the main

optional engine oil tank and oil cooler drain

transmission drive shaft.

kit.

The oil cooler contains a thermostat for

2. Troubleshooting the Oil Supply System

bypassing oil around the cooler until the

engine oil reaches operating temperature and

(Ref. Table 13−1)

Table 13-1. Troubleshooting the Oil Supply System

Symptom

Probable Trouble

Corrective Action

No oil pressure or low oil

Restriction in oil lines

Inspect, clean, or replace as

pressure

necessary.

Oil filter element restricted

Inspect and clean as necessary.

(Refer to engine operation and

maintenance manual.)

Defective sender or indicator

Inspect and replace as necessary

(Ref. Sec. 17).

Oil pressure regulator valve

Adjust as necessary (Ref. Engine

improperly adjusted

Operational and Maintenance

Manual).

Oil supply low

Check oil supply and refill as

necessary.

Contaminated oil

Drain oil system and refill.

Oil pressure drops off severely

Oil supply low

Check oil supply and refill as

necessary.

Defective sender or indicator

Inspect and replace as necessary

(Ref. Sec. 17).

Oil pressure regulator valve

Adjust as necessary. Replace valve if

sticking or broken spring

spring is broken (Ref. Engine

Operation and Maintenance Manual).

Defective oil pump

Test oil pump (Ref. Engine Operation

and Maintenance Manual).

Page 13-1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 13-1. Troubleshooting the Oil Supply System (Cont.)

Symptom

Probable Trouble

Corrective Action

Excessive oil pressure fluctuation

Defective indicator

Inspect and replace as necessary

(Ref. Sec. 17).

Oil leaks

Inspect oil system hoses and tubes.

Replace as necessary.

Restriction in oil filter or pressure

Clean oil filter; adjust pressure

regulator valve

regulator valve. Replace valve if

pressure cannot be regulated (Ref.

Engine Operation and Maintenance

Manual).

Defective oil pump

Replace oil pump (Ref. Engine

Overhaul Manual).

High oil pressure

Defective indicator

Inspect and replace as necessary

(Ref. Sec. 17).

Pressure regulator valve

Adjust as necessary (Ref. Engine

improperly adjusted

Operation and Maintenance Manual).

Abnormal oil temperature

Defective temperature sender or

Inspect and replace as necessary

indication.

indicator

(Ref. Sec. 17).

Oil consumption exceeds 6.50 oz

Leakage at loose fittings or

Inspect and tighten fittings and

(28.35 g) per hour

connections

connections as necessary.

Restricted vent lines

Inspect and clean as necessary.

Defective internal engine oil seals

Replace seals or engine.

Chip detector waring light comes

System lubricant contaminated

Inspect engine chip detector (Ref.

Engine Operation and Maintenance

Manual).

Page 13-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

3. Engine Oil Tank

B. Engine Oil Tank Installation

(Ref. Figure 13−2) The engine oil tank is

(1). Install new packings and drain tube

constructed of two hemispherical aluminum

union.

alloy halves welded together to form a sphere.

(2). Install replacement sight plug.

Welded fittings for the vent tube, inlet line,

outlet line, sight plug and mounting support

(3). Position oil tank and align nutplate

complete the assembly. The replaceable sight

holes with holes in mounting bracket

plug allows visual reading of the oil level

secure with four bolts and washers.

within the tank without use of a dip stick.

(4). Install oil tank filler seal and retaining

4. Engine Oil Tank Replacement

plate. Check that oil tank filler seal

neck is properly mated over oil tank

A. Engine Oil Tank Removal

filler neck and secure with four screws,

washers, and nuts. Install oil tank filler

(1).

Drain oil system.

seal clamp.

(2).

Remove oil cooler duct for access to oil

(5). Connect drain tube (tank) to oil tank

tank.

fitting and tighten.

(3).

Disconnect oil tank vent hose at oil

(6). Connect oil cooler tank return hose to

tank support by loosening clamp

oil tank fitting and tighten.

securing the fire sleeve and sliding the

clamp and fire sleeve back to clear the

NOTE: After installing engine oil−in hose cou−

fitting; cap open end of hose.

pling and engine oil tank vent hose, steps

(7). and (8)., pull fire sleeves into position

(4).

Disconnect oil−in hose coupling at oil

and tighten clamps.

tank outlet fitting by loosening clamp

(7). Install new O−ring, connect oil−in hose

securing the fire sleeve and sliding the

coupling to oil tank fitting and tighten.

clamp and fire sleeve back to clear

fitting; allow hose to drain; then cap

(8). Install new O−ring, connect engine oil

open end of hose.

tank vent hose to fitting on oil tank

support and tighten.

(5).

Disconnect oil cooler tank return hose

at oil tank fitting; allow tube to drain;

(9). Install oil cooler duct.

then cap open end of fitting.

5. Engine Oil Tank Inspection

(6).

Disconnect tank drain tube at oil tank

fitting; allow tube to drain; then cap

Inspect engine oil tank assembly for cracks,

open end of fitting.

corrosion distortion, obvious damage, leaks

and security. Inspect all associated hoses, lines

(7).

Remove oil tank filler seal clamp.

and fittings for oil leaks and security.

Remove four nuts, washers and screws;

then cap retaining plate and the filler

6. Engine Oil Tank Repair

seal.

(1). Weld all cracks, loose fittings, open

(8).

Remove four bolts and washers that

seams, and tubes with acetylene (76,

mount tank and remove the tank.

Table 2−4), oxygen (77), and welding

rod (85). Replace a damaged tank when

(9).

Remove sight plug and O−ring when

repair is impractical or excessive.

tank repair is necessary or the plug

becomes defective.

(2). Remove or smooth scratches and nicks

by sanding and touch up the surface

(10).

Remove engine oil temperature sender

with chemical film (8).

when tank repair is necessary or if the

sender becomes defective (Ref. Sec. 17).

(3). Replace a damaged sight plug.

Page 13-4

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

BELT−DRIVEN BLOWER

UPPER OIL TANK

OIL TANK

MOUNT NUTPLATE

SIGHT PLUG

DECAL

WL LOCATOR

MARKS

SHAFT−DRIVEN

BLOWER

WL 48.63

ENGINE OIL TANK

SIGHT PLUG

80−90 IN. LB

(9.04−10.17 NM)

ENGINE OIL TANK

VENT HOSE

O−RING

OIL COOLER TANK

ENGINE OIL TANK

RETURN HOSE

ENGINE OIL IN HOSE

AND COUPLING ASSY

(NOTE)

STA. 124.00

FIREWALL

CHECK VALVE

ENGINE OIL OUT HOSE

BUSHING

AND COUPLING ASSY

TANK DRAIN TUBE

(NOTE)

WASHER OR GASKET

ENGINE OIL TEMP SENDER

OVERBOARD DRAIN TUBE

WASHER OR GASKET

O−RING

OIL TANK FILLER SEAL

UNION

OIL TANK CAP

RETAINING PLATE

FILLER SEAL

DRAIN TUBE (TANK)

CLAMP

ENGINE OIL IN HOSE

ENGINE OIL TANK

AND COUPLING

VENT HOSE

(NOTE)

NOTE: SELF−CLOSING COUPLING NOT

INSTALLED ON ALL HELICOPTERS.

30−097D

Figure 13-2. Engine Oil Tank

Page 13-5

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

7. Liquid Level (Sight) Plug Replacement

(3). Remove oil cooler duct assembly.

(1). Remove lockwire from sight plug.

(4). Remove cooler drain tube. union, and

O−ring. Cap the cooler port.

(2). Remove sight plug by unscrewing

counterclockwise.

Have an assistant hold pressure

CAUTION

with a wrench across flats of the

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

oil cooler inlet fitting during removal of the

O−ring if required, on sight plug.

engine oil− out hose and/or check valve,

steps (5). and (6)., to prevent deformation of

NOTE: When a new sight plug is being

the fitting or cooler frame.

installed the liquid level decal is applied af−

ter the plug is installed and torqued.

(5). Disconnect engine oil−out hose from

check valve.

(4). Coat threads of replacement sight plug

with lubricating oil (3, Table 2−3) and

(6). Remove check valve and O−ring. Install

place new O−ring on sight plug. Torque

protective caps on oil line and in oil

sight plug to 80 − 90 inch−pounds

cooler boss.

(9.04 − 10.17 Nm). Secure with 0.032

(7). Remove screws and washers attaching

inch (0.8128 mm) lockwire (2).

deflector to mounting flange: remove

(5). Project a line from the oil tank upper

deflector.

mounting nutplate center across the

(8). Remove six bolts, washers, and nuts

center of the sight plug and pencil mark

attaching oil cooler to structure; remove

as shown in Figure 13−2, detail A.

cooler.

Position decal WL locator marks to

match pencil marks and install decal.

(9). Cut lockwire and remove shields from

oil cooler, if installed.

8. Engine Oil Cooler

B. Engine Oil Cooler Installation

(Ref. Figure 13−3) The engine oil cooler is a

radiator−type heat exchanger that is

(1). Position shields on sides of oil cooler so

constructed of aluminum alloy tubes welded to

that missing tab on outboard shield is

an aluminum frame.

adjacent to oil in fitting. Tie shields in

place with lockwire completely around

Engine outlet oil enters the cooler through an

front and rear sides of cooler.

inlet fitting at the lower right corner, circu−

lates through the tubes, and exits through an

(2). Position oil cooler on the firewall.

outlet fitting at the upper left corner of the

Install union with a new O−ring and

cooler.

install cooler drain tube.

The pressure relief bypass valve opens at

(3). Install six bolts, washers and nuts to

25−30 psi (172−207 kPa); the thermostat valve

attach cooler to firewall.

closes at +140°−180 °F (60°−82 °C).

(4). Coat threads of check valve with

9. Engine Oil Cooler Replacement

lubricating oil (3, Table 2−3).

A. Engine Oil Cooler Removal

Have an assistant hold pressure

CAUTION

on a wrench across flats of the

NOTE: Oil cooler removal requires two people.

oil cooler inlet fitting during tightening of

the check valve and/or engine oil−out hose,

(1). Drain oil system.

steps (5). and (6)., to prevent deformation of

the fitting or cooler frame.

(2). Disconnect oil cooler tank return hose

from cooler fitting and allow to drain

(5). Install check valve with a new O−ring.

into a suitable container. Cap open end

of the oil cooler tank return hose and

(6). Install engine oil−out line with a new

the cooler port.

O−ring.

Page 13-6

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(7). Install plastic deflector using screws

Use only recommended cleaning

CAUTION

and washers.

solutions or one that is satisfac−

tory for use on aluminum. Many solutions

(8). Install tank return hose.

satisfactory for cleaning copper or copper

nickel are highly corrosive to aluminum

(9). Install oil cooler duct (para 13−23).

and. if used, will result in the destruction of

the oil cooler assembly. If equipment has

(10). Fill oil tank with lubricating oil.

been previously used with any other clean−

(11). Start and operate engine according to

ing solutions, it should be thoroughly

the Owner’s Manual. Inspect oil cooler

washed out and flushed with the recom−

and related parts for oil leaks.

mended solution.

10. Oil Cooler Inspection

(3).

Establish flushing setup as shown in

Figure 13−4. Use solvent (1, Table 2−4)

Inspect engine oil cooler for cracks, corrosion,

to clean oil cooler interior.

damaged or bulged plates, broken welds,

foreign matter clogging, oil leaks, and security.

(4).

Connect hose from discharge side of

Inspect all associated hoses and fittings for oil

pump to oil cooler outlet to provide a

leaks and security.

cleaning solution flow opposite to

direction of normal flow.

11. Oil Cooler Flushing

(5).

Connect hose from storage tank to inlet

(Ref. Figure 13−4)

port of oil cooler.

(1). Remove thermostatic valve and plug all

openings in engine oil cooler.

(6).

Start centrifugal pump and allow to

flush for 30 minutes or until the

(2). Clean exterior of engine oil cooler with

cleaning solution appears clean after

steam.

flowing through oil cooler.

HYDRAULIC PRESSURE

GUAGE

100 MESH SCREEN

INLET

HYDRAULIC PRESSURE

GUAGE

COOLER

PRESSURE RELIEF VALVE

SET FOR 75 PSI (517 KPA)

TANK

100 MESH SCREEN

CENTRIFUGAL PUMP

OUTLET

28−56 GPM (26.5 LPM);

75 PSI (517 KPA)

FULL−FLOW FILTER

DISCHARGE PRESSURE

OUT

30−094A

Figure 13-4. Oil Cooler Cleaning Setup

Page 13-8

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

NOTE: After each flushing operation, (7). thru

S−403−I FRONT FERRULE

(11)., examine the 100 mesh screens for met−

(SWAGELOK)

OIL COOLER GASKET

al or other foreign particles. If metal par−

A4972−6−02

ticles are found, clean screens with solvent

NUTPLATE

AN960PD10L WASHER

and dry with clean, filtered compressed air.

(7). Drain oil cooler.

(8). Flush oil cooler with compound (75) in

reverse direction for 30 minutes.

NAS1303−6 BOLT

(9). Reverse hoses and flush engine oil

cooler for 10 to 15 minutes in normal oil

flow direction.

(10). To rinse, flush engine oil cooler with

solvent for 10 minutes.

369A8302 ENGINE OIL

COOLER ASSY

369H8301 OR 369A8304

(11). Check filter screens for metal particles.

ENGINE OIL COOLER

Discard oil cooler if metal particles still

DUCT ASSY

appear in filter screens.

30−222

Figure 13-5. Nutplate Installation - Oil

12. Engine Oil Cooler Repair

Cooler Duct Attachment

(1). Replace a defective thermostatic valve.

14. Oil Cooler Duct Assembly

(2). Straighten bent cooling fins with a pair

of duckbill pliers ground to fit between

(Ref. Figure 13−3) The engine oil cooler duct is

a plastic assembly that directs cooling air from

cooling tubes.

the oil cooler blower to the engine oil cooler.

(3). Weld all small holes, cracked seams, or

loose fittings with welding rod (85,

15. Oil Cooler Duct Assembly Replacement

Table 2−4).

A. Oil Cooler Duct Assembly Removal

(4). Smooth scratches and nicks by sanding,

(1). Remove two clamps and air duct

and touch up the surface with chemical

connector.

film (8).

(2). Remove four bolts, spacers, washers,

13. Upper Flanges, Oil Cooler Duct and

and nuts; remove engine oil cooler duct

Engine Oil Cooler Assembly Attachment

assembly. Use care to retain spacers for

reinstallation of duct.

A nutplate installation to facilitate field

maintenance is accomplished as follows:

B. Oil Cooler Duct Assembly Installation

(1). Disconnect oil cooler duct from engine

(1). Position oil cooler duct. Install spacer at

oil cooler assembly. Discard existing

each attaching bolt location.

two nuts and 369A8304−13 spacers

Overtightening bolts can crack

used at upper flanges of duct and oil

CAUTION

the duct flange. Tighten nuts

cooler.

only to the point of firm contact.

Overtorquing bolts can crack

CAUTION

(2). Install four bolts, washers, and nuts.

duct flange; tighten bolts only to

point of firm contact and security.

(3). Install air duct connector and clamps.

(2). Reconnect duct to engine oil cooler with

16. Oil Cooler Duct Assembly Inspection

existing hardware, except install front

ferrules and clip−type nutplates to

Inspect oil cooler duct assembly for cracks,

secure top two bolts as shown in

foreign matter clogging, security and other

Figure 13−5.

signs of damage.

Page 13-9

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

17. Oil Cooler Duct Assembly Repair

(4). Plug opening at inlet fitting of oil cooler

and cap open end of engine oil−out hose

(1). Repair polycarbonate duct assembly

coupling.

body cracks by bonding a patch accord−

(5). Disconnect tube assemblies at drain

ing to the criteria and methods speci−

valve, and cap open ends of tubes.

fied for acrylic plastic in FAA AC

43.13−1, Aircraft Inspection and Repair.

(6). Remove two bolts, and the valve

Use dichloromethane (38, Table 2−4) or

mounting bracket.

ethylene dichloride (39) as the bonding

agent.

(7). Cut lockwire and remove the two

screws that attach drain valve to

(2). Repair small areas of seam separation

bracket.

by injecting ethylene dichloride into the

void area and clamping together under

B. Oil Supply System Drain Valve and Check

light pressure.

Valve Installation

(1). Install new O−ring in oil cooler inlet

18. Engine Oil Supply System Drain Valve and

fitting.

Check Valve

Have an assistant hold pressure

CAUTION

(Ref. Figure 13−3) The oil supply system drain

on a wrench across the flats of

valve is a three port plug−type valve mounted

the oil cooler inlet fitting during installation

on a bracket beneath the oil cooler.

of the engine oil−out hose and/or check valve

to prevent deformation of the fitting or cool−

Three oil tubes are connected to the drain

er frame.

valve; one from the oil tank, one from the oil

(2). Coat threads of check valve with

cooler, and the third providers an overboard

lubricating oil (3, Table 2−3), install

drain. The drain valve is spring−loaded in the

check valve and tighten to secure.

close position. When the valve is opened, all

ports are closed.

(3). Install new O−ring in inlet port of check

valve.

The oil system check valve is a one−way, ball

type valve mounted at the inlet fitting of the

(4). Connect engine oil−out hose coupling to

oil cooler. The check valve functions to prevent

inlet port of check valve and tighten to

hot oil from flowing back into the engine when

secure.

the engine is not operating.

(5). Install the drain valve on mounting

bracket and safety with lockwire (2,

19. Oil Supply System Drain Valve and Check

Table 2−4).

Valve Replacement

(6). Install bracket on oil cooler flange.

A. Oil Supply System Drain Valve and Check

Valve Removal

(7). Install bracket on oil cooler flange.

Connect tube assemblies to drain valve,

and tighten to secure.

(1). Drain oil system.

(8). Start and operate engine according to

Have an assistant hold pressure

CAUTION

the Owner’s Manual. Check oil supply

on a wrench across the flats of

system check valve, drain valve, and

the oil cooler inlet fitting during removal of

associated plumbing for oil leaks.

the engine oil−out hose and/or check valve to

prevent deformation of the fitting or cooler

20. Oil Supply System Drain Valve and Check

frame.

Valve Inspection

(2). Disconnect engine oil−out hose coupling

Inspect the oil system drain valve and check

and allow to drain.

valve for cracks, corrosion, security, and leaks.

Check connected hoses and tubing for leakage

(3). Remove check valve and O−ring.

at connections.

Page 13-10

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

21. Oil Supply System Hoses, Fittings and

(3). Install upper end of oil line.

Tubing

NOTE:

During tightening, rotate coupling nut

(Ref. Figure 13−2 and Figure 13−3) The hoses

of hose or tubing with one wrench while

and tubing used in the oil supply system are

holding the fitting to which it is being at−

lightweight assemblies incorporating perma−

tached securely with another wrench. This

nent fittings. The hoses located near the

procedure will prevent twisting and possible

engine are provided with fire shields.

deformation of the hose or tubing.

22. Oil Supply System Hoses, Fittings and

(4). Torque nuts of 1/4 inch tubes to 80 −

Tubing Replacement

100 inch−pounds (9.04 − 11.30 Nm)

and nuts on 5/16 inch tubes to 150 −

A. Oil Supply System Hoses, Fittings and

200 inch−pounds (16.95 − 22.60 Nm).

Tubing Removal

23. Oil Supply System Hoses, Fittings and

When removing an oil supply system hose or

Tubing Inspection

tube that is connected to lower end of oil cooler

or oil tank, drain the oil from the cooler or

(1). Inspect oil lines for kinks, uniformity of

tank before disconnecting the hose or tube.

diameter, breaks, and freedom from

Tagging or otherwise identifying fittings,

interference with adjoining structure or

tubing and hardware will facilitate reassemb−

other components.

ly.

(2). Replace defective oil lines. Inspect and

(1). Disconnect lower end of oil line. Drain

reject oil tubes for the following:

residual oil from line into suitable

(a). Kinks or dents which could obstruct

container.

oil flow. Dents are allowable up to

(2). Disconnect upper end of oil line and

0.015 inch (0.381 mm) deep.

remove line.

(b). Cracked or broken tubes or coupling

(3). Cap oil lines and all open lines to

nuts.

prevent entry of foreign matter.

(c). Cross−threaded, crushed, or other−

B. Oil Supply System Hoses, Fittings and

wise damaged coupling nuts.

Tubing Installation

(d). Chafing within clamp areas in excess

(1). Remove caps or plugs from fittings, oil

of 0.010 inch (0.254 mm). No chafing

hoses and tubes. Apply lubricating oil

is allowed at or near the flared

(3, Table 2−3) to all fittings.

tubing end.

(2). Install lower end of oil line but do not

(e). Nicks are allowable up to 0.010 inch

tighten.

(0.254 mm) deep.

Page 13-11

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 14

ENGINE IGNITION SYSTEM

1. Engine Ignition Control System

Current configuration helicopters are equipped

with start circuitry protection. A dedicated

The engine starter−ignition switch is a

START circuit breaker (optional equipment)

push−button switch located on the pilot’s

can be installed on earlier model helicopters.

collective stick. The switch is marked START

Refer to Section 20 for information on engine

and is spring−load to the OFF position.

ignition control system wiring.

Once the keyswitch is turned on, depressing

Electrical power to the key switch is controlled

the start switch energizes both the start relay

by the main power switch (master switch).

and ignition exciter, and causes the generator

The engine operation and maintenance

field circuit in the voltage regulator to open so

manual provides detailed information for

that the starter will operate as a series motor.

maintenance of the ignition system.

Electrical power to the keyswitch, starter and

Refer to CSP−H−3 for information on optional

ignition system is controlled by the main

engine automatic reignition equipment.

power selector switch on the instrument panel.

2. Troubleshooting the Ignition System

Refer to Section 19 when keyswitch or start

switch replacement is necessary.

(Ref. Table 14−1)

Table 14-1. Troubleshooting Ignition System

Symptom

Probable Trouble

Corrective Action

WARNING: Before removing or installing components of the electrical system, check that all electrical

power is OFF. If units are not immediately replaced, ensure that all electrical connector are suitably

capped and stowed and all loose cable ends are properly insulated and stowed to prevent the

possibility of shorting. Serious injury or death could result from voltages present in the electrical

system.

Engine fails to ignite (Starter

Preservative oil fouling spark

Try a second start.

operation normal)

igniter

Faulty circuit to ignition unit

Listen for ignition operation. Check for

fuel from vapor exhaust.

Check input power to ignition unit.

Isolate and replace defective part.

Faulty igniter exciter

Listen for ignition operation. Check for

fuel vapor from exhaust. Replace with

serviceable unit (Ref. Engine

Operation and Maintenance Manual).

Page 14-1

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

Table 14-1. Troubleshooting Ignition System (Cont.)

Symptom

Probable Trouble

Corrective Action

Faulty spark igniter

Listen for igniter operation. Check for

fuel vapor from exhaust. Replace with

serviceable unit (Ref. Engine

Operation and Maintenance Manual).

Spark igniter firing intermittently

Check input voltage to exciter. Check

ignition exciter by temporarily

replacing with serviceable unit (Ref.

Engine Operation and Maintenance

Manual).

Starter-generator fails to function

Key switch, start switch or

Replace defective switch or repair

with START switch pressed

interconnecting wiring defective

defective wiring (Ref. Sec. 19).

Battery voltage low

Start with APU or charge battery (Ref.

Sec. 2).

Start relay defective

Replace relay.

Voltage regulator defective

Replace regulator.

Circuit breaker out

Replace circuit breaker (If installed).

Page 14-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 15

ENGINE EXHAUST SYSTEM

1. Exhaust System

During steps (2). thru (5)., an

CAUTION

assistant must support the aft

ends of the exhaust tailpipes while the tail−

(Ref. Figure 15−1) The exhaust system consists

pipes are being secured in place. Do not al−

of two engine tailpipes attached to the engine

low the aft ends of the tailpipes to become

exhaust collector outlets by two engine−to

displaced from their proper mounting loca−

tailpipe clamps and supported at the airframe

tions; to do so may damage the forward

exhaust outlet by a cushioned hanger assem−

mounting flanges or result in a poorly mated

bly. The hanger assembly is suspended from an

clamp joint. When assembling the tailpipe

attach fitting located above the tailpipes. The

and hanger assemblies, take care not to tear

upper and lower hangers are spring−loaded

or otherwise damage the inconel pads that

together. The inconel wire mesh cushions and

serve as cushions between the hangers and

the adjoining spring provide a flexible coupling

tailpipes.

between the aft ends of the tailpipes and the

supporting structure.

(2).

Position the forward end of each

tailpipe over its respective engine

exhaust outlet opening and install the

2. Tailpipe Assembly Replacement

two clamps. Position the clamp joints at

the upper surfaces of the tailpipes and

partially tighten the clamp; final

(Ref. Figure 15−1)

tightening will be accomplished later.

(3).

Taking care not to displace the ends of

A. Tailpipe Assembly Removal

the tail pipes, install the two hanger

assemblies as shown in Figure 15−1.

(1). Remove right side thermocouple

Make certain that the hanger assembly

hardware if installed; then remove

saddles are properly positioned between

tailpipe clamp nuts and clamps.

the locating flanges at the aft ends of

the tailpipes.

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

(4).

Secure the tailpipes and hanger

bolt attaching tailpipe hanger to

assemblies together by installing the

structure fitting,

spring over the rivets connecting each

pair of hanger clips. Attach the upper

Whenever tailpipes are re−

spring hook so that the four captive

CAUTION

moved, cover the engine ex−

washers on the rivet are divided equally

haust ports with barrier material (44,

on either side of the spring hook (two

Table 2−4) or other suitable material into

washers separating the hook from each

the engine power turbine section.

hanger clip), Attach the lower spring

hook between the left side of the lower

hanger support link and the adjacent

(3). Remove the two tailpipes as an assem−

clip,

bly.

(5).

Attach the vertical link of the lower

hanger assembly to the support fitting

(4). Remove spring and hangers; then

on the structure with a bolt, two

separate the tailpipes.

washers and nut (all CRES hardware).

Tighten the nut only finger−tight at

B. Tailpipe Assembly Installation

this time.

(6).

Torque the two engine−to−tailpipe

(1). Remove the protective covers from the

clamp nuts to 15 − 18 inch−pounds

engine exhaust ports.

(1.69 − 2.03 Nm). On helicopters with a

Page 15-1

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MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

250−C20 engine installed, install

(b). If a welded pad has been installed,

thermocouple wire support on right

use a hand file and carefully grind

tailpipe clamp and secure with nut and

spot welds and residue of pad from

washer as shown in Figure 15−1.

hanger.

(7). Using a plastic or rawhide mallet, tap

(c). Install replacement cushion assembly

lightly around the outer circumference

by positioning on the hanger and

of both clamps to ensure that they are

then bending the five tabs as shown

properly seated; then re−torque the

in Figure 15−1.

clamp nuts.

(8). Torque the support fitting bolt and nut

(d). Install the replacement wire pad by

to 12 − 15 inch−pounds (1.36 − 1.69

resistance welding (poke weld) the

Nm) and safety with a cotter pin.

edges of the pad (inconel wire,

Tadpole−type, Johns−Manville PN

Tailpipe Assembly Inspection

2069 Rev. 2) to the hanger. The weld

spots should be approximately 0.250

(1). Inspect for cracks and broken weld

inch (6.35 mm) apart.

seams.

(2). Inspect for dents and bends.

(3). Repair cracks and breaks in the

tailpipes (CRES material No. 21−6−9)

(3). Inspect inconel wire pads or cushion

as follows:

assemblies on hanger assemblies for

wear, tears and for spotweld security.

(a). Using a stainless steel brush, thor−

oughly clean at least 1 inch (2.54 cm)

Tailpipe Assembly Repair

on all sides of the cracked area. The

cleaning should remove all carbon

(1). Repair dents and bends using a form

from both inner and outer surfaces

block and suitable mallet.

and from the crack itself.

NOTE: Either inconel wire pads welded to the

hanger assembly or replaceable wire cush−

(b). Weld, using the inert arc method,

ion assemblies may be installed on the ex−

with rod (78, Table 2−4). Shield the

haust system. If so desired, the welded wire

back side of the weld with inert gas

pads may be replaced with PN 369H8202

or a suitable stainless steel flux.

cushion assemblies after the welded pad is

removed and the hanger is cleaned up.

(c). Repair single cracks less than 2

inches (5.08 cm) in length by stop−

(2). Replace hanger assembly inconel wire

drilling a 0.040 inch (1.016 mm)

pads or cushions as follows:

diameter hole at the termination of

(a). Remove damaged pad by tearing off

the crack. This method of repair does

inconel wire pad or by bending five

not apply to intersecting racks that

tabs to release each cushion assem−

form an acute angle leaving an

bly.

unsupported section.

Page 15-2

Revision 18

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

Section 16 Engine Air Induction System .

16−1

Engine Air Induction System

16−1

Engine Air Induction System Inspection

16−1

Engine Air Inlet Screen

16−1

Engine Air Inlet Screen Replacement

16−1

A. Engine Air Inlet Screen Removal

16−1

Figure 16−1. Air Induction System (Without Air Inlet Screen) .

16−2

Figure 16−2. Air Inlet Screen Installation

16−3

B. Engine Air Inlet Screen Installation

16−4

Engine Air Inlet Screen Inspection

16−4

Engine Air Shield Screen Assembly

16−4

Engine Air Shield Screen Assembly Replacement

16−4

Engine Air Shield Screen Assembly Inspection

16−4

Engine Air Inlet Bell, Engine−to−Firewall Seal Ring and Engine Air

Inlet−to−Firewall Seal

16−4

10. Engine Air Inlet Bell and Engine−to− Firewall Seal Ring Replacement .

16−5

A. Engine Air Inlet Bell and Engine−to− Firewall Seal Ring Repair .

16−5

B. Engine Air Inlet−to−Firewall Seal Replacement

16−5

11. Air Induction System Drains

16−5

12. Air Induction System Drain Tubing Replacement

16−5

Figure 16−3. Air Induction System Drain Installations

16−6

Page 16−i

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

SECTION 16

ENGINE AIR INDUCTION SYSTEM

1. Engine Air Induction System

(3). Inspect engine inlet bell for cracks

breaks or other damage.

(Ref. Figure 16−1) The basic air induction

system consists of an engine air inlet installa−

(4). Inspect engine−to−firewall seal ring for

tion (plenum chamber), engine air shield

weak springs, cracks, corrosion or

screen, engine air inlet bell, engine−to−firewall

damage that prevents complete sealing

seal ring, and engine air inlet−to−firewall seal.

of the firewall. Repair or replace a

damaged ring.

(Ref. Figure 16−2) The current type engine air

induction system includes an air inlet screen

(5). Inspect engine air inlet−to=firewall seal

vertically mounted in the forward position of

for conditions that prevent complete

the aft fairing.

contact of the seal ring, Replace a

damaged seal.

The screen provides filtration of air flowing

into the engine air intake and protects against

(6). On current type system with plenum

foreign object entry. The upper portion of the

chamber drain tubing, check that

air inlet screen ends approximately 1−1/2

tubing is not deformed, corroded or

inches from the top of the aft fairing to provide

clogged.

a bypass air area.

3. Engine Air Inlet Screen

Air enters the engine air inlet fairings which

are part of the airframe. Air flows from the

The engine air inlet screen assembly is shaped

to fit the inlet area of the aft fairing. The

inlet fairings to the plenum chamber above the

screen assembly is constructed of a polycarbo−

engine air inlet bell, through the engine air

nate material bonded to an aluminum alloy

shield screen (when used) above the inlet bell

frame. The filter screen is arranged in a

and to the compressor inlet.

saw−tooth pattern to provide maximum

Air loss from the inlet chamber is prevented by

filtering capacity.

the engine−to−firewall seal ring that is

spring−loaded against the engine side of the

4. Engine Air Inlet Screen Replacement

firewall.

(Ref. Figure 16−2)

Refer to Section 10 for engine drive shaft

A. Engine Air Inlet Screen Removal

firewall seal information.

(1). Remove engine air inlet forward

Refer to CSP−H−3 for maintenance instruc−

fairings.

tions.

(2). Open hinge−mounted plenum chamber

2. Engine Air Induction System Inspection

access door on aft fairing (Section 2).

(Ref. Figure 16−1 or Figure 16−2)

(3). Install a temporary cover of cardboard

or suitable material over the engine air

(1). On helicopters equipped with the air

intake.

inlet vertical screen, inspect for security

of attachment, deformation, and screen

Use care to avoid dropping

damage. Check that screen area is not

CAUTION

screws, washers or any foreign

clogged. Inspect boot(s) on station 100

material into the engine air intake. The en−

tail rotor control rod for condition and

gine can be badly damaged by the entry of

security of attachment.

such objects.

(2). On helicopter equipped with plenum

(4). Remove clamps securing tail rotor

chamber engine air shield screen,

control rod boot to inlet screen.

inspect unit for security of attachment,

cracks, breaks and screen damage.

(5). Remove Sta. 100 tail rotor control rod.

Page 16-1

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

ENGINE AIR INLET FAIRING

AFT FUSELAGE

STRUCTURE

TAIL ROTOR SHAFT FAIRING

NOTE 1

SCREW (NOTE 2)

ENGINE AIR SHIELD SCREEN (NOTE 3)

ENGINE AIR INLET BELL

ENGINE AIR INLET−TO−FIREWALL SEAL

ENGINE SHAFT FIREWALL SEAL

ENGINE AIR INLET−TO−FIREWALL SEAL

ROTATED

ENGINE−TO−FIREWALL

SEAL RING

ENGINE AIR

INLET BELL

ENGINE SHAFT

NOTES:

FIREWALL SEAL

SHADED AREA REPRESENTS PLENUM CHAMBER.

RIVE ATTACHING SCREWS USED ON EARLY CONFIGURATION SCREEN;

TWO SCREWS USED WITH TWO SCREEN−MOUNTED CLIPS ON CURRENT

CONFIGURATION.

USED ON HELICOPTERS NOT EQUIPPED WITH AIR INLET SCREEN.

30-149

Figure 16-1. Air Induction System (Without Air Inlet Screen)

Page 16-2

Revision 19

MD Helicopters, Inc.

CSP−H−2

500 Series − Basic HMI

(6). Remove two bolts securing screen to aft

Use care to avoid dropping

CAUTION

fairing. Remove six screws securing aft

screws, washers, or any foreign

base of screen to air inlet panel.

material into the engine air intake. The en−

Remove nine screws securing forward

gine can be badly damaged by the entry of

base of screen to mast support struc−

such objects.

ture.

7. Engine Air Shield Screen Assembly

Replacement

B. Engine Air Inlet Screen Installation

(Ref. Figure 16−1)

(1). Position inlet screen in place and install

(1). Open plenum chamber access door.

attaching hardware.

(2). Remove two screws and washers and

(2). Install Sta. 100 tail rotor control rod.

un−clip engine air screen from engine

air inlet pan, or remove five screws and

(3). Install tail rotor control rod boot on

washers and lift screen from support

inlet screen and secure with clamps.

clips (early configuration).

(3). Tape a temporary cover of card board or

Before removing the temporary

CAUTION

suitable material over the engine air

cover for reinstallation of the

intake.

screen , check the entire plenum area for

any foreign material that could fall into the

Before removing the temporary

CAUTION

engine as the is removed. The engine can be

cover for reinstallation of the

badly damaged by the entry of such objects.

screen, check the entire plenum area for any

foreign material that could fall into the en−

(4). Remove temporary cover from engine

gine as the cover is removed. The engine can

air intake.

be badly damaged by the entry of such ob−

jects.

(5). Close hinge−mounted plenum chamber

(4). Remove temporary cover from engine

access door on aft fairing and be sure

air intake.

door is locked closed.

(5). Install replacement engine air shield

(6). Install engine air inlet forward fairings.

with two screws and washers, or five

screws and washers (early configura−

tion).

Engine Air Inlet Screen Inspection

(6). Inspect air inlet, base of mast, and

(1). Inspect filter for cleanliness, clogged

entire plenum chamber; remove any

areas, and foreign particle accumula−

foreign material (dirt, cotter pins, chips,

tion. Refer to Section 2 for cleaning of

etc.).

air inlet screen.

8. Engine Air Shield Screen Assembly

Inspection

(2). Inspect unit for cracks, breaks and

distortion. Check fiberglass filtering

Inspect the engine air shield screen for holes,

screen for cuts, breaks and other

breaks, tears, corrosion, or other damage.

damage.

Replace a damaged screen.

9. Engine Air Inlet Bell, Engine-to-Firewall

Engine Air Shield Screen Assembly

Seal Ring and Engine Air Inlet-to-Firewall

Seal

(Ref. Figure 16−1) The engine air shield screen

assembly is used on early helicopter configura−

(Ref. Figure 16−1) The engine air inlet bell is a

tion not equipped with an air inlet screen. The

molded nylon assembly with the bell and

engine air shield screen consists of four

mounting flange formed as a unit. The engine

aluminum alloy frames and a six−mesh,

air inlet bell provides a method of collecting

aluminum screen which are assembled and dip

and directing air from the plenum chamber to

brazed.

the engine compressor.

Page 16-4

Revision 19

CSP-H-2 BASIC HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369H HELICOPTERS - page 9