HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990)

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

INSPECTION/CHECK

WARNING

Consumable Materials

(Ref. Section 91−00−00)

D Avoid fuel vapor ignition and fire.

Item

Nomenclature

Use only nonsparking tools and ex

plosion proof work lights. Attach he

CM309

Lacquer, green

licopter to an approved electrical

N/A

Lockwire CRES

ground. Switch OFF all electrical

CM714

Tape, pressure sensitive

power. Disconnect external power

and battery before opening fuel sys

tem. Ensure work area is adequately

(1). Remove left instrument panel fairing.

ventilated.

Check for control cables marked (Jairen

D Air entering the airframe fuel supply

Inc. 16722 PN 110262-15N) with a date

lines may cause a power reduction or

of (5/18) or later, and having a swage

flameout. Fuel system vacuum leak

less than 0.50 inch (12.70 mm) in

check and fuel air bleed procedures

length. These cables are MDHS part

must be performed after opening fuel

numbers 369A8137-503 and -603.

the supply system for any reason,

prior to releasing helicopter for

(a). Inspect cable casing for a green

flight.

stripe. The green stripe indicates

that cable has been previously pull

Fuel System General Inspection

tested.

(1). Remove right and left fuel tank floor

(2). Unpainted control cables, P/N

access panels.

369A8137-503 and -603 fitting the

preceding description require a manda

(2). Inspect fuselage bottom skin for

tory 50 pound (222.4 N) pull test to

evidence of fuel leakage. No leaks

determine cable swage integrity.

allowed. Determine source and repair

as required.

(a). Unclamp cable from canopy or

(3). Inspect fuel lines, fittings, cell access

instrument panel support structure

covers, fuel quantity unit, clamps and

(Ref. Figure 401).

attaching hardware for leakage,

corrosion and security. Inspect fire

(b). Behind instrument panel; back cable

sleeves for cuts, tears and punctures.

retaining nut completely off threaded

No leakage allowed. Repair or replace

portion of casing.

components as required.

(c). Wrap a 12 inch (30.48 cm) length of

(4). Inspect electrical wiring and connectors

two inch 5.08 cm) wide duct tape or

for corrosion and security. Replace or

equivalent around cable casing about

repair wiring as required.

0.50 inch (12.70 mm) behind casing

swage or instrument panel, whichev

(5). If start pump wire is ty-rapped to start

er is furthest from front of instru

pump line, inspect security and condi

ment panel.

tion of ty-raps.

Fuel Shutoff Valve Control Cable Swage

(d). Wrap one end of 0.042 lockwire

Test (369D/E)

around cable and attach the other

end to the spring scale (Ref.

(Ref. Figure 601)

Figure 601).

Page 601

28-00-00

Revision 19

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(e). Notch a 0.265 ID x 0.063 inch (6.73

(5).

Ensure shutoff valve control knob is

ID x 1.60 mm) thick washer and

pushed in. Valve ball must be wide

position over cable between tape and

open.

back of instrument panel.

(6).

Pull control knob out to stop. Valve ball

Sudden cable separation

should be closed.

WARNING

may cause serious personal

(7).

Valves that can not be fully closed or

injury. Be properly braced while pull

opened must be overhauled or replaced

ing on the cable.

prior to further flight.

(f). Apply a steady tension through the

spring scale up to 50 pounds (222.4

(8).

Disconnect control cable from valve.

N). Relax the tension.

(9).

Inspect shutoff valve lever and cable

(g). Inspect cable casing swage for

swivel hardware for corrosion and wear.

separation.

Check lever for smooth movement from

closed to open stops.

(h). Replace separated/unserviceable

cable assemblies.

(10).

Use a spring scale to check tension

required to move valve lever from full

(i). If the swage held without apparent

open to closed. Design force require

damage, paint a green lacquer

ment is 1.5 - 3.5 pounds (6.7 - 15.6 N)

(CM309) stripe around the swage/

maximum.

casing joint.

(11).

Inspect valve for evidence of external

(3). Install and secure cable hardware.

leakage. External leakage not allowed.

(4). Perform the following inspections and

(12).

Check that lever detents at open and

checks on all model helicopters.

closed positions. Repair or replace valve

as required.

(a). Remove left fuel cell floor access

panel.

(13).

Connect and rig valve control cable.

Install cotter pin on cable swivel.

(b). Inspect fuel shutoff cable, nylon

grommets and attaching hardware

4. Fuel Quantity Transmitter Inspection

for condition and security.

(1). Remove left fuel cell floor access panel.

(c). Operate cable and check for binding.

Cable bend radius to be 3.5 inches,

(2). Check 369D helicopters for potting

minimum.

compound on top of transmitter. Apply

missing potting compound per repair

(d). Push knob in and check for 0.090 -

instructions. Check transmitter

0.150 inch (2.286 - 3.81 mm) gap

electrical terminals and wire harness

between bottom of plunger and top of

where exposed for security and condi

plunger housing (Ref. Figure 401).

tion.

Fuel Shutoff Valve Inspection

(3). Where potting compound has been

installed, use a pointed probe and

(1). Shut down and disconnect all electrical

bright light to inspect interface between

power.

potting compound and flange plate for

(2). In cargo/passenger compartment, open

voids, debonding and separations.

left fuel cell access panel.

Inspect area around terminal fasteners

for voids. No separations or voids are

(3). Disconnect fuel supply tube from fuel

allowed.

shutoff valve.

(4). Remove and test unit as required.

(4). Use an inspection mirror and flashlight

to check shutoff valve ball position.

(5). Repair or replace potting compound.

Page 603

28-00-00

TR13-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

Tank Vent System Inspection

Reconnect hose P/N 369D281071 at the

forward vent crossover fitting.

(1).

Remove the controls access door,

forward fuel vent crossover cover, right

(9). Check lower and side overboard vent

hand fuel compartment access door and

fairing passages for obstructions and

the compartment beneath the right

condition. Repair or replace fairings as

hand flight crew member's structural

required (Ref. Sec. 53-20-00).

seat.

(10). Emergency rollover valve part numbers

(2).

Inspect visible portions of the vent

OTHER than 369H8108M,

system hoses for deterioration and look

369H8108501M, 369H8108503M

for surface cracks. Replace hoses if

369H8108505 and 369D281081 are

cracks are apparent.

subject to the functional check in step

(a). below.

(3).

Inspect visible portions of the vent

tubes and crossover fittings for dents,

(a). With vent tube removed, inspect vent

cracks, deformation or corrosion.

tube emergency shutoff valve for

Smooth nonrestrictive dents are

condition. Valve should remain open

permissible.

when held vertical. Valve should be

closed when held in the 45° from

(4).

Inspect visible portions of the emer

vertical position. While held in the

gency shutoff valve for dents, cracks,

45° position, blow in the valve

deformation or corrosion. None allowed.

assembly and check that valve is

closed (do not use compressed air).

(5).

Disconnect hose P/N 369D28107-1 from

Valve shall open when returned to

the forward crossover fitting and plug

the 25° position. If obstructed,

the hose end.

replace valve.

(6).

Open the fuel filler port. Blow low-

(11). Reinstall the controls access door, the

pressure compressed air (less than 2.0

forward fuel vent crossover cover, the

psig) into the open end of the forward

right hand fuel compartment access

vent crossover fitting and listen for air

door and the compartment beneath the

passing through the tank vent to verify

right hand flight crew member's

the passage is clear and unobstructed.

structural seat.

(7).

Plug the side overboard vent fairing

openings and blow low pressure

6. Fuel System Vacuum Leak Inspection

compressed air (less than 2.0 psig) into

the lower overboard vent fairing. Listen

Fuel is drawn out of the tank by the engine

driven fuel pump when the START PUMP is

for air passage thru the fuel tank at the

switched OFF on Model 250-C20 Series

filler port. This verifies the aft vent

engine installations and at all times in Model

system and emergency shutoff valve

250-C30 engine installations. Water, ice, dirt,

will pass air and system is clear and

fungus or a few pinhole leaks in the supply

unobstructed. Unplug the side over

board vent fairing openings, plug the

system between the fuel tank sump pickup and

lower overboard vent fairing openings

engine driven fuel pump may cause power

and blow low pressure compressed air

surges, deceleration and, or flameout. A

into the side overboard vent fairing.

vacuum leak inspection will determine

Verify unobstructed airflow.

whether or not air is being drawn into the

engine fuel supply system.

(8).

Unplug hose P/N 369D281071 and

blow low pressure air (less than 2.0

Special Tools

psig) into the side overboard vent

(Ref. Section 91−00−00)

fairing. Feel for air coming out of the

Item

Nomenclature

open end of the hose, verifying unob

structed airflow. Unplug the lower

ST801

Hand operated vacuum pump kit

overboard vent fairing openings.

Page 604

TR13-001

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Air entering the airframe

(12). If system continues to leak, disconnect

WARNING

fuel supply lines may cause

and install airtight caps on lines and

a power reduction or flameout. Fuel

fitting ports in a progressive sequence

system vacuum leak check and fuel air

from fuel shutoff valve toward engine.

bleed procedures must be performed

The fuel shutoff and drain valve

after opening the fuel supply system

installations should be especially

for any reason, prior to releasing heli

suspect. Apply vacuum at each stage

copter for flight.

until leak has been isolated. Replace

parts as required.

(1).

Remove left fuel cell floor access panel.

NOTE: If the vacuum held at 7.5 Hg or better,

(2).

Pull FUEL shutoff valve knob out to

airframe system seal is satisfactory and

stop. Verify that fuel shutoff valve lever

leak is due to an engine fuel system prob

is hard against its OFF stop.

lem. Refer to the applicable Allison and Ben

dix manuals for additional information.

(3).

In engine compartment; remove the

upper drain plug from the fuel pump

(13). Apply a torque stripe to all effected fuel

filter bowl.

line fittings and nuts.

(4).

On C30 and C20R installations, remove

and plug the fuel vapor return line.

7. Start Pump Operational Check (Model

250−C20 Series Engines or 250−C30 Engine

(5).

Assemble vacuum pump (ST801) hoses,

With Optional Maintenance Fuel Pump)

filter port adapter, shutoff valve and

vacuum gauge.

(1). Remove fuel cell floor access panels.

(6).

Install the vacuum gauge in the line

Do not operate start pump in an

between the filter port adapter and

CAUTION

empty fuel tank.

shutoff valve. Attach the vacuum pump

above the shutoff valve.

(2). Refuel helicopter.

(7).

Attach vacuum test vacuum pump to

engine fuel filter upper drain port.

(3). Connect battery and external power.

Apply 8.0 Hg vacuum. Close vacuum

line shutoff valve.

(4). Set battery switch to EXT PWR.

(8).

Fuel system shall hold vacuum between

(5). Push FUEL shutoff valve knob in to

8.0 and 7.5 Hg for two minutes.

open shutoff valve.

NOTE: Vacuum loss exceeding 0.5 Hg in two

(6). Set START PUMP switch ON to

minutes indicates a leak in the system be

pressurize fuel system.

tween, and including, the fuel shutoff valve

and engine.

(7). Inspect all line connections for leaks.

(9). If test is satisfactory, remove test

vacuum. Inspect and replace filter plug

(8). Shut down start pump.

O-ring as required. Install filter plug.

(a). Repair leaks as required.

(10). On C30 and C20R installations,

reconnect and torque the fuel vapor

8. Drain Valve Inspection

return line.

(11). Retorque fuel line connections (Ref.

(1). Inspect tank sump drain valve for

Table 401) and where installed, anti-ice

leakage and security. No leakage

(airframe) fuel filter fittings and line

allowed.

nuts (Ref. Sec. 28-25-00). Repeat

vacuum test.

(2). Replace valve as required.

Page 605

28-00-00

TR13-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

9. Fuel Cell Inspection

10. Fuel Cell Leak Inspection

Consumable Materials

CAUTION

(Ref. Section 91−00−00)

Item

Nomenclature

N/A

Ammonia

D Do not work on Uniroyal fuel cell in ambi

N/A

Cloth, cotton flannel

ent temperatures below 50°F (10°C).

N/A

Phenolphthalein, crystalline

D Do not work on Engineering Fabric Corp.

CM218

Alcohol, denatured

fuel cell in ambient temperatures below

CM810

Leak detector, liquid

70°F (21°C).

CM820

Cheesecloth

D Do not remove fuel cells unless absolutely

required.

Any one of three techniques can be used to find

leaks in non-self-sealing and self-sealing fuel

cells. The methods are listed in ascending

D The barrier can be invisibly torn, punc

order of effectiveness and complexity in terms

tured or cracked by careless handling.

of required equipment, materials, time, and

effort.

D Do not carry or move cell by its metal fit

tings.

Soap bubble leak inspection.

D Never probe cell material with sharp

Phenolphthalein stain inspection.

edged or pointed tools.

Liquid stand inspection.

NOTE: The soap bubble and phenolphthalein

NOTE:

inspections require the cell to be inflated

with air.

D Non-self-sealing and self-sealing cells

are primarily a 0.002 inch (0.051 mm)

(1). Manufacture or supply the following

thick nylon barrier membrane sand

equipment necessary to do soap bubble

or phenolphthalein inspections:

wiched between lightweight construc

tions of either rubberized (Uniroyal) or

(a). Rigid, airtight closures or plugs to

plasticized (Engineered Fabrics Corp.)

seal all cell openings. Fit one cover

nylon fabric that protects and strength

plate with:

ens the barrier.

(b). An air pressurization inlet fitting.

D Self-sealing cells may have one or more

(c). A manometer or an extremely

thin layers of natural rubber sandwiched

accurate and sensitive low pressure

between the barrier and fabric plies.

air gauge.

A. Soap Bubble Leak Test Procedures

(1). Apply protective tape to all machined

metal fittings.

NOTE: Soap bubble test reliability is good for

bladder type non-self-sealing cells.

(1). Remove cell from helicopter.

(2). Perform cell inspection on a padded,

clean, craft paper covered surface.

(2). Lay cell out on a padded table. Install

cell closures.

(3). Inspect fuel cells per applicable man

(3). Inflate cell to 1/4 psi (1.7 kPa), maxi

ufacturers requirements.

mum.

Page 606

TR13-001

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(4). Unless leak is immediately evident,

(e). A red spot will appear on the cloth

maintain 1/4 psi (1.7 kPa) pressure for

where there is a leak in the cell wall.

two hours to allow any air trapped in

Mark each leak.

cell exterior laps and seams to escape.

(f). Inspect the entire exterior surface of

(5). Run soap solution around all patches,

the cell.

lap joints, seams, fittings, creases,

abrasions and any other suspicious

(5). Repair cell as required.

areas. Bubbles will appear over a leak.

(6). Mark leak areas with a white or yellow

C. Liquid Stand Inspection

crayon.

NOTE:

(7). Repair cell as required.

D Engineered Fabrics Corp. recommends

B. Phenolphthalein Stain Inspection

VITHANE\R cells be supported in a fix

Procedures

ture for the liquid stand inspection.

(1). Remove cell from helicopter.

D Uniroyal rubberized fabric cells do not re

(2). Lay cell out on a padded table. Install

quire support for this test.

all but one of the cell closures.

(1). Remove cell from helicopter and place

(3). Make phenolphthalein solution as

on a clean, padded, kraft paper covered

follows:

table.

(a). Add 40 grams phenolphthalein

crystals to 1/2 gallon (1.9 L) of

(2). Fabricate closure plates for each cell

denatured alcohol (CM218) and stir.

opening as follows:

(b). Add 1/2 gallon (1.9 L) of water. Allow

(a). The object is to completely fill the cell

to stand 30 minutes. Stir before

and eliminate all air pockets.

using.

(4). Pour commercial ammonia on an

(b). Equip one of the plates with liquid

absorbent cloth in a ratio of one

filler and vent stand pipes at least six

teaspoon (3 ml) per cubic foot of cell

inches (15 cm) tall.

capacity (minimum of 10 ml or 3.3

teaspoons).

(3). Fill the cell with Stoddard solvent,

Stanisol or Varsoline.

(a). Place the ammonia saturated cloth

inside the cell and install the remain

(4). Permit cell to stand undisturbed for 24

ing cover.

hours.

(b). Inflate cell with air to 1/4 psi (1.7

kPa) maximum. Maintain 1/4 psi (1.7

(5). Inspect paper to determine where cell is

kPa) pressure for 15 minutes mini

leaking.

mum, before proceeding.

(6). Change paper as required. Drain, turn

(c). Soak a large white cloth in the

over, refill and let cell stand for another

phenolphthalein solution. Thoroughly

24 hours to ensure liquid has contacted

wring cloth out.

all cell surfaces.

(d). Spread and smooth cloth onto cell. Do

not let cloth dry out.

(7). Repair cell as required.

Page 607

28-00-00

TR13-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

11. Fuel Tank Pressure Leak Test

forces trapped air from between fuel

cells and helicopter structure. If

Check installed fuel tanks and plumbing for

necessary, repeat until cells adjust to

leaks as follows:

contour of cell bay.

Special Tools

(5). Apply 2 psi (14 kPa) air pressure for 15

(Ref. Section 91−00−00)

minutes with no visible, less than 1/4

Item

Nomenclature

inch (6.35 mm) drop on manometer.

N/A

Manometer

NOTE: If pressure drop occurs, check all vent

plugs, fittings and re-test cells.

(1). Plug vent system.

(6). Repair or replace parts as necessary to

(2). Remove left and right cell floor access

eliminate pressure drop.

panels.

(7). Unplug vent system. Remove manome

(3). Install manometer and air pressuriza

ter and pressurization equipment.

tion equipment.

(4). Apply 2 psi (14 kPa) air pressure for 10

(8). Install left and right cell floor access

minutes to precondition cells. This

panels.

Page 608

TR13-001

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

REPAIRS

1. Fuel Shutoff Valve Control Cable Repair

(a). Only personnel specifically trained to

inspect and repair the fuel cells

installed in 369/500 series helicopters

Consumable Materials

perform the work.

(Ref. Section 91−00−00)

Item

Nomenclature

(b). Customers planning to do their own

CM118

Grease

fuel cell repairs order manuals from

the applicable cell manufacturer

before beginning repair tasks (Ref.

NOTE: Worn fuel shutoff valve control cables

Sec. 01-00-00).

are normally replaced as an assembly.

(c). Cell inspections, maintenance and

(1). The only authorized repair is replace

repair be only per the cell manufac

ment of a missing detent ball, as

turers advice and instructions.

follows:

(2). Bladder or self sealing fuel cells are

(a). Disconnect cable from fuel shutoff

supplied to MDHS by Uniroyal, Inc.,

valve lever swivel.

and Engineered Fabrics Corporation.

(b). Pull plunger out until detent ball

Engineered Fabrics Corp., and

CAUTION

hole is visible. Insert detent release

Uniroyal fuel cell construction

rod in plunger. Align notch in detent

materials, inspection requirements, repair

release rod with plunger detent ball

methods and requirements, supplies and

hole.

materials are not compatible or inter

changeable.

(c). Apply grease (CM118) between

plunger and plunger housing.

(3). Cells manufactured by Uniroyal are an

assembly of nitrile rubber impregnated

(d). Insert detent ball in plunger hole.

woven nylon inner and outer coverings

Push release rod and plunger to full

with an impervious 0.002 inch (0.051

open position.

mm) thick, nylon barrier membrane

sandwiched between the coverings.

(e). Rig fuel shutoff valve cable.

(4). Fuel cells produced by Engineered

Fuel Shutoff Valve Repair

Fabrics Corp. are constructed of

VITHANE/R polyurethane plastic

(1). Overhaul Dukes Inc. valves with repair

impregnated fabric.

kit, part No. 1595-1000. No other

repairs are authorized.

4. Uniroyal Self−Sealing and

Non−Self−Sealing Cell Repairs

(2). Electric pencil the letter M at the end of

the part number, i.e., 369A8104-5M.

Procedures in this section cover Uniroyal

self-sealing and non-self-sealing fuel cell

Fuel Cell Repair

repairs as follows:

(1). MDHS cannot guarantee the currency,

D Scuff Mark Repairs.

completeness or technical accuracy of

fuel cell repair procedures provided

D Reinforcements, Hangers and Splice

herein. Since cell repair materials,

Repairs.

techniques, and procedures may be

D Loose Patch Repair.

changed or deleted by the cell manufac

turers without notice to MDHS light

D Patch Installation.

helicopter publications; we strongly

recommend that:

D Loose Edges and Lap Seam Repair.

Page 801

28-00-00

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

D Blister Repairs.

A. Scuff Mark Repair

(1). Fabric exposed by a scuff mark may be

Fuel cells are fragile. Do not at

buffed, cleaned, coated with cement and

CAUTION

tempt to fold/unfold or handle

allowed to air-dry for 8 hours.

cells in temperatures below 50°F (10°C).

Cell material is easily cut, torn or punc

(2). No patch is required unless fabric is

tured. Never use sharp edged or pointed

torn.

tools to probe damage or to puncture blis

(3). Install patches where required (Ref.

ters. Puncturing the 0.002 inch (0.051 mm)

Patch Installation).

thick nylon fuel barrier of a non-self-seal

ing cell will cause the cell to leak. Punctur

B. Reinforcements, Hangers and Splice

ing the nylon barrier of a self-sealing cell

Repairs

will allow fuel to activate the rubber sealing

(1). Loose reinforcement edges, hangers or

agent that will swell over time and possibly

lap splices must be lifted, buffed,

rupture the cell. In any case, cells with acti

cleaned, cemented and cured under

vated seal compound are not repairable.

pressure per applicable instructions

Barrier membrane can be invisibly torn by

provided (Ref. Patch Installation).

rough handling or impact. Handle cells with

care and no more than necessary. Protect

C. Loose Patch Repair

metal fittings from damage.

(1). Replace loose patches with new patch

installations (Ref. Patch Installation).

NOTE: Accomplish fuel cell repair work in tem

peratures ranging from 60 - 80°F (16 -

(2). Where two opposing patches have been

27°C) and in less than 50% humidity.

installed over cell wall damage, unless

otherwise indicated by inspection,

replace only the loose patch.

Consumable Materials

D. Patch Installation

(Ref. Section 91−00−00)

Item

Nomenclature

(1). Drain, remove and thoroughly dry cell

as soon as possible after determining

N/A

Polyethylene plastic, sheet or roll

cell repair is required. Drying time may

CM211

Solvent

be accelerated by keeping cell at 80°F

CM219

Methyl-ethyl-ketone

(27°C) and ventilating interior with dry,

low pressure air.

CM603

Patching material

CM604

Patching material

(2). Inspect fuel cell.

CM605

Fuel cell repair kit

CAUTION

CM607

Cement

CM608

Cement

D Do not repair tears or holes over two in

ches long using cold patch repair. Do not

CM609

Repair kit

attempt to repair bonded fittings or cor

CM804

Emery cloth, fine

ners. Contact Uniroyal, Inc. when corner

CM820

Cheesecloth

or fitting damage is discovered or when

cell wall damage exceeds two inch (5.08

cm) length limit.

Special Tools

D Never expose a dry cell to high tempera

(Ref. Section 91−00−00)

tures and, or direct sunlight for long peri

Item

Nomenclature

ods of time. If repairs will not be started

N/A

C-Clamp, 8 - 12 inch

within ten days, prepare cell for storage.

N/A

Patch pressure plates, 1/2 inch thick

NOTE: Damp air, especially in combination

aluminum stock

with low temperatures, will cause water to

N/A

Brayer

condense on cement applications. Water in

hibits patch adhesion.

Page 802

Revision 19

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(3).

Both sides of a cell must be patched to

(12). Continue to wipe cell and patch,

repair any one hole or tear.

changing cheesecloth and applying

clean solvent as required, until no stain

(4).

Thoroughly clean cell internal and

or particles appear on cheesecloth pad

external repair areas with cheese cloth

after the last wipe.

(CM820) dampened with solvent

Use cement sparingly. Two,

(CM211) or MEK (CM219).

CAUTION

thin, even coats provide better

(5).

Collapse cell and expose external

adhesion than one thick coat.

damage area on a clean, flat working

(13). Position a sheet of polyethylene plastic

surface.

beneath cell damage to keep cement off

(6).

Use a greaseless silver pencil to outline

opposite cell wall.

patch installation area two inches

NOTE: Determine cement adhesive tack with a

beyond damage in all directions.

test specimen. Apply cement to a piece of

buffed, scrap patch material each time ce

(7).

Hand-buff an area 1/2 inch (12.7 mm)

ment is spread on cell and repair patch.

larger than space occupied by patch

with fine emery cloth (CM804) to

(14). Coat patch, test specimen, and fuel cell,

provide a roughened substrate for

including edges of damage, with EC678

cement application. Do not cut through

cement (CM607) or Uniroyal #3230

cell fabric.

cement (CM608). Allow cement to dry

15 minutes before application of a

(8).

Select a patch (CM604) of #5218

second coat. Allow second coat to dry 15

material for non-self-sealing cell

minutes.

exterior, or Uniroyal #5241/5241

sandwich material for self-sealing cells.

(15). Press a bare knuckle into cement on

Trim patch to extend two inches (5.08

test specimen. Cement that tears away

cm) beyond edges and ends of damage

from skin leaving a rough, finely

in all directions. Tilt scissors to bevel

peaked imprint without transferring to

patch edges away from cell surface.

knuckle, is ready for patch installation.

Radius all patch corners.

(16). Wipe cement with cheesecloth moist

ened with solvent to reactivate adhesive

(9).

Hand-buff patch gummed surface with

when required.

fine emery cloth. Ensure entire patch

joint surface has been abraded.

NOTE: A brayer or similar tool is required to

systematically roll patch into contact with

(10).

Repeat buffing procedures on cell

cell. Apply patch as follows:

interior surface. Buff internal patch

(CM603) trimmed from Uniroyal

(17). Center patch on repair area. Stick one

#5200/5187/5194 sandwich material.

edge down and double check patch

alignment. If required, release adhesive

Fuel cell and patch contact sur

by flooding joint with solvent. Check

CAUTION

faces must be perfectly clean

adhesive tack again before proceeding

and dry prior to adhesive and patch applica

with patch installation.

tion. Rubber and fabric particles, moisture,

NOTE: The object of the next step is to get the

and fuel or oil from fingers will prevent

patch down without trapping any air under

proper patch/cell adhesive cure and may

it.

subsequently provide a leak path. Wear

clean, lint free gloves to handle patch and

(18). Hold free edge of patch off cell. Follow

cell after preparing surfaces for cement and

one line and roll tool back and forth

patch application.

over patch. Advance toward loose end,

1/4 inch (6.35 mm) per pass until patch

(11). Install exterior patch first. Wipe cell

is down and free of trapped air.

exterior and patch faying surfaces with

clean cheesecloth dampened with

(19). An alternate technique is to lay

Uniroyal #3339 solvent or MEK.

prepared patch on a perfectly clean

Page 803

28-00-00

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

sheet of polyethylene plastic about

E. Loose Edge and Lap Seam Repairs

twice the size of the patch. Locate

Loose lap seams should be re

plastic sheet and patch over cell repair

CAUTION

paired as soon as possible after

area; then, slip sheet from under patch

discovery.

as patch is rolled down, 1/4 inch (6.35

mm) at a time.

NOTE: Loose lap seam edges not more than two

inches long on cell interior or exterior sur

faces may be repaired. Contact Uniroyal,

(20). Fabricate two smooth, flat, rigid, metal

Inc. for repair data addressing lap seam sep

plates with no sharp edges or corners.

arations exceeding two inch (5.08 cm) length

Plates must be larger than cemented

limit. Seam separation repairs require buff

repair area.

ing, cementing and a patch installation.

Excessive clamp pressure may

(1). Lift seam separation and buff flap and

CAUTION

deform cell and, or squeeze ce

cell faying surfaces with emery cloth

ment out of joint.

(CM804).

(2). Buff an area on exterior surface

(21). Cover both sides of repair with sheet

extending 2 inch (5.08 cm) in all

polyethylene plastic or oiled paper large

directions from seam separation.

enough to cover entire cemented area.

CAUTION

NOTE: Do not include opposite cell wall in

D Fuel cell and patch contact surfaces must

clamp up. Work through cell access opening

be perfectly clean and dry prior to adhe

and arrange cell as necessary to clamp only

sive and patch application. Rubber and

the wall with the patch installation.

fabric particles, moisture, and fuel or oil

from fingers will prevent proper patch/

(22).

Sandwich repair area and barrier

cell adhesive seal and may subsequently

material between pressure plates.

provide a leak path. Wear clean, lint free

Install at least two C-clamps over

gloves to handle patch and cell after pre

pressure plates. Equalize clamp

paring surfaces for cement and patch

pressure.

application.

D Careless application of compressed air be

(23).

Do not disturb cell. Maintain pressure

tween lap joints may separate seam fur

for six hours, minimum, after which cell

ther.

is ready for internal patch installation.

(3). Either air-vacuum or blow buffing dust

out of separation with dry, low pressure

(24).

Remove clamps and plates.

compressed air.

(25).

Clean patch and cell internal repair

(4). Wipe inside and outside of repair area

area with solvent or MEK saturated

clean with cheesecloth (CM820)

cheesecloth swabs.

moistened with solvent (CM211) or

MEK (CM219). Continue wiping with

fresh solvent dampened cheesecloth as

(26).

Apply two coats of cement, allowing 15

required until no stain or particle

minutes drying time between coats.

appears on the swab after the last wipe.

Allow 15 minutes for second coat to set.

Allow area to dry.

Use cement sparingly. Two,

(27).

Install and roll out patch.

CAUTION

thin, even coats provide better

adhesion than one thick coat.

(28).

Position a barrier sheet under each

pressure plate. Clamp and cure instal

NOTE: Determine cement adhesive tack with a

lation for a minimum of 24 hours at 60

test specimen. Apply cement to a piece of

- 80°F (16 - 27°C) before leak testing

buffed, scrap patch material each time ce

and returning cell to service.

ment is spread on cell and repair patch.

Page 804

Revision 19

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(5). Apply two coats of EC678 cement

(15). Prepare cell wall and patch for installa

(CM607) or Uniroyal #3230 (CM608)

tion (Ref. Patch Installation). Install

allowing 15 minutes between applica

patch.

tions. Allow second coat to dry 15

F. Blister Repair

minutes.

(1). Blisters can occur on cell interior and

(6). Roll separation together starting from

exterior surfaces. blisters are caused by

the bottom of the pocket toward the

a separation of the cell laminates and

open end, 1/4 inch (6.35 mm) per pass.

may contain air or a combination of air

Ensure no air is trapped underneath.

and fuel.

NOTE: Exterior blisters that contain fuel indi

(7). Cover repair with a sheet of polyethyl

cate that the barrier has been penetrated.

ene plastic or oiled paper large enough

to cover entire cemented area.

Contact Uniroyal for repair information be

fore proceeding. Blisters inside cell measur

(8). Fabricate two smooth, flat, rigid, metal

ing under one inch (2.54 cm) diameter are

plates with no sharp edges or corners.

acceptable and need not be disturbed.

Plates must be larger than cemented

(2). Buff surface of blister and area extend

repair area.

ing two inch (5.08 cm) in all directions

from its edge.

Excessive clamp pressure may

CAUTION

deform cell and, or squeeze ce

Avoid damaging nylon barrier

CAUTION

ment out of joint.

membrane. Do not probe, cut, or

puncture blisters with tool perpendicular to

(9). Cover both sides of repair with polyeth

cell wall.

ylene plastic or oiled paper sheets large

(3). Slit blister open with an X cut to expose

enough to cover entire cemented area.

all of the delaminated surface. Lift flaps

and mop interior with clean cheesecloth

NOTE: Do not include opposite cell wall in

(CM820) and solvent (CM211) or MEK

clamp up. Work through cell access opening

(CM219). Buff underlying cell surface

and arrange cell as necessary to clamp only

and blister flaps with emery cloth

the wall containing the seam repair.

(CM804). Air-vacuum or blow away all

traces of buffing dust.

(10).

Sandwich cell wall repair area and

barrier material between pressure

(4). Wipe inside and outside of repair area

plates. Install at least two C-clamps

clean with cheesecloth moistened with

over pressure plates. Equalize clamp

solvent or MEK. Continue wiping with

pressure.

fresh solvent dampened cheesecloth as

required until no stain or particle

(11).

Do not disturb cell. Maintain pressure

appears on the swab after the last wipe.

for six hours, minimum, after which cell

Allow area to dry.

is ready for patch installation.

Use cement sparingly. Two,

CAUTION

(12).

Remove clamps and plates.

thin, even coats provide better

adhesion than one thick coat.

(13).

Use Uniroyal #5200/5187/5194 sand

NOTE: Determine cement adhesive tack with a

wich patch material (CM603) on

test specimen. Apply cement to a piece of

non-self-sealing and self-sealing cell

buffed, scrap patch material each time ce

interiors.

ment is spread on cell and repair patch.

(14).

Use Uniroyal #5241/5241 sandwich

(5). Apply two coats of EC678 cement

patch material (CM604) on self-sealing

(CM607) or Uniroyal #3230 (CM608)

cell exterior surfaces or Uniroyal #5218

allowing 15 minutes between applica

patch material on non-self-sealing cell

tions. Allow second coat to dry 15

exterior surfaces.

minutes.

Page 805

28-00-00

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(6). Roll blister together starting from the

5. Fuel Quantity Transmitter Repair

bottom of each flap pocket toward the

open end, 1/4 inch (6.35 mm) per pass.

Consumable Materials

Ensure no air is trapped underneath.

(Ref. Section 91−00−00)

Item

Nomenclature

(7). Fabricate two smooth, flat, rigid, metal

CM220

Naphtha aliphatic

plates with no sharp edges or corners.

CM425

Sealing compound

Plates must be larger than cemented

CM815

Solder

repair area.

Special Tools

(Ref. Section 91−00−00)

Excessive clamp pressure may

CAUTION

Item

Nomenclature

deform cell and, or squeeze ce

N/A

Solder gun

ment out of joint.

A. Resistor installation, Transmitters

(8). Cover both sides of repair with polyeth

PN 369D296303, 369D296303−701 and

ylene plastic or oiled paper sheets large

369A4245

enough to cover entire cemented area.

(1). Remove transmitter from helicopter.

NOTE: Do not include opposite cell wall in

(2). Remove potting compound from top of

clamp up. Work through cell access opening

transmitter to expose terminals and

and arrange cell as necessary to clamp only

circuit board.

the wall containing the blister repair.

(3). Solder resistor to transmitter circuit

with tin alloy solder (Ref. Figure 501).

(9).

Sandwich cell wall repair area and

(4). Perform FUEL LEVEL LOW Caution

barrier material between pressure

Light System Test and Fuel Quantity

plates. Install at least two C-clamps

Transmitter Calibration and Adjust

over pressure plates. Equalize clamp

ment procedures.

pressure.

Naptha is a fire hazard. Per

WARNING

form work in a well venti

(10).

Do not disturb cell. Maintain pressure

lated area away from potential sources

for six hours, minimum, after which cell

of ignition.

is ready for patch installation; remove

NOTE: All transmitters with exposed wire ter

clamps and plates.

minals and, or circuit boards must be sealed

(potted) before they can be returned to ser

(11).

Use #5200/5187/5194 sandwich patch

vice.

material (CM603) on non-self-sealing

(5). Remove all grime and oily residue from

and self-sealing cell interiors.

sealing compound application area with

naptha (CM220) and a soft bristle

brush. Blow away excess solvent with

(12).

Use Uniroyal #5241/5241 sandwich

dry low pressure compressed air.

patch material (CM604) on self-sealing

cell exterior surfaces or Uniroyal #5218

(6). Ensure transmitter terminal connec

patch material (51) on non-self-sealing

tions are clean, tight, free of corrosion

cell exterior surfaces.

and dry.

(7). Heat soak transmitter assembly in an

(13).

Prepare cell wall and patch for installa

oven set at 100°F (38°C), maximum for

tion per instructions (Ref. Patch

one hour to vaporize trapped volatiles.

Installation). Install patch.

A heat gun may be used as an alternate

Page 806

Revision 19

28-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

DESCRIPTION AND OPERATION

Engine Fuel System

(8). A check valve attaches to the filler neck

fitting. The check valve located within

(1). Engine fuel system operational infor

the fuel cell. opens when the fuel cap is

mation is provided in the applicable

removed by pulling a lanyard for

Allison Engine Operation and Mainte

refueling and defueling operations. The

nance Manuals (Ref. Sec. 01-00-00).

valve closes when the fuel cap is

secured to the filler neck fitting pre

Fuel Cells

venting fuel leakage.

(9). The left-rear cell cover supports the

(1).

The MDHS helicopter standard fuel cell

manually actuated fuel shutoff valve,

consists of two interconnected crash-re

fuel supply hose, motive flow hose, fuel

sistant non-self-sealing bladder type

quantity probe wire harness and

cells having a total capacity of 116.2

attaching hardware.

U.S. gallons (439.9 Liter), with 114.6

U.S. gallons (433.8 Liter) usable.

3. Fuel Distribution

(2).

Bladder crash-resistant non-self

(1). The fuel distribution system supplies

sealing fuel cells are supplied by

fuel to the engine. The engine driven

Engineered Fabrics Corporation (Ref.

fuel pump sucks fuel from the fuel cell.

Sec. 01-00-00).

(2). Fuel is supplied from the fuel cell

through supply lines located under the

(3).

Cells are located in separate fiberglass

passenger/cargo compartment floor and

lined bays below the passenger com

within the fuel cell.

partment floor. Both cells are supported

by a system of airframe brackets,

(3). The ejector pump is driven by pressur

hangers, grommets and nylon suspen

ized fuel (motive flow) returning from

sion cords.

the engine driven fuel pump.

(4).

Each fuel cell is equipped with two

(4). The ejector pump scavenges fuel from

access covers, forward fuel vent aft fuel

the forward portion of fuel cell and

vent forward vent crossover fittings and

transfer fuel to the aft portion of the

fuel interconnect fittings.

cell, thus motive flow.

(5).

Each fuel cell contains two sump plates

4. Fuel Vent System

and two fuel drain valves

(1). Fuel cells are vented to the atmosphere

through the bottom and side fuselage

(6).

Each fuel cell is divided by an internal

ports by a system of interconnected

lateral baffle which reduces fuel

hoses and tubes attached to the forward

sloshing during changes in flight

inboard and aft inboard ends of each

attitudes. The baffles have openings

fuel cell.

across their face to allow fuel to pass

through them. This reduces the load on

(2). The fuel vent float/rollover valves are

the baffles and provides even fuel

located internally at each inboard

distribution within the cell.

upper corner of the fuel cell. The vent

float/rollover valve allows the fuel cell

(7).

Fuel tank servicing is through the cell

to vent to the atmosphere during

filler neck on the right side of the

aircraft fueling/defueling.

fuselage. The right side fuel cell

contains the gravity filler port, filler

(3). Each vent float/rollover valve is

check valve, neck, cap and attachment

designed so that when not submerged

hardware.

in fuel and with airflow through the

Page 1

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

valve between zero and the rated flow,

the instrument panel face. The flexible

the valve remain open within 25°

cable and housing is routed aft under

conical angle from vertical.

the floor to the shutoff valve lever on

the left fuel cell access cover.

(4). The valve automatically closes when

the fuel level is at or above the float

7. Fuel Shutoff Valve

actuation level to prevent fuel loss

through the vent system. The valve will

(1). The cable actuated, mechanically

detented fuel shutoff valve is located on

also close with changes in aircraft

the left fuel cell access cover. Valve

ground attitudes from 25° to 180° with

lever arm travel from full open to closed

fuel present.

is 90°.

(5). Flame arrestors located in the outlet

vent tube or standpipe prevents any

8. Fuel Filter Caution Light Pressure Switch

potential flames from reaching the vent

(1). A differential pressure switch is

float/rollover valves and fuel cell.

installed across the engine fuel pump

filter pressure AF (after filter) and BF

Fuel Quantity System

(before filter) ports just upstream of the

engine fuel pump. The switch is

(1).

The fuel quantity system is powered by

sensitive to a preset differential

24 - 28 Vdc current and consists of an

pressure. An increase in BF pressure

electromechanical fuel quantity

with a concurrent decrease in AF

indicator, a signal conditioner, two

pressure due to partial or complete

capacitance type fuel quantity probes

filter blockage may intermittently or

mounted in the left fuel cell, a float

completely close the switch depending

switch located on the aft fuel quantity

on the nature of the filtered material.

probes, a FUEL LEVEL LOW caution

Switch contacts complete an electrical

light on the instrument console and

circuit through a case ground that

interconnecting wire harness.

switches on the FUEL FILTER

caution lamp, a part of the instrument

(2).

The system is protected by a 5 ampere

console caution and warning light

circuit breaker. Power is supplied to the

array.

system from the DC bus, through a

circuit breaker.

9. Drain System and Drain Valves

(3).

The float switch provides a electrical

(1). Two spring loaded plunger tank sump

signal to the FUEL LEVEL LOW

drain valve are installed in each cell

caution light panel located on the

sump mount plate on the bottom of the

instrument panel. Refueling breaks the

left and right fuel cell. The valve is

float switch circuit and switches off the

accessed from under the helicopter.

FUEL LEVEL LOW caution lamp. The

switch is fixed to the aft fuel quantity

10. Fuel Supply Lines

probe and is not adjustable.

(1). The engine fuel supply lines consist of:

(4).

Calibrating of the fuel system is

accomplished on the fuel quantity

(a). A fuel inlet hose between the inlet

indicator calibration switch. By holding

screen to the fuel shutoff valve.

the switch in the empty or full calibra

(b). A engine feed hose between the fuel

tion positions a resistance is stored in

shutoff valve and firewall fitting.

the gauge memory circuit.

(c). A hose from the firewall fitting to the

Fuel Shutoff Valve Control

engine filter inlet port.

(1). A red fuel shutoff control knob labeled

(d). A return flow hose from engine to the

FUEL, PULL TO CLOSE is located on

firewall fitting.

Page 2

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

FAULT ISOLATION

1. Fuel System Fault Isolation

Table 101. Fuel Supply System Fault Isolation

Symptom

Probable Trouble

Corrective Action

Insufficient or no fuel to engine.

Fuel tank empty.

Refuel helicopter.

Disconnected or ruptured fuel line.

Check all fuel lines for security and

condition. Repair or replace parts as

required.

Clogged fuel line.

Repair as required.

Clogged fuel cell and start pump

Clean as required.

inlet screens.

Twisted or kinked fuel supply hose.

Repair as required.

Defective fuel shutoff valve.

Repair or replace fuel shutoff valve.

Fuel shutoff valve control cable

Repair or replace control cable.

failed or disconnected.

FUEL FILTER warning light on.

Clogged engine fuel filters.

Replace pump and gas producer fuel

control filters. Clean fuel control

pneumatic (air) circuits (refer to

Allison Engine Operation and

Maintenance Manual). When

installed, replace anti−ice (airframe)

filter (Ref. Sec. 28−25−00). Bench

check FUEL FILTER caution light

pressure switch.

Fuel contamination.

Inspect and clean the fuel cell and

start pump inlet screens if large

amounts of foreign material are

found in the engine driven fuel pump

filter (or the optional airframe fuel

filter if installed).

Defective fuel filter pressure switch.

Replace pressure switch.

Wiring fault.

Repair wiring.

Engine power surge or flameout.

Water/ice in fuel system.

Drain water out of tank and fuel

supply system.

Air in fuel system.

Bleed fuel system.

Air leaking into system.

Vacuum leak check fuel supply

system.

Page 101

28-00-60

Revision 29

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

Table 101. Fuel Supply System Fault Isolation (Cont)

Symptom

Probable Trouble

Corrective Action

Bottom of fuselage stays wet with

Loose or broken lines or fittings.

Inspect and repair as required.

fuel.

Fuel cell leak.

Remove, test and repair, or replace

cells.

Fuel cell interconnects leak

Replace cell interconnect O−rings.

FUEL LEVEL LOW caution light

Defective aft fuel quantity probe

Replace fuel quantity probe.

stays on, glows or flickers with

low level switch.

known quantity above low level.

Erroneous fuel quantity gauge

Loose or defective wiring or

Inspect wiring and repair.

readings.

connections.

Loose or incorrect wiring at the fuel Inspect wiring and repair.

quantity probes.

Defective gauge.

Remove, test and replace a defective

gauge.

Defective forward or aft fuel

Remove, test, calibrate and repair or

quantity probe.

replace probe.

Page 102

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Table 102. Fuel Quantity System Wire Data List

Wire No.

From

Termination

Specification

FQ1A22−WHT

J251−1

HSD4123−915

600N8107−7−1

87F5544

M27500−22SP2T23

FQ1A22−BLU

J251−2

HSD4123−915

600N8107−7−2

87F5544

M27500−22SP2T23

FQ2A22−WHT

J251−3

HSD4123−915

600N8107−7−S

87F5547

M27500−22SP2T23

FQ3A22−WHT

600N8107−9−S

87F5547

600N8107−7−S

87F5547

M27500−22SP3T23

FQ2A22−BLU

J251−4

HSD4123−915

600N8107−7−R

87F5546

M27500−22SP2T23

FQ3A22−BLU

600N8107−9−R

87F5546

600N8107−7−R

87F5546

M27500−22SP3T23

FQ2A22−ORN

J251−5

HSD4123−915

600N8107−7−L

87F5548

M27500−22SP2T23

FQ3A22−ORN

600N8107−9−L

87F5548

600N8107−7−L

87F5548

M27500−22SP3T23

JMPR

J251−6

HSD4123−915

OUTER SHLD

FQ4A22N

OUTER SHLD

OVERBRAID

600N8107−7

NOTE

M27500−22SP2T23

FQ5A22N

OUTER SHLD

OVERBRAID

600N8107−9

NOTE

M27500−22SP2T23

JMPR

J251−2 SHLD

HSD4123−830

J251−5 SHLD

HDS4123−915

JMPR

J251−5 SHLD

HSD4123−830

J251−7 SHLD

HDS4123−817

JMPR

P1A22 SHLD

HSD4123−830

P2A22 SHLD

HDS4123−817

J251−8

SPARE

J251−9

SPARE

J251−10

SPARE

J251−11

SPARE

J251−12

SPARE

J251−13

SPARE

NOTE: To −3 probe flange mount bolt.

OUTER

MS27474P10F35

SHIELD BRAID

OUTER

SHIELD BRAID

J25

WHT

TO LOW LEVEL SWITCH TERM.. 1 (#4 LUG)

FQ1A2

BLU

TO LOW LEVEL SWITCH TERM.. 2 (#4 LUG)

WHT

TO PROBE TERM.. S (#8 LUG)

BLU

AFT PROBE

FQ2A2

TO PROBE TERM.. R (#6 LUG)

ORN

TO PROBE TERM.. L (#10 LUG)

FQ4A2

TO AFT PROBE FLANGE MOUNTING BOLT

OUTER SHIELD

BRAID

ORN

TO PROBE TERM.. L (#10 LUG)

BLU

FQ3A2

TO PROBE TERM.. R (#6 LUG)

FORWARD PROBE

WHT

TO PROBE TERM.. S (#8 LUG)

FQ5A2

TO FORWARD PROBE FLANGE MOUNTING BOLT

6G28 020A

Figure 101. Fuel Quantity System Wiring Diagram

Page 103

28-00-60

Revision 21

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

MAINTENANCE PRACTICES

Fuel Cell Cleaning − General

(2). If a fuel cell that has previously

contained fuel is to be stored for longer

(1). Fuel cells are susceptible to fungus

than three days, coat inside of cell with

growth after contact with contaminated

a light coating of #10 weight, non-syn

fuel. Fungus trapped in the fuel filters

thetic engine oil.

indicates fuel tank contamination.

Remove, inspect, clean or replace filter

CAUTION

elements per applicable Allison Engine

Operation and Maintenance Manual.

D Engineered Fabrics Corp. cells removed

Where installed, service anti-ice

from service must not be left dry for more

(airframe) filter (Ref. Sec. 28-25-00).

than 3 days without the application of oil

as a plasticizing agent. The cell liner will

(2). Periodic incorporation of an FAA

loose pliability if left dry for extended pe

approved anti-fungal fuel additive will

riods and subsequent flexing may cause

kill and prevent new fungus growth.

the material to crack.

D Do not work on fuel cell in ambient tem

Engineered Fabrics Corp. Fuel Cell

peratures below 70°F (21°C).

Cleaning

(a). Fold cell over protective wadding as

Do not steam clean Engineered

loosely as possible and with a mini

CAUTION

Fabrics Corp. fuel cells. Steam

mum number of folds.

cleaning may cause irreparable damage.

(b). Wrap the cell in a protective cover.

(1). Clean cell exterior and interior surfaces

(c). Put cell in a suitable storage/ship

with warm soapy water and clean lint

ping container. Use wadding as

free cloth. Rinse away all soap residue

required to prevent movement. Do

and wipe dry.

not stuff cell into an undersized

container.

3. Fuel Cell Handling, Storage and Shipping

(d). Store cell at 70°F (21°C) away from

Do not use cell fittings as hand

sunlight and moisture.

CAUTION

holds. Do not store fuel cells un

Fuel System Air Bleed (Model 250−C47

crated or exposed to direct sunlight, ozone,

Engine Installation)

dirt, moisture, solvents, chemicals, or ex

tremes of heat and humidity.

Fuel/air vapor discharged

WARNING

during bleeding is a fire haz

(1). Store and ship cells in a suitable

ard. Prevent fuel vapor accumulation,

protective container.

ignition and fire. Perform work in an

open, well ventilated area away from

(a). Apply protective tape over all cell

all potential ignition sources. Attach

machined fittings.

helicopter to an approved electrical

ground. Wear approved eye protection.

(b). Use packing material to keep the cell

from shifting in transit.

(1). Helicopters with C47 engines and

standard fuel supply systems are not

(c). Suspended self-sealing cells to

equipped with a start pump.

maintain cell shape.

(2). Helicopters equipped with an airframe

4. Fuel Cell Preservation and Storage

mounted fuel filter are equipped with

(Engineered Fabrics Corp. Cells)

an airframe mounted fuel pump inside

the left fuel cell and can be primed

(1). Thoroughly clean cell with warm soapy

using the same procedure as helicopters

water. Wipe completely dry.

with the 250-C20 Series engines.

Page 201

28-00-60

Revision 32

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(3). The standard helicopter fuel system

(e). Open fuel shutoff valve.

only has an engine driven self priming

(f). Open throttle to ground idle position.

pump that will fill the fuel system when

the engine is motored with the starter.

(g). Squeeze primer bulb until fuel comes

Motor engine per the appropriate Pilot's

out of fuel line.

Flight Manual.

NOTE: When reinstalling fuel lines, refer to ap

(4). Bleed air out of helicopter engine fuel

propriate Rolls-Royce Operation and Main

controls per Rolls-Royce Engine

tenance Manual for proper torques.

Operation and Maintenance Manual.

(h). Remove primer bulb assembly from

(5). If fuel system fails to bleed properly,

fuel line and reconnect fuel line to

proceed as follows:

HMU.

(a). Field fabricate a primer bulb assem

(i). Crank engine for approximately 15

bly (Ref. Figure 201).

seconds to verify fuel to fuel nozzle is

free of air in the system.

(b). Disconnect fuel line between CEFA

and HMU at HMU side.

(j). Repeat above procedure as required.

(c). Disconnect fuel line from fuel nozzle.

(k). Reinstall fuel line to fuel nozzle.

(d). Install primer bulb assembly in line

(l). Close throttle.

between HMU GEAR INLET and the

CEFA.

(m). Close fuel shutoff valve.

CLAMPS

BULB PRIMER 5/16

AN807-8 ADAPTER

SEASIDE #73800

AN818-8 NUT

TYGON-TYPE TUBING

(FUEL RESISTANT)

FUEL SYSTEM BLEEDING TOOL

(FIELD FABRICATE)

6G28-076

Figure 201. Field Fabricated Fuel System Bleeding Tool

Page 202

Revision 39

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

REMOVAL/INSTALLATION

1. Fuel Shutoff Valve Control Cable

and grommets to fuel shutoff valve.

Replacement

Maintain a cable bend radius greater

than 3.5 inches (8.89 cm).

A. Fuel Shutoff Valve Control Cable

Removal

(2). Secure forward end of cable in instru

ment panel with lockwasher and

(Ref. Figure 401)

jamnut.

(1). Remove left aft access panel from

(3). Slip control cable wire through fuel

passenger/cargo compartment floor.

shutoff valve lever swivel.

(2). Disconnect control cable from fuel

shutoff valve swivel.

(4). Secure end of cable housing to cell cover

with a clamp, washer and screw.

(3). Remove control cable ty-raps and

clamps.

(5). Install remaining clamps and ty-raps.

(4). Remove instrument panel left fairing

(6). Rig cable with shutoff valve lever hard

and lower cover panels.

against open stop. Adjust cable to get a

0.090 - 0.150 inch (2.29 - 3.81 mm) gap

(5). Completely back jamnut away from

between bottom of control knob and

cable plunger housing (Ref. Figure 401,

cable housing end fitting. Tighten cable

view A).

swivel pinch nut. Install cotter pin.

NOTE: Attach a trace wire or cord to the valve

Control action must move valve

end of the cable before pulling assembly out

CAUTION

to full open against mechanical

of the instrument panel. Trace will guide re

stop without bottoming control knob on

placement cable into correct position.

cable housing. Control cable operation shall

(6). Pull cable assembly out through

be smooth with no binding.

washer, jamnut and instrument panel.

(7). Pull valve control knob out with a

B. Fuel Shutoff Valve Control Cable

spring scale. Required valve actuation

Installation

force not to be more than 12 pounds

(5.443 kg).

(Ref. Figure 401)

(8). Repair, adjust or replace valve control

Pulling detent knob out of cable

CAUTION

system components to meet force limit.

housing two or more inches may

result in loss of the detent ball.

(9). Install left aft fuel cell access panel

(1). Thread cable assembly aft through

from passenger/cargo compartment

instrument panel, lockwasher, jamnut

floor.

Page 401

28-00-60

Revision 19

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

2. Fuel Shutoff Valve Replacement

(6). Unclamp and disconnect control cable

from fuel shutoff valve (Ref. Fuel

Avoid fuel vapor ignition

Shutoff Valve Control Cable Replace

WARNING

and fire. Use only nonspark

ment).

ing tools and explosion proof work

lights. Attach helicopter to an ap

Handle fuel cell cover with care.

CAUTION

proved electrical ground. Switch OFF

Prying cover from cell opening

all electrical power. Disconnect exter

or rough handling may damage seal or cell

nal power and battery before opening

fitting.

fuel system. Ensure work area is ade

(7). Unbolt cell access cover. Prop cover

quately ventilated.

open with suitably padded blocks.

CAUTION

(8). Using a backup wrench on valve,

separate engine feed fuel cell supply

D Air in fuel system may cause power

hose from fuel shutoff valve.

surges or flameout. Bleed off trapped air

after opening system at any point be

(9). Remove fuel shutoff valve attaching

tween fuel tank and engine fuel nozzle.

hardware.

D Prevent fuel system contamination. In

B. Fuel Shutoff Valve Installation

stall caps on the ends of hoses, tubes and

fittings as parts are removed. Bag and

(Ref. Figure 402)

identify small parts to prevent loss or

damage.

Consumable Materials

(1). Defuel helicopter. Drain remaining fuel

(Ref. Section 91−00−00)

from cell sump drain valve into a

Item

Nomenclature

suitable container.

CM114

Petrolatum

(2). Disconnect electrical power.

(1).

Apply a coating of petrolatum (CM114)

A. Fuel Shutoff Valve Removal

to a new fuel shutoff valve/cover

(Ref. Figure 402)

sealwasher.

(1). Remove left aft fuel cell access panel

(2).

Install fuel shutoff valve with seal

from passenger/cargo compartment

washer and nut. Use a backup wrench

floor.

on shutoff valve so it will not rotate.

Torque nut 240 - 280 inch-pounds

(2). Disconnect fuel quantity probe wire

(27.12 - 31.64 Nm).

harness connector from cell cover

receptacle.

(3).

Connect engine feed fuel supply hose to

fuel shutoff valve. Using a backup

(3). Unfasten and remove Sta. 91.00 and

wrench on valve, torque fuel supply

102.00 left aft fuel cell cover support

hose 230 - 260 inch-pounds (25.99 -

brackets.

29.38 Nm).

(4). Disconnect motive flow fuel hose

(4).

Start bolts onto aft fuel cell access

assembly between Sta 124.00 bulkhead

cover.

and fuel cell access cover. Use backup

wrench on check valve so it will not

(5).

Install and fasten Sta. 91.00 and 102.00

rotate.

left fuel cell cover support brackets.

(5). Disconnect engine feed fuel supply hose

(6).

Connect engine feed fuel supply hose

assembly between fuel shutoff valve

and Sta. 124.00 bulkhead. Use backup

and Sta. 124.00 bulkhead. Torque hose

wrench on fuel shutoff valve so it will

assembly 230 - 260 inch-pounds

not rotate.

(25.99 - 29.38 Nm).

Page 403

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

CAP

ENGINE FEED HOSE

SHUTOFF

SHUTOFF VALVE TO FIREWALL

BULKHEAD

VALVE

UNION

MOTIVE FLOW HOSE

FIREWALL TO FUEL CELL

BOL

SEALING

WASHER

SCREW

WASHER

REF.

NUT

CARGO FLOOR

STRUCTURE

WASHER

BRACKET

ASSEMBLY

BOLT

WIRE

WASHER

HARNESS

RECEPTACLE

NUT

ACCESS COVER

FUEL INLET

BOLT

HOSE ASSEMBLY

WASHER

SEALING WASHER

NUT

SUBMERGED

SEALING

MOTIVE FLOW

WASHER

BULKHEAD

HOSE ASSEMBLY

ELBOW

REF. CARGO

FLOOR STRUCTURE

CHECK

VALVE

BOLT

WASHERS

BRACKET

ASSEMBLY

WASHER

NUT

FUEL CELL SCAVENGE

BRACKET ASSEMBLY

HOSE ASSEMBLY

6G28-022

Figure 402. Fuel Shutoff Valve and Fuel Cell Cover Installation

Page 404

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(7). Connect motive flow fuel hose assembly

(a). Remove right side floor panels from

between Sta 124.00 bulkhead and fuel

passenger/cargo compartment floor.

tank access cover. Torque hose assem

(b). Remove bonding jumpers then

bly 55 - 65 inch-pounds (6.21 - 7.34

remove fuel cell access cover bolts

Nm).

and washers.

(8). Connect fuel quantity transmitter

(2). To remove left aft fuel cell access cover

connector from cell cover receptacle.

(Ref. Figure 402):

(9). Progressively torque fuel cell cover

(a).

Remove left aft fuel cell access panel

bolts to 70 - 90 inch-pounds (7.91 -

from passenger/cargo compartment

10.17 Nm) in a cross pattern.

floor.

(10). Clamp and connect control cable to fuel

(b).

Unclamp and disconnect control

shutoff valve. Rig fuel shutoff valve

cable from fuel shutoff valve (Ref.

control cable (Ref. Fuel Shutoff Valve

Figure 401).

Control Cable Replacement).

(c).

Disconnect engine feed fuel supply

(11). Install left aft access passenger/cargo

hose assembly between fuel shutoff

compartment floor panel.

valve and Sta. 124.00 bulkhead. Use

backup wrench on fuel shutoff valve

so it will not rotate.

3. Fuel Cell Cover Replacement

(d).

Disconnect motive flow fuel hose

Avoid fuel vapor ignition

WARNING

assembly between Sta 124.00 bulk

and fire. Use only nonspark

head and fuel cell access cover.

ing tools and explosion proof work

lights. Attach helicopter to an ap

(e).

Disconnect fuel quantity probe wire

proved electrical ground. Switch OFF

harness connector from fuel cell cover

all electrical power. Disconnect exter

receptacle.

nal power and battery before opening

fuel system. Ensure work area is ade

(f).

Unfasten and remove Sta. 91.00 and

quately ventilated.

102.00 left aft fuel cell cover support

brackets.

CAUTION

(g).

Remove cover bolts and washers.

Prop cover open with suitably padded

D Air in fuel system may cause power

blocks.

surges or flameout. Bleed off trapped air

after opening system at any point be

(h).

Using a backup wrench on valve,

tween fuel tank and engine fuel nozzle.

separate engine feed fuel cell supply

hose from fuel shutoff valve and fuel

D Prevent fuel system contamination. In

inlet from fuel cell access cover.

stall caps on the ends of hoses, tubes and

fittings as parts are removed. Bag and

(i).

Disconnect submerged motive flow

identify small parts to prevent loss or

fuel hose assembly between fuel

damage.

check valve and ejector pump from

fuel cell access cover.

(1). Defuel helicopter. Drain remaining fuel

from cell sump drain valve into a

(j).

Disconnect fuel cell scavenge hose

suitable container.

assembly from bottom of fuel cell

access cover bracket assembly to

(2). Disconnect electrical power.

ejector pump (Ref. Figure 404).

A. Fuel Cell Cover Removal

(k).

Cut safety wire from fuel probe

electrical connector base nut and

(1). To remove right side fuel cell access

remove connector from fuel cell

covers (Ref. Figure 406).

access cover.

Page 405

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(l). If applicable, remove fuel cell scav

jamnut to 240 - 280 inch-pounds

enge hose bracket assembly,bulkhead

(27.12 - 31.64 Nm).

union and fuel shutoff valve from fuel

(d). Install support bracket to cover with

cell cover.

bolts, washer, and sealwashers.

Apply a coating of petrolatum

B. Fuel Cell Cover Installation

(CM114) to sealwasher. Torque bolts

36 - 46 inch-pounds (4.06 - 5.19

Consumable Materials

Nm).

(Ref. Section 91−00−00)

(e). Install bulkhead union to cover with

Item

Nomenclature

sealwasher next to union. Apply a

CM114

Petrolatum

coating of petrolatum (CM114) to

sealwasher. Install washer and

CM124

Kerosene

jamnut. Torque jamnut to 120 - 150

CM702

Lockwire CRES

inch-pounds (13.56 - 16.95 Nm).

Install cap outside of cell. Torque cap

to 110 - 130 inch-pounds (12.43 -

(1). Wipe fuel cell and cover sealing sur

14.69 Nm).

faces clean with kerosene (CM124) on a

clean lint free cloth.

(5). Place left forward fuel cell access cover

into position on fuel cell.

(2). Inspect fuel cell cover seals for debond

(6). Connect fuel quantity probe wire

ing, nicks or cuts and any other damage

harness connector to cell cover. Torque

having a leak producing potential.

connector jamnut and safetywire to

Replace covers or left aft cover as

bulkhead union with (CM702) lockwire.

required.

CAUTION

(3). Install bonding jumper with right cell

access covers, bolts and washers (Ref.

D On early aircraft, the fuel inlet hose and

Figure 406). Progressively torque cover

the fuel cell scavenge hose have the same

bolts to 70 - 90 inch-pounds (7.91 -

size end fitting. Care must be taken to not

10.17 Nm) in a cross pattern.

misconnect these two hoses

(Ref.

Figure 404).

(4). To install left aft fuel cell access cover

D The fuel inlet hose is the hose that runs

(Ref. Figure 402):

from the fuel inlet fitting at the bottom of

the fuel cell aft of the fuel cell baffle.

(a). Apply a coating of petrolatum

(CM114) to a new fuel shutoff valve/

D The fuel cell scavenge hose is the hose

cover sealwasher. Install valve on cell

that runs forward over the fuel cell baffle.

cover with sealwasher next to valve

(7). Install left hand fuel inlet hose assem

body and valve properly aligned to

bly to access cover fuel shutoff valve.

make connection with valve control

Torque hose assembly 230 - 260

cable. Install and torque valve

inch-pounds (25.99 - 29.38 Nm).

jamnut to 240 - 280 inch-pounds

(27.12 - 31.64 Nm).

(8). Install submerged motive flow hose

assembly to access cover check valve.

(b). Apply a coating of petrolatum

Torque hose assembly 50 - 65 inch-

(CM114) to sealwasher. Install check

pounds (5.65 - 7.34 Nm).

valve and sealwasher to inside cover

(9). Install scavenge fuel cell hose assembly

and a plain washer outside. Install

to access cover bulkhead elbow. Torque

jamnut and torque to 85 - 105

hose assembly 230 - 260 inch-pounds

inch-pounds (9.6 - 11.86 Nm).

(25.99 - 29.38 Nm).

(c). Install bulkhead elbow to support

(10). Install three support brackets on Sta.

bracket. with washer and nut. Torque

91.00 and 102.00 floor cross-members

Page 406

Revision 34

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

with washers and screws. Torque

(1). Defuel helicopter. Drain remaining fuel

screws to 20 - 25 inch-pounds (2.26 -

from tank sump drain valve into a

2.82 Nm).

suitable container.

(11).

Install cover bolts and washers.

(2). Cap fittings and lines as required.

Progressively torque cover bolts to 70 -

A. Fuel Supply Lines Removal

90 inch-pounds (7.91 - 10.17 Nm) in

a cross pattern.

(Ref. Figure 402, Figure 403 and Figure 404)

(12).

Connect engine feed fuel supply hose to

(1). Remove left aft fuel cell access panel

fuel shutoff valve. Torque hose nut to

from passenger/cargo compartment

230 - 260 inch-pounds (25.99 - 29.38

floor.

Nm).

(2). Disconnect motive flow fuel hose

assembly between Sta 124.00 bulkhead

(13).

Connect fuel motive flow hose to access

and fuel cell access cover. Use backup

cover/check valve. Torque hose nut (50

wrench so fittings will not rotate.

- 65 inch-pounds (5.65 - 7.34 Nm).

(3). Disconnect engine feed fuel supply hose

(14).

Connect fuel quantity probe connector

assembly between fuel shutoff valve

to wire harness receptacle.

and Sta. 124.00 bulkhead. Use backup

(15).

Slip control cable through hole in fuel

wrench on fittings so they will not

shutoff valve lever swivel.

rotate.

(4). Remove Sta. 91.00 and Sta.102.00 fuel

(16).

Rig cable control system (Ref. Fuel

cell cover support brackets.

Shutoff Valve Control Cable Replace

ment).

(5). Remove clamps and attaching hard

ware from passenger/cargo compart

(17).

Apply a torque alignment stripe to fuel

ment floor.

line tube, hose and fitting fasteners.

(6). Remove engine feed fuel supply hose

(18).

Install access panels on passenger

and motive flow fuel hose assemblies.

cargo compartment floor.

(7). Remove Sta. 124.00 bulkhead unions.

4. Fuel Supply Lines Replacement

B. Fuel Supply Lines Installation

Avoid fuel vapor ignition

WARNING

(Ref. Figure 402, Figure 403 and Figure 404)

and fire. Use only nonspark

ing tools and explosion proof work

(1). Install Sta. 124.00 firewall bulkhead

lights. Attach helicopter to an ap

unions, with washer and jam nut on

proved electrical ground. Switch OFF

forward side of firewall. Torque engine

all electrical power. Disconnect exter

feed fuel supply union nut to 240 - 280

nal power and battery before opening

inch-pounds (27.12 - 31.64 Nm).

fuel system. Ensure work area is ade

Torque fuel return by-pass union to 85

quately ventilated.

- 105 inch-pounds (9.60- 11.86 Nm).

(2). Connect fuel cell engine feed supply

CAUTION

hose to fuel shutoff valve and bulkhead

union. Use a backup wrench on valve

D Air in fuel system may cause power

and bulkhead union. Torque fuel supply

surges or flameout. Bleed off trapped air

hose 230 - 260 inch-pounds (25.99 -

after opening system at any point be

29.38 Nm).

tween fuel tank and engine fuel nozzle.

D Prevent fuel system contamination. In

(3). Connect motive flow fuel hose assembly

stall caps on the ends of hoses, tubes and

between Sta 124.00 bulkhead and fuel

fittings as parts are removed. Bag and

tank access cover. Torque hose assem

identify small parts to prevent loss or

bly 50 - 65 inch-pounds (5.65 - 7.34

damage.

Nm).

Page 407

28-00-60

Revision 34

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

HOSE ASSEMBLY

BOLT

WASHER

SEALING WASHER

FUEL INLET

SUPPLY HOSE

CHECK

ASSEMBLY

VALVE

NUT

AFT FUEL

SUBMERGED

PROBE

MOTIVE FLOW

WASHER

HOSE ASSEMBLY

BOLT

BULKHEAD ELBOW

WASHER

BONDING

JUMPER

BOLT

BRACKET

ASSEMBLY

WASHER

FUEL INLET

WASHERS

NUTPLATE

WASHER

FITTING ASSEMBLY

NUT

FUEL CELL SCAVENGE

HOSE ASSEMBLY

BRACKET ASSEMBLY

EJECTOR

NUTPLATE

PUMP

BOLT

WASHER

EJECTOR

FUEL CELL

BRACKET ASSEMBLY

SCAVENGE

HOSE ASSEMBLY

SPACER

SUBMERGED

MOTIVE FLOW

CLAMP

HOSE ASSEMBLY

O-RING

WASHER

BOLT

EJECTOR PUMP

ELBOW

REDUCER

FORWARD

BUSHING

FUEL PROBE

NUT

O-RING

6G28-024-2

Figure 404. Ejector Pump and Fuel Lines Installation

Page 409

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(4). Apply a torque alignment stripe to fuel

A. Fuel Cell Vent System Components

line tube, hose and fitting fasteners.

Removal

(Ref. Figure 405)

(5). Apply chaffing tape between hose

assemblies and fuel cell cover assembly

(1).

Remove fuel vent cross over tube access

to prevent chaffing.

cover and Sta.78.50 chanted bulkhead

stress panel.

(6). Secure engine feed hose assembly and

motive flow hose assembly underneath

(2).

Remove flame arrestor/tube assembly

passenger/cargo floor with clamps and

with clamps and attaching hardware.

attaching hardware.

(3).

Disconnect hoses from vent cross-over-

(7). Secure fuel cell to Sta. 91.00 and

tube and attaching hardware and

Sta.102.00 cell cover support brackets.

remove crossover tube.

(8). Install aft fuel cell access panel from

(4).

Remove passenger/cargo compartment

passenger/cargo compartment floor.

floor fuel cell access panels.

(5).

Disconnect hoses from aft fuel vent

5. Fuel Cell Vent System Components

valves, remove bonding jumper and

Replacement

attaching hardware from vent tubes

and remove fuel vent tubes from under

Avoid fuel vapor ignition

cargo floor.

WARNING

and fire. Use only nonspark

ing tools and explosion proof work

(6).

Remove bonding jumper and fell cell

lights. Attach helicopter to an ap

access covers as required.

proved electrical ground. Switch OFF

all electrical power. Disconnect exter

(7).

Remove retaining ring and spring from

nal power and battery before opening

fuel vent valve and remove fuel vent

fuel system. Ensure work area is ade

valve from inside of fuel cell.

quately ventilated.

B. Fuel Cell Vent System Components

Prevent fuel system contamina

Installation

CAUTION

tion. Install caps on the ends of

(Ref. Figure 405)

hoses, tubes and fittings as parts are re

moved. Bag and identify small parts to pre

vent loss or damage.

Consumable Materials

(Ref. Section 91−00−00)

(1). Defuel helicopter. Drain remaining fuel

Item

Nomenclature

from tank sump drain valve into a

CM114

Petrolatum

suitable container.

CM411

Adhesive, epoxy

(2). Disconnect electrical power.

CM702

Lockwire CRES

Prevent spontaneous com

(1). Coat O-rings with (CM114) lubricant

WARNING

bustion or explosion. Never

and install on vent valves.

use oxygen to purge or ventilate fuel

tank or fuel system components. Fuel,

(2). Insert vent valves thru cell from inside

either vapor or liquid, will violently

and secure using springs and retainers.

react with an oxygen rich atmosphere.

(3). Bond prep aft vent fittings at bond

(3). Ventilate fuel tank with an inert gas,

jumper location.

such as nitrogen, or low pressure

compressed air applied through filler

(4). Coat O-rings with lubricant (CM114)

neck.

and install on vent fittings.

Page 410

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

BOLT

WASHER

SCREW

BONDING

REF. FS 78.50

JUMPER

CANTED BULKHEAD

WASHER

FLAME

CLAMP

BOLT

VENT

WASHER

ARRESTOR

TUBE

WASHER

(3 PLCS)

CLAMP

SCREW

NUT

WASHER

VENT

WASHER

NUT

FITTING

(3 PLCS)

TUBE ASSEMBLY

NUT

(3 PLCS)

CLAMP

SCREW

(3 PLCS)

WASHER

NUT

GROMMET

CONNECTOR

NUT

(2 PLCS)

WASHER

(2 PLCS)

BOLT

CLAMP

(2 PLCS)

HOSE

WASHER

(2 PLCS)

TUBE ASSEMBLY

WASHER

CLAMP

(2 PLCS)

FLAME

ARRESTOR

CROSSOVER

(2 PLCS)

ASSY

BOLT (2 PLCS)

0-RING

WASHER

(2 PLCS)

RETAINING

SPACER

NUT

RING (2 PLCS)

WASHER

(2 PLCS)

SPRING

BOLT

RETAINER

CLAMP

0-RING

WASHER

PIN (2 PLCS)

WASHER

NUT

VENT VALVE

(2 PLCS)

Figure 405. Fuel Cell Vent System Components

Page 411

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(5).

Install aft vent fittings and bond

(21). Safety connector to cross-over tube

jumpers to vent valves with hardware.

with lockwire (CM702).

Torque bolts to 36 - 46 inch-pounds

(22). Tie-rap tube assembly to forward

(4.0 - 5.2 Nm).

bulkhead of Sta. 78.50.

(6).

Bond prep six vent tube clamp screw

(23). Route tube assembly to vent fairing and

holes on cargo deck.

bond using sealant (CM425).

(7).

Install hoses to aft vent fittings with

(24). Bond prep fuel cell access covers.

lockwire (CM702), two wrap around

turns minimum.

(25). Install bonding jumpers and fell cell

access covers. Torque bolts 70 - 90

(8).

Slide vent tubes under cargo floor and

inch-pounds (7.91 - 10.17 Nm).

connect to hoses with lockwire

Install fuel vent access cover.

(CM702), two wrap around turns

minimum.

(26). Install passenger/cargo compartment

floor access panels.

(9).

Attach forward end of tube to cargo

floor with clamps.

6. Fuel Cell Replacement

Avoid fuel vapor ignition

(10).

Install bonding jumpers at aft clamps.

WARNING

and fire. Use only nonspark

(11).

Install hoses on forward ends of vent

ing tools and explosion proof work

tubes and safety using lockwire

lights. Attach helicopter to an ap

(CM702), two wrap around turns

proved electrical ground. Switch OFF

minimum.

all electrical power. Disconnect exter

nal power and battery before opening

(12).

Coat O-rings with lubricant (CM114)

fuel system. Ensure work area is ade

and install on cross-over tube.

quately ventilated.

(13).

Attach vent cross-over tube with

CAUTION

hardware to tops of vent valves. Torque

bolts to 36 - 46 inch-pounds (4.06 -

D Do not work on cell in ambient tempera

5.19 Nm).

tures below 70°F (21°C).

(14).

Bond prep two nutplate holes for

D Prevent fuel system contamination. In

attaching cross-over tube.

stall caps on the ends of hoses, tubes and

fittings as parts are removed. Bag and

(15).

Install clamps on cross-over tube and

identify small parts to prevent loss or

attach to airframe.

damage.

(16).

Install grommet in Sta. 78.50 skin at

(1). Defuel helicopter. Drain remaining fuel

vent outlet using epoxy adhesive

from tank sump drain valve into a

(CM411).

suitable container.

(2). Disconnect electrical power.

(17).

Attach connector to the flame arrestor

and safety with lockwire (CM702), two

A. Fuel Cell Removal

wrap around turns minimum.

(Ref. Figure 406)

(18).

Attach tube to flame arrestor and

safety with lockwire (CM702) two wrap

NOTE: The following procedures are required

around turns minimum.

to access and separate the fuel cell intercon

nect fitting, vent system and gravity fill port

(19).

Bond prep one of the three attaching

before either cell can be removed from its

screw holes for the flame arrestor.

bay.

(20).

Install flame arrestor/tube assembly

(1). Remove forward fuel vent crossover

with clamps.

tube cover, right and left fuel cell access

Page 412

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

panels from passenger/cargo compart

(11). Disconnect submerged fuel cell scav

ment floor.

enge hose assembly from bottom of fuel

cell access cover bracket assembly to

(2).

Disconnect fuel quantity probe wire

ejector pump (Ref. Figure 404).

harness connector from fuel cell access

(12). Cut safety wire from fuel probe electri

cover receptacle.

cal connector base nut and remove

connector from fuel cell access cover.

(3).

Unclamp and disconnect control cable

from fuel shutoff valve.

(13). Unbolt and remove right hand fuel cell

access cover(s) and bonding jumpers.

(4).

Unfasten and remove Sta. 91.00 and

Remove left hand forward fuel cell

102.00 left fuel cell cover support

access cover.

brackets from passenger/cargo floor

structure (Ref. Figure 402).

Prevent spontaneous com

WARNING

bustion or explosion. Never

(5).

Remove attaching hardware from Sta

use oxygen to purge or ventilate fuel

102.230 and Sta 113.850 passenger/car

tank or fuel system components. Fuel,

go compartment floor structure that

either vapor or liquid, will violently

secures engine feed fuel supply hose

react with an oxygen rich atmosphere.

and motive flow firewall to fuel cell

(14). Mop up any remaining fuel in both cells

hose to bottom of floor (Ref.

with clean lint free cloth. Purge fuel

Figure 403).

cells with dry, forced air or inert gas

such as nitrogen through filler neck.

(6).

Disconnect engine feed fuel supply hose

between fuel shutoff valve and firewall

(15). Disconnect wire harness from forward

Sta. 124.00 bulkhead union. Using a

and aft fuel quantity probe and remove

backup wrench on bulkhead union so it

wire harness (Ref. Fuel Quantity Probe

will not rotate, disconnect and remove

Replacement).

engine feed fuel supply hose assembly

(Ref. Fuel Supply Line Replacement).

(16). Remove aft fuel quantity probes, fuel

inlet with fuel supply hose and bracket

(7).

Disconnect motive flow fuel hose

assembly, forward fuel quantity probe,

assembly between fuel cell access cover

ejector pump with submerged motive

and Sta 124.00 bulkhead. Using a

flow fuel hose assembly and fuel cell

backup wrench on bulkhead union so it

scavenge hose as a subassembly (Ref.

will not rotate, disconnect and remove

Figure 404 and Figure 407).

motive flow fuel hose assembly.

(17). Disconnect and remove fuel vent

Handle fuel cell covers with

system components necessary to

CAUTION

care. Prying covers from cell

remove fuel cell (Ref. Fuel Cell Vent

openings or rough handling may damage

System Component Replacement).

the cover seal or cell fitting.

NOTE: At this point either cell may be re

moved, as required.

(8). Unbolt and prop left aft fuel cell access

cover open with suitably padded blocks.

(18). Remove sump drain valve.

(9). Disconnect fuel inlet supply hose

(19). Remove retaining ring and spring from

between fuel shutoff valve fuel cell

fuel cell interconnect fittings (Ref.

access cover and fuel inlet support

Figure 406).

bracket (Ref. Figure 402 and

(20). Remove cell suspension cords.

Figure 404).

(21). For right fuel cell removal:

(10). Disconnect submerged motive flow fuel

hose assembly between fuel check valve

(a). Remove fuel filler neck fairing from

fuel cell access cover and ejector pump.

passenger/cargo compartment floor.

Page 413

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(b). Unclamp fuel gravity filler port from

cell. Coat O-rings with lubricant

fill valve, remove hose from fill valve

(CM114) and install O-ring, spring and

and disconnect lanyard.

retaining ring.

Cells are thin-walled and frag

CAUTION

ile. Avoid snagging or dragging

cell over pointed or sharp edges. Do not

scratch or nick any of the cell's metal fit

tings.

tings. Avoid hard contact between cell and

fuselage structure when inserting.

(22). Collapse and fold cell lengthwise and

(4). Fold cells lengthwise and position in

remove through floor access opening.

bay through floor opening. Unfold cell

B. Fuel Cell Installation

and smooth out all creases.

(Ref. Figure 406)

(5). Align cell openings with airframe

openings. Hook up fuel cell cross over

Consumable Materials

interconnects into right fuel cell. Coat

(Ref. Section 91−00−00)

O-rings with lubricant (CM114) and

Item

Nomenclature

install O-ring, spring and retaining

CM114

Petrolatum

ring.

CM220

Naphtha aliphatic

(6). Install a new O-ring on sump drain

CM702

Lockwire CRES

valve. Install valve and torque to 95 -

105 inch-pounds (10.73 - 11.86 Nm).

CM809

Nylon cord

Safety wire drain valve with lockwire

(CM702).

Avoid fuel vapor ignition

WARNING

(7). For right fuel cell installation:

and fire. Use only nonspark

ing tools and explosion proof work

(a). Install rubber hose to fill valve and

lights. Attach helicopter to an ap

filler neck, hose should be approxi

proved electrical ground. Switch OFF

mately six an one half inches (16.5

all electrical power. Disconnect exter

cm) long. Secure hose to fill valve and

nal power and battery before opening

filler neck with clamps.

fuel system. Ensure work area is ade

(b). Insure lanyard on filler valve is

quately ventilated.

accessible with fill cap removed. Slip

NOTE: Discard used O-rings and sealwashers.

lanyard on fuel cap onto ring of fill

Apply a thin coat of petrolatum (CM114) to

valve. Install fuel cap.

all new O-rings except cell vent system

(c). Connect lanyard of fill valve to

sealwashers.

gravity filler port. Install hose and

(1). Air-vacuum all debris from cell bays.

clamp.

Ensure compartment liner will protect

(8). Connect engine feed fuel supply hose

cell from airframe points and edges.

and motive flow fuel hose assembly to

Repair liner as required.

Sta. 124.00 bulkhead union (Ref. Fuel

Supply Line Replacement).

(2). Bond prep fill valve with fuel cell

fitting. Coat O-rings with lubricant

(9). Install fuel vent system components

(CM114) and install fill valve into right

(Ref. Fuel Vent System Components

fuel cell with O-ring, spring and

Replacement).

retaining ring. Ensure clocking of fill

(10). Route suspension nylon cord (CM809)

valve with flat at top lines up with

thru grommet of fuel cell and thru

shoulder on fuel cell fitting.

eyelets of fuselage. Tighten and tie cord

(3). Hook up fuel cell interconnect fittings

using a bowline knot. Cut excess cord

into left fuel cell. Ensure short end of

after knot to approximately 3 to 4

interconnects are facing into left fuel

inches (7.6 cm to 10.2 cm) in length.

Page 414

Revision 43

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(11). Secure opposite end of cord using a

(13). Aft fuel probe and fuel supply inlet hose

trucker's slip knot. Cut excess cord

installation (Ref. Ejector Pump and

after knot to approximately 3 to 4

Fuel Line Installation):

inches (7.6 cm to 10.2 cm) in length.

(a). Bond attachment holes on fuel cell

(12). Forward fuel probe and ejector pump

aft sump fitting assembly, bracket

subassembly installation (Ref. Ejector

assembly, aft fuel probe attachment

Pump and Fuel Line Installation):

holes and fuel inlet fitting assembly.

(a).

Bond prep ejector pump bracket

(b). Install fuel inlet fitting assembly to

assembly with forward fuel probe and

bracket assembly with four washers

ejector pump assembly.

each between fuel inlet fitting and

bracket assembly.

(b).

Coat O-rings with lubricant (CM114)

and install reducer bushing with

(c). Install aft fuel probe to bracket

O-rings into ejector pump. Torque to

assembly and fuel cell aft sump

50 - 65 inch-pounds (5.65 - 7.34

fitting with bolts and two washers

Nm).

under the head of each bolt, except

bolt with ground wire, only one

(c).

Coat O-rings with lubricant (CM114)

washer is required.

and install jamnut, bulkhead elbow

to reducer bushing. Torque jamnut to

(d). Connect wire harness to aft fuel

85 - 105 inch-pounds (9.60 - 11.86

probe. Attach bonding jumper to

Nm).

outboard bolt of probe. Torque bolts

to 36 - 46 inch-pounds (4.06 - 5.19

(d).

Install fuel cell scavenge hose to

Nm) (Ref. Fuel Quantity Probe

ejector pump. Torque hose nut to 230

Replacement).

- 260 inch-pounds (25.99 - 28.81

Nm).

(14).

Install attaching hardware from Sta

102.230 and Sta 113.850 passenger/car

(e).

Install submerged motive flow fuel

go compartment floor structure that

hose assembly to elbow and torque to

secures engine feed fuel supply hose

50 - 65 inch-pounds (5.65 - 7.34

and motive flow firewall to fuel cell

Nm).

hose to bottom of floor (Ref.

Figure 403).

(f).

Bond prep ejector pump in area of

clamp up and install forward fuel

(15).

Install right hand fuel cell access

quantity probe, ejector pump with

covers, left hand forward and left hand

submerged motive flow hose assem

aft access cover (Ref. Fuel Cell Cover

bly and fuel cell scavenge hose

Replacement).

assembly as a subassembly.

(16).

Connect fuel quantity probe wire

(g).

Install ejector pump subassembly to

harness connector from fuel cell access

bracket assembly with clamps, bolts

cover receptacle.

and washers. Torque bolts to 36 - 46

inch-pounds (4.06 - 5.19 Nm).

(17).

Connect and clamp control cable from

(h).

Connect wire harness to forward fuel

fuel shutoff valve (Ref. Fuel Shutoff

probe. Route submerged motive flow

Valve Control Cable Replacement).

fuel hose assembly, fuel cell scavenge

hose assembly and wire harness thru

(18).

Install forward fuel vent crossover tube

fuel cell fabric retaining loops and

cover, right and fuel cell access panels

baffle (Ref. Fuel Quantity Probe

from passenger/cargo compartment

Replacement).

floor.

Page 415

28-00-60

Revision 43

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

7. Fuel Filler Neck Gravity Fill Port

(4). Insure lanyard on filler valve is

Replacement

accessible with fill cap removed. Slip

lanyard on fuel cap onto ring of fill

(Ref. Figure 406)

valve. Install fuel cap.

Avoid fuel vapor ignition

(5). Connect lanyard of fill valve to gravity

WARNING

and fire. Use only nonspark

filler port. Install hose and clamp.

ing tools and explosion proof work

8. Fuel System Drain Valve Replacement

lights. Attach helicopter to an ap

proved electrical ground. Switch OFF

Avoid fuel vapor ignition

all electrical power. Disconnect exter

WARNING

and fire. Use only nonspark

nal power and battery before opening

ing tools and explosion proof work

fuel system. Ensure work area is ade

lights. Attach helicopter to an ap

quately ventilated.

proved electrical ground. Switch OFF

all electrical power. Disconnect exter

Helicopter must be defueled and

CAUTION

nal power and battery before opening

drained prior to removing grav

fuel system. Ensure work area is ade

ity fill port.

quately ventilated.

(1). Defuel helicopter. Drain remaining fuel

Helicopter must be defueled and

from cell sump drain valve into a

CAUTION

drained prior to removing tank

suitable container.

sump drain valve.

(2). Disconnect electrical power.

(1). Defuel helicopter, as required. Drain

remaining fuel from tank sump drain

A. Fuel Filler Neck Gravity Fill Port Removal

valve into a suitable container.

(1). Remove fuel filler neck fairing from

(2). Disconnect electrical power.

passenger/cargo compartment floor.

A. Fuel System Drain Valve Removal

(2). Unclamp fuel gravity filler port from fill

(1). Remove lockwire from tank sump drain

valve, remove hose from fill valve and

valve.

disconnect lanyard.

(2). Using appropriate socket or wrench,

(3). Remove bolts and washers from filler

remove drain valve.

neck mounting flange and remove

B. Fuel System Drain Valve Installation

gravity fill port.

B. Fuel Filler Neck Gravity Fill Port

Consumable Materials

Installation

(Ref. Section 91−00−00)

Item

Nomenclature

(1). Bond prep attach points for bonding

CM114

Petrolatum

jumper near fuel fill area. Attach

bonding jumper to fuel cell with screw

CM124

Kerosene

and washer. Attach opposite end of

CM702

Lockwire CRES

bonding jumper to passenger/cargo

compartment flooring with screw,

(1). Replace drain valve O-ring packings.

washers and nut.

Lubricate packings with kerosene

(CM124), petrolatum (CM114) or jet

(2). Install bolts and washers from filler

fuel.

neck mounting flange and install

gravity fill port.

(2). Install and torque sump drain valve to

95 - 105 inch-pounds (10.73 - 11.86

(3). Install rubber hose to fill valve and

Nm). Safety valve with lockwire

filler neck. Note, hose should be

(CM702).

approximately six an one half inches

long. Secure hose to fill valve and filler

(3). Apply a torque alignment stripe to fuel

neck with clamps.

line tube, hose and fitting fasteners.

Page 419

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(4). Refuel helicopter.

B. Forward Fuel Quantity Probe Installation

(5). Check drain valve for leakage.

(Ref. Figure 407)

9. Fuel Quantity Probe Replacement

(1). Install fuel quantity probe ground wire

and attaching hardware. Torque bolts

Avoid fuel vapor ignition

to 36 - 46 inch-pounds (4.06 - 5.19

WARNING

and fire. Use only nonspark

Nm).

ing tools and explosion proof work

lights. Attach helicopter to an ap

(2). Connect wire harness connector ends to

proved electrical ground. Switch OFF

forward fuel probe in the same locations

all electrical power. Disconnect exter

as removed.

nal power and battery before opening

fuel system. Ensure work area is ade

(3). Bond prep fuel cell access cover.

quately ventilated.

(4). Install left forward fuel cell access

(1). Defuel helicopter. Drain remaining fuel

cover. Install bonding jumper to fuel

from tank sump drain valve into a

cell access cover. Torque bolts to 70 - 90

suitable container.

inch pounds (7.91 - 10.17 Nm).

(2). Disconnect electrical power.

(5). Install left forward fuel cell access

Prevent spontaneous com

panel from passenger/cargo compart

WARNING

bustion or explosion. Never

ment floor.

use oxygen to purge or ventilate fuel

tank or fuel system components. Fuel,

C. Aft Fuel Quantity Probe Removal

either vapor or liquid, will violently

react with an oxygen rich atmosphere.

(Ref. Figure 407)

(3). Ventilate fuel tank with an inert gas

(1). Remove left aft fuel cell access panel

such as nitrogen or low pressure

from passenger/cargo compartment

compressed air applied through filler

floor.

neck.

(2). Remove left aft fuel cell access cover

A. Forward Fuel Quantity Probe Removal

(Ref. Fuel Cell Cover Replacement).

(Ref. Figure 407)

(3). Disconnect wire harness connector ends

from aft fuel probe.

(1). Remove left forward fuel cell access

panel from passenger/cargo compart

(a). Remove ORANGE wire from termi

ment floor.

nal L.

(2). Remove left forward fuel cell access

cover.

(b). Remove BLUE wire from terminal R.

(3). Disconnect wire harness connector ends

(c). Remove WHITE wire from terminal

from forward fuel probe.

(a). Remove ORANGE wire from termi

(d). Remove low level switch WHITE wire

nal L.

from terminal 1.

(b). Remove BLUE wire from terminal R.

(e). Remove low level switch BLUE wire

(c). Remove WHITE wire from terminal

from terminal 2.

(f). Remove GROUND wire from probe

(4). Remove GROUND wire from probe

mount flange, remove remaining

mount flange, remaining attachment

attachment hardware and remove

hardware and remove probe.

probe.

Page 420

Revision 19

28-00-60

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

AFT FUEL PROBE

BOL

WASHER

BOL

WASHER

GROUND

JUMPER

WASHER

FUEL INLET SUPPLY

HOSE ASSEMBLY

FUEL INLET FITTING ASSEMBLY

BRACKET

ASSEMBLY

AFT FUEL PROBE

6G28-051-2

Figure 407. Fuel Quantity Probes (Sheet 2 of 2)

D. Aft Fuel Quantity Probe Installation

(2). Connect wire harness connector ends to

forward fuel probe in the same locations

as removed.

(Ref. Figure 407)

(3). Install left aft fuel cell access cover

(Ref. Fuel Cell Cover Replacement).

(1). Install fuel quantity probe ground wire

and attaching hardware. Torque bolts

(4). Install left forward fuel cell access

to 36 - 46 inch-pounds (4.06 - 5.19

panel from passenger/cargo compart

Nm).

ment floor.

Page 422

Revision 19

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

ADJUSTMENT/TEST

1. Fuel Level Low Light/Fuel Quantity

(5). Level the helicopter laterally across the

Indicator System Test and Calibration

passenger/cargo compartment floor.

(6). Plug in and switch on 27.5 ±0.5 Vdc

The following procedure is for calibrating the

external power. Set BAT master switch

fuel quantity system when the fuel cell, fuel

to EXT PWR. Make sure the INST and

probes or fuel quantity indicator have been

PNL LT circuit breakers are pushed in.

replaced.

NOTE: All readings are taken from the center

line of the fuel quantity indicator pointer.

Special Tools

(Ref. Section 91−00−00)

(7). Verify the FUEL LEVEL LOW light is

Item

Nomenclature

illuminated.

ST203

Hydraulic jack: 1-5 ton (900-4500 kg)

(8). Add 1.3 gals (4.92 Liter) of fuel from a

ST205

Inclinometer

calibrated delivery system to the fuel

cell. This amount of fuel is trapped fuel

or unusable fuel. Calibrate empty.

Prevent fuel vapor accumu

WARNING

lation, ignition and fire. At

(a). Calibrate zero on the fuel quantity

tach helicopter to an approved electri

indicator by holding the fuel quantity

cal ground. Switch OFF and disconnect

gauging system calibration switch in

external power and battery before

the empty calibration position (down)

opening fuel system. Perform work in

for a minimum of 5 - 10 seconds.

an open, well ventilated area away

from all potential ignition sources. Use

(b). Verify the the fuel quantity indicator

only nonsparking tools and explosion

now reads empty. Empty is the E

proof work lights.

with the pointer centerline between

the outer and inner edge of the E

(1). Attach helicopter to a approved electri

graduation mark.

cal ground.

(9). Add 11.4 gals (44.3 Liter) of fuel from a

calibrated delivery system to the fuel

(2). Defuel and drain fuel cell sumps of all

cell.

fuel from all four sump drains with the

helicopter at normal ground attitude.

(10). Verify the FUEL LEVEL LOW light is

not illuminated.

(3). Place an aircraft jack (ST203) under the

aft jacking point.

(11). Wait 15 minutes and verify the FUEL

LEVEL LOW light is not illuminated. If

Do not apply more than 500 lb.

light illuminates:

CAUTION

(227 kg) pressure on aft jacking

(a). Inspect baffles for damage, tears,

point, damage to tailboom and attachment

punctures or delamination.

points will occur.

(b). Inspect flappers for proper seating.

(4). Locate a inclinometer (ST205) on the

Flappers should seat flush with

passenger/cargo compartment floor at

gravity or very light finger pressure

approximately fuselage Sta. 100.00 -

and should move freely.

104.00. Raise the helicopter at Sta.

(12). Fill the fuel cell and secure the fuel

303.03 with jack (ST204) and P.Sta.

filler cap.

18.76 with jacks (ST203) to obtain a 3

degree nose down simulated flight

(a). Calibrate full on the fuel quantity

attitude as observed on the inclinome

indicator by holding the fuel quantity

ter scale.

gauging system calibration switch in

Page 501

28-00-60

Revision 22

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

the full calibration position (up) for a

(6). With reducer bushing removed from tee

minimum of 5 seconds.

fitting, install an O-ring on a suitable

airtight plug and tighten into tee

(b). Verify the the fuel quantity indicator

fitting.

now reads approximately 759 pounds

(344.28 kg).

(7). Bench test 600N8131 bypass pressure

switch as follows (denoted by six

(13). Place the BAT master switch to OFF

housing screws):

position. Disconnect external power.

(a). Assemble test equipment shown in

2. Fuel Filter (Bypass) Caution Light

Figure 501. Connect tester to pres

Pressure Switch Test

sure switch lead and connect ground

test lead to one of three screws on the

(Ref. Figure 501)

housing body.

Air in the fuel system will

(b). Remove reducer bushing and O-ring

WARNING

cause a power reduction or

from switch. Wipe switch completely

flameout. Do a fuel system vacuum leak

dry so any leakage can be detected

check and system air bleed after open

during the test.

ing fuel system to atmosphere and

(c). Apply 2.0 to 3.0 psig (13.8 - 20.68

prior to releasing helicopter for flight.

Kpa) at port ``A'' .

NOTE: For all torques in the following proce

1). There shall be no evidence of

dures, refer to Engine Build-Up, Section

leakage. Replace a leaky switch.

71-00-47.

2). When air pressure is applied,

(1). Set all switches; OFF. Disconnect

switch shall be close when pres

external electrical power. Disconnect

sure at port ``A'' is 2.1 - 2.9 psid,

battery.

pound per square inch differential

(2). Open engine access doors.

(4.3 - 5.9 in. Hg, inch of mercury).

3). When air pressure is bled off,

(3). Locate pressure switch on engine fuel

switch shall be open when pres

pump filter. Disconnect bypass switch

sure at port ``A'' is 1.0 psid (2.0 in.

wire knife splice.

Hg).

CAUTION

(d). Remove test equipment.

D Pressure switch is easily damaged. A

(8). Remove plug from tee fitting. Install

slight shearing force applied to half the

reducer bushing and bypass switch

pressure switch can cause leakage and, or

assembly with new O-rings on reducer

operational failure. Always grip both

bushing and bypass switch. Torque

halves of pressure switch hex flats with

switch assembly.

wrench when loosening or torquing at

(9). Remove plug from bypass hose. Attach

taching hardware.

hose to switch bushing. Torque hose

D Bypass pressure switch is not field repair

nut.

able. Do not disassemble switch. Return

faulty switches to vender for repair (Ref.

(10). Install insulating sleeve and connect

Sec. 01-00-00).

switch wire knife splice.

(4). Disconnect hose from fuel filter pres

(11). Bleed fuel system.

sure switch. Install an airtight plug to

hose.

(12). Operate engine per Pilot's Flight

Manual and check fuel system for

(5). Remove fuel pressure switch with

correct operation. Shut down engine.

reducer bushing.

Inspect fuel system for leaks.

Page 502

Revision 22

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

INSPECTION/CHECK

2. Fuel Shutoff Valve Inspection

WARNING

(1). Shut down and disconnect all electrical

D Avoid fuel vapor ignition and fire.

power.

Use only nonsparking tools and ex

(a). In cargo/passenger compartment,

plosion proof work lights. Attach he

open left aft fuel cell access panel.

licopter to an approved electrical

ground. Switch OFF all electrical

(b). Disconnect fuel supply tube from fuel

power. Disconnect external power

shutoff valve.

and battery before opening fuel sys

(c). Use an inspection mirror and flash

tem. Ensure work area is adequately

light to check shutoff valve ball

ventilated.

position.

D Air entering the airframe fuel supply

(d). Ensure shutoff valve control knob is

lines may cause a power reduction or

pushed in. Valve ball must be wide

flameout. Fuel system vacuum leak

open.

check and fuel air bleed procedures

must be performed after opening fuel

(e). Pull control knob out to stop. Valve

the supply system for any reason,

ball should be closed.

prior to releasing helicopter for

(2). Valves that can not be fully closed or

flight.

opened must be overhauled or replaced

prior to further flight.

Fuel System General Inspection

(3). Disconnect control cable from valve.

(1). Remove all fuel tank floor access

(a). Inspect shutoff valve lever and cable

panels.

swivel hardware for corrosion and

wear. Check lever for smooth move

(2). Inspect fuselage bottom skin for

ment from closed to open stops.

evidence of fuel leakage. No leaks

(b). Use a spring scale to check tension

allowed. Determine source and repair

required to move valve lever from full

as required.

open to closed. Design force require

ment is 1.5 - 3.5 pounds (6.7 - 15.6

(3). Inspect fuel lines, fittings, cell access

N) maximum.

covers, fuel quantity unit, clamps and

attaching hardware for leakage,

(c). Inspect valve for evidence of external

corrosion and security. Inspect fire

leakage. External leakage not

sleeves for cuts, tears and punctures.

allowed.

No leakage allowed. Repair or replace

(d). Check that lever detents at open and

components as required.

closed positions. Repair or replace

valve as required.

(4). Inspect electrical wiring and connectors

for corrosion and security. Replace or

(4). Connect and rig valve control cable.

repair wiring as required.

Install cotter pin on cable swivel.

Page 601

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

3. Tank Vent System Inspection

hardware. Repair or replace vent

float/rollover valve as required.

Avoid fuel vapor ignition

WARNING

and fire. Use only nonspark

4. Fuel Quantity Probe Inspection

ing tools and explosion proof work

lights. Attach helicopter to an ap

(1). Inspect probe wire harness electrical

proved electrical ground. Switch OFF

connector for serviceable conditional.

all electrical power. Disconnect exter

nal power and battery before opening

(2). Inspect for bent or broken pins, frayed

fuel system. Ensure work area is ade

or broken wires. Repair or replace as

quately ventilated.

required,

Prevent fuel system contamina

5. Fuel System Vacuum Leak Inspection

CAUTION

tion. Install caps on the ends of

hoses, tubes and fittings as parts are re

(Ref. Figure 601) Water, ice, dirt, fungus or a

moved. Bag and identify small parts to pre

few pinhole leaks in the supply system

vent loss or damage.

between the fuel tank sump pickup and engine

driven fuel pump may cause power surges,

(1).

Defuel helicopter. Drain remaining fuel

deceleration and, or flameout. A vacuum leak

from tank sump drain valve into a

inspection will determine whether or not air is

suitable container.

being drawn into the engine fuel supply

system.

(2).

Disconnect electrical power.

(3).

Remove all four passenger/cargo access

Special Tools

panels.

(Ref. Section 91−00−00)

Item

Nomenclature

(4).

Remove fuel vent cross over tube access

ST801

Hand operated vacuum pump kit

cover and disconnect hoses from

forward vent crossover tubes.

Air entering the airframe

(5).

Blow low-pressure compressed air

WARNING

fuel supply lines may cause

through vent system to verify passages

a power reduction or flameout. Fuel

are clear.

system vacuum leak check and fuel air

(6).

Check vent fairing passages for obstruc

bleed procedures must be performed

tions and condition. Repair or replace

after opening the fuel supply system

fairings as required.

for any reason, prior to releasing heli

copter for flight.

(7).

Inspect vent system hoses for deteriora

tion. Pinch or bend hoses and look for

(1). Remove left fuel cell floor access panel.

surface cracks. Replace hose if cracks

are apparent.

(2). Pull FUEL shutoff valve knob out to

stop. Verify that fuel shutoff valve lever

(8).

Inspect vent tubes for dents, cracks,

is hard against its OFF stop.

deformation or corrosion. Smooth

nonrestrictive dents are permissible

(3). In engine compartment; remove and

except at lower vent end which must fit

plug the motive fuel line at the CEFA.

flush within vent fairing flared riser.

(4). Assemble vacuum pump (ST801) hoses,

(9).

Inspect crossover fittings for cracks,

filter port adapter, shutoff valve and

dents or corrosion. Smooth nonrestric

vacuum gauge.

tive dents are permissible.

(a). Install the vacuum gauge in the line

(10).

Inspect fuel vent float/rollover valves

between the filter port adapter and

for serviceable condition, leakage and

shutoff valve. Attach the vacuum

corrosion. Inspect for loose or missing

pump above the shutoff valve.

Page 602

Revision 31

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MOTIVE FUEL LINE

FUEL FILTER UPPER

DRAIN PORT

FUEL FILTER

OIL FILTER

VACUUM GAGE

SHUT-OFF VALVE

FUEL IN PORT

VACUUM

OIL OUT PORT

PUMP

TEE FITTING

FUEL OUT PORT

FILTER PORT ADAPTER

OIL IN PORT

6G28-077

Figure 601. Fuel System Vacuum Leak Inspection

(5).

Attach vacuum test pump to engine fuel

The fuel shutoff and drain valve

filter upper drain port. Apply 8.0 Hg

installations should be especially

vacuum. Close vacuum line shutoff

suspect. Apply vacuum at each stage

valve.

until leak has been isolated. Replace

parts as required.

(6).

Fuel system shall hold vacuum between

8.0 and 7.5 Hg for two minutes.

NOTE: If the vacuum held at 7.5 Hg or better,

airframe system seal is satisfactory and

(7).

If test is satisfactory, remove test

leak is due to an engine fuel system prob

vacuum.

lem. Refer to the applicable Allison and Ben

dix manuals for additional information.

(8).

Reconnect and torque the fuel vapor

return line.

(11). Apply a torque stripe to all effected fuel

NOTE: Vacuum loss exceeding 0.5 Hg in two

line fittings and nuts.

minutes indicates a leak in the system be

tween, and including, the fuel shutoff valve

6. Drain Valve Inspection

and engine.

Air in the fuel system will

WARNING

(9). Retorque fuel line connections and

cause a power reduction or

where installed, anti-ice (airframe) fuel

flameout. Do a fuel system vacuum leak

filter fittings and line nuts (Ref. Sec.

check and fuel system air bleed after

28-25-00). Repeat vacuum test.

opening fuel system to atmosphere and

prior to releasing helicopter for flight.

(10). If system continues to leak, disconnect

and install airtight caps on lines and

(1). Inspect tank sump drain valves for

fitting ports in a progressive sequence

leakage and security. No leakage

from fuel shutoff valve toward engine.

allowed. Replace valve as required.

Page 603

28-00-60

Revision 31

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

7. Fuel Cell Inspection

8. Fuel Cell Leak Inspection

Consumable Materials

(Ref. Section 91−00−00)

CAUTION

Item

Nomenclature

N/A

Ammonia

D Do not work on Engineered Fabric Corp.

N/A

Cloth, cotton flannel

fuel cell in ambient temperatures below

N/A

Phenolphthalein, crystalline

70°F (21°C).

CM218

Alcohol, denatured

CM810

Leak detector, liquid

D Do not remove fuel cells unless absolutely

required.

CM820

Cheesecloth

D The barrier can be invisibly torn, punc

Any one of three techniques can be used to find

tured or cracked by careless handling.

leaks in non-self-sealing and self-sealing fuel

cells. The methods are listed in ascending

D Do not carry or move cell by its metal fit

order of effectiveness and complexity in terms

tings.

of required equipment, materials, time, and

effort.

D Never probe cell material with sharp

Soap bubble leak inspection.

edged or pointed tools.

Phenolphthalein stain inspection.

NOTE:

Liquid stand inspection.

NOTE: The soap bubble and phenolphthalein

D Non-self-sealing and self-sealing cells

inspections require the cell to be inflated

are primarily a 0.002 inch (0.051 mm)

with air.

thick nylon barrier membrane sand

wiched between lightweight construc

(1). Manufacture or supply the following

tions of either rubberized (Uniroyal) or

equipment necessary to do soap bubble

or phenolphthalein inspections:

plasticized (Engineered Fabrics Corp.)

nylon fabric that protects and strength

(a). Rigid, airtight closures or plugs to

ens the barrier.

seal all cell openings. Fit one cover

plate with:

D Self-sealing cells may have one or more

(b). An air pressurization inlet fitting.

thin layers of natural rubber sandwiched

between the barrier and fabric plies.

(c). A manometer or an extremely

accurate and sensitive low pressure

air gauge.

(1). Apply protective tape to all machined

A. Soap Bubble Leak Test Procedures

metal fittings.

NOTE: Soap bubble test reliability is good for

bladder type non-self-sealing cells.

(2). Perform cell inspection on a padded,

clean, craft paper covered surface.

(1). Remove cell from helicopter.

(2). Lay cell out on a padded table. Install

cell closures.

(3). Inspect fuel cells per applicable man

ufacturers requirements (Ref. Sec.

(3). Inflate cell to 1/4 psi (1.7 kPa), maxi

01-00-00).

mum.

Page 604

Revision 31

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(4). Unless leak is immediately evident,

(f). Inspect the entire exterior surface of

maintain 1/4 psi (1.7 kPa) pressure for

the cell.

two hours to allow any air trapped in

(5). Repair cell as required.

cell exterior laps and seams to escape.

C. Liquid Stand Inspection

(5). Run soap solution around all patches,

lap joints, seams, fittings, creases,

(1). Remove cell from helicopter and place

abrasions and any other suspicious

on a clean, padded, kraft paper covered

areas. Bubbles will appear over a leak.

table.

(6). Mark leak areas with a white or yellow

(2). Fabricate closure plates for each cell

crayon.

opening.

(7). Repair cell as required.

(a). The object is to completely fill the cell

and eliminate all air pockets. Equip

B. Phenolphthalein Stain Inspection

one of the plates with liquid filler and

Procedures

vent stand pipes at least six inches

(1). Remove cell from helicopter.

(15 cm) tall.

(b). Fill the cell with Stoddard solvent,

(2). Lay cell out on a padded table. Install

Stanisol or Varsoline.

all but one of the cell closures.

(c). Permit cell to stand undisturbed for

(3). Make phenolphthalein solution as

24 hours.

follows:

(d). Inspect paper to determine where cell

(a). Add 40 grams phenolphthalein

is leaking.

crystals to 1/2 gallon (1.9 L) of

denatured alcohol (CM218) and stir.

(e). Change paper as required. Drain,

turn over, refill and let cell stand for

(b). Add 1/2 gallon (1.9 L) of water. Allow

another 24 hours to ensure liquid has

to stand 30 minutes. Stir before

contacted all cell surfaces.

using.

(f). Repair cell as required.

(4). Pour commercial ammonia on an

absorbent cloth in a ratio of one

Fuel Tank Pressure Leak Test

teaspoon (3 ml) per cubic foot of cell

capacity (minimum of 10 ml or 3.3

teaspoons).

Special Tools

(Ref. Section 91−00−00)

(a). Place the ammonia saturated cloth

Item

Nomenclature

inside the cell and install the remain

N/A

Manometer

ing cover.

(b). Inflate cell with air to 1/4 psi (1.7

NOTE: Always test and inspect a repaired fuel

kPa) maximum. Maintain 1/4 psi (1.7

cell for leaks using soap bubble, phenolph

kPa) pressure for 15 minutes mini

thalein or liquid stand method before in

mum, before proceeding.

stalling the cell in the helicopter.

(c). Soak a large white cloth in the

(1). Use the following procedures to check

phenolphthalein solution. Thoroughly

installed fuel tanks and plumbing for

wring cloth out.

leaks.

(d). Spread and smooth cloth onto cell. Do

(a). Plug vent system.

not let cloth dry out.

(b). Remove cell floor access panels.

(e). A red spot will appear on the cloth

where there is a leak in the cell wall.

(c). Install manometer and air pressur

Mark each leak.

ization equipment.

Page 605

28-00-60

Revision 31

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(d). Apply 2 psi (14 kPa) air pressure for

WARNING

10 minutes to precondition cells. This

forces trapped air from between fuel

cells and helicopter structure. If

D Avoid fuel vapor ignition and fire.

necessary, repeat until cells adjust to

Use only nonsparking tools and ex

contour of cell bay.

plosion proof work lights. Attach he

licopter to an approved electrical

(e). Apply 2 psi (14 kPa) air pressure for

ground. Switch OFF all electrical

15 minutes with no visible, less than

power. Disconnect external power

1/4 inch (6.35 mm), drop on manome

and battery before opening fuel sys

ter. If pressure drop occurs, check all

tem. Ensure work area is adequately

vent plugs, fittings and re-test cells.

ventilated.

Repair or replace parts as necessary

to eliminate pressure drop.

D Engine operation or helicopter flight

(f). Unplug vent system. Remove ma

must be accomplished in accordance

nometer and pressurization equip

with requirements and limitations

ment.

specified in the 600N Rotorcraft

(g). Install cell floor access panels.

Flight Manual and applicable sup

plements.

10. Fuel Transfer System Functional Check

NOTE: This check is only done on aircraft

Prevent fuel system contamina

without the airframe fuel filter option.

CAUTION

tion. Install caps on the ends of

(Ref. Figure 602)

hoses, tubes and fittings as parts are re

moved. Bag and identify small parts to pre

vent loss or damage.

Special Tools

(Ref. Section 91−00−00)

Item

Nomenclature

NOTE: Gross weight, fuel load and ambient

ST803

Fuel Transfer System Functional Tester

conditions are optional for this functional

check.

FUEL PRESSURE

SWITCH HOSE

FUEL PRESSURE SWITCH

UNION

CEFA BEFORE FILTER

CEFA

PORT

MOTIVE FLOW

SUPPLY HOSE

LOOKING FORWARD

6G28-078

Figure 602. Fuel Transfer System Functional Check

Page 606

Revision 43

28-00-60

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(1). Make sure fuel transfer system tester

lective to increase N1 speed. Reduce throttle

calibration is current.

twist grip to decrease N1 speed.

(2). Disconnect motive flow supply hose

(5). Record N1, pressure altitude, outside

from CEFA before filter port union.

air temperature, motive flow rate and

motive flow pressure.

(3). Connect inlet line of tester to CEFA

(6). Use the calibration chart provided with

before filter port union.

the fuel transfer system tester and

(4). Torque tester fitting to 50 - 65 inch-

calculate the calibrated motive flow

pounds (5.64 - 7.34 Nm).

rate.

(7). The minimum calibrated motive flow

(5). Connect motive flow supply hose to

rate shall be 0.18 GPM.

outlet line of tester.

(8). If the calibrated motive flow rate is less

(6). Torque motive flow supply hose fitting

than 0.18 GPM, check the following

to 50 - 65 inch-pounds (5.64 - 7.34

components for correct operation.

Nm).

(a). Check valve

B. Check Procedures

(b). Jet (ejector) pump

(Ref. Figure 602 and Figure 603)

(c). Motive flow hoses

(1). Make sure test setup is complete.

(9). Shut down engine ground run in

(2). Ground run engine in accordance with

accordance with Rotorcraft Flight

Rotorcraft Flight Manual.

Manual.

(10). Disconnect motive flow supply hose

(3). Operate the helicopter on the ground at

from outlet line of tester.

100 percent main rotor speed (Nr) with

collective down.

(11). Disconnect inlet line of tester from

CEFA before filter port union.

(4). Stabilize motive flow pressure from

42.0 PSIG minimum to 44.0 PSIG

(12). Connect motive flow supply hose to

maximum. N1 at approximately 81

CEFA before filter port union.

percent.

(13). Torque motive flow supply hose fitting

NOTE: Motive flow pressure increases or de

to 50 - 65 inch-pounds (5.64 - 7.34

creases with engine N1 speed. Increase col

Nm).

Page 608

Revision 43

28-00-60

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

FUEL SYSTEM

REPAIRS

1. Fuel Shutoff Valve Control Cable Repair

NOTE: MDHS cannot guarantee the currency,

completeness or technical accuracy of fuel

cell repair procedures provided herein.

Consumable Materials

Since cell repair materials, techniques, and

(Ref. Section 91−00−00)

procedures may be changed or deleted by

Item

Nomenclature

the cell manufacturers without notice to

CM118

Grease

MDHS light helicopter publications; we

strongly recommend that:

NOTE: Worn fuel shutoff valve control cables

(1). Only specially trained personnel are

are normally replaced as an assembly.

allowed to inspect and repair the fuel

cells installed in 369/500/600 series

(1). The only authorized repair is replace

helicopters.

ment of a missing detent ball, as

(2). Customers planning to do their own

follows:

fuel cell repairs must order any re

quired manuals from the applicable cell

(a). Disconnect cable from fuel shutoff

manufacturer before beginning repair

valve lever swivel.

tasks (Ref. Sec. 01-00-00).

(b). Pull plunger out until detent ball

(a). Cell inspections, maintenance and

hole is visible. Insert detent release

repair must be per the cell manufac

rod in plunger. Align notch in detent

turers advice and instructions.

release rod with plunger detent ball

hole.

(3). Bladder or self sealing fuel cells are

supplied to MDHS by Engineered

(c). Apply grease (CM118) between

Fabrics Corporation.

plunger and plunger housing.

Use only approved inspection

CAUTION

(d). Insert detent ball in plunger hole.

requirements, repair methods,

Push release rod and plunger to full

materials and supplies designed for Engine

open position.

ered Fabrics Corp.

(4). Fuel cells produced by Engineered

(e). Rig fuel shutoff valve cable.

Fabrics Corp. are constructed of Nitrile

polyurethane plastic impregnated

Fuel Cell Repair

fabric.

3. Scuff Mark Repair

Consumable Materials

(Ref. Section 91−00−00)

Fabric exposed by a scuff mark may be buffed,

Item

Nomenclature

cleaned, coated with cement and allowed to

CM219

Methyl-ethyl-ketone

air-dry for 8 hours. No patch is required

CM603

Patching material

unless fabric is torn. Install patches where

required (Ref. Patch Installation).

CM604

Patching material

CM605

Fuel cell repair kit

4. Reinforcements, Hangers and Splice

CM607

Cement

Repairs

CM804

Emery cloth, fine

Loose reinforcement edges, hangers or lap

CM820

Cheesecloth

splices must be lifted, buffed, cleaned, cem

N/A

Polyethylene plastic, sheet or roll

ented and cured under pressure per applicable

instructions (Ref. Patch Installation).

Page 801

28-00-60

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

5. Loose Patch Repair

(b). Use a greaseless silver pencil to

outline patch installation area two

Replace loose patches with new patch installa

inches beyond damage in all direc

tions (Ref. Patch Installation). Where two

tions.

opposing patches have been installed over cell

(6). Hand-buff an area 1/2 inch (12.7 mm)

wall damage, unless otherwise indicated by

larger than space occupied by patch

inspection, replace only the loose patch.

with fine emery cloth (CM804) to

provide a roughened substrate for

6. Patch Installation

cement application. Do not cut through

cell fabric.

(1). Drain, remove and thoroughly dry cell

as soon as possible after determining

(7). Select a patch of #5218 material

cell repair is required. Drying time may

(CM604) for cell exterior. Trim patch to

be accelerated by keeping cell at 80°F

extend two inches beyond edges and

(27°C) and ventilating interior with dry,

ends of damage in all directions. Tilt

low pressure air.

scissors to bevel patch edges away from

cell surface. Radius all patch corners.

(2). Inspect fuel cell.

(8). Hand-buff patch gummed surface with

fine emery cloth. Ensure entire patch

Do not repair tears or holes over

CAUTION

joint surface has been abraded.

two inches (5.08 cm) long using

cold patch repair. Do not attempt to repair

(9). Repeat buffing procedures on cell

bonded fittings or corners. Contact Engine

interior surface. Buff internal patch

ered Fabrics Corporation when corner or fit

(CM603) trimmed from

ting damage is discovered or when cell wall

#5200/5187/5194 sandwich material.

damage exceeds two inch length limit.

Fuel cell and patch contact sur

(3). Accomplish fuel cell repair work in

CAUTION

faces must be perfectly clean

temperatures ranging from 60 - 80°F

and dry prior to adhesive and patch applica

(16 - 27°C) and in less than 50%

tion. Rubber and fabric particles, moisture,

humidity.

and fuel or oil from fingers will prevent

proper patch/cell adhesive cure and may

NOTE: Damp air, especially in combination

subsequently provide a leak path. Wear

with low temperatures, will cause water to

clean, lint free gloves to handle patch and

condense on cement applications. Water in

cell after preparing surfaces for cement and

hibits patch adhesion.

patch application.

Never expose a dry cell to high

(10). Install exterior patch first. Wipe cell

CAUTION

temperatures and, or direct sun

exterior and patch faying surfaces with

light for long periods of time. If repairs will

clean cheesecloth (CM820) dampened

not be started within ten days, prepare cell

with MEK (CM219).

for storage.

(a). Continue to wipe cell and patch,

changing cheesecloth and applying

(4). Both sides of a cell must be patched to

clean solvent as required, until no

repair any one hole or tear.

stain or particles appear on cheese

cloth pad after the last wipe.

(5). Thoroughly clean cell internal and

external repair areas with cheese cloth

Use cement sparingly. Two,

(CM820) dampened with solvent MEK

CAUTION

thin, even coats provide better

(CM219).

adhesion than one thick coat.

(a). Collapse cell and expose external

(11). Position a sheet of polyethylene plastic

damage area on a clean, flat working

beneath cell damage to keep cement off

surface.

opposite cell wall.

Page 802

Revision 19

28-00-60

HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 11