TB 1-1520-238-20-48
2. Task/Inspection Suspense Date. One time inspection prior to next days mission flight for fuel leakage
and security.
3. Reporting Compliance Suspense Date. Report compliance to commander, ATCOM, AMSAT-C-XS no
later than 25 November 1993 per para 14a of this message.
4. Summary of the Problem.
a. Fire damage to an AH-64 aircraft during ground taxi operations is attributed to fuel leakage from an improp-
erly installed preformed packing and backup o-ring in the APU fuel solenoid valve. It is suspected that the valve
was improperly assembled by the manufacturer. An improperly assembled valve will allow fuel to escape and be
ignited by either the hot power turbine plenum or a flashback (APU backfire). This inspection is to confirm proper
assembly of the APU fuel solenoid valve in fleet AH-64A aircraft.
b.
c. The purpose of this TB is to direct a one time inspection of the APU fuel solenoid valve (P/N 692545-6,
692545-1 ) for fuel leakage and looseness prior to next days mission flight.
5. End Items to be inspected. All AH-64A aircraft. Aircraft Serial Numbers 82-23355 and subsequent will
be inspected/corrected.
6. Assembly Components to be Inspected. N / A
7. Parts to be Inspected.
NATIONAL STOCK NUMBER
PART NUMBER
NOMENCLATURE
692545-6
Solenoid Valve
692545-1
Solenoid Valve
Two personnel are required to accomplish this inspection.
8. Inspection Procedures NOTE:
a.
Safe the aircraft per ref 13a, task 1-7-2.
b. Gain access to APU area and remove APU upper center cover per ref 13a, task 15-2-2, step a.1 thru a.3.
Station an observer at the APU fuel solenoid valve.
c.
d. Enter pilot's crewstation and locate APU start/run switch.
Select APU start/run switch to "RUN". Hold run position for duration of inspection to pressurize APU fuel
e.
system.
f.
Observer is to inspect fuel solenoid valve for leakage by any of the following methods:
(1) Feel fuel solenoid valve for fuel dampness.
(2) Note if there is any increased fuel odor when line is pressurized.
(3) Visually check fuel solenoid valve for leakage by using an inspection mirror with an explosion proof flash
light.
(4) Feel area below fuel solenoid valve for fuel/dampness.
g. While APU fuel system is pressurized, observer is to place the index finger only on top of valve and attempt
to wiggle/move valve. Any indication of fuel leakage during this procedure requires valve replacement IAW para
h. If fuel leakage/odor is detected from fuel solenoid valve, see para 9 of this message for instructions.
i.
Return APU stat/run switch to "off" position.
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