3-5. PRELIMINARY CHECKS.
3-6.
The following checks should be made prior to operating the auxiliary power unit.
Check plumbing and electrical wiring connections for security of attachment.
a.
CAUTION
Do not operate the APU with the air inlet screen removed.
Ensure operating area is clean of loose items. The greatest
hazard to a gas turbine engine is the possible ingestion of
foreign material into the engine compressor.
Lock the exhaust silencer pipe in the upright position, and direct the stand to
b.
allow safe exit of the exhaust gas (from both the exhaust pipe and the bypass
door).
Open the exhaust silencer bypass door.
C.
Check the tires for sufficient air pressure (40 to 45 psig).
d.
Check the fuel tank dipstick for sufficient quantity of fuel.
e.
Check the speed increaser oil sight glass for full quantity of lubricating oil.
f.
Ensure that the parking brakes are applied (brake handle up).
g.
Check all gages on the instrument panel for zero indication.
h.
Check that all switches on the instrument panel are either in the OFF position
i.
or in neutral, and that the circuit breakers are pulled.
Check the APU oil sump for full quantity of engine lubricating oil (3 U.S.
j.
quarts).
k. Purge the APU fuel system.
Refer to paragraph 3-7 for the purging procedure.
3-7. PURGING THE APU FUEL SYSTEM.
3-8. The following purging procedure is for the purpose of depreserving, or purging,
the APU fuel system when a preserved or repaired engine is to be operated.
Disconnect the harness connector from the APU ignition exciter. Insulate the
a.
connector to prevent accidental contact.
3-4
