Starting APU without APU Tester Box (P/N 161226-200) installed.

TM 55-4920-424-13&P

b. Connect the Battery terminal, check Battery Voltmeter (on console) for 22 VDC minimum.

c. Push in MAIN POWER and LOAD RELAY circuit breakers.

d. Move START-RUN-OFF switch to RUN.

e. Move LITES TEST/ESU RESET switch to LITES TEST and hold. Check that all lights illuminate by pressing on

each indicator.

f. Move LITES TEST/ESU RESET switch to ESU RESET three times. Move FUEL BOOST PUMP switch to ON.

Let run approximately 30 seconds, and turn OFF. Check all fuel lines for leaks.

WARNING

Post fire watch.

CAUTION

If any abnormal condition is observed/heard during APU start or operation, move

the START-RUN-OFF switch to OFF IMMEDIATELY.

CAUTION

If APU test stand is allowed to run out of fuel, the APU fuel control may be

damaged.

Note

Before starting engine, refer to items (g) through (j) below and read in its entirely.

g. Move START-RUN-OFF switch to START, hold for two seconds, then release.

Note

1. Start fuel Light ON at approximately 14% RPM (no Indicator).

2. Main fuel Light ON at approximately 70% RPM, Start Fuel Light OFF at

approximately 30 seconds from sequence initiation, Rdy-to-Load light ON. (These

parameters are approximates, refer to appropriate TM.)

h. Observe that APU accelerates smoothly to operating speed.

WARNING

Exhaust duct and APU combustor section are hot during operation. Keep clear of

combustibles. Avoid physical contact to preclude personal injury.

E-20 Change 2