Starting APU with APU Tester Box installed

TM 55-4920-424-13&P

i. Battery charging is automatic. Indications are, LOADED light ON and an increase in voltage, above 24 VDC on

the Battery voltmeter

CAUTION

If APU is to be restated or another start attempt tried, wait at least 30 seconds after

APU has stopped before placing the START-RUN-OFF switch to START. This

allows residual fuel to drain from APU, thereby preventing an overspeed or

overtemp condition.

j. If APU fails to start or automatically shuts down, note ESU BITE indicators and refer to appropriate TM for

troubleshooting procedures.

3-13. Starting APU with APU Tester Box installed (Fig E-11).

a. Ensure all switches on the instrument panel and APU Tester box are OFF or in the DOWN position.

b. Install the APU Tester box on the shelf in the Control Console and latch support arms.

(1) Connect APU Tester Harness 161229-200 as follows:

P2 APU Tester to J2 of APU Tester

P1 A/C Harness to P2 of Control Console

P2 ESU to J2 of ESU

(2) Connect APU Tester Harness 161228-200 as follows:

P1 APU Tester to J1 APU Tester

P1 ESU to J1 ESU

(3) Connect APU tester Harness 161227-200 as follows;

P5 APU Tester to J5 APU Tester

J1 Engine Harness to P1 of Control Console

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

d. Push in MAIN POWER and LOAD RELAY circuit breakers, on instrument panel.

e. Move OFF-RUN-START switch on instrument panel to RUN.

f. Move the LITES TEST/ESU RESET switch on the instrument panel to LITES TEST and hold. Check that all

lamps on instrument panel illuminate by pressing on each lamp.

Change 2 E-21