Section IV. OPERATION UNDER USUAL CONDITIONS

TM 55-4920-431-13

Section IV.

OPERATION UNDER USUAL CONDITIONS

2-4. Preparation for Use.

a. Turn pressure equalizer knob to OPEN. Open case. Turn knob to CLOSE.

b. Remove harnesses from case lid.

c. Connect harnesses as shown in figures 2-2 or 2-3.

d. Zero meters.

e. Perform your before (B) PMCS.

2-5. APU Test. Connect the tester for use in the aircraft in accordance with figure

2-2. Perform test in accordance with the applicable maintenance manual.

NOTE

During tests, leave BLEED AIR OPEN/CLOSE switch,

MAX. AIR switch, and ECONO AIR switch in down

position.

2-6. ESU Test. Bench test of the ESU is accomplished by using an oscillator to

simulate the tach input from the magnetic pickup in the APU. Millivolt supplies are

used to simulate EGT thermocouple inputs from the APU. Connections are made

through the ST93930 simulation device as shown in figure 2-3. Perform check in

accordance with TM 55-1520-240-T.

Section V.

Not applicable.

2-7