TM 55-1520-240-T
15-1.5 APU OPERATIONAL CHECK
15-1.5
INITIAL SETUP
Ext Hydraulic Power Off
Applicable Configurations:
APU Start Accumulator Charged to 2850 Psi
All
APU Visual Check Performed (Task 15-1.4)
Tools:
Helicopter Positioned Nose into Wind
Stopwatch
Rotor Blades Positioned So That One Aft Blade is
Materials:
Behind and 30 Degrees Off Centerline
None General Safety Instructions:
Personnel Required:
Medium Helicopter Repairer (2)
Aircraft Electrician
WARNING
References:
TM 55-1520-240-23
Keep hands away from flight controls.
Application of hydraulic power will
Equipment Condition:
cause flight controls to move and rotor
TM 55-1520-240-23:
blades to flap. Injury to personnel can
Battery Connected
occur.
Ext Electrical Power Off
TASK
RESULT
1.
Set BATT switch (1) to ON.
MASTER CAUTION lights (2) shall come on. If not, go to
task 9-1.4.
2.
Press pilot's MASTER CAUTION light (2).
MASTER CAUTION lights (2) shall go out. If not, go to
task 9-18.3.
3.
Check that APU CONT NORM and EMERG circuit
If circuit breaker (3 or 4) is open, close it. If either circuit
breakers (3 and 4) are closed.
breaker opens again, go to task 15-2.7.
NOTE
Post fireguard at APU.
4.
Check that POWER XFR NO. 1 and POWER XFR NO.
If switches (5 or 6) are ON, set them to OFF.
2 switches (5 and 6) are at OFF.
5.
Position helper to observe bite indicators on ESU (7).
6.
Set APU switch (8) to RUN. Hold at RUN for a
BITE indicator #1 on ESU (7) changes from black to white
minimum of 3 seconds.
and then is reset to black. All other indicators remain black
or are reset to black.
NOTE
If Bite #1 is already white, this task resets it to
black, along with the other BITE indicators.
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15-16 Change 23
