TM 55-1520-240-23-1
1-103
SERVICE HELICOPTER AFTER SHORT TERM STORAGE (Continued)
1-103
AUXILIARY POWER UNIT
13.
Prepare APU for service as follows:
a.
Remove electrical power from aircraft.
b.
Remove APU exhaust protective cover, and
stow it.
CAUTION
Make sure solvent does not enter
APU air inlet. The presence of solvent
could cause the APU to explode
during initial operation.
c.
Remove tape (E388) and barrier material
(E81) from APU air inlet. Remove tape
residue. Use solvent (E161).
d.
Service APU oil sump to FULL (Task 1-53).
e.
Remove cap from fuel filter inlet port.
Remove plug from fuel filter inlet line.
f.
Connect fuel filter inlet line to fuel filter inlet
port.
g.
Disconnect fuel lines from main fuel manifold
and start fuel nozzle.
h.
Connect drain hoses to each disconnected
line. Place free ends of drain hoses into a 1
quart container.
CAUTION
If the following operation is not carried
out, the APU will be motored, and
ignition might occur.
i.
Unplug power supply connector from ignition
exciter.
j.
Remove APU PRESERVED tag from APU
switch.
k.
Apply external dc power to aircraft (Task
1-37).
l.
Have helper, in cockpit, hold APU switch to
START.
m.
Observe flow from drain hoses into 1 quart
container.
n.
After preserving oil has been purged from
system and a steady flow of clear air-free fuel
is observed coming from drain hoses, have
helper in cockpit set APU switch to OFF.
o.
Remove external dc power from aircraft.
p.
Remove drain hoses.
q.
Connect fuel lines to main fuel manifold and
start fuel nozzle.
r.
Connect power supply connector to the
ignition exciter.
CAUTION
Deleted.
s.
Check that aft transmission is serviced with
oil (E254) (Task 1-54).
CAUTION
The APU can be seriously damaged
if the intake or exhaust airflow is
restricted.
t.
Make sure the APU air inlet and exhaust
openings are free from obstructions.
u.
Make sure turbine fuel drain valve is not
restricted. (Refer to TM 55-2835-205-23.)
v.
Make sure residual unburned fuel is drained
from the turbine section.
w.
Apply external dc power to aircraft (Task
1-37).
x.
Start and operate APU. (Refer to TM
55-1520-240-T.)
y.
Shut down APU. (Refer to TM 55-1520-240-T.)
z.
Check APU oil sump level. Service if
necessary (Task 1-53).
ENGINES
14.
Refer to TM 55-2840-254-23.
LOG BOOK ENTRIES
15.
Enter in aircraft log book date aircraft and
component were prepared for service. Use forms
DA 2408-13 and 2408-15 (DA PAM 738-751).
FOLLOW-ON MAINTENANCE:
None
END OF TASK
Change 3
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