TM 11-6125-240-12
a. Typical Installation Procedure.
(3) Secure the inverter to the aircraft mounting
with the four sets of mounting hardware.
(1) Make sure that the portion of the aircraft
(4) Connect the power cable to the ac power con-
mounting that corresponds to the inverter mounting
nector of the inverter.
base is free from oil and grease to insure good electrical
(5) Connect the dc input leads to the terminal
grounding.
(2) Position the inverter on the aircraft mounting;
board studs; maintain the proper polarity.
b. Removal. To remove the inverter for mainten-
line up the holes in the inverter mounting base with the
ance or repair, reverse the procedures in a above.
holes in the aircraft mounting.
Section Il. OPERATION
2-4. General
The PU-545/A must be energized before use and de-
tension of the ground tests in the applicable aircraft
energized after use; no other operation is required. The
operator's condensed checklist. The checks should be
inverter contains no on/off switch. It is energized
performed in the order given.
automatically when the aircraft 28V dc power is ap-
NOTE
plied and deenergized when the power is removed. No
Use an external power source for making
warmup is required before use.
functional checks to prevent drain on air-
craft batteries. (Refer to applicable aircraft
2-5. Starting and Stopping Operation
technical manual.)
a. Starting. Turn on the necessary aircraft switches
(1) Start the inverter. If the aircraft in which the in-
to apply the 28V dc to energize the inverter. The motor
verter is installed is equipped with panel meters for
should start.
reading the ac voltage and frequency, check the output
CAUTION
of the inverter on the meters, (Refer to applicable air-
After starting the inverter, check for smoke
craft technical manual.) If the inverter is performing
or any other sign of malfunction. If any mal-
satisfactorily, the voltmeter should read between 109
function is noted, immediately remove the
and 121 or 202 and 214 volts ac, and the frequency
28V dc power.
meter should read between 390 and 410 Hz (deter-
b. Stopping. T u r n o f f t h e n e c e s s a r y a i r c r a f t
mined by external hookup). Vary the load from no load
switches to remove the 28V dc from the inverter.
to full load by turning on the aircraft equipment that
operates with the ac supplied by the inverter. (Refer to
2-6. Initial Operational Check
the applicable aircraft technical manual.) The voltage
a. General. The operational check (b b e l o w )
indicated on the voltmeter should not vary more than 1
V, and the indicated frequency variation should be less
supplements the inspection procedures in the aircraft
operator's condensed checklist. The operator's inspec-
than 6 Hz.
tion consists of checking serviceability by performing
(2) If no ac panel meters are installed in the air-
an operational check. The checks listed should be ac-
craft, check to see that the inverter is running by listen-
complished before a flight. The pilot or copilot should
ing to the motor. Turn on any aircraft equipment that
report any malfunction or failure noted during the
operates from the ac supplied by the inverter and check
flight, or any discrepancy noted in the preflight check
to see that the equipment is operating. (Refer to the ap-
(TM 38-750).
plicable aircraft technical manual.)
b. Operational Check. The following preflight
(3) Turn off the necessary aircraft switches to stop
checks should be made during engine warmup as an ex-
the inverter.
2-2
