Table 3-5. Sequence of events during performance check-Continued
Power unit Indication
Place 400 Hz out-
400 Hz ac convenience
receptacle and power
switch in RESET
position and hold
Release 400 Hz
400 Hz main contactor
K12 400 output con-
If not, and environ-
relay (K10) remains
tactor lamp stays il-
mental control com-
ponents are also de-
energized, there is
probably a generator
fault signal produced
by connection of
400 Hz load.
If not, but environmental
probably 400 Hz
contactor switch (S9)
failed or contacts of
400 Hz output con-
tactor relay (K12)
Acceleration and overtemperature control thermostat. If acceleration and overtemperature control
thermostat (fig. 3-9) is replaced, or if controlling temperature is not as specified, check and adjust as follows.
Connect gas turbine engine analyzer to power unit as described in paragraph 3-8b above except
paragraph 3-8b(6) above.
Disconnect line from load control thermostat (fig. 3-24). Connect a control air plumbing line from the
load control thermostat line to the AIR IN fitting on the analyzer panel. Open needle valve on analyzer panel (fig. 33).
Remove cap from acceleration limiter valve. tee. Connect the 0-100 psig gage set, provided with
the analyzer, to the open leg of the tee.
Open conditioned air outlet compartment access door (fig. 1-2) and refrigeration compartment
access door (fig. 1-1).
Start engine and accelerate to noload governed speed. Operate at this speed for approximately two
minutes to stabilize operation.
Operate both heated air systems at full heat as described in paragraph 2-16d.
With heated air systems operating at full heat, place the mode select switch to COOL on both
systems. The heated air flow control valves will remain open but the engine load control valve will close. Open the
engine load control valve by installing a jumper between analyzer jacks identified LOAD VALVE and DC POWER.
This condition delivers both cooled air and heated air at the same time to provide sufficient engine load to raise exhaust
gas temperature to 671°C to 682°C (1240°F to 1260°F) for checking the thermostat setting.
This bypasses the over-temperature thermoswitches in the air out compartment. Monitor the
air out temperature and shut down the power unit if air discharge temperature exceeds 93 °C
With engine operating at full bleed load, slowly close needle valve (fig.3-3) on gas turbine engine
analyzer panel until the AIR IN pressure gage (fig. 3-3) drops to approximately 14 psig. The exhaust gas temperature at
which engine speed and fuel pressure start to decrease is the acceleration and overtemperature control thermostat