Learjet 60 - APU Switch; APU SYSTEM TEST Switch

Pilot's
Manual
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Learjet 60
APU FAULT/STOP
SWITCH
This switch/ indicator is a momentary, two cell, lighted switch . The
lower portion is labeled STOP (white) and during normal operation
this switch is used to shut down the APU by sending an overspeed sig-
nal to the Electronic Sequence
Unit
of the APU . A normal shutdown
will not cause the FAULT half of the switch to illuminate . The top por-
tion of
this
switch is labeled FAULT (amber) and shows a malfunction
e APU system . The APU
will automatically shut
down if a fault is
sensed . The FAULT indicator circuit is latched and is cleared by the
FAULT RESET switch on the APU relay box, located near the APU .
PU RUNNING/START
switch/ indicator is a momentary, two cell, lighted switch .
sling
this switch initiates the APU start sequence . The lower
i is labeled START (white) and is illuminated whenever the
Th on to identify the switch .e top portion is labeled
G (green) and is illuminated when the APU is running and
supplying or ready to supply power to the aircraft .
APU MASTER SWITCH
The APU MASTER
switch
is used to power up the APU control circuits
from the aircraft normal electrical system . The legend is daylight read-
able and illuminated white when the aircraft NAB light switch is on .
APU ON INDICATOR
The
APU (311 (green) indicator illuminates when the MASTER switch
is on,
APU `STEM TEST
SWITCH
ITCH
The APU SYSTEM TEST switch tests the integrity of the APU fire loop/
thyguishing system . Depressing this switch will also test all annunci-
ator fights on the APU control panel, sound the APU fire horn, close the
APU fuel shutoff valve and illuminate the aircraft Master WARN/
CAUT lights . Depressing this switch while the APU is running will
close the APU fuel shutoff valve and shut down the APU .
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