INTRODUCTION
The optional Auxiliary Power Unit (APU) provides an electrical power supply and a pneu-
matic source for operation of the aircraft environmental system during ground opera-
tions. The APU is certified for ground use only and can be operated while the engines
are running to augment aircraft electrical and bleed-air systems.
The APU is an AlliedSignal Aerospace, Inc.
model RE100 (LJ) and is located within a con-
tainment box in the aircraft tailcone above
the baggage compartment. It is certified for
ground use only and circuitry within the squat
switch will shut down the APU at takeoff. The
APU air inlet is located above the left engine
pylon and the exhaust is vented through a lou-
vered port located above the right engine
pylon, just aft of the ECU exhaust.
The APU is a fully automatic, constant speed
gas turbine engine designed to provide both
electrical and pneumatic (bleed air) while on
the ground. Electrical power is supplied by the
auxiliary generator mounted to the accessory
gearbox. Pneumatic and electrical power may
be supplied simultaneously or independently.
Where both types of power are demanded,
electrical power has priority. Selector switches
located in the flight crew compartment initi-
CHAPTER 6
AUXILIARY POWER UNIT
6-1
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
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