Спомагателна силова установка (APU) на Boeing 737

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Ludovic ANDRE / version 00

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BOEING 737 SYSTEMS REVIEW


Page 1


AUXILIARY POWER UNIT (APU)


1. GENERAL

¡ The auxiliary power unit (APU) is a self-contained gas turbine engine. It is installed within a fireproof,
sound-reducing shroud located in the tail of the aircraft.

¡ The APU supplies bleed air that may be used for engine starting and air conditioning.

¡ An AC electrical generator is provided which may be used as an auxiliary AC power source.

¡ Electrical power from the aircraft battery and fuel from the No.1 tank are used to start and operate
the APU.
¡ The APU is monitored and controlled by an Electronic Controller.
¡ Automatic shutdown protection is provided in case of APU fire or when certain limits are exceeded.
737 NG
The APU is equipped with an automatic fire extinguishing system.



2. COMPONENTS

¡ The APU consists of a load compressor, engine compressor, turbine and a gearbox which drives the
generator and other accessories. The APU is monitored and controlled by an Electronic Controller.
Automatic shutdown protection is provided in the event of low oil pressure, system fault, overspeed,
overtemperature or fire.

¡ For the 737NG, automatic shutdown protection is also provided for a high oil temperature or a Fuel
Control Unit failure.

¡ The APU oil cooler and electrical generator are provided with positive cooling a irflow by a gear-
driven fan. Inlet air is ducted to the fan through a shutoff valve which opens