APU Flashcards
Overview 1
The standard APU provides electrical power and bleed air for aircraft use on the ground or in flight.
Overview 2
The APU’s main control, the electronic control unit (ECU), is integrated with other aircraft systems and is responsible for the majority of APU automatic operations and protections. The system operation is controlled from the cockpit via the APU SYSTEM control panel. APU generator power can be used to assist in ground engine starts or supply power for the entire aircraft up to the APU maximum operational altitude.
Overview 3
APU bleed air can be Used in case of engine bleed if a pressurisation environmental and service a purposes. APU Lead is not available for the anti-icing systems.
Overview 4
The APU Is a self-contained gas turbine engine with an attached accessory gearbox. The APU Serves as a source of bleed air. The accessory gearbox houses a starter generator used to supply electrical power to the main electrical system. Bleed air is provided for use in the pressurization / air-conditioning system and to the systems that utilize service air.
Overview 5
Bleed air from the APU is extracted from the compressor section and piped to the service air manifold and the bleed air control valve (BCV). APU bleed air is available for environmental, pressurization and service bleed systems only.
Electron control unit
The ECU in the tailcone is a fully automatic digital unit that communicates with other aircraft systems.
Where is the APU starter generator found?
On the accessory gearbox.
How is the APU starter generator cooled?
It is air cooled.
Is the starter generator interchangeable with the engine generator?
Yes.
Specs of the generator?
The generator is rated at 28 VDC, limited to 275 amps.
How many hours can you run the APU for with the low oil indication?
20 APU hours.
What is the APU RPM provided by?
By the ECU for display.
What is the APU EGT provided by?
Provided by a thermocouple extending into the exhaust gas stream.
What does the ECU use the APU EGT for?
For fuel scheduling, controlling the bleed air control valve and automatic shutdown due to over temperature.
Will the DC voltage indicate if the generator is selected OFF?
Yes.
