How does an aircraft APU start?

How does an aircraft APU start?

The APU can be started utilizing only the aircraft battery(s) and, once running, will provide electrical power to aircraft systems as well as bleed air for air conditioning and for engine start.

How is APU aircraft powered?

The APU is equipped with an extra electrical generator to create enough power to operate onboard lighting, galley electrics and cockpit avionics, usually while the aircraft is parked at the gate. Drawing bleed air from its own compressor, an APU also drives the environmental packs used to heat and cool the aircraft.

Does APU need fuel?

APUs are fitted to some tanks to provide electrical power without the high fuel consumption and large infrared signature of the main engine.

What is the APU actually used for?

An APU (auxiliary power unit) works in a similar way to an aircraft’s engine and has three roles: to supply conditioned air to the cabin, as a source of electrical power for the aircraft and lastly as a means of engine starting.

What is an APU that starts the jet?

The APU is a small engine that is used to start the larger jet engines. It provides cabin air and electric power before the engines are started (saving battery power). It provides an emergency source of electric power in the event of engine failure.

Can an airliner take off if the APU is inoperative?

Yes in general aircraft can depart with an inoperative (INOP) APU’s. In flight the APU generally serves as a backup in the case of a failure of other systems (e.g. electrical failure). Prior to departure the pilots will check the aircraft “tech log” (aircraft technical logbook) which will indicate if the APU is not working.

What is an APU on aircraft?

The APU is a small jet engine that is used to start the larger jet engines. In airliners it’s usually at the very rear of the aircraft, below the tail. Large engines are heavy and require a lot of torque to spin up, more than a starter battery can generate.