Asked by: Pasqualino Zitzelsberger
asked in category: General Last Updated: 9th June, 2020

What is an APU on a jet?

The Auxiliary Power Unit (APU) is a small jet engine housed in the tail of the aircraft used to provide a source of electricity to power the aircraft on the ground when the engines are switched off and as a source of air in order to start the engines.

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Simply so, what does an APU do on an airplane?

The auxiliary power unit is usually run on the ground during passenger boarding and deplaning. The APU turns an electric generator that powers the electrical system on the aircraft when the main engines are off. It also provides pneumatic pressure for air conditioning and, more importantly, starting the main engines.

Beside above, does the APU stay on during flight? The APU, in the early days, was never meant for in-flight use. When the engines are finally shut down at the gate, the APU smoothly takes on the electrical power load of the aircraft. If needed, the crew also keep the air-conditioning running with pneumatic (air) supply coming from the APU.

Hereof, how does an APU start a jet engine?

APUs are like small jet engines, small enough to be started electrically. So you would use the power of the battery or an electric ground power cart to spin up the APU by its electric starter motor, and then introduce fuel into it once its spinning fast enough, just like a jet engine is started.

Is an APU an engine?

The APU is a small turbine engine installed near the rear of the fuselage. But calling the APU an extra jet engine is not accurate because the turbine exhaust from the APU is vented overboard. A jet engine would be used to propel the aircraft forward.

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