What is aircraft APU used for?

What is aircraft APU used for?

The auxiliary power unit (APU) is a small gas turbine engine mounted in the tail cone of an aircraft to provide autonomous electrical and mechanical power for the following: Starting power for the main engines. Pneumatic power for cabin air conditioning systems.

How do aircraft engines start?

This starting process normally uses an electric motor to spin the main turbine shaft. The electric motor spins the main shaft until there is enough air blowing through the compressor and the combustion chamber to light the engine. Fuel starts flowing and an igniter similar to a spark plug ignites the fuel.

What happens when APU fails?

Failure of an APU in air or ground results in cancellation or delay in flight departure, which inhibits flight operations. An aircraft APU that requires maintenance after 7000 flight hours, would require a maintenance cost of nearly $0.4 Million [4].

How does an APU start an engine?

Providing power on the ground The APU will run a generator that provides electrical power for the cockpit and cabin systems. It will also produce pneumatic pressure to operate the cabin air conditioning systems. Power from a battery will start the engine motor spinning. Fuel is added, and the engine starts quickly.

Do all airplanes have APU?

Do all airliners have an APU? Most every modern turbojet powered airliner (including the smaller regional jets) have an APU installed in the tail. Only a few large turboprop aircraft have them due to the weight restrictions of smaller aircraft.

Which aircraft component is used during the startup of the main engine?

Gas turbine aircraft engines such as turbojets, turboshafts and turbofans often use air/pneumatic starting, with the use of bleed air from built-in auxiliary power units (APUs) or external air compressors now seen as a common starting method. Often only one engine needs be started using the APU (or remote compressor).

Can an APU fly a plane?

The APU also uses far less fuel than the main engines, so while the aircraft is at the gate, the APU can power the aircraft and A/C without engaging one of the big engines, for a significant cost savings.

Does the 787 have an APU?

The APS5000 APU was designed exclusively for the Boeing 787 Dreamliner. It is the quietest APU in its class with the lowest emissions in the industry. Pratt & Whitney APS3200 is the Airbus baseline APU of choice for the Airbus A320 family of aircraft.

How do aircraft manufacturers determine Apu requirements?

The aircraft manufacturer determines APU requirements after considering the size of the cabin, the amount of bleed air required to power the environmental packs, and the generator size needed to power the cockpit and cabin and start an engine.

What do auxiliary power units (APUs) do on aircraft?

What do Auxiliary Power Units (APUs) do on aircraft? 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. Many of these roles are used routinely in day-to-day flying,

What is the difference between a jet engine and Apu?

However, unlike the main engines, the APU does not provide thrust (hence it would be wrong to call it a jet engine). Instead, it powers an electric generator and provides air pressure. A Honeywell APU (it produces APUs for all Boeing 737 and Airbus A320 aircraft).

Is it possible to run the car without the APU?

Yes it is. Without the APU the airconditioning and electronics also won’t work when the engines are shut down, so a ground power unit is connected to provide the electricity and enough compressed air to run the air-conditioning. Starting the engines will need a air start unit to start one of the engines using compressed air provided by hoses.