What Is An APU? - Simple Flying
simpleflying.com › what-is-an-apuSep 25, 2022 · APU - The little turbine engine. All large commercial aircraft have an auxiliary power unit onboard, usually located in the tail of the aircraft (although some regional jets vents to the side). This is a small turbine engine, essentially the same design and operation as the main aircraft engines but on a smaller scale.