What Is That Thing

Kent Wien posted this photo of the tail of a Boeing 757 showing what looks like the exhaust end of a turbine.

I had to ask what it was all about, and Kent explained:

Ahh, very good question! There actually IS an engine back there. It’s the APU (auxiliary power unit) and it’s what keeps the airplane cool on the ground without being plugged into the gate. It also provides electrical power and high pressure air that starts the engines after we push back from the gate.

This engine is the same as the one found on the Jetstream 31 commuter airplane, but without the prop.

aircraft, aviation, boeing 757, tail, apu, auxiliary power unit, answer

One thought on “What Is That Thing

  1. Hi
    I found this site as I searched “757 APU”. I wonder if you have any knowlage concerning the use of an APU to restart a 757 engine during flight. The reason for this question is a 757 flight I had, with an unsevicible APU. The company claimed it’s completly safe and legal and that Boing engine restart procedure do not demand ab APU.
    Can you help here.

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