Jetliners usually have their engines mounted on the wings, so what is the exhaust port on the tail for?

  • 1
    $\begingroup$ This is called the apu unit on an airplane. It uses jet fuel to make electricity to power the screen on the back of the seat or the cabin lights. It can also be referred as a tailcone. $\endgroup$
    – Ethan
    Aug 7, 2015 at 17:58

1 Answer 1


That's the exhaust port for the APU (Auxillary Power Unit).

The APU is usually used to power on-board electronics when at the gate, or used to start the main engines. They may or may not be running while in-flight.


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