Kris asked in Cars & TransportationAircraft · 1 decade ago

Whats the hole at the back of aircraft used for?

Whats the hole at the back of aircraft used for?

9 Answers

  • 1 decade ago
    Favorite Answer

    The hole in the end of the tail cone in airliners today is the Axillary Power Unit (A.P.U.) exhaust. The APU is a small jet engine hooked to an electrical generator that is used to run the systems on the airplane when it's engines have not been started yet and is not hooked to any ground power supply. The power is used to start the engines. They are located in the tail cone because usually it is unused space.


  • 1 decade ago

    It's hard to guess what aircraft you are asking about, or which "hole."

    Airliners like the Boeing 737, 747, 757 and up have a small oval shaped opening under the tail, which is the exhaust pipe for the Auxiliary Power Unit (APU). The APU is a small turbine powered generator that provides electric power, heat, and air conditioning when the main engines are not running.

    Other aircraft have other types of "holes at the back." The most common is a rear cargo door on cargo airplanes. The Martin 4-0-4 and the Boeing 727 had passenger stairways under the tail.

    Source(s): retired airline pilot
  • 4 years ago

    What type of aircraft and where is the hole? What you want is a flush repair if you are using a doubler. How big is the hole? Your rivet pattern depends on the width of the doubler. Look up different repairs on the net. You should be able to find many if you search airframe repair.

  • 1 decade ago

    Which one, if the its the one in the tail, then this is the outflow vavle used in the pressuration system. It allows air to flow out of the cabin at a controlled rate to allow for the cabin to maintain cabin pressure at altitude, while allowing for air to be exhausted which allows for fresh air to circulate.

    If its the small one in the the rear on the side of the aircraft, ahead of the elevator, this is where the exhause from the APU is expelled.

    Ifs its a B-727 then this is the air inlet for the engine located in the tail.

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  • susan
    Lv 5
    1 decade ago

    That is for the A.P.U. It forces air through the turbines to start the aircraft's engines. It's like a jumpstart for a car, only using air

  • Otto
    Lv 7
    1 decade ago

    The exhaust for the APU.

  • 1 decade ago

    I take it your talking about a C-130 transport or similar. Its used for loading and unloading of freight,people or vehicles. Some loads can be dispatched while in flight via parachute

  • Anonymous
    1 decade ago

    its used for air con to keep the passengers cool and pressure right

  • 1 decade ago

    to dump the loads

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