Talk:Auxiliary power unit

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Boeing 747 APU's develop up to 1100 horsepower

Yeah, it's pretty impressive... They're LOUD... Shreditor 00:44, 26 August 2007 (UTC)

[edit] APU Fuel

From my little experience, I know that the when an aircraft is in the cold and dark state, you have to ensure that all crossfeed valves are open but you have to make sure all the fuel pumps are off. Does this mean that the APU has its own separate fuel tank or does the fuel just flow to the APU because of gravity?

Ans: Not sure what aircraft you are talking about. The start sequence for most APUs automatically positions valves and energizes the appropriate aircraft fuel pump(s) prior to starter rotation. Depending on aircraft make and model, the APU is fed by pressure pump or eductor from either a main wing tank, or a collector tank often located in the fuselage (typical of some regional jets). The APU does not have its own fuel tank. The APU also has a fuel pump driven off the accessory gearbox that provides high pressure fuel required to produce atomized spray patterns from the fuel nozzels. Gravity feed would not likely provide adequate fuel pressure to the APU fuel pump that could result in cavitation or starvation.