2016年10月24日 · When the N2 rotor speed is 8%, the APU controller energizes the ignition exciter and sends a signal to the fuel metering unit to supply fuel to the combustion chamber. The ignition exciter causes the two igniter plugs to make sparks. The APU engine has combustion and starts to increase in speed.

It provides power for the Boeing 747-8 and its predecessor, the PW901A-powered Boeing 747-400. During on-ground operation, it provides bleed air for cabin conditioning from a low spool-driven load compressor, and electrical power from two gearbox-mounted 90kVA generators.

The 747 Auxillary Power Unit, or APU, is a gas turbine engine that is housed in the tail section of the aircraft. The APU can supply electrical and pnuematic...

2009年12月27日 · Auxiliary Power System (APS): The APS comprises the auxiliary power unit (APU), and the inlet, exhaust, control, and mounting hardware. The first all electric APU will be 50 percent quieter and have 10 percent lower emissions compared to the Boeing 767 APU. B747-8 Pratt & Whitney APU PW901A, same as installed in 747-400 series.

2021年8月9日 · Hello everyone, in this one I am showing you how to start up a B747-400. Enjoy#miami #boeing #aircraft #b747 #cockpit #cockpitview

The implementation and installation of Boeing's 747 auxiliary power unit (APU) was the result of efforts tailored to the 747 airplane's needs. Greater power requirement of the plane and its size made unique demands in formulating an APU design specification.

2018年11月3日 · At the 747 classic it was from the production start possible to have two APU options : - operation allowed untill 15.000ft after APU starting at the ground. - start and operation possible in the air (max 15.000 ft.) Only APU pneumatic air could be …

2021年9月24日 · This course does an excellent job of describing the components, normal/abnormal operations, controls, indications of the B747 APU and includes the following information: The APU systems to include the start and shutdown procedures for normal and abnormal conditions.

2009年12月1日 · The EICAS message APU indicates that the APU is unusable; no further attempt should be made to use the APU until maintenance clears the fault C. If the APU continues to operate after the APU Selector is OFF, the APU may be shut down manually by …

2016年10月25日 · On the 744 the APU start is a spring loaded rotary switch. You momentarily hold it to START and then move to the ON position. There's some debate that selecting ON to 'open the door' has some supposed advantage, but it makes no difference.