Big777jet From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 9 months 6 days 19 hours ago) and read 696 times:
APU stands for Auxilury Power Unit. That aircraft has power small engine to keep supply power for electricity and air conditioner or heat while the plane is on the ground. Also, APU must running while take off or landing for in case engine failure and APU is running to re-start engine.
BDDLCW From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 9 months 6 days 13 hours ago) and read 681 times:
Can anyone confirm that the APU is running during takeoff and landing? I know it doesn't have to be, because airliners fly with inop APUs all the time. I thought they were always shut down prior to flight and not restarted until they were back on the ground. I would think that you would want all the fuel going to the engines for flight and if an engine were to fail you could use the still running engine/s to cross-start the failed engine.
SA365C1 From United Kingdom, joined Apr 2001, 131 posts, RR: 0
Reply 3, posted (12 years 9 months 6 days 11 hours ago) and read 673 times:
No APU's are not running during take off and landing think about it, the APU is distibuuting power to the aircraft while the engines are not running, when the engines are running the generators are providing power so why would you need the APU?????
SQ325 From Germany, joined Jul 2001, 1447 posts, RR: 7
Reply 4, posted (12 years 9 months 6 days 11 hours ago) and read 664 times:
APU is a gas-turbine which provides energie and hydraulic pressure, when the engines are out and the plane is on the ground. APU will be stopped after engine start and be activated at the gate before the engine shutdown. But inflight the Apu is out if you need energie for the restart of a engine
(what i truely doubt, because if an engine is giong to die inflight there is a reason, maybe I try it once but then I'll leave it off) take the energie supply of the other engine(s)