HAWK21M From India, joined Jan 2001, 31875 posts, RR: 54 Posted (9 years 11 months 2 weeks 3 days 11 hours ago) and read 2732 times:
On a B752 If the APU Generator is u/s.
Can the APU be run with the Generator Installed.
Or does the APU gen have to be removed to avoid damage to the rotating Gen & blanked to enable the Gen Scavenge pump to function.
Anyone done it practically.
Buzz From United States of America, joined Nov 1999, 697 posts, RR: 20
Reply 2, posted (9 years 11 months 2 weeks 3 days 9 hours ago) and read 2714 times:
Hi Hawk21M, Buzz here. No problems with running the APU if the generator has gone bad, as long as it keeps oil inside. It's an oil cooled generator.
Sometimes we get 757's where the APU pneumatics have failed, or generator has failed. SO we use what it'll supply, if there's no physical damage: if it'll supply air... then we don't need the Huffer for an engine start. If the pneumatics have failed, but the electricity is good - that's one less thing to trip over at departure time.
Tonight we had an Airbus through-trip, APU was dead and it would not accept external power. The advice we were given was to trip the generator on the left engine (which was running to supply power) and re-boot the GPCU circuit breakers. After a minute the airplane recognized that external power ws plugged in and life was back to normal.
Fr8mech From United States of America, joined Sep 2005, 6694 posts, RR: 16
Reply 3, posted (9 years 11 months 2 weeks 3 days 8 hours ago) and read 2709 times:
We've had the same problem on our 'Buses. Except everytime I've seen it, we were trying to power from a dead airplane. Batteries on, generator switches off, GPU on, 1 generator switch at a time, repeat as required while throwing choice words at the Eurotrash.
CF or c/f = carried forward [Deffered].
At a Transit Stn if APU pneumatics are Available & B752 at High temp would else need Min Two Ideal Three Ground connections for start [RB211 Engines].
If APU can be run without deffering under MEL would be beneficial by not using Electricals.
But can a damaged Generator be destroyed if it is permitted to rotate.