Originally Posted by
Glenntilton
I commute before and after the merger, the guppy is always too hot for me. We used to be able to have ground air and APU air at the same time, has that changed? BTW, on the Airbus and 747, my walk around is to shut off external air, as the APU does a better job.
Someone put a note in the FM that having both on could over pressure and damage the plenum, which several mechanics have told me is not possible. Inversely, there's nothing to my knowledge that prevents the rampers from plugging in the air and starting it up while the APU is running the packs.