If memeory serves, the APU on our E-3 was used on the ground only....
After the engines were up and running...and the after taxi check was completed, the FE switched from the APU to the generators and shut down the APU...
After runway turn-off, the FE powered the APU back up and then cut off no.1 and 4 engine...so the E-3 was manoevered with no.2 and 3 engines only.
It's been 5 years that I flew the E-3 last, and can't remember 100% though... I've been an operator, only...not a FE or crewchief...
That doesn't really answer your question, but I think that the APU can be operated in flight.... ANY E-3 Mechs around??????
"That's the good thing about the 707...it can do anything, but read!" Joe Patroni, Airport '70
Venus6971 From United States of America, joined Dec 2004, 1432 posts, RR: 1 Reply 3, posted (8 years 6 months 1 day 16 hours ago) and read 1508 times:
Ok Bully, here is the scoop. The E-3 APU cannot repeat cannot be operated in flight. First it is tied to the squat switch on the gear plus if the inlet and exhaust doors are opened in flight or stuck open the aircraft will not pressurize since it is in the aft lower lobe. I remember on one certain acft once we had engines and generators on line I told the FE to shut down the APU so I could make sure the exhaust door will not get hung up , if it did it took a well placed hit with a rubber mallet to seat. Also after it shutdown the sequence valves and solenoids got out of wack and had to jump in the aft lobe on numerous hammerheads to open the big start box next to the apu to manually close the inlet and exhaust doors.
The APU generator also will not pararell or share power with the other 8 engine generators. So when engines are started and generators are brought in line and when you are in the back on headset you get that tone when they switch power and APU gen automatically goes off line.
Wingnut135 From United States of America, joined Feb 2005, 134 posts, RR: 0 Reply 6, posted (8 years 6 months 1 day 9 hours ago) and read 1468 times:
I worked the E-8 for three years, and it was designed to be operated in flight to augment the air coming from the engines, but never really worked. It was inside it's own unpressurised "can" in the aft lower lobe. There wasn't an inlet or exhaust door, just holes in the side of the plane. Not sure why it didn't work though.
[Edited 2005-06-10 00:08:45]
A good friend will get you out of jail. A real friend will be there with you saying, "Damn that was fun!"