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THe Hole At The Back Of The Plane  
User currently offlineBruce From United States of America, joined May 1999, 5099 posts, RR: 13
Posted (15 years 2 months 4 weeks 1 day 17 hours ago) and read 12772 times:

I don't know any other way of describing it, on some 757/767 models it kind of looks like the plane's ***hole.

It looks like some kind of exhaust port at the extreme rear fuselage. What does that do? Do all jets have them?

Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
10 replies: All unread, jump to last
User currently offlineExpratt From United States of America, joined Mar 2000, 311 posts, RR: 0
Reply 1, posted (15 years 2 months 4 weeks 1 day 17 hours ago) and read 12631 times:

The hole in the tails of 737, 757, and 767 airplanes is the auxiliary power unit (APU) exhaust. On the 727, it is in the right wing. On the 777, it is on the left side of the tail. On the DC-9/MD80, it is on the right side of the tail just over the engine.

User currently offlineVictor Hotel From Australia, joined Aug 2000, 305 posts, RR: 1
Reply 2, posted (15 years 2 months 4 weeks 1 day 13 hours ago) and read 12570 times:

I know about the APU's, and where they are, and what they do, but I am unsure as to how they work. I have a feeling they are a type of turbine(am I correct?), if so what sort and how does it work, If im wrong what is it and how does it work? Thanks in advance.

User currently offlineFBU 4EVER! From Norway, joined Jan 2001, 998 posts, RR: 7
Reply 3, posted (15 years 2 months 4 weeks 1 day 11 hours ago) and read 12561 times:

Yes,modern APU's are very small jet engines running at a constant speed.In earlier days (read piston engine times) they were small piston engines almost invariably referred to as "putt-putt's".
All output is being used to generate electric power for ground and in-flight use when ground or engine-driven generators are not available.They also provide a source of compressed air for air conditioning and engine start.Some planes do not have APU's,or it may have been an option.SAS DC-8's did not have them.

"Luck and superstition wins all the time"!
User currently offlinePHLYboy From United States of America, joined Feb 2001, 70 posts, RR: 0
Reply 4, posted (15 years 2 months 3 weeks 6 days 1 hour ago) and read 12428 times:

As I understand, Boeing's 727 was the first Airliner to have an APU. I used to work for a Cargo carrier and always wondered why our old DC-8's needed a huffer cart to start the 4 noisy engines.

User currently offlineJjbiv From United States of America, joined Jan 2001, 1226 posts, RR: 5
Reply 5, posted (15 years 2 months 3 weeks 5 days 21 hours ago) and read 12389 times:

I believe most -8s had them when delivered -- correct me if I'm wrong. Perhaps the cargo haulers removed them for the weight advantage?

User currently offlineExnonrev From United States of America, joined Oct 1999, 621 posts, RR: 3
Reply 6, posted (15 years 2 months 3 weeks 5 days 6 hours ago) and read 12389 times:

The 707 and DC-8 never came from the factory with an APU. A few DC-8s got them when they recieved the CFM-56 conversion, but they had an overheating problem and were removed.

The only 707s to get a factory installed APU were the E-3 AWACS and the E-6 Mercury TACAMO aircraft. The installation is almost identical to the 727. The C-135 series (the real 717) has one installed in left rear cabin just forward of the boom operator position.

User currently offlineCX flyboy From Hong Kong, joined Dec 1999, 6805 posts, RR: 55
Reply 7, posted (15 years 2 months 3 weeks 4 days 13 hours ago) and read 12336 times:

?? I thought this was where they throw rubbish out, and where the toilet flush goes when airborne!

User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4300 posts, RR: 34
Reply 8, posted (15 years 2 months 3 weeks 2 days 23 hours ago) and read 12292 times:

Anyone know how the fuel the APU turbine is? I have always wondered if they burn alot of fuel sitting there.

Chicks dig winglets.
User currently offlineCapt.Picard From , joined Dec 1969, posts, RR:
Reply 9, posted (15 years 2 months 3 weeks 2 days 10 hours ago) and read 12279 times:


Seeing you're a pilot with Cathay, please tell me you were joking about what you posted above!!

User currently offlineAeroGlobeAir7 From United States of America, joined Jan 2001, 586 posts, RR: 2
Reply 10, posted (15 years 2 months 1 week 6 days 1 hour ago) and read 12232 times:

The hole you speak of is the aircraft's APU (Auxhilary Power Unit). The APU provides electricity on the ground for the aircraft, for such functions such as engine start, air conditioning, heating, etc.

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