Expratt From United States of America, joined Mar 2000, 311 posts, RR: 0 Reply 1, posted (12 years 3 months 2 weeks 3 days 17 hours ago) and read 4368 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.
Victor Hotel From Australia, joined Aug 2000, 305 posts, RR: 1 Reply 2, posted (12 years 3 months 2 weeks 3 days 13 hours ago) and read 4307 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.
VH
FBU 4EVER! From Norway, joined Jan 2001, 998 posts, RR: 7 Reply 3, posted (12 years 3 months 2 weeks 3 days 11 hours ago) and read 4298 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.
PHLYboy From United States of America, joined Feb 2001, 70 posts, RR: 0 Reply 4, posted (12 years 3 months 2 weeks 1 day 1 hour ago) and read 4165 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.
Exnonrev From United States of America, joined Oct 1999, 621 posts, RR: 4 Reply 6, posted (12 years 3 months 2 weeks 6 hours ago) and read 4126 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.
XFSUgimpLB41X From United States of America, joined Aug 2000, 3958 posts, RR: 36 Reply 8, posted (12 years 3 months 1 week 4 days 23 hours ago) and read 4029 times:
Anyone know how the fuel the APU turbine is? I have always wondered if they burn alot of fuel sitting there.
AeroGlobeAir7 From United States of America, joined Jan 2001, 586 posts, RR: 2 Reply 10, posted (12 years 3 months 1 day 2 hours ago) and read 3969 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.