What is this part on the tail? — Tech Ops Forum

Sponsor Message:


My Starred Topics \| Profile \| New Topic \| Forum Index \| Help \| Search

What is this part on the tail?

Imiakhtar From , joined Dec 1969, posts, RR:
Posted (4 years 10 months 3 weeks 5 days 2 hours ago) and read 3217 times:

Hi. I was spotting today at BHX when I saw this thing protruding just aft of the rudder on a PK 77L (AP-BGL)

Big version: Width: 448 Height: 336 File size: 16kb

From another angle, during engine start

Big version: Width: 448 Height: 336 File size: 18kb

I saw that it was extended during the taxi for takeoff, but couldn't tell whether it was still sticking out during take. Apologies for the poor quality pics. Does anyone know what it is?

Thanks Smile

14 replies: All unread, jump to last

Brendows From Norway, joined Apr 2006, 1020 posts, RR: 4
Reply 1, posted (4 years 10 months 3 weeks 5 days 2 hours ago) and read 3216 times:

Quoting Imiakhtar (Thread starter):
Does anyone know what it is?

This is the APU (auxiliary power unit) intake door, in its open position. The door is closed when the APU is off (for example when the 777 gets power from the generators in the engines.)

474218 From United States of America, joined Oct 2005, 6340 posts, RR: 10
Reply 2, posted (4 years 10 months 3 weeks 5 days 2 hours ago) and read 3212 times:

Quoting Imiakhtar (Thread starter):
Does anyone know what it is?

APU inlet.

Imiakhtar From , joined Dec 1969, posts, RR:
Reply 3, posted (4 years 10 months 3 weeks 5 days 2 hours ago) and read 3198 times:

Quoting Brendows (Reply 1):
This is the APU (auxiliary power unit) intake door, in its open position. The door is closed when the APU is off (for example when the 777 gets power from the generators in the engines.)

Quoting 474218 (Reply 2):
APU inlet.

I should have realised it had something to do with the APU considering the close proximity to the APU exhaust. Thanks for the prompt replies Smile

.

Regards
Imi

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 4, posted (4 years 10 months 3 weeks 4 days 20 hours ago) and read 3132 times:

APU Inlet.
Very similiar to the B757,however its more forward mounted on the type.
How is the routing on the pic like,as it seems far aft.

regds
MEL

Think of the brighter side!

Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81
Reply 5, posted (4 years 10 months 3 weeks 4 days 20 hours ago) and read 3122 times:

Quoting HAWK21M (Reply 4):
How is the routing on the pic like,as it seems far aft.

I believe the air duct runs straight into the side of the APU. The load compressor and generators are probably forward of the air inlet.

Tom.

AA737-823 From United States of America, joined Mar 2000, 5336 posts, RR: 11
Reply 6, posted (4 years 10 months 3 weeks 4 days 15 hours ago) and read 3062 times:

Quoting Tdscanuck (Reply 5):
The load compressor and generators are probably forward of the air inlet.

Indeed.
The load compressor and accessory section are forward, while the combustion compressor is aft of the air inlet, which does, as someone mentioned, go directly into the side of the APU plenum.

UAL747 From , joined Dec 1969, posts, RR:
Reply 7, posted (4 years 10 months 3 weeks 4 days 14 hours ago) and read 3038 times:

Stupid question, but is the APU the thing that makes the high pitched swoooshing noise when the aircraft is at the gate?

UAL

Boeing767mech From United States of America, joined Dec 2000, 992 posts, RR: 3
Reply 8, posted (4 years 10 months 3 weeks 4 days 14 hours ago) and read 3037 times:

Quoting UAL747 (Reply 7):
Stupid question, but is the APU the thing that makes the high pitched swoooshing noise when the aircraft is at the gate?

That's the one, some people would joke and say it turns air and fuel into noise. Since on a hot day some of our APU's have problems cooling the cabin.

David

Never under-estimate the predictably of stupidty

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 9, posted (4 years 10 months 3 weeks 4 days 13 hours ago) and read 3019 times:

Quoting Tdscanuck (Reply 5):

Quoting AA737-823 (Reply 6):

Thanks.
Do you have a pictoral view of the routing?

regds
MEL

Think of the brighter side!

Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81
Reply 10, posted (4 years 10 months 3 weeks 3 days 21 hours ago) and read 2891 times:

Quoting HAWK21M (Reply 9):
Do you have a pictoral view of the routing?

I've hunted around the web quite a bit and haven't found a good one of the 777 yet. It's in section 1 of the AMM, but I can't post that here.

You can get a rough idea of how its' done from here:
http://www.b737.org.uk/apu.htm

About 1/4 of the way down the page is a labelled picture lookup up at the 737 APU from below. Just aft (to the right) of the oil tank you can see a flat metal band that appears to wrap all the way around the APU...that's the inlet plenum. It's a radial inlet. The inlet duct hooks on to the plenum about 180 degrees around the APU from what you can see here. The duct basically runs straight from the side of the APU to the side of the airplane. The 777 is similar, only the duct goes almost straight up to the inlet beside the vertical stab. As you can tell, about half of the APU is ahead of the inlet.

Tom.

AA737-823 From United States of America, joined Mar 2000, 5336 posts, RR: 11
Reply 11, posted (4 years 10 months 3 weeks 3 days 17 hours ago) and read 2859 times:

Quoting HAWK21M (Reply 9):
Thanks.
Do you have a pictoral view of the routing?

I do NOT... isn't that a SHAME????
I have some training stuff from Alteon, but it's proprietary, so I'm not inclined to post it on the Net.

The picture in the link is of a classic 737 APU. This design doesn't have a separated load compressor at all... only the 737NG, 744, and 777 have that design. I don't even know whether the 75/67 do.

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 12, posted (4 years 10 months 3 weeks 3 days 17 hours ago) and read 2854 times:

Quoting AA737-823 (Reply 11):
I have some training stuff from Alteon, but it's proprietary, so I'm not inclined to post it on the Net.

I understand.

Quoting Tdscanuck (Reply 10):
I've hunted around the web quite a bit and haven't found a good one of the 777 yet. It's in section 1 of the AMM, but I can't post that here.

Any page reference,I could check the AMM with friends at AI & 9W.

regds
MEL

Think of the brighter side!

Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81
Reply 13, posted (4 years 10 months 3 weeks 3 days 2 hours ago) and read 2768 times:

Quoting HAWK21M (Reply 12):

Quoting Tdscanuck (Reply 10):
I've hunted around the web quite a bit and haven't found a good one of the 777 yet. It's in section 1 of the AMM, but I can't post that here.

Any page reference,I could check the AMM with friends at AI & 9W.

777 AMM Section 1, 49-00-00, Page 3 & 11

Tom.

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 14, posted (4 years 10 months 3 weeks 2 days 17 hours ago) and read 2700 times:

Quoting Tdscanuck (Reply 13):
777 AMM Section 1, 49-00-00, Page 3 & 11

Thanks.tom.
regds
MEL

Think of the brighter side!