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B737-112
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A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:13 am

If you go to about the 5:30 mark of the attached video, you'll see what appears to be a plume of smoke come out of the top of the Boeing 727's wing. If anybody has any insight as to why this would happen, please let me know.

Thanks,
Ryan





http://www.youtube.com/watch?v=JdB5HfI3DZ0

 
nutsaboutplanes
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:19 am

I believe that the 727's APU vented from the wing. This looks like an APU start-up shortly after arrival.
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aussiebrat
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:21 am

Its the auxiliary power unit doing its thing. The vent is visible from the cabin, located around the wing exit markings.

[Edited 2011-11-24 01:22:55]
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:23 am

OK, thanks guys! I had no idea that the APU vented there.
 
nutsaboutplanes
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:28 am

Here is something that I found that you might be interested in. While I worked at NW, there were several instances where evacutations were initiated by passenger onboard the 727 due to "APU torchngs". This link talks a bit about the spectacle and my understanding is that it can light up a dark cabin at night.

http://actacting.com/theatre-acting/aa-flight-panic-487838.html
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:51 am

nutsaboutplanes, that's a fascinating read. Thanks!
 
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Tomassjc
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 9:56 pm

Quoting nutsaboutplanes (Reply 4):
While I worked at NW, there were several instances where evacutations were initiated by passenger onboard the 727 due to "APU torchngs".




We had 2 such instances with the 727-264 when I worked at MX. One at LAX, when the aircraft was clearing the runway and the "U-pa" (APU in Spanish) was fired up, pax seated on the starboard side initiated an evacuation after seeing a flame shoot out of the APU exhaust. Fortunately the flight attendants knew what was going on and got everyone under control.

The second one on taxi in at SFO in the early 80s (In the alley between the original international terminal and the old WA gates) resulted in a full evacuation through the L1 door by a not so savvy crew. I vaguely remember piles of shoes in the forward galley and walking passengers to customs in their stocking feet. Talk about embarrassing!

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maxpower1954
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RE: A Puff Of Smoke From The Wing Of A 727?

Thu Nov 24, 2011 11:21 pm

During the original design period of the 727, small gas turbine APUs were still impractical. Late in the development phase, Garrett perfected one, but the 727 design was already frozen. So the APU was located in the left wheel well area, with the APU exhaust on the top of the left wing. BTW, the APU cannot be used in flight on the 727 because of this location.
 
shufflemoomin
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 1:08 am

To be honest, the video explains itself why it happens. It told you exactly what you just heard here.
 
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 4:50 am

Quoting shufflemoomin (Reply 8):
To be honest, the video explains itself why it happens. It told you exactly what you just heard here.



I added that text when the answer was explained to me above, the video is on my channel and I did that to answer the question for people who may be curious as I was.

 
oldtimer
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 9:29 am

Quoting maxpower1954 (Reply 7):
with the APU exhaust on the top of the left wing.



Exhausts on top of right wing, inboard and some models had a flap that opened prior to startup, others had a grill. A well worked APU was evident by the exhaust stains under the overwing exits.
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n901wa
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 12:37 pm

Man I remember changing the 727 APU. Here's a photo I took back when, that shows the exhaust and half of the APU in the RT Main W/W, looking fwd in a WAL 727-247. The Oil tank is right below the duct.
WAL 727-200 WW
 
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 7:58 pm

Quoting n901wa (Reply 11):
Here's a photo I took back when, that shows the exhaust and half of the APU in the RT Main W/W, looking fwd in a WAL 727-247. The Oil tank is right below the duct



Awesome pic, thanks man!

 
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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 9:02 pm

Quoting n901wa (Reply 11):
Man I remember changing the 727 APU. Here's a photo I took back when, that shows the exhaust and half of the APU in the RT Main W/W, looking fwd in a WAL 727-247. The Oil tank is right below the duct.


WAL 727-200 WW

Thanks for that pic. Wow that brings back some old memories. I worked on Fed-X 727s at the old Dalfort MRO and removed and installed a few APUs. That is an awfully clean wheelwell. Usually never see them that clean. I work strictly 737s now.

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RE: A Puff Of Smoke From The Wing Of A 727?

Fri Nov 25, 2011 9:22 pm

Quoting 737tdi (Reply 13):
That is an awfully clean wheelwell.

Yeah that is the cleanest well I've ever seen! You get dirty just looking in ours.
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maxpower1954
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RE: A Puff Of Smoke From The Wing Of A 727?

Wed Nov 30, 2011 9:09 am

Quoting oldtimer (Reply 10):
Quoting maxpower1954 (Reply 7):
with the APU exhaust on the top of the left wing.



Exhausts on top of right wing, inboard and some models had a flap that opened prior to startup, others had a grill. A well worn APU was evident by the exhaust stains under the overwing exits

It's been over 20 years since I last flew the 727, my memory let me down - thanks for the correction!

Maxpower1954

[Edited 2011-11-30 01:13:33]

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