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Boeing 757 At SJC Vid & Question...  
User currently offlineSJC-Alien From United States of America, joined Jul 1999, 919 posts, RR: 0
Posted (8 years 3 months 4 weeks 15 hours ago) and read 3800 times:

http://video.google.com/videoplay?do...d=-3767439211363772892&q=tom+vance

I filmed this last saturday at SJC.....when the '57 rolls out towards the exit, it was rather loud and was making a sound that sounded like a real loud hiss as it rolls by, then it goes quiet........then listen to the audio just before 1:18 on the ticker, as the jet turns right of 30L,,and then you hear the noise start up again, a very loud hiss as the wing-slats are retracted...then it goes away. What makes this noise...?

Thanks

SJC Alien

10 replies: All unread, jump to last
 
User currently offlineAS739X From United States of America, joined Apr 2003, 6200 posts, RR: 24
Reply 1, posted (8 years 3 months 4 weeks 14 hours ago) and read 3771 times:

Without watching the video I think its the APU. They are notoriously loud on the '57. I'll watch the video when I get home (can't watch from work). But its not the flaps and slats, you can't even hear that next to the plane when the engines are running.

ASLAX



"Some pilots avoid storm cells and some play connect the dots!"
User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4863 posts, RR: 25
Reply 2, posted (8 years 3 months 4 weeks 13 hours ago) and read 3757 times:
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I know what you are talking about. Without watching the video, I'm guessing it's either a UA or DL 757...

I have only ever heard it on P&W powered 757s so I'm assuming it deals with that specific engine type. Not really sure what the sound is though.

[Edited 2006-08-30 09:17:06]


ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineSJC-Alien From United States of America, joined Jul 1999, 919 posts, RR: 0
Reply 3, posted (8 years 3 months 4 weeks 7 hours ago) and read 3694 times:

Ok,,usually, we only get UA and DL 75's at SJC...and I have heard this noise on the UA 75's also.....but since this is the only airport I can get this close to the braking action, this is only where I have heard this,,( plus it was fairly quiet this night, (no SJC parking shuttle bus going by behind me ruining the noise as usual..) re-watching the video, right after the tower clears them to KILO and the gate, the read-back is complete, then the hiss starts again, then quits as the flaps drop, but yeah, I figured it wasn't the flaps making that noise.... Wink

SJC Alien


User currently offlineDakota123 From United States of America, joined Aug 2006, 116 posts, RR: 0
Reply 4, posted (8 years 3 months 4 weeks 6 hours ago) and read 3675 times:

I've wondered this, too. I believe the sound is air flowing from the bleed doors which are located between the low pressure compressor and the high pressure compressor. The doors are there to help match airflow between the low and high pressure compressors at low loads.

Dakota123


User currently offlineJacobin777 From United States of America, joined Sep 2004, 14968 posts, RR: 59
Reply 5, posted (8 years 3 months 4 weeks 5 hours ago) and read 3651 times:

Quoting SJC-Alien" class=quote target=_blank>SJC-Alien (Reply 3):
Ok,,usually, we only get UA and DL 75's at SJC...

don't forget we'll be getting the return of the "Nerd Bird" AA 757-200 too.. Smile


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User currently offlineBatonOps From United States of America, joined Jun 2006, 752 posts, RR: 4
Reply 6, posted (8 years 3 months 4 weeks 5 hours ago) and read 3636 times:

Maybe it could from the thrust reversers closing?

User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4863 posts, RR: 25
Reply 7, posted (8 years 3 months 4 weeks 3 hours ago) and read 3590 times:
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Quoting Dakota123 (Reply 4):
I believe the sound is air flowing from the bleed doors which are located between the low pressure compressor and the high pressure compressor. The doors are there to help match airflow between the low and high pressure compressors at low loads.

Bleed air of some kind would be my only guess.

Quoting SJC-Alien" class=quote target=_blank>SJC-Alien (Reply 3):
Ok,,usually, we only get UA and DL 75's at SJC...and I have heard this noise on the UA 75's also.....but since this is the only airport I can get this close to the braking action, this is only where I have heard this

When I worked at SJC, AA had daily 757s, most commonly RR powered 757s. I never heard the sound from AA's 757s so I pretty much drew the conclusion that it is something only heard on P&W 757s.


Quoting SJC-Alien" class=quote target=_blank>SJC-Alien (Reply 3):
re-watching the video, right after the tower clears them to KILO and the gate, the read-back is complete, then the hiss starts again, then quits as the flaps drop, but yeah, I figured it wasn't the flaps making that noise....



Quoting BatonOps (Reply 6):
Maybe it could from the thrust reversers closing?

I hear this sound all the time when UA or DL 757s land here at SAN. Typically at SAN it is heard at the very end of the roll-out seconds after the reversers stop making their noise. I have never really payed attention to the reversers to see if they were open, closed, or closing while the sound in question in being heard. But I don't think it has anything to do with the state of the reversers. I do remember that when I was at SJC it was actually more common to hear this sound after the aircraft exited the runway and begun it's taxi back to terminal C. It was SOOOOOOOOOOO loud for us on the WN ramp since they were right in front of us moving slowly when they would make the sound. We used to jokingly say they did it on purpose just to piss us off.

I'm surprised the answer hasn't popped up yet in this thread. Maybe if it was in Tech/Ops we would see more activity in here. I have been too afraid to ask this question myself as I was certain this has probably been discussed before and a simple search (that I am too lazy to do) would lead me to the answer.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineSJC-Alien From United States of America, joined Jul 1999, 919 posts, RR: 0
Reply 8, posted (8 years 3 months 3 weeks 6 days 18 hours ago) and read 3512 times:

...yes, thanks for all of the info.......I was 'directed' to post videos on this forum only....but it was just for fun to see of anybody knew off-hand, Dakota 123 might be the closest to the correct answer.............I feel. But thanks to all.

Alien


User currently offlineSjsu2sjcAA777 From United States of America, joined Oct 2004, 43 posts, RR: 0
Reply 9, posted (8 years 3 months 3 weeks 6 days 15 hours ago) and read 3479 times:

hey buddy i hear this sound all the time when the 757 lands, my guess would be the thrust reversers.

User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4863 posts, RR: 25
Reply 10, posted (8 years 3 months 3 weeks 6 days 14 hours ago) and read 3461 times:
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Quoting Sjsu2sjcAA777 (Reply 9):
hey buddy i hear this sound all the time when the 757 lands, my guess would be the thrust reversers.

It is not the thrust reversers. It happens after the reversers have completed their job. Please read the thread before posting.

[Edited 2006-08-31 08:19:30]


ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
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