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trent1000
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Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 5:48 am

Why is it that the A350, such a new aircraft type, has incredibly noisy, churning flaps extension/retraction? Wouldn't new or improved technology make this practically silent? Or are manufacturers trying to reassure timid passengers that following "the big noise", the plane will turn?
 
kcrwflyer
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 7:09 am

I think it's generally accepted that airplanes will make noises. After all, these are the people cranking out thousands of jets that literally sound like a dog in the cargo bin is barking.

Quieter technology could also be heavier, larger, more expensive.. etc.
 
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LAX772LR
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 7:54 am

Quoting trent1000 (Thread starter):
Or are manufacturers trying to reassure timid passengers that following "the big noise"

Sincerely doubt that they're trying for that effect, but I for one am glad that it's there. I find the sound of flaps extending to be comforting... knowing that they're properly doing their thing.
I myself, suspect a more prosaic motive... ~Thranduil
 
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sturmovik
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:01 am

Quoting LAX772LR (Reply 2):
I find the sound of flaps extending to be comforting... knowing that they're properly doing their thing.

Normally I would agree, but on a plane as quiet as the A350, I found the noise to be startling.
'What's it doing now?'
 
VAAengineer
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:03 am

If ever get the chance to see the system and transmissions that make the movement of the slats and flaps possible, then you will appreciate it more. There is a lot of monkey motion on involved in this process.
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DocLightning
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:03 am

The 787 is the worst:

http://www.youtube.com/watch?v=QAfk5ZlQNfs

If you sit near the trailing edge of the wings, there is the most obnoxious hydraulic pump that starts up pretty much just before the flaps are extended and then makes the most horrid, ear-shatering, positively tooth-grinding high pitched noise as in the video above until the flaps are retracted after departure. And then from time to time it briefly comes on randomly during the flight, penetrating through the most robust of earplugs.

Ugh. It's dreadful.
-Doc Lightning-

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briguychau
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:06 am

Quoting kcrwflyer (Reply 1):
that literally sound like a dog in the cargo bin is barking.

Wait so what exactly is that noise? I've only heard it on some A320s and not others and I thought I was going mad!
 
coolian2
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:41 am

Quoting DocLightning (Reply 5):
makes the most horrid, ear-shatering, positively tooth-grinding high pitched noise as in the video above until the flaps are retracted after departure

Sweet unholy....that was bad enough for me, and I think that might have driven the dogs in my neighbourhood mental.
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777Jet
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:46 am

Quoting briguychau (Reply 6):
Quoting kcrwflyer (Reply 1):
that literally sound like a dog in the cargo bin is barking.

Wait so what exactly is that noise?

Power Transfer Unit

http://www.youtube.com/watch?v=9ffJgk1-tCA

Quoting briguychau (Reply 6):
I've only heard it on some A320s and not others and I thought I was going mad!

I've heard it on all A320's I've flown on.
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col
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 9:15 am

The A350 is very quiet, typical of Airbus, so when the flaps extend you notice it more.
 
masi1157
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 9:27 am

That barking noise is from the A320 family PTU (power transfer unit) and has been discussed hundreds of times. What we are talking about here is the A350 PCU (power control unit, no idea why it has that name). That is a very powerful nachine installed in the rather lightweight structure of an otherwise very quiet aircraft. Hard to reduce that noise without a lot of extra weight.

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tonystan
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 1:27 pm

If the consumer wants quieter planes with quieter cabins then they must expect the pitfalls which includes hearing every snore, fart, galley latch, trolley break, conversation and yes, aircraft systems that make noises due to their very nature.

Personally I prefer the slightly noisier aircraft cabins of the 747 and 777 ilk. It's ambient noise drowns out so much of the other stuff.
My views are my own and do not reflect any other person or organisation.
 
bx737
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 1:55 pm

I don't think that for flap noises the BAe146 can be beaten. The loud whine after take off and before landing was fantastic.
 
planewasted
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 1:59 pm

Sat next to the engine on a 777 a few days ago. The flaps was very noisy. Similar to the A350 I would say.
If you want to hear noisy flaps, try the BAe 146!
 
sulzerjan
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 3:59 pm

Now that was funny , while watching the video of replay 8 ( A320 barking dog ) our dog wakes up looks around and starts to make this growling sound when there are other dogs around.
 
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AirPacific747
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 6:18 pm

I found the A380 landing gear extension very loud and noisy.
 
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LAX772LR
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 6:38 pm

Quoting planewasted (Reply 13):
If you want to hear noisy flaps, try the BAe 146!

Anyone recommend a good video?
I myself, suspect a more prosaic motive... ~Thranduil
 
kaneporta1
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:08 pm

Quoting bx737 (Reply 12):
I don't think that for flap noises the BAe146 can be beaten. The loud whine after take off and before landing was fantastic.

Beat me to it! Although the 146 flap noise was aerodynamic rather than mechanical.
I'd rather die peacefully in my sleep, like my grandfather, not terrified and screaming, like his passengers
 
bx737
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 8:43 pm

Quoting kaneporta1 (Reply 17):
13):

I believe it does have to do with air flow through/over the flaps as they are being retracted.

Quoting LAX772LR (Reply 16):

About 6:50 into the video you can hear the noise.

http://youtu.be/VS6ANeyQrFs
 
kaneporta1
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 9:47 pm

Or this video...

http://www.youtube.com/watch?v=RNZ92B7QsOA

I did not take that video, but I have also heard the noise from the ground!
I'd rather die peacefully in my sleep, like my grandfather, not terrified and screaming, like his passengers
 
Capt.Fantastic
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 10:35 pm

Why is it that flap extension/retraction on the MD-80 and DC-10/MD-11 is practically silent from inside the cabin?
Why such noisy disparities with Boeing and Airbus models?

Edit: I've heard flap mechanisms / actuators on every aircraft I've flown on with the exception of the above

[Edited 2016-04-24 15:40:19]
 
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caoimhin
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 10:52 pm

Quoting bx737 (Reply 12):
I don't think that for flap noises the BAe146 can be beaten.

A few weeks ago I flew on a Swiss Global BAe146. My first time on that type. I couldn't believe how noisy it was. I loved every minute of it though.

I kind of look forward to flap extension and retraction. It's a chance to observe some of the aircraft's mechanics in operation. The sounds are all part of the experience.  
 
AngMoh
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 11:32 pm

There are two reasons:

1) The aircraft is more quiet in many areas, so whatever still makes noise is more audible (remember the complaints about passenger noise and how it affected crew rest on the A380?)

2) The aircraft is majority CFRP. One of the problems is that an CFRP structure transmits sound better than Al. My previous company had a research collaboration agreement with Boeing and during a meeting sometime in 2008, someone from Boeing R&D had a coffee chat with my colleague about their effort on reducing noise as the sound transmission on the 787 structure was higher than anticipated due to the significant increase in CFRP over Al.
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Ty134A
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 11:35 pm

TU-134 and TU-154M are completely silent, you would not even notice them when not looking out the window!
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Flaps
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 11:43 pm

Quoting Capt.Fantastic (Reply 20):
Why is it that flap extension/retraction on the MD-80 and DC-10/MD-11 is practically silent from inside the cabin?
Why such noisy disparities with Boeing and Airbus models?

The DC10 stabilizer trim was rather obnoxious if you happened to be seated far enough aft. I'm not sure that anything tops the 146 though.
 
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Aeroflot777
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RE: Noisy Flaps Extension And Retraction

Sun Apr 24, 2016 11:54 pm

Quoting Ty134A (Reply 23):
TU-134 and TU-154M are completely silent, you would not even notice them when not looking out the window!

  

I would always marvel at the silence on the TU-154.
 
col
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 12:58 am

Quoting tonystan (Reply 11):
If the consumer wants quieter planes with quieter cabins then they must expect the pitfalls which includes hearing every snore, fart, galley latch, trolley break, conversation and yes, aircraft systems that make noises due to their very nature.

Personally I prefer the slightly noisier aircraft cabins of the 747 and 777 ilk. It's ambient noise drowns out so much of the other stuff.

Why is it that those who support the Randy white noise argument, throw in the strange reasons to accept the noisier aircraft. The conversation argument I find to be the most ridiculous. It does not drown out conversation, it makes having a conversation worse. People raise their voices to be heard. You can do a simple test at home to see how it actually works.
Snore, fart, baby crying, trolley brake, galley latch, sneeze, toilet flush, teeth brushing, hair combing, meal tray, window slide hard to believe you can sleep with all that noise on a quiet frame.
 
alyusuph
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 2:50 am

Quoting trent1000 (Thread starter):
incredibly noisy, churning flaps
Quoting DocLightning (Reply 5):
the most horrid, ear-shatering, positively tooth-grinding high pitched noise

The use of words here will frighten any new flier
I am not an Airbus or Boeing fan, just an aircraft fan
 
n797mx
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 2:54 am

Quoting DocLightning (Reply 5):
The 787 is the worst:

http://www.youtube.com/watch?v=QAfk5ZlQNfs

If you sit near the trailing edge of the wings, there is the most obnoxious hydraulic pump that starts up pretty much just before the flaps are extended and then makes the most horrid, ear-shatering, positively tooth-grinding high pitched noise as in the video above until the flaps are retracted after departure. And then from time to time it briefly comes on randomly during the flight, penetrating through the most robust of earplugs.

Ugh. It's dreadful.

Ugh, that Hydraulic pump is the worst for sure.

http://www.youtube.com/watch?v=gtMwzToEj1k

You can hear it shut off at the 7:10 mark. The video doesn't do it much justice.
Clear skies and strong tail winds.
 
solarflyer22
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 2:55 am

Quoting DocLightning (Reply 5):
The 787 is the worst:

Are the newer composite planes louder? Less insulation than aluminium perhaps?

Quoting Ty134A (Reply 23):
TU-134 and TU-154M are completely silent,

I flew an Iran Air Tu-134 and it was strangely a little quieter. I also hit my head on a strangely low roofline when you exit. I am only 5'10 ish.

I too hate the sound but I do appreciate the back and then down motion it has to do.
 
crownvic
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 5:34 am

Even better than the BAe-146 sound was the BAC-111 hands down. Does anyone have a video? The howling from the lowering of the flaps of this a/c was second to none.
 
lilxlakerbo1
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 5:44 am

From what I can recall, the flap extension/retraction sounds on the A380 is pretty bad too. Especially sitting on the lower deck.
 
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DocLightning
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 6:14 am

Quoting lilxlakerbo1 (Reply 31):
From what I can recall, the flap extension/retraction sounds on the A380 is pretty bad too. Especially sitting on the lower deck.

It's definitely audible. Same on the A350. But neither are anywhere near the 787's constant whine.

Quoting solarflyer22 (Reply 29):

Are the newer composite planes louder? Less insulation than aluminium perhaps?

I'm assuming there is some reason why the new hydraulic systems are so tooth-grinding. On older models, like the A330, the flap extension is audible, but much quieter and lower-pitched. Check out 8:00 in this video: http://www.youtube.com/watch?v=_9ZMYg50DZw
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
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masi1157
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 10:48 am

Quoting caoimhin (Reply 21):
A few weeks ago I flew on a Swiss Global BAe146. My first time on that type. I couldn't believe how noisy it was.

What you hear on a BAe146 has absolutely nothing to do with the noise on an A350. It is aerodynamically generated on BAe146, while it is rotating machinery on A350.

Quoting DocLightning (Reply 32):

I'm assuming there is some reason why the new hydraulic systems are so tooth-grinding. On older models, like the A330, the flap extension is audible, but much quieter and lower-pitched.

There is a reason, or rather a number of reasons. One is that the PCU on an A350 is much more powerful than on A330, it is rather in the range of A380. Another one is a different type of hydraulic motor used on A350 and A380 than on earlier types. The stiff and lightweight structure also contributes, while the fact it is CFRP is not too much of a problem.


Gruß, masi1157
517 different segments on 101 airlines to 212 airports in 55 countries
 
SJCMSP
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RE: Noisy Flaps Extension And Retraction

Mon Apr 25, 2016 12:05 pm

Quoting Capt.Fantastic (Reply 20):
Why is it that flap extension/retraction on the MD-80 and DC-10/MD-11 is practically silent from inside the cabin?
Why such noisy disparities with Boeing and Airbus models?

I was going to ask this same question. On DC-9s it's pretty much silent as well. Although when the slats are extended prior to takeoff they go in a sudden thud which jars the whole plane a bit.
 
NASBWI
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RE: Noisy Flaps Extension And Retraction

Thu Apr 28, 2016 5:21 pm

I tried searching a video that demonstrates it, but haven't been successful: on the E190, whether you're sitting in front, over, or behind the wing, there is an audible low-pitch "rubbing" sound the slats make inflight when they are either extended or retracted on both takeoff and descent. The sound is most likely attributed to the change in airflow, but some have described it as the "E190 burp".
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Passedv1
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RE: Noisy Flaps Extension And Retraction

Thu Apr 28, 2016 5:34 pm

Wow...that 787 noise is awful. Im a little surprised with all the "attention" paid to the inflight experience.

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