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Strange Noise In A320 On Climbout  
User currently offlineJoePatroni From United States of America, joined Mar 2007, 204 posts, RR: 0
Posted (5 years 6 months 6 days 6 hours ago) and read 6956 times:

Hi!
So, as a disclaimer, I fly very often and average about 130,000 miles a year. I also work in the airline industry and know quite a bit about these beasts I fly on. That being said, I'm pretty tuned into the "sounds" that airplanes make throughout the different phases of flight especially the A320 which seems to be the aircraft I fly the most.
Yesterday, I was on UA519 from PHX to SFO on N339UA- a TED configured A320 now in UA mainline paint:

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So just after we lifted off there was a fairly high pitched sound and a distinct vibration which kept getting louder and stronger. The noise and vibration dissipated for a little while and then started even stronger than before as soon as we started to bank to the right. The vibration was really remarkable especially during this turn and then seemed to get less and less the higher we went. It was so remarkable that it was louder than the sound of the engines (which I was sitting next to in 6A) and the vibration was so distinct that it was almost hard to see clearly.

I was listening to Channel 9 the whole time and nothing was mentioned and the crew carried on as completely normal so I knew that this was probably no big deal (actually, Thank Goodness for Channel 9 because I'm sure my anxiety level would have gone through the roof!) but I was wondering if anyone has experienced this before or if any of you have any insight as to what the heck this was.

Some of my thoughts as to what was going on was perhaps an open panel (i.e. cargo door control panel or maybe the ground power panel) or something wrong with the engine- but obviously that was not the case.

Anyway, any insight would be greatly appreciated!
Thanks!
JP


Oh Stewardess, I speak Jive.
26 replies: All unread, showing first 25:
 
User currently offlineSashA From Russia, joined May 1999, 861 posts, RR: 0
Reply 1, posted (5 years 6 months 6 days ago) and read 6890 times:

Weather conditions? Probably some significant turbulence area... also thinking if there could've wing and stab config that would cause that? I hope anyone with an actual piloting background could comment on this.

BTW, what does Channel 9 transmit? Is it what I think it is - crew to ATC comms? Wow...



An2/24/28,Yak42,Tu154/134,IL18/62/96,B737/757/767,A310/320/319,F100,BAe146,EMB-145,CRJ,A340-600,B747-400,A-330-300,A-340
User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 2, posted (5 years 6 months 6 days ago) and read 6889 times:



Quoting JoePatroni (Thread starter):

Sound anything like this?

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

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17068 posts, RR: 66
Reply 3, posted (5 years 6 months 5 days 23 hours ago) and read 6877 times:

Could be some interior part close to you vibrating. Maybe a big panel or something. If the engines hit the right frequency for a part, it will vibrate. Not uncommon.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 4, posted (5 years 6 months 5 days 11 hours ago) and read 6717 times:

Did the vibration & sound reoccur on Descent or was this only with climb thrust?
regds
MEL.



Think of the brighter side!
User currently offlineJoePatroni From United States of America, joined Mar 2007, 204 posts, RR: 0
Reply 5, posted (5 years 6 months 5 days 5 hours ago) and read 6621 times:



Quoting JetMech (Reply 2):
Sound anything like this?

It was definitely not that. I'm quite familiar with that sound on the Airbus'. It's the hydraulics, right?

Quoting Starlionblue (Reply 3):
Could be some interior part close to you vibrating. Maybe a big panel or something. If the engines hit the right frequency for a part, it will vibrate. Not uncommon

I thought about that, but the vibration was a lot heavier sounding that a big piece of thin plastic if that makes sense. It definitely felt heavier and more dense that that.

Quoting HAWK21M (Reply 4):
Did the vibration & sound reoccur on Descent or was this only with climb thrust?

No, the vibration and sound only occurred during climb. I guess what was remarkable was that it really got stronger as we banked to the right and lessened as we leveled. The flaps/slats were still down at that point. I really thought the fuselage was going to split in two during that turn but there really wasn't that much turbulence.

JP



Oh Stewardess, I speak Jive.
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 6, posted (5 years 6 months 5 days 4 hours ago) and read 6604 times:

Since you were in fairly far forward (Row 6) my guess (that's all any one can do) is that it was the nose wheels spinning in the wheel well. There are pads in the nose gear wheel well that stop the spinning wheels. However, operation with the spin brake pads removed is allowed by the MMEL. The spinning wheels would resonate throughout the fwd cabin.

User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 7, posted (5 years 6 months 5 days 1 hour ago) and read 6547 times:

Had a similar experience while flying on an MD 80 some years back.

Loud, almost squealing sound and an accompanying vibration. It was so loud that the passengers around me were getting freaked out. The noise changed with airplane banking. I went up front and identified myself to the flight crew, we discussed the noise, and the first officer and I went back to listen. We continued on to our destination, and it was annoying.

I went out on the ramp with the crew when we got to the gate, and there was about two feet of gear door seal left on the door, the area around the gear door was fairly beat up, and some small dents. What was causing all the trouble must have torn away when the gear door opened.

You may have experienced a fairing seal that had come loose, or a panel that had come loose.  scratchchin  Just an idea.



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offlineJoePatroni From United States of America, joined Mar 2007, 204 posts, RR: 0
Reply 8, posted (5 years 6 months 5 days ago) and read 6529 times:

Thanks all, for the feedback.

Quoting Ex52tech (Reply 7):
You may have experienced a fairing seal that had come loose, or a panel that had come loose.    Just an idea



Quoting 474218 (Reply 6):
There are pads in the nose gear wheel well that stop the spinning wheels. However, operation with the spin brake pads removed is allowed by the MMEL. The spinning wheels would resonate throughout the fwd cabin.

These two ideas definitely sound more like it. I wish I had the chance to go out on the ramp to check out the bottom of this aircraft because it was my definite gut feeling that whatever was making this sound/vibration was on the lower side of the fuselage.

JP



Oh Stewardess, I speak Jive.
User currently offlinePilotaydin From Turkey, joined Sep 2004, 2539 posts, RR: 51
Reply 9, posted (5 years 6 months 4 days 21 hours ago) and read 6484 times:

I fly the A340 a/c, and well...although i havent been a pax on my airplane yet, depending on the temperature for the day, and the pressure altitude, the selected flex temp or toga, the a/c will make a different pitch noise depending on the N1 speed...

there have been times where we've sounded like 4 horizontal washing machines, whining through the sky  Smile



The only time there is too much fuel onboard, is when you're on fire!
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 10, posted (5 years 6 months 4 days 19 hours ago) and read 6457 times:



Quoting 474218 (Reply 6):
Since you were in fairly far forward (Row 6) my guess (that's all any one can do) is that it was the nose wheels spinning in the wheel well. There are pads in the nose gear wheel well that stop the spinning wheels. However, operation with the spin brake pads removed is allowed by the MMEL. The spinning wheels would resonate throughout the fwd cabin.

would that NW spin continue for so long.....
Very unlikely.

Quoting Ex52tech (Reply 7):
You may have experienced a fairing seal that had come loose, or a panel that had come loose.

The sound would have reappeared on descent...it did not.

I feel its some thing to do with the engine on high thrust.Just a guess.
regds
MEL.



Think of the brighter side!
User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 11, posted (5 years 6 months 2 days 13 hours ago) and read 6176 times:



Quoting HAWK21M (Reply 10):
The sound would have reappeared on descent...it did not.

Unless whatever was causing the noise was no longer with the airplane at that phase in the flight.

I have been trying to think of what on a engine could have caused that much transitional vibration, and not have caused the crew to notice, (from the sound of the Chan.9 conversations, they did not). I have balanced a few high vibe fans over the years, and you could barley feel the worst ones, and we knew there was going to be vibrations.

Maybe a pneumatic duct that had broken loose in the fuselage, and was rattling against a frame.



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 12, posted (5 years 6 months 2 days 12 hours ago) and read 6157 times:



Quoting HAWK21M (Reply 10):
would that NW spin continue for so long.....

How long do you think a 100 lb wheel, mounted on a roller bearing, spinning at 170 mph would take to stop spinning? I would guess a couple of minutes minimum.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 13, posted (5 years 6 months 2 days 8 hours ago) and read 6100 times:



Quoting 474218 (Reply 12):


How long do you think a 100 lb wheel, mounted on a roller bearing, spinning at 170 mph would take to stop spinning? I would guess a couple of minutes minimum.

Firstly what are the chances that both NLG snubbers are not touching the wheels on retraction due to wear,and presuming one is.....Then wouldn't the gyroscopic loads be significant to be noticed in the Flight deck?

regds
MEL.



Think of the brighter side!
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 14, posted (5 years 6 months 2 days 6 hours ago) and read 6069 times:



Quoting HAWK21M (Reply 13):
Firstly what are the chances that both NLG snubbers are not touching the wheels on retraction due to wear,and presuming one is.....Then wouldn't the gyroscopic loads be significant to be noticed in the Flight deck?

You didn't read what I said in reply 6 did you?

Spin brakes are a MMEL item and as I stated that if they were removed (as required by the the MMEL) the nose wheels would have to spin down, after takeoff.

If the spin brakes were removed (as per the MMEL) the crew would know. So they would not be alarmed by the vibration the spinning nose wheels would cause.

I don't know what the noise was, I presented a plausible scenario, if you have a better one present it.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 15, posted (5 years 6 months 1 day 18 hours ago) and read 5969 times:



Quoting 474218 (Reply 14):
Spin brakes are a MMEL item and as I stated that if they were removed (as required by the the MMEL) the nose wheels would have to spin down, after takeoff.

Whats the MMEL for inop snubber,do both have to be removed?
Would need to check that out.

Quoting 474218 (Reply 14):
I don't know what the noise was, I presented a plausible scenario, if you have a better one present it.

Reply 10.

I guess its tough,unless we had access to the next flight report after this one.How does one explain the noise from the RH side & increasing with bank.

regds
MEL



Think of the brighter side!
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 16, posted (5 years 6 months 1 day 13 hours ago) and read 5936 times:



Quoting HAWK21M (Reply 15):
Whats the MMEL for inop snubber,do both have to be removed?
Would need to check that out.

MMEL Item 32-42-06 Nose Wheel Brake Pads, Installed 2, Required for Dispatch 0. Note reads: Maybe inoperative provide pads are removed.

Quoting HAWK21M (Reply 15):
How does one explain the noise from the RH side & increasing with bank.

I am not trying to explain anything. Like I originally stated in reply 6, all I or anyone else that was not there can do is, guess.


User currently offlineEireRock From Ireland, joined Nov 2007, 301 posts, RR: 4
Reply 17, posted (5 years 5 months 3 weeks 3 days 4 hours ago) and read 5594 times:



Quoting 474218 (Reply 16):
MMEL Item 32-42-06 Nose Wheel Brake Pads, Installed 2, Required for Dispatch 0. Note reads: Maybe inoperative provide pads are removed.

Actually alot of A320 operators don't even have them installed. I don't think it was NW spin however because it was felt more on a right bank, by that stage (considering a straight ahead departure) the wheels would have been retracted and have stopped spinning.
But i do agree about the idea, i was recently in a 737NG and the nose wheel vibration on T/O (with pads installed) was pretty bad.

I dont have much of an idea as to the noise myself, but i know CFM56-5's can make a lot of noise/vibration at T/O thrust, although from the picture it seems UA/Ted have V2500's on their 320's.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 18, posted (5 years 5 months 3 weeks 3 days 2 hours ago) and read 5571 times:



Quoting EireRock (Reply 17):
Actually alot of A320 operators don't even have them installed.

I highly doubt that any operator has removed the NW spin brake pads. Because, if they did they would be operating illegally.

The MMEL lists the NW spin brake pads as a "C" item and "C" items must reinstalled within 10 days (240 hours) of their removal.


User currently offlineEireRock From Ireland, joined Nov 2007, 301 posts, RR: 4
Reply 19, posted (5 years 5 months 3 weeks 2 days 13 hours ago) and read 5490 times:



Quoting 474218 (Reply 18):
I highly doubt that any operator has removed the NW spin brake pads. Because, if they did they would be operating illegally.

I have seen various LH A320's and BD A320's without such pads.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 20, posted (5 years 5 months 3 weeks 2 days 13 hours ago) and read 5483 times:



Quoting EireRock (Reply 19):
I have seen various LH A320's and BD A320's without such pads.

I have read the MMEL. Maybe LH and DB should?


User currently offlineEireRock From Ireland, joined Nov 2007, 301 posts, RR: 4
Reply 21, posted (5 years 4 months 3 weeks 1 day 14 hours ago) and read 4829 times:



Quoting 474218 (Reply 20):
I have read the MMEL. Maybe LH and DB should?

Can anybody else shed some light on this? I have been looking into A320 Nose Gear bays for quite a while and have seen some airlines with the braking pads and some without. As far as i know the wheels don't actually spin against the nose wheel well structure, there is a gap to allow the wheels to spin without rubbing on anything.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 22, posted (5 years 4 months 3 weeks 1 day 13 hours ago) and read 4796 times:



Quoting EireRock (Reply 21):
Can anybody else shed some light on this? I have been looking into A320 Nose Gear bays for quite a while and have seen some airlines with the braking pads and some without. As far as i know the wheels don't actually spin against the nose wheel well structure, there is a gap to allow the wheels to spin without rubbing on anything.

You can look at the MMEL like I did. If you have access to the NWW you should must have access to the MMEL. Additionally all the MMEL's are on the web you just have to do a search.


User currently offlineRoseflyer From United States of America, joined Feb 2004, 9666 posts, RR: 52
Reply 23, posted (5 years 4 months 3 weeks 1 day 12 hours ago) and read 4782 times:



Quoting 474218 (Reply 12):
How long do you think a 100 lb wheel, mounted on a roller bearing, spinning at 170 mph would take to stop spinning? I would guess a couple of minutes minimum.

On the plane I work on, about 2-5 minutes. Usually closer to 2.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineWirelock From Spain, joined Sep 2007, 126 posts, RR: 0
Reply 24, posted (5 years 4 months 2 weeks 6 days 8 hours ago) and read 4533 times:

the A320 from time to time can suffer from fuselage vibrations. these can be caused by various things.
vibrations from the front can be caused by (amogst other things) nlg wheels imbalance, or nlg door seal wear or nlg aft door vibration due to wear of the attach lugs.

the engines are a common source of vibration. there is a possibility that one of the engines was experiencing a N1 or N2 vibration with an associated rumble or noise in the cabin. these vibrations are common enough. the crew have a vibration monitor in the cockpit. if the vibration goes above 6.0mils then the a/c must be grounded. anything between 4 and 6 is acceptable for flight but maybe the passengers will worry about the noise of this.

in the rear area vibrations can occur from the elevator, rudder or ths. the a320 has big issues with wear in the elevator hinge bearings that cause big vibrations and costs operators lots of money due to trouble shooting and grounding the aircraft.

my advise is if you are a frequent flyer and are unsure about the noises that you are hearing is to inform the cabin crew. they might be aware of the problem and might be able to tell you what it is. if not then you should tell them to inform the crew.... chances are though that if you can hear these noises , sitting in 6A, then your flight crew can as well


25 AirframeAS : The A320 aircraft has a industry wide problem with nose gear vibrations and it continues to be a problem. Airbus knows about the situation and is try
26 EireRock : Thanks for confirming this.
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