747-400 Massive Vibration?
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747-400 Massive Vibration?
Guys and Gals, can you help...
I am a Heli and fixed wing pilot with about 800hrs combined (hopefully to qualify that I am not a total prat)
I flew BA017 on the 12th November LHR-Singapore (21.15, Seat 33c) and as we rotated from 27R there was the most awful vibration through the airframe. Not your usual wheels still turning, but a very harsh shuddering which I guess lasted for about 4-5 seconds. My fellow passengers all thought it was very serious, so I thought it should be reported. I was quite worried.
I contacted the local cabin crew as soon as the seatbelt lights were out and they also said they had felt nothing like it. I suggested very seriously that they report it to the flight crew - which they did.
The CSR came back about 15 minutes later and was very dissmissive about the noise and said that the captain said that it was either the wheels still spinning, or wake turbulence from the previously departing aircraft and not to worry.
I asked if he or the pilot felt the vibration, however they said they did not as they were at the front of the aircraft.
I suggested again, that had this been my aircraft, it would be noted in the tech log and I would have taken (as PIC) it very seriously, especially as it was reported by some cabin staff and a qualified pilot.
Again, the CSR went off, but never came back to me.
Should this be escalated? Your thoughts would be interesting?
Regards, Jon P
I am a Heli and fixed wing pilot with about 800hrs combined (hopefully to qualify that I am not a total prat)
I flew BA017 on the 12th November LHR-Singapore (21.15, Seat 33c) and as we rotated from 27R there was the most awful vibration through the airframe. Not your usual wheels still turning, but a very harsh shuddering which I guess lasted for about 4-5 seconds. My fellow passengers all thought it was very serious, so I thought it should be reported. I was quite worried.
I contacted the local cabin crew as soon as the seatbelt lights were out and they also said they had felt nothing like it. I suggested very seriously that they report it to the flight crew - which they did.
The CSR came back about 15 minutes later and was very dissmissive about the noise and said that the captain said that it was either the wheels still spinning, or wake turbulence from the previously departing aircraft and not to worry.
I asked if he or the pilot felt the vibration, however they said they did not as they were at the front of the aircraft.
I suggested again, that had this been my aircraft, it would be noted in the tech log and I would have taken (as PIC) it very seriously, especially as it was reported by some cabin staff and a qualified pilot.
Again, the CSR went off, but never came back to me.
Should this be escalated? Your thoughts would be interesting?
Regards, Jon P
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It sounds as if the auto braking failed and the sounds You were hearing and the subsequent vibration(which presumably ceased)was caused by the wheels spinning after gear retraction.
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Just on rotation? sounds like a bad case of nosewheel shimmy.
Flew upfront on one of our A330's back from Toronto, just as we began to rotate the a/c shook violently, with things looking like they were going to tear from their mounting.
The Captain looked at me and said, "Now when I say we have got a nose wheel shimmy will you believe me?"
err yes! was about the best I could muster.
Aircraft sometimes shake, the flightdeck will have felt it and reported it. They will have fobbed you off because they thought that it is all you need to know. How would you have reacted if the attendant came back and said "Yes there was a problem, we lost a wheel on departure, it's nothing to worry about!"
It's only As I See It
Flew upfront on one of our A330's back from Toronto, just as we began to rotate the a/c shook violently, with things looking like they were going to tear from their mounting.
The Captain looked at me and said, "Now when I say we have got a nose wheel shimmy will you believe me?"
err yes! was about the best I could muster.
Aircraft sometimes shake, the flightdeck will have felt it and reported it. They will have fobbed you off because they thought that it is all you need to know. How would you have reacted if the attendant came back and said "Yes there was a problem, we lost a wheel on departure, it's nothing to worry about!"
It's only As I See It
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Thanks for the replies...
It was just on rotation, and it seemed to happen before the rear wheels were off the ground, and then continue for about 5 seconds.
I understand the issue of the wheels not stopping on lift, but I would be amazed if they were so far off balance to create such a vibration. It was really severe.
If the vibration was not felt much by the flight crew, then I guess it was not the nose wheel?
Does anyone have a contact for BA to report this to?
JonP
It was just on rotation, and it seemed to happen before the rear wheels were off the ground, and then continue for about 5 seconds.
I understand the issue of the wheels not stopping on lift, but I would be amazed if they were so far off balance to create such a vibration. It was really severe.
If the vibration was not felt much by the flight crew, then I guess it was not the nose wheel?
Does anyone have a contact for BA to report this to?
JonP
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Vibration
Nothing to worry about.
The problem you encountered is quite common on -400's and is cured by replacing both nose wheels.
A good grease job on the nose gear steering collar might also help.
Regards,
Ballpoint.
The problem you encountered is quite common on -400's and is cured by replacing both nose wheels.
A good grease job on the nose gear steering collar might also help.
Regards,
Ballpoint.
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I experienced a mild 1 or 2 hz. lateral (yaw) oscillation during a reduced-thrust TO in a TriStar. The captain suspected a FCU instability in #3 RB211 engine; I expressed my doubts - the frequency was too high to be induced by an engine.
On the next TO we used full rated thrust, with no oscillation noted. Maybe it was the FCU after all - but only at reduced thrust TO.
On the next TO we used full rated thrust, with no oscillation noted. Maybe it was the FCU after all - but only at reduced thrust TO.
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744 vibration on gear up selection. Shakes the sh
out of everyone and aircraft.
At Q this was a problem early in the intro of this aircraft. Main gear wheels out of round were believed to be the problem and subsequently 100s of wheels were changed until defect persisted with 16 new wheels fitted to one of the aircraft with this recurring defect.
White stripes were painted on the tyres (not tires) and take offs were filmed to see if wheels were spinning as the gear lifted into the wheel bay to identify the time of vibration during gear up selection.
For info. When filmed the wheels don't wind down slowly they came to a complete stop within a couple of frames.
At the same time UA BA were having similar defects.
From memory as this was 10 years + ago
The problem was traced to a bad batch of valves that provide the "inflight braking". From memory this valve is sequenced thru the R/H wing landing gear door. Upon gear up selection the gear doors open and this positions a hyd valve to send a hydraulic "signal to the inflight braking ops valve to apply the ALT brake system to stop the wheels rotating. This vave was shuddering/occilating/worn and was creating the vibration by not applying correct braking pressure allowing wheels to shudder as their rotation is slowed by a on-off-on-off-on-off-on braking.
Now that this problem is known. If it is reported a part replacement is scheduled to fix, Most tech crews have seen it so its no drama either.
Remember you are in good hands
Yes I know I haven't used correct nomenclature or techo words but trying to please all reading this post, and most importantly this thread was started by a helicopter pilot
I was once told that the big blades above the helicopter pilots head were put there to keep the pilot cool.
Because you should see him sweat if they stop
out of everyone and aircraft.At Q this was a problem early in the intro of this aircraft. Main gear wheels out of round were believed to be the problem and subsequently 100s of wheels were changed until defect persisted with 16 new wheels fitted to one of the aircraft with this recurring defect.
White stripes were painted on the tyres (not tires) and take offs were filmed to see if wheels were spinning as the gear lifted into the wheel bay to identify the time of vibration during gear up selection.
For info. When filmed the wheels don't wind down slowly they came to a complete stop within a couple of frames.
At the same time UA BA were having similar defects.
From memory as this was 10 years + ago
The problem was traced to a bad batch of valves that provide the "inflight braking". From memory this valve is sequenced thru the R/H wing landing gear door. Upon gear up selection the gear doors open and this positions a hyd valve to send a hydraulic "signal to the inflight braking ops valve to apply the ALT brake system to stop the wheels rotating. This vave was shuddering/occilating/worn and was creating the vibration by not applying correct braking pressure allowing wheels to shudder as their rotation is slowed by a on-off-on-off-on-off-on braking.
Now that this problem is known. If it is reported a part replacement is scheduled to fix, Most tech crews have seen it so its no drama either.
Remember you are in good hands
Yes I know I haven't used correct nomenclature or techo words but trying to please all reading this post, and most importantly this thread was started by a helicopter pilot
I was once told that the big blades above the helicopter pilots head were put there to keep the pilot cool.
Because you should see him sweat if they stop
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I was once told that the big blades above the helicopter pilots head were put there to keep the pilot cool.
Because you should see him sweat if they stop
Because you should see him sweat if they stop
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marty McBolt is on the right track but not quite there. The Brake Metering Valves used to get a hydraulic lock condition which would prevent porting of landing gear 'up' hydraulic pressure to send braking to the MLG brakes. This meant the main gear wheels would continue to spin. When the Body gears retracted the heavy side of the tyre always would be down when the tyres finally stopped. When gear was extended at the other end the effect was that with rotation etc the result was that the lightest (in this case most worn) point was always now at the bottom. On landing the worn part of the tyre always copped the first hit and the problem just got worse and worse. The fix was a small port in the piston in the brake metering valves.
Since the above fix was introduced the problem has pretty much gone away. having said that I rode on a BA flight BKK-SYD this year (2005) and on takeoff out of BKK the vibes were very very bad. I just sat there and waited for my bourbon/coke. It's up to the crew to decide to write such things up when they're that bad.
My suspicion is that you may have had a brake locked out or similar short term anomoly. The description suggests a landing gear issue - if it was NLG you'd expect the crew to notice which apparently they did not.
AP
Since the above fix was introduced the problem has pretty much gone away. having said that I rode on a BA flight BKK-SYD this year (2005) and on takeoff out of BKK the vibes were very very bad. I just sat there and waited for my bourbon/coke. It's up to the crew to decide to write such things up when they're that bad.
My suspicion is that you may have had a brake locked out or similar short term anomoly. The description suggests a landing gear issue - if it was NLG you'd expect the crew to notice which apparently they did not.
AP
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This is nose wheel shimmy. First time it will be penned with an inspection and spin check - second or third time the nose wheels will be replaced which will cure the problem. It is very very common on 400s. I certainly would not escalate this as it is nothing and you would make yourself look pretty silly. I would think that it was put in the tech log once reported by cabin crew. The crew would not report this back to you as they have no reason to discuss the contents of the tech log with a punter - pilot or not.
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Re: 747-400 Massive Vibration?
Originally Posted by geldap
This is nose wheel shimmy. First time it will be penned with an inspection and spin check - second or third time the nose wheels will be replaced which will cure the problem. It is very very common on 400s. I certainly would not escalate this as it is nothing and you would make yourself look pretty silly. I would think that it was put in the tech log once reported by cabin crew. The crew would not report this back to you as they have no reason to discuss the contents of the tech log with a punter - pilot or not.
Anyway, plane's still flying - a good thing with 747s - one of the best and safest designs around.
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I don't know if this is related or not. When I recently flew a UAL flight to Sydney there was a massive vibration near my seat.
I thought it sounded like something was wrong with the landing gear - I was sitting in the emergency exit row near the right main landing gear.
The vibration seemed to go on for a rather long time. My estimate was about 3-5 minutes.
My initial guess was that it may be from the gear being jammed and our operating speed being too high.
Anyway, after pummeling the flight attendent with questions, she finally called the cabin. They said they were working on it, and that they had to try and cycle the gear a few times.
They finally resolved the problem, and the vibration went away. My concern for the next 14 hours was now could they get the gear down? Which they did get it down without further problems.
Does this sound like the Brake Metering Valves and wheels spinning? Or does it sound like the gear was actually jammed?
Thanks.
Originally Posted by Aussie Pete
marty McBolt is on the right track but not quite there. The Brake Metering Valves used to get a hydraulic lock condition which would prevent porting of landing gear 'up' hydraulic pressure to send braking to the MLG brakes. This meant the main gear wheels would continue to spin. When the Body gears retracted the heavy side of the tyre always would be down when the tyres finally stopped. When gear was extended at the other end the effect was that with rotation etc the result was that the lightest (in this case most worn) point was always now at the bottom. On landing the worn part of the tyre always copped the first hit and the problem just got worse and worse. The fix was a small port in the piston in the brake metering valves.
Since the above fix was introduced the problem has pretty much gone away. having said that I rode on a BA flight BKK-SYD this year (2005) and on takeoff out of BKK the vibes were very very bad. I just sat there and waited for my bourbon/coke. It's up to the crew to decide to write such things up when they're that bad.
My suspicion is that you may have had a brake locked out or similar short term anomoly. The description suggests a landing gear issue - if it was NLG you'd expect the crew to notice which apparently they did not.
AP
Since the above fix was introduced the problem has pretty much gone away. having said that I rode on a BA flight BKK-SYD this year (2005) and on takeoff out of BKK the vibes were very very bad. I just sat there and waited for my bourbon/coke. It's up to the crew to decide to write such things up when they're that bad.
My suspicion is that you may have had a brake locked out or similar short term anomoly. The description suggests a landing gear issue - if it was NLG you'd expect the crew to notice which apparently they did not.
AP
