747-400 Massive Vibration?

[gbreuder]

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