VS744 From United Kingdom, joined Aug 2001, 677 posts, RR: 1 Posted (13 years 7 months 1 week 3 days 22 hours ago) and read 2254 times:
Last night I flew DUB-LHR on a BMI A320-200.
When it was on the ground, either still or moving, there were a lot of banging noises coming from beneath in the hold/undercarriage type area. It wasn't a pleasent sound, and it stopped as soon as we left the ground....
I have been on the 319, 320 and 321, and never heard this noise!
AC_B777 From Canada, joined Aug 2000, 827 posts, RR: 12
Reply 12, posted (13 years 7 months 1 week 3 days 17 hours ago) and read 2026 times:
If it's the sound that I'm thinking of, then it is the hydraulic pump.
It's located around the center of the plane and it makes this aweful sound when it is turned on. I would describe it as two grinders in heat. It also bangs.
The reason for this pump is to provide hydraulic pressure to the plane. Whenever I ride the brakes on an Airbus plane, I turn this pump on so that the brakes work and anything on the plane that uses hydraulics works.
It's usually only used when the a/c is being moved or for engine start and taxi. When the plane is airborne, there would'nt really be a need for hydraulics as all the flight controls are elecric.
Anyway, I hope this is the answer to you question.
This noise does'nt mean that the plane is falling apart. It is perfectly normal so you can still continue to like and fly Airbus.
In life, some days you are the bug..... some days you are the windshield!
Demoose From Canada, joined Mar 2001, 1952 posts, RR: 22
Reply 15, posted (13 years 7 months 1 week 3 days 13 hours ago) and read 1959 times:
I thought it was the landing gear rolling over the centre lights but as I found out from the previously linked post, its not. I've only heard this noise on the airbus and not on a boeing. I was sat in the middle of an Emirates A330 and heard a metallic banging sound every so often during taxi, like a sheet of metal being dropped. It didn't worry me one bit, I'm trying to think why it didn't worry me now but I think I just love planes so much and know what most noises in the cabin are; I just assumed it was perfectly normal - which it was! Certainly wouldn't say it was something that would put me off flying on an Airbus.
Jeff G From United States of America, joined Jan 2002, 442 posts, RR: 1
Reply 18, posted (13 years 7 months 1 week 3 days 5 hours ago) and read 1887 times:
The grinding sound is the hydraulic PTU self-testing when the second engine starts. It usually only runs when there's low pressure from one of the engine pumps. There is an electric hydraulic pump that runs all the time when the engines are running, but it's not particularly loud, and you won't hear it start up usually. The yellow pump you turn on for towing is pretty noticeable from the cabin, but it is typically not turned on for flight. And, though the flight controls are controlled by computer, they are actuated hydraulically. Hydraulic power is essential to aircraft control, so your statement that it's not needed in flight isn't entirely accurate. Just thought you'd want to know.
As far as that banging sound is concerned, it's probably the sound of the brakes being released. There are huge drum brakes on the gear, and they can make a racket.