Clunking noise in undercarriage...

[LadyL2013]

Flew home from BVC yesterday on a 757-200 G-OOBB Thomson.

At what seemed to be random intervals during the flight a rhythmic 'clunking' sound came from the undercarriage area (we were sitting just alongside the flaps of the wing). It would make anywhere between 4 - 20 clunks at about every 2 seconds and then stop.

I tried working out if it was happening during any particular action, but it seemed to happen at all stages of flight at random intervals. It was loud enough that you could hear it above music and you could feel it vibrate through the floor.

I've never experienced this before and I've flown a lot. What could it be?

[OMAAbound]

Sounds like you had brought a baggage handler back to the UK with you!!

[RevMan2]

you could feel it vibrate through the floor
And we didn't bring it to the crew's attention...?

[LadyL2013]

A couple of passengers asked the FA's, but they didn't seem to know what it was or seem particularly bothered.

Maybe it is a regular noise on that specific aircraft?

[parabellum]

Possibly a pump or motor associated with the flight controls, maintaining accumulator pressure? "There will be an engineer along shortly".

[LadyL2013]

Ahhhh.

It could have been a pump, the thumping did sound sort of like that.

Should it have been making that noise?

[G&T ice n slice]

"There will be an engineer along shortly"

well, I've check in Jetblast and it looks like the thronomister has gone out of factory spec, which suggests possibly an old version with the flanged adaptor module, rather thasn the later versions with the electronic trifungulator which absolutely cures the old problem of reverse polarity occuring in the thronomister assembly.

then again I could be wrong

[ExXB]

G&T, get thee to R&N ... where postings of such nature are given the due regard that they deserve. :uhoh:

[LadyL2013]

In Layman's speak?

[ShyTorque]

It could have been a pump, the thumping did sound sort of like that.

Possibly the bilge pump. Were you over the sea at the time?

[PAXboy]

LadyL2013 I fear that some of the pax in this 'cabin' are being less than helpful ...

It is quite possible that a hydraulic pump was in use, transferring fluid between two systems. For example, there might have been a reduction in fluid in one and the flight crew balanced them. This is just an educated guess! On some Airbus aircraft this kind of noise is more common and readily explained.

It is always correct to draw anything that worries you to the attention of the cabin crew. They should either reassure you that it is normal - or find out what it is.

[RevMan2]

Ms RM2 has a dark past as a FA back in the 707 days, when she heard a bang against the fuselage during taxi. Used semaphore (or drums - not sure which...) to communicate with the cockpit who had a engineer inspect a fractured MLG wheel with a significant chunk missing.
Always good to have someone take things seriously (even if she *is* a Nervous Nellie...)

[LadyL2013]

Shy,

No, happened during taxi, climb, cruise, descent and again taxi. No pattern to it whatsoever.

PAX,

I think you may be onto something it did sound like a hydraulic thumping, almost like a suction-thud noise if that makes sense. As you say I've heard hydraulic noises on Airbus before, but not coming from the same place and certainly not as loud! Never heard it on a Boeing before, so was wondering why this time, what situation would cause this to be heard?

Cabin crew kind of just shrugged when a few passengers brought it up in a kind of 'No idea what it is, but we've heard it before and it's fine' kind of way.

[PAXboy]

If cabin crew have heard it a thousand times and know it to be nothing to worry about - they need to rassure the pax rather than shrug.

[RevMan2]

@ PaxBoy
Agree 100%