Strange noise on Airbus

[F i F]

One for the aircrew / EricMC

Noticed it on the A320 but only on Airbus, never on Boeings iirc.

Strange noise which sounds like some bloke attacking the plane with a hacksaw, somewhere around central fuselage near wing section?

Usually just after mooring up at the gate, occasionally hear it during taxi in after landing. Also have heard it before push back from gate, but not always.

WTF is it?

[Extra 300 Driver]

Its the PTU

The PTU is mechanical pump that links the yellow and the green hydraulic systems. It is energized when either system has been turned off( ex: one engine off) it produces a loud high frequency noise when it turns and produces 3000 psi hydraulic pressure for oppsosite system.

The reason it "barks" is because it switches on and off so quickly. As pressure drops it comes on just long enough to build the pressure back to 3000 psi. Once that is done it shuts off until the pressure drops again... in about 5-15 second intervals normally, depending on how good the pressure bleed down rate is on that particular aircraft.

If you lower the flaps for instance the barking will stop and you will hear the pump run continuously (which is also quite loud) until the pressure is built back up after system demand has stopped.

I believe the A320/319 is the only aircraft you can hear the PTU so distinctly during normal operations. The 757/767 ETOPS for instance, it is heard only with a system failure.

[F i F]

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

[jimmyjimjim]

Extra 300 Driver said:

I believe the A320/319 is the only aircraft you can hear the PTU so distinctly during normal operations.

I was on a flight in the US where the pilot made a point of announcing at the departure gate that this was a noise unique to the A320, and was nothing to be worried about; obviously they'd had questions on it before.

[Dugiet]

F i F said:

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

His google fingers must have been quick on the mark

[HRG]

F i F said:

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

[Neil_H]

I know the noise you mean, I've heard it as well.

[benoli]

was it on a Quantas plane ? maybe one for the gripe list :

Pilot: Left inside main tire almost needs replacement.
Engineer: Almost replaced left inside main tire.

Pilot: Test flight OK, except auto-land very rough
Engineer: Auto-land not installed on this aircraft.

Pilot: Something loose in cockpit.
Engineer: Something tightened in cockpit.

Pilot: Evidence of leak on right main landing gear.
Engineer: Evidence removed.

Pilot: Target radar hums.
Engineer: Reprogrammed target radar with lyrics.

Pilot: Mouse in cockpit.
Engineer: Cat installed

Pilot: Noise coming from under instrument panel. Sounds like a midget pounding on something with a hammer.
Engineer: Took hammer away from midget.

[s,one]

Christ every time I fly I could write a book on the noises I imagine!. Still impressive response but who's to know he's not making it up.

[Extra 300 Driver]

[quote=s,one]Christ every time I fly I could write a book on the noises I imagine!. Still impressive response but who's to know he's not making it up.
[/quote]

Oh, its so true, its actually a small dog in the centre tank.

[F i F]

Extra 300 Driver said:

s one said:

Christ every time I fly I could write a book on the noises I imagine!. Still impressive response but who's to know he's not making it up.

Oh, its so true, its actually a small dog in the centre tank.

Well drop some Bob Martins tablets in and tell him to STFU.

edited to sort quotes out

Edited by F i F on Monday 15th December 16:08

[srebbe64]

Off topic I know, but last week I went round the Airbus Factory in China where they build the A320s - they'll be building one per week in 2009.

It's an astonishing site. It was so clean it felt like a hospital not a factory. And the sheer scale of everything was breathtaking.

[Extra 300 Driver]

srebbe64 said:

Off topic I know, but last week I went round the Airbus Factory in China where they build the A320s - they'll be building one per week in 2009.

It's an astonishing site. It was so clean it felt like a hospital not a factory. And the sheer scale of everything was breathtaking.

You should see the A380 production facility, stunning!

Its so much better than Boeings.

[srebbe64]

Extra 300 Driver said:

srebbe64 said:

Off topic I know, but last week I went round the Airbus Factory in China where they build the A320s - they'll be building one per week in 2009.

It's an astonishing site. It was so clean it felt like a hospital not a factory. And the sheer scale of everything was breathtaking.

You should see the A380 production facility, stunning!

Its so much better than Boeings.

Yes I've seen it on telly (in France I recall) - it does look stunning.

[tonyvid]

F i F said:

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

And in a couple if minutes!

I didn't know the Chinese were building Airbussesssesss, one a week

[Famous Graham]

Having spent all of last year making weekly flights on BMI (A320s mainly, occasionally A319s), I know exactly which noise you mean. Personally I'd put it down to a man punching a baboon, but it's interesting to hear the real answer.

[bob1179]

Is it a little sad that I now want to go and fly on an A319/A320 just so I can here this noise?

I flew on a combination of F70s and F100s a couple of weeks ago and had no such noisy excitement, other than I think the old Fokkers are quite cool aircraft.

[Nick_F]

I was sure it was the handbrake ratchet...

[Munter]

tonyvid said:

F i F said:

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

And in a couple if minutes!

I didn't know the Chinese were building Airbussesssesss, one a week

Yeah. Cant say I'm too impressed with that idea. If my China made Toaster fails it's no big deal. However....

[Shaw Tarse]

F i F said:

Thank you very much, much appreciated.

Don't you just love PH for the ability to get answers to this sort of random stuff.

But it took 3 minutes to answer Way too long