A321 strange noise?

[SynergyX]

Hi,
I recently flew on an A321 from TFS-MAN seated in 19A I could hear a fairly loud knocking sound emanating from under the floor near my left foot-almost like someone was tapping the underfloor with a hammer.

It was audible ptetty much constantly during taxi,t/o and climb but not in the cruise-it then reappeared during taxing at MAN along with the usual brake noises.

I reported it to the crew but they stated it was the Hydraulics working?

Anyone had any similar experience or any further knowledge-I know its a shot in the dark but Iam just ineterested?

[sapperkenno]

Some people call it a "barking dog"... It's likely to be from the PTU (Power Transfer Unit), and if you search this site with words like "Airbus" and "Strange Noise" you'll find it's been mentioned quite a bit. :ok:

In simple terms, without getting too technical, the A321 you flew in has 3 hydraulic systems (GREEN, YELLOW and BLUE - same as the A319/A320) and this PTU device works between the GREEN and YELLOW systems, allowing one system to pressurise the other and vice versa.
So you'll likely hear it after engine start as the engine driven pumps start doing their thing and the whole hydraulic system gets up and running.

Hope that helps. You'll find a lot more technical answers using the search if you want to know more about the hydraulic systems, how they are powered, why the PTU works when it does etc etc.

[Bluejet]

All true S. Worth also mentioning most airlines now will taxi in and out with one engine off for fuel savings. So the aircraft interprets this as an engine fail and runs the PTU to pressurise the non working engines hydraulics. So you do tend to get the noise on taxi in and out.

[Beavis and Butthead]

All true S. Worth also mentioning most airlines now will taxi in and out with one engine off for fuel savings. So the aircraft interprets this as an engine fail and runs the PTU to pressurise the non working engines hydraulics. So you do tend to get the noise on taxi in and out.

Most airlines run the Yellow Elec Pump when single engine taxiing to avoid this happening.

[SynergyX]

It wasnt the barking sound which I have heard before,but I just suspected something wasnt quite right when this knocking sound appeared.I have flown on quite a few of them and never noticed it before.

I hope I did the right thing and reported it-Its seems strange doing that on such a well respected aircraft,the FA did look quite concerned when she heard it though.

[LogieBear]

Syn, You did indeed do the right thing. Flight Safety is simply, a concern for all.

[simonchowder]

Possibly it was actually barking you heard, its quite common for dogs to be carried in the holds

[Nicholas49]

Question for Airbus A320 crew: do passengers frequently ask about the 'barking dog' / sawing noise on this aircraft type?

It is quite noisy and I would have thought most PAX think it means there something wrong with the aircraft.

[smudgethecat]

Its possible it was a dog in the cabin, flew to ACE the other day and there was a blind chap on board with a very well behaved black lab travelling with him

[Dr Illitout]

I saw a passenger get of a trans atlantic flight the other day with an "Emotional support dog"............................................................ ............WHAT THE :mad: is an "Emotional support dog"?????

Rgds Dr I

[BadgerGrowler]

I know Wiki can be wrong.. but it seems a sensible answer to Emotional Support Dogs.


Emotional support animal - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Emotional_support_animal)

[Malaysian28]

I heard this the other day onboard an A319 from row 21, I refer to this sound as the Taxiway Speed Humps.

[Dr Illitout]

The sensible answer would be a "Pull your self together woman!!!" dog:)
Also the cleaners who found the results of keeping a dog in the cabin for seven hours needed some"Emotional support"!

Rgds Dr I