A320 / A321 Noise on Push Back

[Golf Alpha Whisky]

Just wondered if anyone can tell me what the wierd noise is that can be heard from under the floor of an A320 / A321 on push back. The best way of describing it is the loud noise of a car cranking on a flat battery! Same noise also heard after parking on stand. Is it parking brake? Its something unique to Airbus and not heard on a Boeing.

[JEANS42TRF]

Noise of the PTU (POWER TRANSFER UNIT)

[Bus429]

How many times has this question been asked?:ugh:

[howflytrg]

Out of interest which system(S) power the brakes on the scarebus?

Also does the activation of the PTU cause distracting messages on the ECAM or are they inhibited during start?

[Wodrick]

4,921

Green then Yellow

Not sure

[SFCC]

Nothing untoward on ECAM.
HYD PTU shows on bottom right hand side of EWD during its self test on engine start. Would also be indicated on HYD page on SD if you were to select it.
Must be at least a week since this question was asked last:}

[howflytrg]

Mercy bucket monsieurs.

I shall remind myself of the search function. :}

[ruddman]

HA! Told ya. More weird noises on an A320 then my dads 1979 Acco truck.

[Rainboe]

Well I think it sounds like an Alsation in the hold barking. I was wondering once whether to insist before pushback they dealt with the poor dog in distress in the rear hold! Could have been so embarrassing.

[Golf Alpha Whisky]

Thanks JEANS42TRF.

To the others who ridicule those of us less well informed - I never knew asking a simple techncial question out of curiosity having just been on 4 airbuses in 3 days would cause so much distress and inconvenience to you all. Apologies.

[titi]

Don't GAW, ask the questions you want and forget about the other one.
Carry on with knowledge

[Speevy]

Here to be corrected, but I think that the Ptu is inhibited during first engine start (so it will not be working) and during 2nd engine start is TESTED (that's when you hear it). So the ptu during the 1st engine start will not Sense any dp since it's inhibited.
[PTU pb sw
AUTO : The bidirectional power transfer unit is armed and both the yellow and the green electrohydraulic valves are open.
The power transfer unit runs automatically when the differential pressure between the green and yellow systems is more than 500 PSI.
Note : The PTU is inhibited during the first engine start and automatically tested during the second engine start. ] from the FCOM but

I don't really get when it kicks in, during the 2nd engine start or between the 2 start???
If it's inhibited it will not work, but if it's tested will it? or it's just a self test?
Anybody?


Note: You would also hear it if you did single engine taxing and when on the gate forgot to switch off the yellow elec pump.

Speevy

[dartagnan]

where is the PTU?( relatively to the plane)

close of the engine, or close of the Pack (behind the main landing gear).
any picture?

[Jet II]

where is the PTU?( relatively to the plane)


In the main wheel bay

[JEANS42TRF]

Speevy, you're right....I should have read my FCOM before posting!:ok:

[Old Smokey]

If I've said it once, I've said it 1000 times, we need a separate PPRune forum dedicated entirely to weird Airbus noises!:E

How about some weird Boeing noises?

Regards,

Old Smokey

[cod liver oil]

Smokey,
Do you mean like the HMG on the B763???
cod

[Old Smokey]

That's a good start cod liver oil, how about the ghostly howling banshee noises from the Air Driven Hydraulic pumps on the B777?

Regards,

Old Smokey

[Dan Winterland]

I don't really get when it kicks in, during the 2nd engine start or between the 2 start??? Speevy

Just after the start of the second engine.

[kaype]

TASK 32-20-00-810-801- 01
Grinding Noise from the NLG during Taxiing or Towing (Trouble Shooting procedure Weight on Wheels)

NOTE:
The noise is because there is not sufficient lubrication in the shock absorber.This condition does not have an effect on safety.If it is not possible to do the lubrication procedure immediately (because there is not sufficient time or equipment),do it at the first opportunity.



If you mean grinding noise during towing(with tow bar) and taxiing above note answers your question and the TSM Task is given for rectification.

[allthatglitters]

kaype, it's actually called an airflon bearing.

NOTE:
The noise is because there is not sufficient lubrication in the shock absorber.This condition does not have an effect on safety. If it is not possible to do the lubrication procedure immediately (because there is not sufficient time or equipment),do it at the first opportunity.


The noise is because there is not sufficient lubrication in the shock absorber:-The shock absorber is almost full of oil.

If it is not possible to do the lubrication procedure immediately (because there is not sufficient time or equipment),do it at the first opportunity.

How much equipment does it take to squirt about a half to a litre of mil-prf-5606 into a hole at the rear of the NLG.

[kaype]

All that glitters Thanks for ur info on Airflon coated Ring :)

This note I had attached is taken from A320 Trouble Shooting Manual.
In simple English if the transit time is short U can do the lubrication later,being an Engineer myself if I have limited time i would rather diferr it to be done during night stop.So safe for dispatch nd no delays.

[allthatglitters]

On some our new A320's the barking PTU is less audiable and not so obvious.

[DGD]

Hello,

I am just wondering about a nosie on a recent A320 flight.

I am used to the PTU noise (many A320 flights..) at startup on the push back etc...but, I heard this noise for over a minute several times yesterday on my flight back from Cancun. It was over a minute on the ground. Then heard it for short spurts during flight, then again for almost two minutes mid flight and then it was in spurts again on appraoch and then ran again fro 1-2 minutes after we got to the gate.

I have never heard so much from noise and wonder if we were in any danger or if something was not working, leaking or whatever?

I appreciate any responses as I have many more A320 flight scoming up.

Thanks
DGD

[DGD]

just to clarify my question - does the ptu normally run for minutes during flight whike at 34000 feet?

thanks
DGD

[I-2021]

Hi DGD,

No it doesn't. It is probably a spurious PTU activation when it's not supposed to. Had it a few times on some old A321s.

[Ground Point 9er]

It's been awhile,but I want to say that I've heard a sound similar to the A32X PTU activation noise during push back on board the B717 too. Anyone else ever heard it on this type? I know that I've also heard it on Airbus narrowbodies.

Cheers GP9

[pm90012]

Here is a video of the ptu:

YouTube - Airbus A320 PTU or...the barking dog! (http://www.youtube.com/watch?v=9ffJgk1-tCA&feature=youtube_gdata_player)

[I-2021]

Great!:ok:

[ChristiaanJ]

Question from ancient engineer (AFCS for the pointy one).

What's this PTU, what does it do, and why does it bark when it operates (yes, I've looked at/listened to the U-Tube videos) ?

And no, I don't have any A-320 manuals I can refer to....

CJ

[squeaker]

Power Transfer Unit. Transfers hydraulic power from green system to yellow system (or vice versa) if a pump (or an engine) fails.

[I-2021]

http://www.pprune.org/tech-log/435328-why-does-airbus-ptu-bark.html