Airbus question

[Driver 170]

Got a question on a winning noise when travelling on a A319 near the wing or right above the MLG. Its like some sort of hydraulic motor noise revving up and down. This happened after pushback!

[Amadis of Gaul]

I believe this is Airbus PTU question #13,703 or 704.

[EZY Rider]

Yep, it's likely to be the PTU.

You tend to hear it a lot more now that operators are taxiing around on one engine trying to save fuel.
After pushback sounds like a normal place to hear it (its inhibited during pushback).

Some say it sounds like a dog barking.

If you're wondering what a PTU is, this may help:

A bidirectional power transfer unit enables the yellow hydraulic system to pressurize the green hydraulic system and vice versa.
The power transfer unit comes into action automatically when the differential pressure between the green and the yellow systems is greater than 500 PSI (hence why you hear it more when only one engine is running.)

Hope that helps a bit.

[noflynomore]

Winning noises are usually a sign of a successful football match on the IFE..

[Driver 170]

Thanks for clarifying that for me EZY Rider! Keep up the good work!!!

[EZY Rider]

Glad to help :)