strange noise on Airbus
 

I recently took a friend to Italy on a A319. She is not a good flier, and was unsettled by a strange sawing sound while the aeroplane was loading. Assurances that "they all do that", and pointing out to her that the crew could hear it and weren't worried didn't totally calm her, so I was curious as to what is actually causing it.

Its the PTU or power transfer unit which allows two of the hydraulic systems to share pressure through a mechanical connection if one of them has a higher demand placed on it.

Totally normal and nothing to worry about.

Hi Wriggly Monkey and welcome to the 'cabin' of PPRuNe. You have the answer from Metro Man and might like to read this item from our FAQ to give more detail to your friend [below]. The sound of the Power Transfer Unit is often referred to as 'the barking dog'.

Do stay around and join in.

https://www.pprune.org/passengers-sl...what-they.html

In the good old (pre-Airbus) days we called it a banana pump.

MATELO, many thanks for posting that very helpful video. It is technical but should reassure many visitors to the PPRuNe Cabin. :ok:

never thought of it as a barking dog, always thought it was a sawing sound