Noise Before Take Off - Airbus Mainly

[Lucky747]

Just before i begin i would like to point out i'm not a pilot, but i do fly a lot and i have noticed before take off mainly on Airbus 319 / 320 there is a sound that sounds like someone is putting rivets into the metal work, a sound i almost expect each time i take off now.

Can anyone inform me what this noise is ?

[Paracab]

Hydraulic power transfer unit (PTU). Sounds like sawing or a dog barking. A quick search will provide a more thorough answer, this question is asked about once a week so better not take up much more bandwidth with it! ;)

[Lucky747]

Thanks for clearing that up for me.

I shall ask no more.

Regards

[rogerg]

so better not take up much more bandwidth with it!

Why do us pruners have to worry about "bandwidth"? What is that in relatation to posting?
Or is that just your way of reminding him of the "search" facility, which in itself probably took up some "bandwidth"