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View Full Version : Sawing up an A319 just after it's parked?


Jumbo Jockey
29th May 2006, 13:50
Been doing a bit of positioning up and down twixt LHR and MAN lately on BMI A319s, and I can't help noticing that shortly after they've parked it, a sound comes from underneath the floor which sounds for all the world like somebody's sawing the thing up. Wossat?

palmdeira
29th May 2006, 14:16
it's the hydraulic power transfer unit - PTU. Shouldn't really be operating unless the yellow system electric pump has been turned on, perhaps due to single engine taxiing.

TopBunk
29th May 2006, 14:43
It will also operate when the loaders activate the opening of the cargo doors to get out your luggage, irrespective of taxi practices.

IFixPlanes
29th May 2006, 18:32
It will also operate when the loaders activate the opening of the cargo doors to get out your luggage...
Sorry, but not true. PTU-Funktion is inhibited when the Yellow electric pump is in operation to open/close the cargo doors.

TopBunk
30th May 2006, 04:43
IFix

Sorry, you are of course correct, the Yellow system Electrical pump powers the hydraulics to open the cargo doors. No longer fly the 'bus - how quickly one forgets detail....

Jumbo Jockey
30th May 2006, 10:16
Thanks to all!

mcdhu
30th May 2006, 15:44
Yup, usually due to the SE taxi procedure. On stand the procedure is Ylo Elec Pump OFF, Eng 1 Shutdown which finds the Ylo(Eng2) hyd system now powered via the Ptu from the running down Eng1 (Green) hyd system and is so until 5% or so N2 whereupon it all dies.

Cheers,
mcdhu

Swedish Steve
1st Jun 2006, 18:28
I reckon that about 50% of A320 that arrive on gate after a single engine taxi have the PTU running. Our crew have a drill to turn on the Hyd pump before shutting down Nbr 1 engine, but turning the pump off is not in the shutdown drill.

mcdhu
2nd Jun 2006, 20:18
But it is in the SE Taxi Procedure at 3.4.90 which says:

"At parking :

-Y ELEC PUMP OFF

-ENG 1 SHUT DOWN"

Cheers,
mcdhu