Airbus sound question

[kf4amu]

If its a pump, why does it turn on and off so quickly? I'd expect those conditions for PTU operation to be pretty static and unchanging from second to second.

 

[Cardinal]

It's not so much a pump as two hydraulic motors bolted to each other. And like everything else is electronically controlled. When it senses a differential of 500 psi between systems it will "run" (allow one hydraulic motor to turn the other) in order to bring the low side up to 3000psi, then stop until the system bleeds down and the differential agains reaches the 500 psi threshold for activation.

The system will also run during periods of high demand when one system's pressure is pulled down, i.e., gear retraction. Why build each hydraulic system to be up to it's task? Better to do it the socialist way, a team effort, with each system helping out when times get tough. I am the green system, and I am my brother's keeper.

 

[CA1900]

The system will also run during periods of high demand when one system's pressure is pulled down, i.e., gear retraction. Why build each hydraulic system to be up to it's task? Better to do it the socialist way, a team effort, with each system helping out when times get tough. I am the green system, and I am my brother's keeper.

:laugh:

Well-done.

 

[Vingus]

Jetblue SOP is to turn on the yellow pump during single engine ops to keep it quiet. We used to have a SOP that shut the PTU off on engine shutdown which would keep it quiet at the gate. That SOP went away when too many guys forgot to turn it back on when the left the cockpit. It was a good idea, but as usual, a few dummies ruined it for everyone.

 

[lowtimedriver]

It's a fly-by-wire baggage handler.

 

[BLUE BAYOU]

I still turn the PTU off at shutdown until at least a cargo door is opened (which actuates the yellow hydraulic pump). This usually resolves the barking dog issue which is at its worst at engine shutdown at the gate.

 

[ACL65PILOT]

Most big jets have them. That is why on the 767/757 we start the left engine first. That way it will not go on.

 

[Ralph Cramden]

Fifi plays both ways. It's a French tradition! PTU can be powered by yellow or green (that's L & R to the non french speaking), and powers the lower pressure side. Blue (center to non french speaking) is lonely, only plays with itself (the rat is it's backup).

 

[PreContact]

Just say the words RED RUM, that's what it sounds like to me!~

 

[Guppiedriver]

If you turn on the yellow electric pump you never have that noise..

The high pitched whine of the yellow electric pump is just as annoying as the PTU.