APU questions

[Barthandelus 1]

Got, it thanks.

So now my only problem is restarting the APU after shutting it down, them im done:)

[ajacied551 1]

Got, it thanks.

So now my only problem is restarting the APU after shutting it down, them im done:)

Let the APU do it's cooldowm cycles for approx 60 seconds by leaving the Battery switch in the ON position If you switch the battery to OFF after the APU is switched OFF without waiting for 60 seconds, you intterrupt the cooldown cycles of the APU, the APU door stays in open. Next time you want to start the APU it finishes it's intterrupted cooldown cycles with closing the APU door. The APU start will fail and the FAULT light will illuminate.

[scandinavian13 5,192]

Let the APU do it's cooldowm cycles for approx 60 seconds by leaving the Battery switch in the ON position...

 

Manual (QRH) says 5 minutes, along with Andrea. I'd go with that.

[rfelger 71]

I always let my FO handle the APU with FS2Crew!!! :P

[ajacied551 1]

Manual (QRH) says 5 minutes, along with Andrea. I'd go with that.

The QRH says when a APU automatic shutdown occurs due to a FAULT, If the FAULT light extinguishes the APU maybe restarted after 5 minutes.

I was taking about a normal shutdown of the APU. When you shutdown the APU the normal way APU switched OFF wait approx 60 seconds to switch of the Battery to allow the APU to do it's cooldown cycles, If you don't wait 60 seconds you intterupt the cooldown cycles of the APU. The APU door will stay open and the APU fuel shutoff will stay open when the Battery is switched OFF before the 60 seconds. Because the last thing in the cooldown of the APU is closing the APU door To allow the APU door to close it needs 28 VDC from the Switched Hot battery bus. Thats way you should keep the battery switch in ON for approx 60 seconds.

 

Next time you start the APU. The APU ECU noticed that the cooldown cycle was intterrupted and will be stored as a DC powerloss shutdown, This shutdown is a protective shutdown and a Protective shutdown is a FAULT. So the FAULT light will illuminate. To reset this Switch the APU master Switch to OFF and back to ON (not START) with APU speed less than 7 precent or the ECU deenergized. the ECU deenergizes after 5 minutes when these condition occur:

* APU master switch in OFF

* APU fuel shutoff valve is closed.