APU Indications

[samer747]

Hello Pilots,
I noticed that PSX APU indications shows on the lower status EICAS when selecting (APU start ) only, as far as I remember the APU indications also show on status page every time ( ON ) switch selected, especially to view APU oil quantity, other indications such EGT, N1 will also show but static until APU is started. Correct me if I'm wrong please.

Regards
Sam

[Hardy Heinlin]

Hello Sam,

I think we discussed this on the forum a few times in the past decades. If I recall correctly, it is company specific or user confusion with the ground test switch on the maintenance panel which, when selected on, displays the APU data even when the APU is off.


Regards,

|-|ardy

[John H Watson]

I remember the APU indications also show on status page every time ( ON ) switch selected, especially to view APU oil quantity, other indications such EGT, N1 will also show but static until APU is started.

Sounds familiar. From memory, the oil quantity at least will show if the Ground Test Enable switch is activated. Sometimes the pilots would shut down the APU on arrival before the oil quantity had been checked, so we had to use this switch to check oil quantity. According to my training notes, the parameters are active if the APU Controller is powered "internally". This is achieved by either START or turning on the Ground Test Enable.

On our aircraft, on APU shutdown, all the parameters go blank except the oil quantity possibly after the APU inlet door has closed. Oil quantity lingers for about 135 seconds, then also blanks. 

It's unclear whether there are any company specific variations. Other 744 desktop simulators may be based on what casual observers saw on the real aircraft or in videos, but they may not have been aware of the GRD TEST switch operation or the lingering oil quantity after shutdown.