Maybe someone here can help me with these questions referenced to a Garret GTCP331:
1) APU EGT rise:
I was told that normal EGT for a stabilized APU is 370 deg (99 RPM) and on the
first start, it may reach 650 deg at 35 RPM
Now, in this hypothetical case, immediately after APU shut down (0 RPM), EGT
would be around 250 deg.
In case a restart is attempted, I guess EGT would first go down quite a
number , maybe to 140 deg, while RPM increase from 0 to 16 %, and then would
reach a final peak of around 750 deg because it was hot when the restart
begun. It this a valid reasoning?
Besides, at stabilized RPM (99%), EGT would have come down to the same 350
deg, or it will stabilize at a higher temp, around 450-500 deg (GEN OFF and
BLEED OFF) because of having reached a hotter peak?
2) APU Bleed air duct pressure
What would be the numbers for a wealthy APU ? (AT MSL)
Duct pressure with APU Bleed Valve On and
- Packs Off
- one Pack On
- both Packs On
- Engine Start - Packs Off
- Engine Start leaving one or both Packs On