In FMC i load Cold/dark status then connect ground power.Battery on,standby power auto,grd power on,bus trans auto,then open all fuel pump,now apu start.Strange is apu EGT should be rising to 8 position then drop to 4 and apu gen bus will illuminates,BUT i i try to start apu then EGT just rising to 4 position and APU gen bus illuminates.Does any wrong about my start up APU procedure??

I was seem solved my problem but still don't know why...And how to start APU in flight? I quick see manual but not found.I try to moving APU switch to start then few min passing just saw LOW OIL PRESSURE illuminates.

Actually, I experienced the same problem (first post) once. Why that happen? I dont know.

That's strange,same procedure,but different result......... BTW sign you name.

I'm not sure I understand your problem. First of all it's perfectly normal for the EGT to rise to about 800 degs, then drop back and settle around 400. Furthermore the LOW OIL PX light will for sure come on as long as oil pressure is not within normal operating range. Or are you saying the light stays on, or comes on after APU start? Even then there's not much you could do than place the switch back to OFF since the APU would shutdown on its own in this case.

I know in normal condition is EGT rising first then drop to about 400 degs,and then APU gen bus illuminates.But in my most condition is whatever i turn APU switch to start,EGT not rising OR only rising to 400 degrees with Low oil pressure.