Hi,Is theere any way to silence the low battery alarm on the bus when you go for APU start without a ground cart? I can have everything turned off bar the battery switch and a single fuel pump and I still get the alarm for about twenty seconds. It's very loud :)Small but annoying feature. I'm guessing it can't be silenced in RL? (without power to the busses obv)bestjake

Sounds like that's the ON DC alarm for your IRU's. Turn them off and enjoy the bliss of silence.

Umm, just start the battery, guard/close the Emergency Exit Lights, then start the APU. You shouldn't hear the beeping, at least I don't.

The only alarm on DC only mode can be the IRS not in OFF position. In cold and dark the switch must be in OFF. If you put off the IRS when you already turned on battery it will need few seconds to stop the sound.

Thanks, guys. It was the IRS..I start them up immediately to give them a run up (realistic wake-up time set) I will leave themn until the APU is started.

IRU's don't like power interruptions during alignment. So make sure you don't switch power supplies while they are still aligning. At some airports external power can fluctuate (you'll see this as a passenger if you see the emergency lights flash up briefly in the cabin). In such situations, it's best to start the APU and perform alignment on APU power only. If external power is ok, you can also align but make sure you don't connect the APU gen's before alignment is complete.Note, this info is based on the classic - perhaps the NG can better cope with fluctuating power.RegardsMark

it's best to start the APU and perform alignment on APU power only.

That's what I'm now doing.Out of interest, and with SBF turned on, would the action described by Mark above if performed a few times actually mash up my IRU's? (if the NG isn't better protected from fluctuating power that is)bestjake