PACK RST sys fault when turning off APU

[downscc 1,327]

I think I'm repeating myself... turn off packs before APU off.   Also, not important but for you consideration,  I shut down IRS when I am turning off pumps (hrdra and fuel), and the emerg light goes off when the cabin door opens.  Also, be sure packs are off before connecting ground air.

[Sven Cella 14]

42 minutes ago, downscc said:

I think I'm repeating myself... turn off packs before APU off.   Also, not important but for you consideration,  I shut down IRS when I am turning off pumps (hrdra and fuel), and the emerg light goes off when the cabin door opens.  Also, be sure packs are off before connecting ground air.

I think I'm repeating myself too because I already tried that as stated in my other comment

"5. packs off, and just turn the apu off via the dial, I get the fault. (same if i repeat this with packs of and turn the APU gens off one by one)"

 

[Sven Cella 14]

this is what happens

[downscc 1,327]

Oh okay... you are going dark..., yeah, unless testing I never remove all power from the aircraft because real world they are going to be on external power during the turn around.

I am wondering what happens if you delay a little longer after shutting off the packs before you remove electrical power.  I am thinking one explanation is that the packs are still cycling down before you remove APU, and the FCOM infers that loss of bleed or power will trigger the pack reset.  I would expect it takes some time for the air cycle machine that is the heart of the pack to spin down and allow itself to enter a shut down state.  Give that a try.

Missing from the video is when you apply air/power and turn on packs you get a pack reset indication... I just assume that happens.

[Sven Cella 14]

7 hours ago, downscc said:

I am thinking one explanation is that the packs are still cycling down before you remove APU, and the FCOM infers that loss of bleed or power will trigger the pack reset.

Yes I read that but I can't see why it would still happen even if I'm on ground power (apu off) after parking. This was just a quick vid to show the basic fault. it doesn't matter which gens are on at the time, as soon as i switch the gens off I get this.

 

7 hours ago, downscc said:

I would expect it takes some time for the air cycle machine that is the heart of the pack to spin down and allow itself to enter a shut down state.  Give that a try.

Tried it, still happens.

7 hours ago, downscc said:

Missing from the video is when you apply air/power and turn on packs you get a pack reset indication... I just assume that happens.

You assumed correct

I don't know it's not that big of a deal, I was just curious if it was supposed to happen or not. 

7 hours ago, downscc said:

Oh okay... you are going dark

Yeah that's a thing I do, I like to role play or something that I fly it somewhere and then I power it up the next time I fly to a new destination. 

anyway thanks for the replies! I think I'll dig through the FCOM or something to find out what it could be exactly.