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Sven Cella

PACK RST sys fault when turning off APU

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So I don't know if this is normal for the 747-8 or if it's a bug..

What happens is when the APU is turned off I get the PACK RST sys fault and I have to reset it every time I do the electrical power-up.

I tried a lot of things to narrow down what the problem is but every time it's the same. 

1. when I follow the FCOM I get the fault

2. tried turning APU gen 1 or gen 2 off first, i get the fault

3. leaving packs on or off, I get the fault

4. trim air on or off and then apu off, i get the fault.

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)

So my default is the cold and dark I made from using the FCOM electrical power down. But I still get the fault even if I load the default panel state from the FMC.

Is anyone else experiencing this? Is this probably a bug?

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18 minutes ago, Sven Cella said:

Is anyone else experiencing this?

Nope.

18 minutes ago, Sven Cella said:

Is this probably a bug?

Probably not.

If anything, perhaps an old panel state from a much earlier version?

I'd ask that people be a little more careful with throwing "bug" around. Just because something is unexpected doesn't mean it's a bug.

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Just now, scandinavian13 said:

Nope.

Probably not.

If anything, perhaps an old panel state from a much earlier version?

I'd ask that people be a little more careful with throwing "bug" around. Just because something is unexpected doesn't mean it's a bug.

Not an old panel state because the exact same thing happened on a complete reinstall. I mean complete reinstall because I deleted everything, I even had to get additional installs on the key via the support.

I'm asking if it is a bug, not implying. any idea what it could be?

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I am having a hard time following your description.  From my view it appears as if you are turning off APU and then get a pack fault but I cannot tell from your description if you are switching to ground power or engine generators.

The few times I've seen a pack fault in the -8 was when I interrupted power, and then it was a simple push of the button to reset packs once power was normalized.

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2 minutes ago, downscc said:

I am having a hard time following your description.  From my view it appears as if you are turning off APU and then get a pack fault but I cannot tell from your description if you are switching to ground power or engine generators.

The few times I've seen a pack fault in the -8 was when I interrupted power, and then it was a simple push of the button to reset packs once power was normalized.

Yes to resolve it it's a simple push of the reset button. The point is it's not supposed to happen when I follow the FCOM to the letter. 

It happens when I just follow the normal procedures after landing all the way to secure and then do the supplementary electrical power down.

the other things I described are just things I tried to figure out the problem to my knowledge.

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Okay... I am also looking at the amplified normal procedures for securing the aircraft.  The packs are turned off while there is power available from either APUs or ground power.  If you do the electrical power down you do not remove power until the packs have completed their shutdown cycle.

Exactly where in the steps do you get the pack fault and what power is supplied at that time?

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9 minutes ago, downscc said:

until the packs have completed their shutdown cycle.

I think this is the whole issue... going too fast with the shutdown. 

Got to be gentle with the queen!

I'll try this out, thanks!

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33 minutes ago, downscc said:

Okay... I am also looking at the amplified normal procedures for securing the aircraft.  The packs are turned off while there is power available from either APUs or ground power.  If you do the electrical power down you do not remove power until the packs have completed their shutdown cycle.

Exactly where in the steps do you get the pack fault and what power is supplied at that time?

Nope tried it, still happens. Even when long on external power and the APU switched off.

APU completed its shutdown cycle, I was on external power (which means the packs are already switched off automatically), followed the secure procedure, waited a bit then after checking the ECS and everything dissabled the external power and the PACK SYS error light illuminated before shutting off. Then when I apply external power the PACK SYS fault light is on and I have to reset it every time...

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Turn off packs while APU power is on.... before turning off APU.  Ground power is not going to power packs.

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3 minutes ago, downscc said:

Turn off packs while APU power is on.... before turning off APU.  Ground power is not going to power packs.

I did that, still get the fault.

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You lost me... you still get the fault when?  The packs are off, you remove power, and then you get a pack fault?  This is so hard to follow because I am not getting a picture in my mind of the exact steps you take.  You say you follow the checklists, if that were true you would not get a fault so we are trying to figure out what you are doing to help you though the problem.  If you insist it is a bug and you are doing nothing wrong then we are done here.

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Sven, there is confusion about *when* you get the fault. The sentence "What happens is when the APU is turned off I get the PACK RST sys fault and I have to reset it every time I do the electrical power-up" has two meanings...

1) I turn the APU off and *immediately* get a PACK RST sys fault reported on the EICAS (unlikely). 

or

2) I turn the APU off. Some time later when I later do an electrical power-up, I get a PACK RST fault that I have to reset. 

If the answer is (1) then the issue is related to shutdown and that is what Dan has been trying to help you with, but I think that is very unlikly. 

If the answer is (2) then the issue has nothing to do with how you shut-down. Given that you say you get teh same result with default and saved cold&dark, I think this is the more likely option.

Can you list the steps you follow from cold & dark until the warning is reported.

 

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1 hour ago, Paul_Smith said:

Sven, there is confusion about *when* you get the fault. The sentence "What happens is when the APU is turned off I get the PACK RST sys fault and I have to reset it every time I do the electrical power-up" has two meanings...

1) I turn the APU off and *immediately* get a PACK RST sys fault reported on the EICAS (unlikely). 

or

2) I turn the APU off. Some time later when I later do an electrical power-up, I get a PACK RST fault that I have to reset. 

If the answer is (1) then the issue is related to shutdown and that is what Dan has been trying to help you with, but I think that is very unlikly. 

If the answer is (2) then the issue has nothing to do with how you shut-down. Given that you say you get teh same result with default and saved cold&dark, I think this is the more likely option.

Can you list the steps you follow from cold & dark until the warning is reported.

 

It's both 1 and 2. I get the fault, then it switches off, then when I turn it back on the fault persists. It resets when I press the PACK RST button.

Edited by Sven Cella

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16 hours ago, Paul_Smith said:

Can you list the steps you follow from cold & dark until the warning is reported.

 

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The steps are in the FCOM from after landing to the supplementary electrical powerdown. 

1. Hydrolics off aux 4 on.

2. parking brake.

3. APU gen 1 on, gen 2avail for cargo handling

4. fuel cutoff

5. fuel pumps off.

6. set wheel blocks. parking brake off hyd 4 off.

7. set ground power, ground power 1 on 2 avail for cargo handling.

8. APU off.

9. after everything is complete close the doors, switch the IRS off, packs off, emerg light off. 

10. ground power off

This is the point where I get the fault right before the airplane powers down. 

11. stby power off, battery off.

There is also an option in the FCOM to work with the APU running untill switching everything off. makes no difference since the fault happens as soon as I switch the gens off (either ground power or APU). 

then when I power back up The trim air valves stay closed and I get the sys fault on the PACK RST switch. until I press the PACK RST switch. 

 

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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.

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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)"

 

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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.

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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.

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