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alvin

Bleed air riddle

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Hi,During today's flight I've got quite interesting pattern of failures. I have an impression that something might be going wrong here, but before I submit a ticket, I want to make sure I understand everything.Just after engine start, I noticed bleed air is not produced by engine #2; I closed the respective engine bleed valve, and elected to take off anyway using bleed air from engine #1 only (according to the procedures I should have used APU too, but I did not), with the isolation valve opened automatically (auto mode).After over 1 hrs of cruise flight, BLEED TRIP OFF light on the left side illuminated, indicating overpressure or too high temp coming from engine #1; according to FCOM 2.20.1 engine #1 bleed valve should have automatically closed, and that should leave me without any bleed air! But this did not happen - there was still pretty nice duct pressure - you can see it in the attached picture. Am I wrong somewhere here?thanks,Jakub

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The panel states were generated by NGX SP1b, so this should be ok. What I did though, was artificially increasing frequency of failures 13 times: by changing values of timers in the airframe .ini file (dividing second values in Failure Items section by 13). This should not however influence how bleed air systems logic... I think.Jakub

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Apart for the need of a second source expecially if you want to use both packs, i never see the bleed trip off on the NGX.However you're right, wit the configuration shown on the picture, the bleed trip off will result in no pressure for the ducts.I will try to manually trip the bleed with the failure menu and see what happen.PS: use the onside pack in that condition.

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After over 1 hrs of cruise flight, BLEED TRIP OFF light on the left side illuminated, indicating overpressure or too high temp coming from engine #1; according to FCOM 2.20.1 engine #1 bleed valve should have automatically closed, and that should leave me without any bleed air! But this did not happen - there was still pretty nice duct pressure - you can see it in the attached picture. Am I wrong somewhere here?thanks,Jakub
You're correct, you should have no bleed air with the trip. I think Kyle is onto something, though. Some panel states seemingly can have funky side effects.
PS: use the onside pack in that condition.
I was going to ask. Thanks!

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On my system it seems to be normal if simulating the bleed overpressure.It Trip off and pressure will go to 0.Try to turn on and off the failures manually to check if it was a random error when you loaded the flight. It could happen that sometimes not all things work correctly.

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The panel states were generated by NGX SP1b, so this should be ok. What I did though, was artificially increasing frequency of failures 13 times: by changing values of timers in the airframe .ini file (dividing second values in Failure Items section by 13). This should not however influence how bleed air systems logic... I think.
It shouldn't affect the logic, through the .ini, no.You did load a default panel state, though, right? Not one you'd saved (even post SP1B)?

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The only thing I cannot have working (try it) is the overtemp trip off.I tried and waited about a minute but no trip from the bleed. It seems that te 490°F temp switch is inoperative.

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Thanks guys for the helpful comments!I always use "continuous" states - after each flight segment I save my flight and panel, and then reload it for the next leg some time later. So no default panel, for a many segments now.But, the picture seems even more complicated:I started the flight with 3 failures on (Engine #1 overtemp and overpressure, and #2 bleed air valve failure). The last failure was probably caused by the first two. However, I had no TRIP OFF light at take-off, so I pretended I didn't notice this (how would I know in RL). After the abovementioned 1hr of cruise flight, at the time the screenshot was taken, I had 6 failures. The three new were: apu bleed, eng1 bleed, and eng1 9th stage bleed; I assume they were caused by the eng1 overtemp and overpressure failures.So now the virtual life of my virtual plane is spared by this probable bug, because even if I wanted to use APU bleed now, I wouldn't be able to. Another thing is why I didn't get TRIP OFF light after engine start.. but its interesting to see "bad" air from an engine can actually damage valves in other parts of the aircraft. Jakub

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You did not mention the Master Caution light...AIR COND !Did the Master Caution light come on ? (as it should)Did you then press the trip reset ? (as you should)Fred.

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Fred, yes and yes: master caution was there, and I tried the trip reset, but the light didn't extinguish.Jakub

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Fred,yes and yes: master caution was there, and I tried the trip reset, but the light didn't extinguish.Jakub
Sounds like a dodgy panel state file so !Fred.

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Thanks, really sounds like a solution! Does it mean you always start each flight with loading a fresh default panel?Jakub

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Does the overtemperature work on your system guys? My bleed trip off only with overpressure.

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Does the overtemperature work on your system guys? My bleed trip off only with overpressure.
Overtemp solo doesn't seem to work - loaded from a clean panel now. No trip off and no master caution. It also didn't trip any other failures after some time of flight.Jakub

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I know I'm opening an ancient thread, but I just had this exact same thing happen.

 

Departed KLAS just a bit ago and was climbing to cruise. Got a master caution light and looked up to see the left bleed tripped off. I tried the reset button and followed the QRH as published. No luck. Currently flying on bleed 2 only. I'd read about if it was an over-pressure, you could switch on the EAI and then back off to relieve the pressure, but that also didn't work, so I'm assuming it was an overheat or something else completely.

 

I do have service based failures on and always use the short run panel state. Super excited to have my first failure  :lol:

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Had this sort of thing a while ago.. check the service based failures.. 
Mine was on without me knowing it.

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