Budbud

Decrypting failures (technical)

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Hi,

I have just performed a two engines inoperative landing at KJFK due to several failures and I'm wondering if they are relative and what could be the reasons behind a repetitive failure on engine 4.

First, while I had started the descent from FL390 after 14h00 of flight (from VHHH) I got the Elec Gen off 4. I tried to switch the gen nowcont on and off as per the QNH to no avail.

Then at FL250, I saw both engines 3 and 4 oil temperature rising above the red limit and had to shut both engines. I declared an emergency and configured the aircraft for a two engine inoperative landing as per the QRH (once again) and landed safely on rwy 31L.

When I checked the failures, I had obviously gen 4 failure and both oil pressures and temperatures failures on engine 3 and 4.and I had 16 qrts of oilremaining in both engines instead of 21.

Engines were serviced after the previous flights due to a repetitive oil pressure and temperature failures on engine 4.

Is there a reason to get the same failures on engine 4 on three successive flights despite servicings and engine oil refills in between each flights and a reason why I got also the same failures on the engine 3 despite the servicing or is it just a coincidence?

Either the mechanics did something wrong at each servicings or I'm quite unlucky lately. I flew several hundreds hours with any failures and suddenly these concurrent failures...

I'm using a custom short panel state that I did again recently after the update for P3D 4.1 and got the repetitive and cumulative failure short after.

Is it possible that there is a condition of the aircraft saved with the panel state that would trigger these failures despite the few number of running hours of the engines?

Something that would somehow override the MTBF for these failures?

It was fun anyway to train to a two engine inoperative landing and found the 744 surprisingly smooth to landing with two engines off.

Thanks.

 

 

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What are the fuel levels?  Adequate fuel remaining is required for the fuel/oil heat exchangers. 

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Hi Dan,

I had about 15T remaining dispathed equally on four main tanks and AOT was around -30°C.

I didn't think of the fuel quantity in the process but since I always end up my flights between 12-14T there was no change here compared to other flights with no failures.

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51 minutes ago, Budbud said:

I had about 15T remaining dispathed equally on four main tanks and AOT was around -30°C.

Okay, just checking.  I agree this path isn't going anywhere.  I don't know enough about their reliability modelling to venture a guess here, but on going problems with one engine is odd.

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What surprised me is having the same failure again after servicing and engine oil refill.

I know that in real life, a servicing may bring some new problems (in merchant navy, we are used to saying that the planned maintenance period in dry dock, usually don't fix the know issues but bring some others due to the mandatory servicing of equipment that worked properly :biggrin:).
But here in the addon, I would have been more prone to thing that the servicing would be a reset of the failures and counters for MTBF...

 

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4 hours ago, Budbud said:

But here in the addon, I would have been more prone to thing that the servicing would be a reset of the failures and counters for MTBF...

I agree..., unless there was a devious developer who programmatically made it possible to end up with a hanger queen.

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I had the exact same issue while getting ready to land at EDDF, but since I was merely 18nm from the airport, I simply followed the shut down procedures, and landed her on two engines, at which point she became maintenance’s problem.

Performed a full service on the plane, but the next time I loaded her up, she loaded with the same problem in the same two (3 and 4) engines. Not sure what she was going to do after that, because shortly afterwards, Windows 10 downloaded that security update that caused the Queen to crash the sim and that was pretty much that for my swimming days in any case.

So, I’m also curious to know what causes these failures in the Queen.

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If this thread doesn't bring an answer after some time, I will eventually send a ticket but I'm quite reluctant to do that because I don't want to disturb too much the support for something that that is a bug but more a matter of understanding.

And furthermore it adds some thrill to the flight so I have nothing to complain about.

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Romain,

My suspicion based on what your describing is a Panel state issue since it would highly  unusual to have 2 random failures occur on the same side like that.  You indicated it was a custom short panel state.  Did you create it from the latest version default state or was it one created from another state?  Also if you don't reload that panel state do the faults clear? 

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Hi Paul,

I created the panel state from the default panel state.

In my last flight today, I noticed few hours before the descent that the quantity of oil on both engines 3 and 4 was lower than on the left side.

I don't remember the exat figures, but I have at least 2qrt difference between engines 1/2 and engines 3/4.

I must confess that I failed to check the oil quantity before start up on almost all my flights :blush:

But since I have the option "USE LAST FLIGHT ENG OIL" selected, I naively thought that the engine oil quantity would be good when loading the aircraft after having refilled the engine oil at the end of the previous flight.

However, if the oil quantity is saved in the panel state and overrides the option, it is well possible that I took off with an already lower quantity on the right side and didn't notice it.

I will check in my next flight. It would be plausible reason for the recurrent oil failure on the right side.

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Yeah, that option to use last flight oil level should be used carefully.  I always keep it off, and the level provided for in the panel state file is what I'm starting with.

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A couple months ago I had almost the same thing happen.  Service based failures off and (was) using previous oil levels.  Late in the flight, oil temps on 3/4 climbed into yellow.  At TOD, engines rolled back normally but oil temps on 3/4 both quickly red lined.  #4 failed then as I was running the QRH checklist, #3 failed as well.

Only happened once so not a recurring issue.  I now service the oil before each flight instead of after the previous one.

I was actually quite supprised at how pleasantly the aircraft handled with a dual engine failure (same side).  I found it a bit more challenging to handle it on the ground than in the air while in that state.

 

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18 hours ago, Budbud said:

 

I must confess that I failed to check the oil quantity before start up on almost all my flights :blush:

 

Oops........You are not the only one....:huh:

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4 hours ago, Ep3man said:

I found it a bit more challenging to handle it on the ground than in the air while in that state.

Oh yeah!! I know exactly what you mean.  I had to shut down an engine in the C-414 enroute from Dallas to Corpus, after getting the trim set and letting her settle down from 16500 to 9500 she was easy to handle.  The visual landing was a little more interesting with a crosswind from the dead engine side but not too exciting. The PNF warned me just before touchdown (this was my first engine shutdown) to be careful after pulling the power after landing...., and OMG the warning was understated. That bird was bent on heading for the grass but I had enough runway to get things sorted out and gave a big sigh of relief.  That attaboy feeling dissolved when I tried to taxi and turn into the live engine:  She would not go there, no matter what I did.  The the experience guy next to me suggested I add a little power approaching the turn then pull the power back to idle to allow the turn.    Finally my friend admitted his first single engine landing with a BE-58 did go into the grass and I felt better.

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