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jgoggi

Engine inflight restart not simulated?

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Hi, I wanted to highlight an issue that I think is simply a feature not simulated, both in the PMDG 777 and 737, but, if it's like this, it is a bit disappointing, because I don't think it's such an in-depth feature and it is practiced during all real life simulator sessions.

 

I would like to set up an engine failure so that the engine

 

1) doesn't relight by itself inflight and

2) doesn't have a severe damage with no N1/N2 rotation.

 

What I want to do is to perform the engine inflight restart procedure, as per QRH 7.20, and restart the engine in flight.

 

Let's see the PMDG  FAILURES page on the CDU:

 

1) ENGINE V1/VR/V2 CUT --> this automatically always (I tried at least 30 times) turns to SEVERE ENGINE DAMAGE and the engine will not start anymore, because no N1/N2 rotation.
2) SEVERE ENGINE DAMAGE --> see point 1)
3) ENGINE FLAMEOUT --> the engine relights by itself almost instantaneously and everything gets back as if no failure had occurred.

 

If I turn AUTOSTART OFF and use 3) (flameout), the engine flames out and does not restart, as I desired, but in normal procedures the autostart is ON, therefore it would not be realistic to switch autostart off in order to have this feature.

Have a look at this video: here they have ENG FAIL R with autostart ON and the engine doesn't restart by itself. It seems that this is not possible in the PMDG 777.

 

https://www.youtube.com/watch?v=vbxl3hc_pL8

 

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1) ENGINE V1/VR/V2 CUT --> this automatically always (I tried at least 30 times) turns to SEVERE ENGINE DAMAGE and the engine will not start anymore, because no N1/N2 rotation.

 

I've already discussed this one with you in the (duplicate) NGX thread.

 

 

 


2) SEVERE ENGINE DAMAGE --> see point 1)

 

Severe damage locks the core. There's no way you're going to restart the engine. This is correct.

 

 

 


3) ENGINE FLAMEOUT --> the engine relights by itself almost instantaneously and everything gets back as if no failure had occurred.

 

This is correct for the 777. Notice that at the top of the engine start panel, the default mode is NORM and not OFF, and AUTOSTART is ON.

 

This will auto-relight if it's possible (unless you turn AUTOSTART OFF just to have the extra challenge). Are you sure you were in a flight regime where a restart shouldn't have been possible?

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Are you sure you were in a flight regime where a restart shouldn't have been possible?

 

Yes, I was in cruise at FL 290. In few words, isn't it possible to simulate what happens in the video, where engine 2 fails, N1/N2 decrease below idle but not to zero and a restart attempt (as per QRH 7.30) could be done (even if in this case the pilots decide to not restart it)? 

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Yes, I was in cruise at FL 290. In few words, isn't it possible to simulate what happens in the video, where engine 2 fails, N1/N2 decrease below idle but not to zero and a restart attempt (as per QRH 7.30) could be done (even if in this case the pilots decide to not restart it)? 

 

FL290 is pretty low, actually, so I'm not sure a restart wouldn't have been possible. The video, as an example, was being filmed while they were flying at FL370. Try flying at a higher altitude where the air is thinner.

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Try flying at a higher altitude where the air is thinner.

 

Just tried at FL 390, no luck, N1 decreases up to about 57-58%, then, after some seconds, back to previous normal value. I also activated EEC 1 and EEC 2 failure before triggering the engine flameout, but no change. 

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I could restart both engines easily inflight in the P3D version.

 

(I deployed RAM AIR Turbine before dual engine failure test)

I cut off both engines manually at FL220 to simulate a dual engine failure. 

Then I was able to start APU (i lost some altitude until it was successful). I configured BLEED AIR to route bleed air from APU to Engine 2. Then I was able to restart engine 2 with manual mode (autostart was not possible, i don't know why) then I was able to restart Engine 1 with manual start too.

 

 

Majzik Mátyás

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Other video taken in a simulator  with engine failure at takeoff and N1 remaining below idle but not to zero and not auto relight:

 

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Other video taken in a simulator  with engine failure at takeoff and N1 remaining below idle but not to zero and not auto relight:

 

Again, you're giving us YouTube "evidence" of a simulator. You can program sims to do things out of the norm simply to practice them. This is likely a case of that. Both our NGX and 777 simulate the real aircraft's ability/function that will automatically relight the engines in the case that power is lost and it's able to restart.

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Kyle, if a real simulator simulates this failure, it means that it might happen in the real airplane as well. On the other hand, why does the QRH procedure 7.20 exist if it can't be used because the engine restarts by itself? 

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Again, you're giving us YouTube "evidence" of a simulator. You can program sims to do things out of the norm simply to practice them. This is likely a case of that. Both our NGX and 777 simulate the real aircraft's ability/function that will automatically relight the engines in the case that power is lost and it's able to restart.

Simulators are like this to train pilots on procedures and in case the auto relight doesn't work for some reason. For example, the condition causing the flameout lasts too long. This is completely realistic.

 

Providing two flameout possibilities, one where relight will work and one where it won't, would be very useful.

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Let me shed some light on this for you as you are not listening to what Kyle has said...

 

1) ENGINE V1/VR/V2 CUT --> There are very few reasons for an engine cut in this low energy regime - most commonly bird ingestion - which would normally result in engine damage)
2) SEVERE ENGINE DAMAGE --> See my comments above!!
3) ENGINE FLAMEOUT --> the engine relights by itself almost instantaneously and everything gets back as if no failure had occurred.  This is the expected behavior.  This is a VERY automated aircraft as in the NGX.  The system will attempt to relight the engine if it can.  As Kyle has suggested, take the aircraft up to the high flight levels (but before doing so, check that your realism settings are where they are supposed to be) and then shut down an engine - watch what happens and what the EICAS tells you.

 

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Let me shed some light on this for you as you are not listening to what Kyle has said...

 

What makes you think people haven't read what Kyle wrote. Repeating it in this way doesn't change anything.

 

Are you saying there are no circumstances when auto-relight won't work when inside the relight envelope? What exactly is the problem with having a "flameout - no relight" malfunction to allow people to practice doing a relight without having first to ensure they are outside the relight envelope?

 

While a fire or severe damage is the most likely reason for a V1 cut that doesn't mean a flameout can't happen. As the checklists (and consequences) are different for the two types of failure trying both scenarios ought to be possible. A full flight sim certainly would have the capability and there's no reason for the PMDG 777 not to purely because of dubious arguments about what's realistic and what isn't.

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What makes you think people haven't read what Kyle wrote. Repeating it in this way doesn't change anything.

 

Kevin I think Dave is  actually  a rw pliot  and  does flies  the t7  I  could be  wrong  though  so I think he should know  what he is talking  about

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Kevin I think Dave is  actually  a rw pliot  and  does flies  the t7  I  could be  wrong  though  so I think he should know  what he is talking  about

Pete, if a RW pilot says something does that mean it can't be challenged or questioned? I'm not saying he's wrong in what he said, just that there's more to it than that. You can, as he said, shutdown an engine and EICAS will give you relight and start envelope cues. However if you select the flameout malfunction the engine auto-relights, even if you are outside the relight envelope. Since Boeing provide procedures and checklists for in-flight restarts they must envisage the possibility that they might be necessary. The way the 777 is currently programmed it's never going to be necessary, unless you manually shut an engine down.

 

There are a number of things in the PMDG 777 which are there for the convenience of the user and which aren't realistic. So realism isn't the be all and end all. What the thread is asking for is to include something which is unlikely but possible (a failure to auto-relight) so users can realistically have an engine flameout and then relight it manually.

 

PMDG has done a great job implementing the relight envelope and inflight start simulation. It's a shame users don't get to see much of it the way the sim is currently set up.

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Kevin, with all due respect, lets break this down logically?  Why would the auto relight fail?  We would need to be missing any of the following or a combination of them - air, fuel, spark.  The most common reason that an engine would not relight would be air.  Air can do a few things to a jet engine at high altitudes which I will explain.  The most obvious and one that Kyle has pointed out to you is the lack of oxygen up in the wild blue yonder.  Secondly, air; in this case speed, can hamper your attempts to do a "windmill" restart if you do not have supplementary air (APU) available.  Thirdly - core lock.  Core lock is a situation in which an engine is shut down for too long a period and the internal components actually shrink because the air is not circulating thought the engine correctly.  The end result is bad and it seizes the engine - locking its core so it will not turn - hence the term core lock.  This is not something I am making up and I do believe that I read in an NTSB report that this was a cause of a crash in the US - I believe on an RJ?

 

I do wonder if the condition you are experiencing (or lack there of) is actually a cross bleed start that is relighting your engines.  When the N2 drops below idle RPM while airborne.  The next time you do this shutdown, see if you get the secondary engine indications and a crossbleed start indication.

 

Were you aware that auto-relight actually provides flameout protection by turning on both engines ignitors?    

 

Another point that I would like to point out is that we are talking about a desktop simulation and a Level D full motion simulator.  HUGE difference - TRUST ME.  The desktop simulator is just that - a great representation of a 777 or 737 (or whatever) with some very accurate modeling of systems and functions contained within built to give you a sense of what it is like to fly a 777.  This is not a multi million dollar piece of training equipment that you are going to be able to throw every failure known to man at.

 

While I have never sat at the console and controlled the simulator (Level D), I can tell you that being on the receiving end of some of he failures I have had thrown at me is not fun (that's a lie, it is fun - just not at that moment).

 

Kevin, I will close by offering a suggestion to you sir.  Rather that spin up two posts in two separate PMDG product forums, perhaps submit a support ticked and mark it as a feature request.  The people at PMDG are good people and respond kindly to these things.  There really is no need to spin up two topics in two forums now is there?

 

DR

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Kevin, your thought is 100% aligned with mine  :wink:

 

Dave, I know that a desktop simulator can't be compared to a Level D, but I think that, after all the failures that have been included in the PMDG airplanes, the failure that includes the possibility to do an inlight restart is not at a much higher level than the other failures, and as such it's a 'feature' that is missing.

 

If you have the 737 NGX and FS2Crew and look at FS2Crew Emergency documentation, the last lines of the engine failure procedure are:

"3. PF Consider running the ENGINE IN FLIGHT START checklist.

4. PF If the engine cannot be restarted: run the ONE ENGINE INOPERATIVE LANDING CHECKLIST FLAPS 15 or ONE ENGINE INOPERATIVE CHECKLIST FLAPS 30",
therefore Bryan York, when programming it, supposed that there was a chance that the engine could be restarted and did not imagine that this can't be accomplished in the NGX.

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Guess we need one of  the Devs  from pmdg to step in and confirm one way or  the other, if  this is possible or  not or  can it be added  in the next update.

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Kevin, with all due respect, lets break this down logically? Why would the auto relight fail? We would need to be missing any of the following or a combination of them - air, fuel, spark. The most common reason that an engine would not relight would be air. Air can do a few things to a jet engine at high altitudes which I will explain. The most obvious and one that Kyle has pointed out to you is the lack of oxygen up in the wild blue yonder. Secondly, air; in this case speed, can hamper your attempts to do a "windmill" restart if you do not have supplementary air (APU) available. Thirdly - core lock. Core lock is a situation in which an engine is shut down for too long a period and the internal components actually shrink because the air is not circulating thought the engine correctly. The end result is bad and it seizes the engine - locking its core so it will not turn - hence the term core lock. This is not something I am making up and I do believe that I read in an NTSB report that this was a cause of a crash in the US - I believe on an RJ?

You mentioned three things: air, fuel and spark. All are required for a relight. Spark we assume to be available for relight. You discussed air but not fuel. However the important thing is what causes the flameout in the first place and whether that condition lasts long enough to prevent auto ignition from relighting the engine until N2 falls too low for it to work.

 

The current flameout failure doesn't define the cause it just momentarily kills the combustion process. That means auto relight always works. A second flameout type could be defined that prevents an immediate relight. Everyone would be happy.

 

Core lock isn't particularly relevant to this discussion. PMDG don't appear to model it and it would only apply if the engine was windmilling for a long period.

 

I do wonder if the condition you are experiencing (or lack there of) is actually a cross bleed start that is relighting your engines. When the N2 drops below idle RPM while airborne. The next time you do this shutdown, see if you get the secondary engine indications and a crossbleed start indication.

I do know the difference between a crossbleed and a windmilling start thanks. Also why they are used. But at very high altitudes with the thin air you were talking about, neither method ought to work.

 

I was at 40,000 ft. I tried both the flameout malfunction and a manual shutdown. The flameout auto relit and the manual restart succeeded (when manually shutdown it indicated a crossbleed start would be necessary). If 40,000 ft is within the relight envelope that's fine, but if it isn't you should have to descend to get the engine started.

 

Were you aware that auto-relight actually provides flameout protection by turning on both engines ignitors?

Yes I was aware thank you. As I was aware of all the other things you've informed us about in this thread too.

 

Another point that I would like to point out is that we are talking about a desktop simulation and a Level D full motion simulator. HUGE difference - TRUST ME. The desktop simulator is just that - a great representation of a 777 or 737 (or whatever) with some very accurate modeling of systems and functions contained within built to give you a sense of what it is like to fly a 777. This is not a multi million dollar piece of training equipment that you are going to be able to throw every failure known to man at.

 

While I have never sat at the console and controlled the simulator (Level D), I can tell you that being on the receiving end of some of he failures I have had thrown at me is not fun (that's a lie, it is fun - just not at that moment).

I've spent my entire professional career designing, integrating, testing and updating Full Flight Simulator software, including many engines simulations. I've probably been in more Level D sims than you have and I certainly know more about how they work than you do. Adding another flameout failure mode to the PMDG 777 would not be a big deal. It could use a time delay or simply inhibit relight until cancelled. It might not be high on the priority list of course.

 

BTW, I have controlled a FFS from the instructor station, as well as designing malfunction logic in the simulation so I know the options available.

 

Kevin, I will close by offering a suggestion to you sir. Rather that spin up two posts in two separate PMDG product forums, perhaps submit a support ticked and mark it as a feature request. The people at PMDG are good people and respond kindly to these things. There really is no need to spin up two topics in two forums now is there?

 

DR

I will offer a suggestion to you, sir. Check who opened these threads before throwing advice at me. I've only contributed to this thread. I didn't start either of them.

 

You might want to read the comments by two 737 pilots in the equivalent NGX thread. Their input is less condescending.

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Sorry you felt that was condescending Kevin. Wasn't the intent. Valid point you raise. One really isn't sure the level of experience of the poster so sorry again. We have such a mix of ages in here one never knows

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Core lock is a situation in which an engine is shut down for too long a period and the internal components actually shrink because the air is not circulating thought the engine correctly.  The end result is bad and it seizes the engine - locking its core so it will not turn - hence the term core lock.  This is not something I am making up and I do believe that I read in an NTSB report that this was a cause of a crash in the US - I believe on an RJ?

 

Got it a little backwards there. Core lock happens because the internal components stay hot - without the air passing through the engine, and the engine core still being very hot from running - while the external (or closer to external) components change in size at different rates. Regardless, you're correct that locking the core is going to be unrecoverable.

 

The crash you're referring to is FLG3701.

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Just to confirm, during our real world sim sessions we often have an engine failure with no apparant damage (engine just spools down).

Thinking about it......I think there is an exercise like that in every sim check.

 

We then go through the Engine Fail L/R checklist including the restart part.

 

They probably make us do this exercise in the sim so often so that we get into the habit of trying to restart an engine rather then automatically saying "oh that is gone see ya later bye" and not even try.

 

Autorelight only lights up the igniters if the system dected an unexpected engine spool down. This is not the same as an EEC reset which is done by fuel control switches off, then on.

Fuel flow for example might have been interupted which maybe is restored after fuel control switch off, then on.....but not by lighting the ignitors (autostart).

 

So the only thing to simulate a flameout condition in the PMDG at the moment is by simply putting the fuel control switch off (I have linked key presses to this action via the CDU).

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By the way......the system that "Autostarts" the engine inflight is the AUTO RELIGHT system.

It only turns on the ignitors (and in case of a subidle stall interupts fuel flow for one second.)

 

This is not the Autostart system!

 

The AUtOSTART system can only be activated by:

on gnd - start selector START + fuel control switch to RUN.

in flight - fuel control switch to RUN.

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If what the OP says is true, that with the AUTOSTART switches off the engines do not automatically restart inflight, then I think PMDG has simulated the AUTOSTART system and the AUTORELIGHT system to be one and the same.

 

Which it is not, as far as I understand things.

 

(I have not yet gone through maintenence manuals, but the MEL says nothing of AUTORELIGHT not working if the AUTOSTART system is dispatched inop.)

 

So all that need be done then is program things so that an inflight engine failure is simulated by a fuel interruption plus the AUTOSTART system not kicking in automatically.

 

The AUTSTART system should then still work for an inflight engine start when the fuel control switch is turned off/on........meaning it will monitor the start and adjust things (or abort the start on gnd) as required for a succesfull start (that is really all AUTOSTART is)

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Look at this video featuring FSiPanel: here they manage to get an engine failure where N1 does not go to zero and there is no auto relight! The video description on Youtube says that the failure is "V1 CUT", but when I select V1 CUT on the CDU it always triggers a severe engine failure, with all parameters going to zero! This one is set from the FSiPanel window, not from the CDU, but what's the difference??

 

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