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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

 


James Goggi

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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?


Kyle Rodgers

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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)? 


James Goggi

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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.


Kyle Rodgers

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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. 


James Goggi

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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:

 


James Goggi

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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.


Kyle Rodgers

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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? 


James Goggi

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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.


ki9cAAb.jpg

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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.


ki9cAAb.jpg

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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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Peter kelberg

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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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