Posts about: "Engine Failure (All)" [Posts: 489 Pages: 25]

In that report, the factual conclusion is:

4. PROBABLE CAUSES
In this serious incident, it is highly probable that, when the Aircraft was descending for
landing, there occurred oscillation in rpm of each engine causing both engines to temporarily fall
below idle at separate times because Residue primarily composed of magnesium salts accumulated
in spools impeded movement of spools that involved in fuel metering of both engines.
(emphasis added)

and the narrative taken from the pilots is that while they happened in short order, the engine issues were not simultaneous. Not to say they couldn't be simultaneous, but they weren't. Also, the problems arose in the descent, as the engines were throttled back. Again, not to say it couldn't happen in the take-off, under full power.

Thanks for straightening me out on that one. Strange though that bird strike theory was ruled out so quickly without examining the wreckage or hearing the CVR? And still, the video potentially shows an right engine surge on the runway. If not a bird strike, then for what reason? Maybe I'm just seeing things since no one else seems to see this so I'll leave it there.

The second box has been recovered and the CVR is being analyzed so hopefully they will give an interim update shortly.

Do we know yet what stop
altitude was set on the FGP?

Suppose they had left it at zero prior to final departure briefing?

Not 787 rated but is it possible that they selected FLCH after take off and the aircraft targeted the zero altitude selection?

Doesn\x92t explain the RAT deployment but I have a feeling there maybe more than one hole in this Swiss cheese\x85

I think you may be inferring something that isn't actually true. It certainly isn't true in my case. Wanting to explore the details of a function known to be designed to shut down engines, in a case where unexplained shutdown of engines appears to be a likely cause or contributing factor, doesn't suggest that we are assuming TCMA is involved. It's just exploring the details of a a function that is designed to do that and doesn't put on a light, smoke and sound show, or produce obvious debris and residue, when it does.

I think those of us who are persistently trying to learn the details of the sensor inputs to and logic of TCMA (I prefer that characterization to "obsessed with") understand quite well the points you make here — at least those of us whose interest survives in this new thread. However, I at least, and I believe others as well, have also come to the tentative conclusions that (a) the accident aircraft had engines providing little to no useful thrust from nearly the first moments after rotation, and (b) the only possible reasons for that which have been considered here so far involve the sudden and approximately simultaneous shutdown of those engines, most likely by interruption of fuel flow (because that's one of the very few things we know that can do that without producing big bangs, flames and smoke, etc.).

I don't agree that it's more logical to posit that something we don't know about has shut down the engines rather than something that we do know about that is intended to shut down engines. Do you know of other routines/subroutines in the FADEC that shut down fuel supply?

I certainly don't assume that and I haven't seen posts from others (that I consider serious and reasonably well-informed) that "seem to assume" that.

Yes, we know that.

Right, and you won't see a serious attempt to do that until we know, at least, what specific sensor inputs the TCMA function uses to determine the air/ground state of the aircraft and the logic that uses those to make the determination.

Many years ago I maintained a Hawker 1000 business jet equipped with PW305 engines with FADEC. The fuel control did not have a separate switch to control fuel flow to shut down the engines. Shutdown was accomplished by pressing a release on the power levers allowing the lever to be pulled past the idle stop all the way to the cutoff position.

One day upon returning from a flight, the crew pulled both power levers to cutoff. The right engine shutdown immediately as expected, but the left engine kept running. By the time we in maintenance got out to the airplane, the engine finally shutdown by itself.

Troubleshooting found the cause of the problem. The cutoff position of the power lever closed a micro switch that sent a ground to the FADEC. That ground went through two discrete wires. One went directly to one input on the FADEC. The other went through a squat switch on the main gear leg to a second input on the FADEC. The engine would only shutdown immediately if both inputs went to ground simultaneously. If only one input went to ground, the FADEC would delay shutdown for 30 seconds. This was to protect against an inadvertent movement of the power lever to the cutoff position in flight causing an immediate shutdown.

The squat switch on the left gear leg had failed in the open position, causing the problem.

I am wondering if more modern FADEC engines have similar protections against immediate shutdown in the air? I can see why the designers of the Hawker implemented the system the way they did, because the shutdown command was integral to the power lever, and it potentially could be pulled to the cutoff position in flight by an inadvertent release of the locking mechanism that would normally prevent it from going past the idle stop, whereas modern FADEC engines like found on the 787 have a discrete locking switch.

But, if a similar protection against immediate shutdown does exist in the 787, would the engines keep running for a period of time (in the air) even if the fuel control switch was accidentally or deliberately moved to \x93off\x94?

Quote:

Originally Posted by Squawk7700

Perhaps?

Some questions, if I may:
When is the crew expected to do this? Wouldn't it be armed prior to commencing the takeoff so that it (one or the other) would engage automatically?

How does the 787 "manage thrust" after takeoff? The jet has only just left the ground; surely the throttles would be at maximum power and pitch would be used to attain and maintain V2 until the end of the second segment.

Are you saying the pilot( s ) just sat there while the ATS reduced the thrust (because is all it could have done, as it was at maximum for the actual takeoff).

Fixed on what? Or did it "decay" because the PF pulled the throttles back?

There is no evidence the jet climbed too steeply; I assume you saw the granular FR24 plot (from FR24 itself) which showed the initial flight path of this one was in the middle of the range, and the video clearly shows a normal initial climb and deck angle before "the @#$% dropped out of it".

So BOTH pilots just sat there, didn't pull the gear up, did nothing else and crashed it (pretty well, I might add, with superb pitch control right to the last second).

Interesting but totally irrelevant as the jet never got above 200ft.

You're clearly implying a complete ballsup by the crew, making multiple serious mistakes or errors of omission.

We DO NOT know that. If that had occurred how did the aircraft achieve initial climb?

If this happens, and hasn\x92t yet led to a fatal accident, is it possible over say incorrect or no data could lead to a fatal accident (not saying it happened here).

Could incorrect or no data coupled with other issues (eg hydraulics, electrical or engine failure) lead to a situation that might have been recoverable with the correct data being unrecoverable?

I don't think it will make any difference, english still isn't his first language and the bang he heard could be anything from a tail strike, load shift, catastrophic engine failure, rat deployment, initial strike/ impact. He is the luckiest guy on earth, lottery ticket stuff.

Do you stand by your previous assertion :-

Maybe you should have kept sitting on your hands, theory a) in particular is about as risable as the last one you posted. Do you still think engine failure takes 30 seconds for the plane to react?! Thanks to rkenyon for alerting us not to take your post seriously. You still don't believe the RAT was out despite the in depth audio analysis done by an expert in the field. You still think its a motorbike?!

Given they took off at a perfectly normal point, at a perfectly normal speed, I don't see how you come to incorrect derate and low v speeds, or how on earth that would lead to a normal takeoff followed by sinking?

BBC's article quotes him as saying the shaking or moving left and right . But on more fresh interviews he didn't say that . He was assuming the plane was landing since it was his first time there . He came an hour before . He wanted to take video for his friends back at the village . Apparently this is a phenomenon called Misinformation Effect "where well-documented phenomenon in psychology that describes the tendency for post-event information to interfere with and alter a person's memory of an original event."

Grand mother was the one saying it was shaking . She said her location was even closer to the airport . She also said the plane was silent compared to how others make the sound Maybe he started incorporating extra information from her and in turn Who know What Information she is getting Misattributed , Overwritten etc herself but her take is also possible take on engine failure.

I really think this is worth looking at. I keep asking a maintenance engineer to comment on what they'd do if a 787 with these issues presented itself to them on a turnaround shift and whether those faults could be connected to engine failure in some way.

The short answer is no.
The 787 has a very sophisticated diagnostic system. Faults are presented through a central maintenance computer system accessible either through the flight deck display units or from a laptop plugged in to the aircraft (there is a WiFi option but honestly it's a bit clunky and I've only ever used it once).
All faults are displayed in ATA order as either active, not active or latched faults.
I cannot see how any IFE, lighting, air con or other non power plant related faults could cause the situation that has brought this aircraft down.
The IFE is entirely seperate and has its own independent diagnostic system.

tdracer explained that earlier: T/O power to sub idle on fuel shutoff only takes 1s, at most 2s.

Slamming the throttles back is a lot slower as the FCU (on a traditional engine)/FADEC spins down the engine slowly - I suppose to make sure that the airflow through the engine remains stable.

Regarding the momentum: As the first few seconds of the climb were normal compared to previous T/Os of the same flight (speed & altitude, confirmed by comparison of the RAW ADS-B data) I don't believe the engine failure happened before or on lift-off.

I agree with this. For all the SLF reading and not posting ( good work!) there is a delay between the end of the takeoff run and the gear being selected up. I fly 737’s so any 78 folk feel free to correct me but it looks like this;
PM: “ V1 ….Rotate”
The PF then begins to rotate the aircraft up to a pre determined attitude which is normally between 13 and 15 degrees. They do this at a rate of between 2 and 3 degrees per second so about 5 or 6 seconds later the aircraft is at its climb out attitude. The PM is then looking at their instruments to confirm that the aircraft has a positive rate of climb, this takes a moment, maybe 1 to 3 seconds then;
PM “ positive rate”
PF: “ gear up”.
So minimum 8 seconds but probably longer between the PM calling “rotate” and the gear being selected up.
The relevance of all that is to say that if you suspect that the gear up cycle has been interrupted by a dual engine failure, then the engines may well have been producing thrust up to an altitude of 50-100ft or so, which ties in nicely with the max height reached, distance travelled etc.
Mods this is clearly not a theory, just info for those who don’t fly airliners to aid understanding.

Could you please elaborate on that?

FR24 did do that raw ADS-B data comparison. Remember the GPS position and barometric altitude are sent by the aircraft itself. The altitude is sent in 25 ft intervals, so a shallow curve that is smooth in reality looks janky in the data, due to the rounding of the numbers. From https://www.flightradar24.com/blog/f...rom-ahmedabad/ :
The red line is the accident flight, and it covers approximately 4.3 seconds.
Obviously the altitudes are all uncorrected for barometric pressure, which would've varied with the weather on that day; you kind of have to mentally shift the lines vertically downward. Now I looked for, but couldn't find, the post in the old thread where the rotation was triangulated\xb9, but I remember that it was near the turnoff to the high-speed taxiway, so a few seconds ahead of this ADS-B capture. We only have the video to show us what occurred then.

That means the ADS-B data doesn't really tell us whether the first few seconds of the climb were normal or not.

When we compare the red line to the blue lines, the data tells us the climb rate had already decayed significantly before the accident aircraft passed over the end of the runway, because the red flight path is much more shallow than the blue flight paths.

Please correct me if I'm wrong: to my eye, the data alone does not show that the engines must have failed after rotation, because the data does not demonstrate a normal climb rate.

But likewise, the engines can't have failed much before rotation:
For completeness' sake: you can look at the CCTV video, consider the 787's wingspan a flying 200 ft yardstick, and hopefully agree that the aircraft did not get much higher than 200 ft AAL, if that.

-----
\xb9 I found one of them, anyway. The reference is the CCTV video:

There has been a lot of discussion of the possibility that the crew shut down the wrong engine or misidentified some other problem as an engine failure, usually followed by an assertion that nobody would touch the engines before x feet. PPRuNe's own survey, at the top of this very subforum, found a really high base rate of wrong engine incidents:

• 31 per cent of the PPRuNe Population reported either having a wrong-engine incident or a close call
• 61 per cent reported witnessing one

This might be biased upwards by people who have had the experience being more likely to engage with a thread about it and to respond to the survey, although on the other hand the difference between self-reported errors and witnessed ones shows there's also some bias to under-reporting. In the light of those observations you should surely have quite a strong prior that an erroneous engine shutdown is possible.

Also, on the point about sitting on your hands to 400/1000 feet AAL, someone who has already deviated from a standard operating procedure is more likely to go on to make another mistake; that is why the procedure existed in the first place.

As a memo item, here are the survey results:

Q1. Have you ever shut off the wrong engine in the sim?
Yes: 5.4% +0.9%
No: 94.6% -0.9%

Q2. Have you ever ALMOST shut off the wrong engine in the sim?
Yes: 26% -1.0%
No: 74% +1.0%

Q3. Have you ever witnessed a colleague shut off the wrong engine in the sim?
Yes: 16% +1.0%
No: 84% -1.0%

Q4. Have you ever witnessed a colleague ALMOST shut off the wrong engine in the sim?
Yes: 45% +2.0%
No: 55% -2.0%

Link to original post

Senior Pilot

Hi all,

Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.

I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.

So, my questions is related to T/O performance.

Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?

By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect…. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?

Thanks for the help !

Lead Balloon:

The requirement for TCMA may have been specified by Boeing, but that doesn' t tell us who designed and built the solution in this case, though it must have been a collaborative effort between the two parties. Anyway, TCMA may be a red herring, since we still have not defined what, if any, other sources would have authority to issue an engine shutdown command