Posts by user "sabenaboy" [Posts: 24 Total up-votes: 0 Pages: 2]

Originally Posted by tdracer

OK, I promised some informed speculation when I got back, so here goes:
Disclaimer: never worked the 787, so my detailed knowledge is a bit lacking.

First off, this is perplexing - especially if the RAT was deployed. There is no 'simple' explanation that I can come up with.

GEnx-1B engines have been exceptionally reliable, and the GE carbon composite fan blades are very robust and resistant to bird strike damage (about 15 years after the GE90 entry into service, I remember a GE boast that no GE90 (carbon composite) fan blades had needed to be scrapped due to damage (birdstrike, FOD, etc. - now that was roughly another 15 years ago, so is probably no longer true, but it shows just how robust the carbon composite blades are - far better than the more conventional titanium fan blades).

Not saying it wasn't somehow birdstrike related, just that is very unlikely (then again, all the other explanations I can come up with are also very unlikely ).

Using improper temp when calculating TO performance - after some near misses, Boeing added logic that cross-compares multiple total temp probes - aircraft TAT (I think the 787 uses a single, dual element probe for aircraft TAT, but stand to be corrected) and the temp measured by the engine inlet probes - and puts up a message if they disagree by more than a few degree tolerance - so very, very unlikely.

N1 power setting is somewhat less prone to measurement and power setting errors than EPR (N1 is a much simpler measurement than Rolls EPR) - although even with EPR, problems on both engines at the same time is almost unheard of.

The Auto Thrust (autothrottle) function 'falls asleep' at 60 knots - and doesn't unlock until one of several things happens - 250 knots, a set altitude AGL is exceeded (I'm thinking 3,000 ft. but the memory is fuzzy), thrust levers are moved more than a couple of degrees, or the mode select is changed (memory says that last one is inhibited below 400 ft. AGL). So an Auto Thrust malfunction is also extremely unlikely. Further, a premature thrust lever retard would not explain a RAT deployment.

TO does seem to be very late in the takeoff role - even with a big derate, you still must accelerate fast enough to reach V1 with enough runway to stop - so there is still considerable margin if both engines are operating normally. That makes me wonder if they had the correct TO power setting - but I'm at a loss to explain how they could have fouled that up with all the protections that the 787 puts on that.

If one engine did fail after V1, it's conceivable that they shut down the wrong engine - but since this happened literally seconds after takeoff, it begs the question why they would be in a big hurry to shut down the engine. Short of an engine fire, there is nothing about an engine failure that requires quick action to shut it down - no evidence of an engine fire, and even with an engine fire, you normally have minutes to take action - not seconds.

The one thing I keep thinking about is someone placing both fuel switches to cutoff immediately after TO. Yes, it's happened before (twice - 767s in the early 1980s), but the root causes of that mistake are understood and have been corrected. Hard to explain how it could happen ( unless, God forbid, it was intentional ).

Originally Posted by Musician

"Both engines failed or shut off close to rotation" explains all of the evidence : it explains an unremarkable take-off roll, loss of lift, absence of pronounced yaw, loss of electrical power, loss of the ADS-B transponder, RAT deployment, the noise of the RAT banging into place and revving up, emergency signs lighting up, a possible mayday call reporting loss of thrust/power/lift, and a physically plausible glide from a little over 200 ft AAL to a crash site 50 feet (?) below aerodrome elevation.
It explains what we saw on the videos, what the witness reported, where the aircraft ended up, and the ensuing sudden catastrophe.

I don't believe we have evidence for anything else right now—I'd be happily corrected on that.

Originally Posted by TURIN

Please read the thread. It has been discussed several times.

Originally Posted by MaybeItIs

Excellent, thank you. More and more I'm convinced, as I was at Day One, that this guy* was a genuinely excellent pilot. More sad than ever.
* (Or to be fair, these guys, this cockpit team were...)

Originally Posted by B2N2

Please stop with this utter nonsense.
The throttle quadrant was replaced in 2023 for unrelated reasons. The report states so.
Crews don\x92t habitually places any items near those switches and ffs how would sand even get in there.
These switches were manipulated by hand and (again) even Indian media is reporting there may have been an issue with the crew.

https://www.ndtv.com/india-news/air-...-probe-8864239

Originally Posted by za9ra22

That totally clears up any doubt then, because a media interview where claims are made without any substantive evidence at all are clearly to be taken as gospel.

What I found interesting when viewing the Captain's background, was that he was a long-time carer for his aging father, and had called home before the flight to confirm that he would be in contact again once arrived in London. Also that he was highly respected with no history of difficult personal interactions, and had passed all medical clearances.

I'm sure we're all open to actual evidence though.

Originally Posted by Mrshed

He is of course incorrect in stating a 10 second delay between CVR statement and FC switch to RUN.

Originally Posted by compressor stall

Look at 5.06 in the video, he simulates the CVR comments immediately after the cutoff and times the gap until they are switched back on. He may be right, but that timeline has no more validity than the CVR comments being 1 second before the switches are turned back on again, which could paint a very different picture (inadvertent or mechanical).

Originally Posted by toiletsaft

The authors of the preliminary report would surely have known that the report as drafted would raise strong suspicions of an intentional act by one of the pilots to shut off the fuel switches. If the investigators had evidence that would indicate that it was not (or may not have been) a deliberate act (from for example the rest of the verbal exchanges between the pilots) then surely they would have included such information in the report in order to avoid such a conclusion from being drawn by the reading public. This suggests that there is no such evidence.

Originally Posted by ChiefT

Of course, we now have to wait and see what the investigation ultimately reveals: technical error or human intervention.

I think that in this phase of flight and situation, it's truly a masterpiece to first recognize the problem and then, with the presence of mind, reset the fuel control switches to "Run."
We don't yet know which of the two pilots did this, the PF or the PM. Nevertheless, it apparently happened in a fraction of a second.

Originally Posted by za9ra22

As I have said before, the people who do this work are professionals, not there to play politics or represent business interests .

Originally Posted by jpsingh

The deployment of RAT has announced Double Engine failure. Also the AutoStart of APU pretty much indicates the same thing . Release of CVR will definitely help.

Originally Posted by CaptainSAC

Not being a jet pilot. If you have the throttles at full power and the engines are set to cutoff, and they spool down, when you reset to run, will they start and go to full power, or do you have to set the throttles to idle first, then when started go back to full power..? and why don't you have to retard the throttle(s) to idle first, before you can shut the engine down..?

Originally Posted by 1stspotter

It is both fascinating and unsettling to observe how the media in India consistently refuse to acknowledge that suicide may be the most likely scenario. Key voices\x97such as former pilots and the airline pilots' union\x97continue to dismiss the possibility that a pilot could have deliberately moved the fuel control switches to the cutoff position. They rely on factually incorrect arguments and emotional reasoning. For instance, some suggest a potential defect in the Boeing 787\x92s fuel cutoff switches. However, the FAA's Special Airworthiness Information Bulletin (SAIB) they reference was specifically issued for the Boeing 737, not the 787.

An overview of public statements made by pilots in the media can be found here.
https://feitoffake.wordpress.com/202...room-in-india/

Originally Posted by barrymung

That's pure speculation!

There are a number of factors that suggest it wasn't suicide. Until further information is released it's impossible to say