Posts about: "Dual Engine Failure" [Posts: 270 Pages: 14]

There isn't enough clarity on numerous issues, and without answers to the following, zero conclusions can be made as to a possible cause. This is definitely one that could go in numerous directions. Anyone claiming to have the definitive answers must have the FDR data, and I'm assuming that shouldn't take too long to be located and analysed.

1a. Were flaps deployed at start of take off roll?
1b. Were flaps retracted coinciding with climb rate reduction?
2. Did the RAT definitely deploy? The videos are grainy low quality. AI improvement surely isn't reliable.
3. If the RAT deployed, would that indicate complete power loss?
4. Was there any other audio indicating thrust loss or variations during departure?
5. Can we confirm the pilot Mayday indicating thrust loss? If so, that needs investigation as a first priority. The pilot was telling us the cause. Unless we have alternative information he should be believed.
6. Why was the gear not retracted? Distraction, hydraulic failure, flap instead of gear, intentionally, the possibilities are endless.
7. If complete thrust loss occurred, other than a severe fuel issue, what could cause simultaneous flameout? That would be almost unimaginable, yet this is what the pilot allergy said happened. It would have massive ramifications if that gets confirmed.

I don't think the video clips we have are clear enough to say anything at all at this stage. Flaps are hard to see on 787 imo for departure settings. All I can say is it appeared to climb well in the first seconds, then coinciding with the point that gear would usually be retracted, lift appears to very quickly be lost. That indicates sudden speed loss, or lift loss. Speed loss would be thrust, lift loss would be flap retraction if thrust was still available.

The pilot allegedly reported thrust loss, that should be highest on the list of causes imo. In the case of double engine failure without any apparent outside influence visible on videos, that would be quite something for investigators to fathom.

I don't know if anyone has data to show speed trend at the point the aircraft starts to descend, or a better audio for thrust variations at that point. I'm guessing that the update frequency on FR24 would be too slow to show that sudden change at the highest point achieved.

We'll have the answers soon enough, all I can say is there appears to be no clear answers here without the data recorders or clear improved information. Indeed no conclusions whatsoever can be made as to crew actions either.

RIP crew and passengers, condolences to the families.

I'm afraid you've waded in without reading the rest of the thread. The poster you quoted has already explained he lives on the flight path in Everett or Paine, and so hears the test flights of all the aircraft before delivery to airlines.

I didn\x92t think this could be a dual engine failure related accident until reports of RAT deployment started to gather steam.
A few years back a B787 previously had a dual engine shutdown after rollout when the TR was deployed too quickly and not allowing the air/GND logic time to transition to ground mode before the TR deployed. If the TCMA had inadvertently latched the TR deployment from the previous rollout then it theoretically could be possible to shutdown on transition back to air mode.
Anything is possible with these high tech machines.

SLF. I don\x92t know how B787 systems work but if that\x92s correct it must be a possibility. It seems as though engines are working fine until airborne. I\x92d just been asking elsewhere if it were possible that an electrical fault with the software could prevent both engines running? I know they don\x92t require outside power to continue to run, but if software was disrupted by a catastrophic electrical fault (issues reported on previous flight supposedly) would they shut down? But an error in the software could be more likely than the sort of failure requiring multiple backups to also fail I guess, and would also explain the timing of the engines shutting down/throttling back.

RIP to all the victims.

Hi everyone, 787 driver here, well lets look at the facts we see
very late rotation, but pitch and departure path look like normal up until stalling point.
mayday was called but without clarification or purpose, for me this indicates stress in the flight deck, especially low level
no smoke or fire from engines, I would rule out severe damage or birdstrikes at this point
Flaps 5 departure would be difficult to see as a pixel on a bad video, but they would not have made the rotation at that speed so I assume they used flaps during departure, also you would neglect to ECL's and a config warning
no RAT to be seen either, again ruling out dual engine failure, also the climb would not have been so parabolic
maybe single engine fuel starvation/Mechanical issue/dirty fuel, but seems unlikely, the flight path is too gentle
Gear stays down, and even though the pitch remains the same, they start losing lift and basically stall the aircraft into the ground
don't forget, Air India uses 64/67K engines on they're 787's, with temp of 41 degrees (ambient, so even more above tarmac) and a QNH of 1001, those engines will be pushed to "hard work mode" already

IMHO, two things I could assume happend
- either single engine failure, no pitch adjustment and speed fell below Vstall, OR, most likely
- mixup of Flaps moved to up position in stead of Gear moved to up position, that would clarify the gear, would clarify the loss of lift and that the engines have no smoke, and no RAT,

a few things stated as fact there without any evidence to support the assertions.

very late rotation - stated several times on this thread but zero evidence for it and some analysis suggests the rotation was at roughly the same location as previous departures of the same flight

no RAT - others, including one with a lot of experience with the sound of a deployed RAT, insist that it was deployed. The video evidence is unclear.

Not saying you\x92re necessarily wrong about anything but I take issue with those that state as fact things that are not (yet) supported by any evidence at all

One has to assume that, given the seeming lack of lateral deviation from the flight path, and with no obvious yawing or rudder input visible on the videos, there's only two realistic conclusions here? Simultaneous dual engine failure of unknown cause if the RAT was indeed deployed; or flaps reduced too early leading to a stall if the RAT wasn't deployed.

Evidence in this thread would lean me toward the RAT deployed and therefore dual engine out scenario. As for the cause of that, well, only a couple of likely scenarios exist that could cause simultaneous shutdown of both engines, including mistaken or intentional use of the fuel cutoff levers.

20+ years retired 777 Captain so not at all up to speed..
If you selected gear up but at that moment or just before there was a dual engine failure, would the gear move?
Just curious as to how things work.

The visual evidence of the RAT being deployed (or not) is a bit dubious, but the audio evidence is pretty solid. It's also corroborated by the best eye witnesses we have, the pilots, explaining that they had lost power in their mayday call. And corroborated again by the second best eye witness we have, the passenger who survived, commenting on the 'green flickering lights' of the emergency exit signs indicating power loss. And corroborated again by the (now confirmed) posts on social media from the previous set of passengers complaining that aircon, entertainment, lights etc on the plain weren't working.

The idea that the flaps weren't set for take off also seems incredibly dubious given that in several frames of the original footage you can see the engines through the wings, on both sides, something not explainable by grainy footage or compression artifacts, and only possible if the flaps are down.

Edit to add: the reports on social media from the previous passengers complaining about non-functional electronics have been confirmed

I would rule out bird strike for lack of audio visual signatures of such an event and fuel contamination due to symmetry of events. Due to my trust in the profession and my distrust in modern engineering practices, my money is on Seattle.

I had wondered about TCMA being involved. Software is extremely complex and there have
been examples in the past where it does something it wasn't supposed to do, causing an incident.

Edit: How do we know it happened at 100ft?

I'm trying to explain the appearance of the RAT and the onboard green/white flashing lights. The alternatives right now are dual engine failure with no birds around.

I said below 100 feet, it didn't get higher than that. Are there any memory items, or indeed emergency checklists, to complete between V1 and 400 feet?

Related question: I asked earlier at what speed the 787's RAT becomes effective in providing hydraulic power. Is it possible that by the time the RAT deployed, the aircraft had lost airspeed to the point that it would have struggled to produce an adequate amount of pressure? Taking the Gimli Glider incident as an example, my understanding (could be wrong, this was from a magazine article) is that as they bled off speed to land, they ended up short enough of hydraulic power that they started to experience control difficulties, with the plane responding fairly sluggishly. If that's the case and this poor crew was going through something similar, it might explain why they seem to do very little about their situation.

Presumably a dual engine shutdown under TMCA (i.e. similar to the ANA incident) would cause the RAT to deploy.

Obviously difficult to envisage what could cause an TMCA activation on both engines simultaneously given the safeguards in place (weight on wheels etc). However maybe the time delay from an erroneous TMCA activation on the runway/at rotation would lead to a loss of power 10 seconds later.

Let\x92s be careful about absolutes. Emirates 521 and Turkish 1951 are both examples of crews not firewalling the thrust levers despite low energy. The late pitch up could be due to the onset of a stall not an order from the crew.

TCMA is function which can reduce thrust on both engines simultaneously. It had done so in error in the past resulting in an AD. It uses air/ground logic so that it only operates on the ground, however note that at the point of thrust loss the gear is still down without any movement of the gear or doors. I would expect gear retraction to start before that height. Could we imagine an air/ground logic fault inhibiting gear retraction and allowing TCMA, which triggered (for whatever reason!) causing dual thrust loss? I would expect this to be in the realms of a combination of failures shown to be extremely impossible, but\x85

The problem with the flap handle/gear handle mix-up theory is that it would appear in the original video that the gear up sequence has started based on the main gear leading axle pointing downwards, which is the first thing that happens (hydraulically) when the gear handle is moved.

This was handled in this PPrune thread:
ANA 787 Engines shutdown during landing
and in AvHerald:
https://avherald.com/h?article=4c2fe53a&opt=0

Just to clarify one point: the ANA B787 was powered with RR Trent 1000 engines while the Air India had GEnx-1B67 engines.
So, the Air India thrust failure may still have its source in the TCMA system, however, if it's the case, the logical path must be somewhat different than for the thrust reversers of the ANA airplane.

A long while ago I posted on the Rumour thread about a ban on drinks on the flight deck sent to a BA, A350 mid Atlantic. It was prompted by 2 separate instances of uncommanded unrecoverable engine shut downs due to drink spills across the fuel cut off switches. It was widely mocked by the professional pilots on here until proven to be absolutely factually correct. If we are into speculation why not a drink left on the flight deck tips on aircraft pitch up and spills across both fuel cut-switches. Just sayin

Hutch

Former Boeing Engineer, actually worked on this specific airplane prior to delivery. To me this all comes down to if the RAT was actually out. If not, lots of different factors people have already debated and likely some sort of pilot error that I'll let the pilots on this forum debate.

If the RAT did come out, then we are looking at simultaneous dual engine failure basically at V2 which is so improbable (without bird strikes or purposeful actions) that it is basically impossible. This is a 330 Min ETOPS aircraft. I saw no rudder deflection or yaw indicating 1 engine failed first and then they shut down the second one on accident.

Only two realistic options for me in that case are:
1. cutoff of the engines by the pilots. Either on purpose or accidental.
2. maintenance actions by the Air India ground team that caused issues with the engine system or power generation system.

2 is the only one I haven't seen mentioned here and I say this as a no longer Boeing employee. We STRUGGLED with AI during the EIS. They were notorious for just parking airplanes and then using them as spare parts and then screaming for help when they had to go back and get the planes ready to fly again.

Still think 1 is much more likely but will just throw out that 2 since there were complaints from previous flights about IFE and AC which to me speaks to issues with the power generation possibly being neglected.