Posts about: "Engine Failure (All)" [Posts: 410 Pages: 21]

Back office Penguin
2025-06-15T01:43:00
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Post: 11902040
MELs?

Originally Posted by Mr Optimistic
From tdracer
However, TCMA is only active on the ground (unfamiliar with the 787/GEnx TCMA air/ground logic - on the 747-8 we used 5 sources of air/ground - three Radio Altimeters and two Weight on Wheels - at least one of each had to indicate ground to enable TCMA). TCMA will shutdown the engine via the N2 overspeed protection - nearly instantaneous. For this to be TCMA, it would require at least two major failures - improper air ground indication or logic, and improper TCMA activation logic (completely separate software paths in the FADEC). Like I said, very, very unlikely.
I assume the dual engine shutdown due to engine overspeed. Could the case occur with increased thrust manually in the end of takeoff phase?
Xeptu
2025-06-15T01:53:00
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Post: 11902043
Originally Posted by SpaceQuality
Also a newcomer here, but an experienced private pilot, Software Engineer with a degree in Aerospace Computer Science and former Head of Quality for Satellites and Interplanetary Missions. We have already seen bad software solutions and the results thereof in the 737 MAX accidents, which makes me wonder, if the TCMA can reach a state, where unintended engine shutdown is possible.

There is one system implemented in the 787, that has the authority to shut down the engines, based on software subsystem decision. Interestingly - according to the description in the patent below - the same TCMA software package determines the shutdown decision, in both redundant subsystems.

Excerpt from the Patent:
"Malfunctions in aircraft power plant thrust control systems can result in uncontrollable high engine power levels that are potentially hazardous or catastrophic for aircraft operation. A particularly hazardous situation is when a thrust control system failure results in one of the aircraft's engines continuing to operate at a high power condition and not responding to a throttle command to reduce power during takeoff, approach or landing. Typically, when this failure mode occurs, the actual thrust either increases to a significantly higher than commanded thrust and/or remains at a high level when the thrust levers are set for low thrust....

In one preferred embodiment the present invention is directed to a system and method for detecting and correcting a thrust control malfunction in an aircraft engine. The system includes an electronic engine control (EEC) unit that includes a first processing subsystem and a second processing subsystem, and a thrust control malfunction accommodation (TCMA) circuit included in the first processing subsystem and the second processing subsystem. Additionally, the system includes a TCMA software package executed by the first processing subsystem and the second processing subsystem, thereby providing redundant execution of the TCMA software package.

The method of the present invention compares the engine's actual power level with a threshold contour defined by the TCMA software package. When the TCMA software package determines that a thrust control malfunction has occurred, based on the engine's power level exceeding the threshold contour, the engine is shut down by the TCMA circuit.
The present invention is still further directed to an electronic engine control (EEC) unit configured to detect and correct an aircraft engine thrust control malfunction using an active-active functionality. The EEC includes a first processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs, and a second processing subsystem for unilaterally monitoring engine operation and shutting down the engine when a thrust control malfunction occurs."

Just my 20 cents
It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight)

2 users liked this post.

bakutteh
2025-06-15T02:13:00
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Post: 11902053
Devil Pprune Mind Traps from overwhelming posts

Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners’ imagination.😖🥴😬

Last edited by bakutteh; 15th Jun 2025 at 09:18 .

11 users liked this post.

Lifer01
2025-06-15T02:29:00
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Post: 11902059
Originally Posted by Someone Somewhere
I can't see how gear pins would stop you doing anything more than raising the gear. They don't cause engine failure, RAT extension, or uncommanded flap retraction.
I'm sure it's not the case, but if an attempt was made to raise the gear with the pins still fitted, you would see the main gear doors open as part of the normal gear retraction sequence.

This applies equally to a normal gear retraction: the centre hydraulic pumps must have stopped very early for the trucks to be in that position on an "interrupted" gear retraction, with the main gear doors still closed (and presumably locked). Seems unlikely.

Originally Posted by Someone Somewhere
I did raise this earlier... FCOMs say that the bogies remain in the stowed tilt after a gravity drop, but I don't know if that's because the gear has springs to hold it that way without hydraulics, or just they close the valves on the hydraulics so it stays in the last commanded position without pressure.
The tilt and stow positions are definite hydraulically achieved positions of the truck positioner actuator. I don't think the actuator is spring-loaded to the stow position on the 787, though perhaps they move that way given my earlier statement...

Alternate extension appears to rely on the truck positioner remaining in its previously "positioned" state - stowed - where it has been sitting cold, unloved and unpowered since the gear was previously retracted. Like other Boeing types, the wheel well has some bars to stop the truck moving while it's up and stowed.

It's remotely possible the main gear priority valves may have prevented more gear movement in the absence of good hydraulic pressure - however this wouldn't stop the nose gear from operating, so not likely.

Last edited by Lifer01; 15th Jun 2025 at 02:39 .

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Someone Somewhere
2025-06-15T02:36:00
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Post: 11902060
Originally Posted by BugBear
Difficult!? Maybe not. If very late the flaps were tagged stowed, and there was a simultaneous gear up command, with FlapDown command, the overload could have failed a GCS. Then it becomes a switching exercise. (Automatics).

Alarms Warnings Impacted EICAS, ETC. it happened long ago, but we know what happens when an engine driven generator quits ..first it bangs for awhile, then it burns itself up, then ...
Originally Posted by MaybeItIs
Thanks for answering the question I hadn't yet asked but wanted to confirm!

I'm still sticking with "Major Electrical Fault" as my most likely cause, and this adds to my suspicions.

As I understand it, the landing gear is raised / retracted by electric motor-driven hydraulic pump (pumps?). This/these would create a significant electrical load.

If the plane's multi-redundant electrical system has a fault which is intermittent (the worst kind of electrical issue to diagnose), and which causes the redundancy controls to go haywire (as there are, of course, electronic controls to detect failures and drive the switching over of primary and backup electrical supplies), then this fault could to triggered by a large load coming on-line. It could even be as simple as a high current cable lug not having been tightened when a part was being replaced at some stage. The relevant bolt might be only finger-tight. Enough to work 99.99% of the time between then and now... But a little bit more oxidation, and particularly, a bit more heat (it was a hot day), and suddenly, a fault.

Having worked in electronics for years, I know that semi-conductors (and lots of other components, especially capacitors [and batteries]) can also degrade instead of failing completely. Electro-static discharges are great for causing computer chips to die, or go meta-stable - meaning they can get all knotted up and cease working correctly - until they are powered off for a while. They can also degrade in a way that means they work normally a low temperatures, but don't above a certain temperature.

Anyway, there MUST be ways that the redundant power supplies can be brought down, simply because, to have a critical bus powered from a number of independent sources, there must be "controls" of some sort. I don't know how it's done in the 787, but that's where I'd be looking.

As there is a lot of discussion already about how the bogies are hanging the wrong way suggesting a started but failed retraction operation, and it's now confirmed that the retraction would normally have taken place at about the point where the flight went "pear shaped", I'm going to suggest that the two things are connected. More than that: I'll suggest that the Gear Up command triggered the fault that caused both engines to shut down in very short succession. Nothing the pilots did wrong, and no way they could have known and prevented it.

It's going to be difficult to prove though.
Gear and flaps are both hydraulic, and the hydraulic pumps typically act as effective fault-containment - a hydraulic failure or excess load doesn't result in excess demand on the electric side; the pump just starts to run out of output flow/pressure.

In addition, the 787 has four main generators and I believe the switching is segregated into at least two controllers, on top of the four separate generator control units.

And again, electrical failure should not cause engine failure - consider QF32 where the wiring to the engine was mostly severed and they had to drown it with a fire truck.

Originally Posted by ILS27LEFT
Best post until now in my view. We will find out very soon I think. Gear up command triggered the instant lack of fuel to both engines. I'm not sure on how the fuel flow is dependant on the power supplies on the 787 but I genuinely believe you are very very close to what might have happened here.
It's not. Boost pumps should be more-or-less unnecessary at sea level.

Originally Posted by MaybeItIs
Yes, thanks, I've seen a few comments to this effect, and I have to accept most of what you say. I understand that they have their own dedicated generators and local independent FADECs (or EECs), but I'm trying to use what I do know to attempt to figure this out. I know that there are Fuel Cutoff switches in the cockpit. Somehow, if switched to Off, these will cut off the fuel to the engines, "no matter what". Of course, even that's not true, as the Qantas A380 engine burst apparently (comment in this thread) showed.

Anyway, the thing I'm looking at is how the fuel cutoff switch function could have been activated in some other way. To me, it seems obvious that there are wires that run between the engine fuel shutoff valves and the cockpit / flight control panel (no doubt with relays etc in between). I don't know where those shutoff valves are located, but logic says they should be located in the fuselage, not out at the engines. I also don't know how those valves operate - are they solenoid valves or electro-mechanically driven? Nor do I know where the power to activate those valves comes from, but using my logic, if those valves close when powered off, such as solenoid valves typically do, then the power cannot exclusively come from the engine-dedicated generators. If it did, you'd never be able to start the engines so they could supply their own power to hold those valves open. So, there must be some power (appropriately) fed from the main aircraft control bus to activate those valves - if the rest of what I'm assuming is correct. Anyway, like I say, I don't know enough about the details at this point, but there are many more ways to activate or deactivate a circuit than by flicking a switch. Killing the relevant power supply, for example. A screwdriver across some contacts (for example), another. Shorting a wire to Chassis, maybe. Just trying to contribute what I can.

You raise another interesting point: "TCMA notwithstanding". Could you elaborate, please? What will happen if the TCMA system, which apparently also has some degree of engine control, loses power? The problem with interlinked circuits and systems is that sometimes, unexpected things can happen when events that were not considered actually happen. If one module, reporting to another, loses power or fails, sometimes it can "tell" the surviving module something that isn't true... My concern is where does the power to the Fuel Cutoff switches come from? Are there relays or solid-state switches (or what?) between the Panel Switches and the valves? If so, is the valve power derived from a different source, and if so, where? Are the valves solenoids, open when power applied, or something else? What is the logic involved, between switch and valve?

Would you mind answering these questions so I can ponder it all further, please? If I'm wrong, I'll happily say so.
I believe the valves are almost all bi-stable power-open power-close. When not powered, they remain in the last commanded position.

The valves are located in the spar (hence being called 'spar valves'. The fuel tank is immediately above the engine so it is a very short pipe for suction feeding. Tail mount engines are potentially a different story...

Originally Posted by lucille
What\x92s the usual time frame for the release of preliminary data and report from the FDR and CVR? Is it around 6 months?

I guess if no directives come from Boeing or the FAA in the next 2 weeks, it can be presumed that a systems failure from which recovery was impossible was unlikely.
A Prelimnary Report must be prepared within 30 days, but does not need to be public. May or may not have CVR/FDR data.

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BrogulT
2025-06-15T03:21:00
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Post: 11902071
Question

Originally Posted by bakutteh
Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT.
I keep reading this theory and I'm baffled. You think the PF is going to attempt a dual engine shutoff and relight during the initial climb based on a hunch that the engines have quit, all without even a sideways glance to see what N1 is or a short word with the PM?

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MaybeItIs
2025-06-15T04:00:00
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Post: 11902086
Originally Posted by Someone Somewhere
Gear and flaps are both hydraulic, and the hydraulic pumps typically act as effective fault-containment - a hydraulic failure or excess load doesn't result in excess demand on the electric side; the pump just starts to run out of output flow/pressure.
Ok, thanks for clarifying. Of course, an overload will simply cause the hydraulic pressure relief valves to activate. There will be a moderate increase in motor current when bypassing, but the electrical side should be fully able to cope with that. Should be! I'm suggesting here that there was a fault somewhere in the electrical supplies that effectively derated some part of it, and that maybe the GearUp load was too much for it on this occasion.

Originally Posted by Someone Somewhere
In addition, the 787 has four main generators and I believe the switching is segregated into at least two controllers, on top of the four separate generator control units.
Thanks for confirming the 4 gens. So there's probably quite a bit of switching required. Not sure how that's done, but I guess robust contactors are required. And even these can fail. Systems usually cannot tell that a contactor has failed on the open side until it's switched. So, a switchover may have been done, but a failed contact meant the backup generator wasn't connected. Who knows, so many possibilities.

Originally Posted by Someone Somewhere
And again, electrical failure should not cause engine failure - consider QF32 where the wiring to the engine was mostly severed and they had to drown it with a fire truck.
Sure, I agree, absolutely shouldn't. Yeah, the A380... Possibly (I suggest likely), the A380 uses different logic from the B787. In the Airbus case, maybe they prioritised keeping the fuel on over shutting it off in emergency. So, severing the Airbus Cutoff signal leaves the fuel on. Boeing may use the opposite priority, that Emergency Shutdown takes precedence over Engine Running, so cutting the signal turns the engine off. I don't know, but don't think the Airbus incident necessarily applies here.

Originally Posted by Someone Somewhere
It's not. Boost pumps should be more-or-less unnecessary at sea level.
I don't think either of us was debating that. I accept it as a fact.

Originally Posted by Someone Somewhere
I believe the valves are almost all bi-stable power-open power-close. When not powered, they remain in the last commanded position.

The valves are located in the spar (hence being called 'spar valves'. The fuel tank is immediately above the engine so it is a very short pipe for suction feeding. Tail mount engines are potentially a different story...
Okay! Many thanks for that! Of course, it very much complicates the picture, and I'm very puzzled as to how the Fuel Cutoff Switches and Valves operate. Apparently, the TCAM system shuts off an errant engine on the ground at least, but my concern is not with the software but the hardware. It obviously has an Output going into the Fuel Shutoff system. If the TCAM unit loses power, can that output cause the Cutoff process (powered by the engine-dedicated generator) to be activated? I guess that's the $64 billion question, but if MCAS is any example, then: Probably!
Smooth Airperator
2025-06-15T04:47:00
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Post: 11902101
Originally Posted by BrogulT
I keep reading this theory and I'm baffled. You think the PF is going to attempt a dual engine shutoff and relight during the initial climb based on a hunch that the engines have quit, all without even a sideways glance to see what N1 is or a short word with the PM?
I don't want to believe it either. It defies belief but given certain confirmation bias (sim), panic and inexperience by the FO, it's not beyond the realms of possibility. It explains both the RAT and loss of lift. The alternative right now is a catastrophic electrical failure that wiped out the engines or engine control leading to loss of thrust, or a dual engine failure due to birds, fuel contamination or FOD. They are also valid, though IMO less likely.

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Icarus2001
2025-06-15T05:02:00
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Post: 11902106
I am sure that if there is any reason to suspect that a systems failure may have been a probable cause, or even contributed in any way to the accident, Boeing, GE, the FAA, or the Indian DGAC will promptly advise 787 operators.
The longer the regulators remain silent, the greater the probability that this has been caused by an operational error...
​​​​​​​ indeed, Occam\x92s razor and all that. If there was a serious design flaw, I highly doubt the fleet would still be operational. It has already been 3 days.
No evidence of engine failure

No evidence of RAT deployment from a poor image.

No evidence of electrical failure.

The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action.

​​​​​​​This is going to get messy.
​​​​​​​
CW247
2025-06-15T05:29:00
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Post: 11902115
No evidence of engine failure - Depends how you look at it, the sinking and inability to remain airborne points towards a possibility

No evidence of RAT deployment from a poor image - There absolutely is, you're not following fully I'm afraid. There's a brilliant video by Juan Brown where he compares the sound of the plane passing with that of an American 787 on final with the RAT deployed. Identical sound. The image is not conclusive but I'd wager a bet on it.

No evidence of electrical failure - Except, mention of flashing lights inside cabin moments before by the sole survivor and (sorry old boy) - The RAT ;-)

The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action - Well....

​​​​​​​This is going to get messy. - Agreed
​​​​​​​

5 users liked this post.

MaybeItIs
2025-06-15T06:09:00
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Post: 11902135
Originally Posted by Icarus2001
No evidence of engine failure

No evidence of RAT deployment from a poor image.

No evidence of electrical failure.

The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action.

​​​​​​​This is going to get messy.
​​​​​​​
I guess it all depends on what you mean!

If the fuel supplies were cut off, causing the engines to stop, is that engine failure ? I'd say not, nothing wrong with the engines until they impacted the buildings etc.

No evidence of RAT deployment - but you're specifically restricting "the evidence" to a blurry amateur video. That alone is not great evidence, but why does that video exist at all? When they lift the relevant section of fuselage, RAT deployment or not is going to be fairly apparent. And Circumstantial evidence is still evidence, no?

No evidence of electrical failure? Do you know that from the downloaded Flight Data?

Icarus2001
2025-06-15T06:31:00
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Post: 11902144
I guess it all depends on what you mean!

If the fuel supplies were cut off, causing the engines to stop, is that engine failure ? I'd say not, nothing wrong with the engines until they impacted the buildings etc.

No evidence of RAT deployment - but you're specifically restricting "the evidence" to a blurry amateur video. That alone is not great evidence, but why does that video exist at all? When they lift the relevant section of fuselage, RAT deployment or not is going to be fairly apparent. And Circumstantial evidence is still evidence, no?

No evidence of electrical failure? Do you know that from the downloaded Flight Data?
A thrust reduction is not an engine failure. Engine shutdown due to an action of crew (or inaction) is not a failure.

There is no evidence of an electrical failure. What evidence? A surviving passenger thought he saw flickering lights? Give me a break.

The word evidence in English has a very specific meaning.

Look for the simplest explanation here and then ask why the worldwide B787 fleet is still flying with no urgent inspection requirements from Boeing or GE. Think about that "evidence".

6 users liked this post.

Someone Somewhere
2025-06-15T06:42:00
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Post: 11902154
Originally Posted by Icarus2001
A thrust reduction is not an engine failure. Engine shutdown due to an action of crew (or inaction) is not a failure.

There is no evidence of an electrical failure. What evidence? A surviving passenger thought he saw flickering lights? Give me a break.

The word evidence in English has a very specific meaning.

Look for the simplest explanation here and then ask why the worldwide B787 fleet is still flying with no urgent inspection requirements from Boeing or GE. Think about that "evidence".
Uncommanded thrust reduction sure sounds like engine failure to me. Neither US1549 nor Ryanair 4102 suffered flameout until the former attempted to switch the engines off and back on. I don't think anyone is going to say those weren't engine failures.

If the aircraft had flaps deployed (the crash site photos look like it), flight controls working (no indications they weren't), and the thrust levers pushed full forwards, there is very very little that will cause it to sink other than lack of thrust.

2 users liked this post.

Compton3fox
2025-06-15T06:48:00
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Post: 11902156
Originally Posted by bakutteh
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners’ imagination.😖🥴😬
If the photo of the flaps deployed at the accident site is actually F1 not F5 or if the flaps were pushed out during impact, then this is certainly plausible. I will look for the photo but it's in the thread somewhere. Others are stating they see a gap between the wing and the flap as an argument for the flaps deployed at F5. This was after the decent started..

However, I think their reaction would likely be to apply more power. I know mine would be. But anything is possible!
Icarus2001
2025-06-15T07:06:00
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Post: 11902171
If the aircraft had flaps deployed (the crash site photos look like it), flight controls working (no indications they weren't), and the thrust levers pushed full forwards, there is very very little that will cause it to sink other than lack of thrust.
Brilliant, now what is your point? Are you suggesting a double engine failure, a roll back to idle thrust or an incorrectly set AAI causing VNAV level off and a thrust reduction. You can only choose one.

For the team pointing to the RAT out as a failure indicator, it could have been deployed by the crew after the initial reduction in climb performance. I am not convinced it is deployed but it really does not make a convincing argument for any type of failure.

For the children on holiday, yes I fly transport category jets, current on two types.
​​​​​​​
Compton3fox
2025-06-15T07:34:00
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Post: 11902190
Originally Posted by Icarus2001
No evidence of engine failure

No evidence of RAT deployment from a poor image.

No evidence of electrical failure.

The teams of lawyers in the UK representing 53 grieving families will be working over the weekend to sign up said families to a class action.

This is going to get messy.
No evidence of engine failure - Not true. No engine noise on video where you would expect TO or TOGA power to be in use. Mayday call stating No Power

No evidence of RAT deployment from a poor image . - You can argue Not from the Image but...: 2 independent audio analysis of the video audio shows the sound comes from a deployed RAT plus JB's video. Plus the guys who live in SEA having heard 100's of RATs deployed during test flight have stated that the sound is a RAT.

No evidence of electrical failure . - Not true. Reported cabin emergency lights going off, FR24 feed stopped just as in the 737 South Korea incident in December. APU intake door partially open at crash scene, suggesting an APU autostart.

Now you can call into question the above evidence but to state there is none, is simply not true.

Last edited by Compton3fox; 15th Jun 2025 at 08:23 .

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VR-HFX
2025-06-15T08:04:00
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Post: 11902209
Originally Posted by Icarus2001
Brilliant, now what is your point? Are you suggesting a double engine failure, a roll back to idle thrust or an incorrectly set AAI causing VNAV level off and a thrust reduction. You can only choose one.

For the team pointing to the RAT out as a failure indicator, it could have been deployed by the crew after the initial reduction in climb performance. I am not convinced it is deployed but it really does not make a convincing argument for any type of failure.

For the children on holiday, yes I fly transport category jets, current on two types.
Yes indeed. I strongly leant toward the incorrectly set AAI and VNAV capture and level off as the a/c reportedly reached max alt of 625ft or about 450ft AGL. Even with startle factor, recovery should have been quite possible. The video I have seen (not the video of the video) clearly shows the RAT deployed and you can hear the whine of the turbine and virtually no engine noise . This complicates it for me as there is no logical reason to deploy the RAT in the VNAV/level off scenario.

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Someone Somewhere
2025-06-15T08:08:00
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Post: 11902212
Originally Posted by Icarus2001
Originally Posted by Icarus2001
A thrust reduction is not an engine failure. Engine shutdown due to an action of crew (or inaction) is not a failure.

There is no evidence of an electrical failure. What evidence? A surviving passenger thought he saw flickering lights? Give me a break.

The word evidence in English has a very specific meaning.

Look for the simplest explanation here and then ask why the worldwide B787 fleet is still flying with no urgent inspection requirements from Boeing or GE. Think about that "evidence".
Uncommanded thrust reduction sure sounds like engine failure to me. Neither US1549 nor Ryanair 4102 suffered flameout until the former attempted to switch the engines off and back on. I don't think anyone is going to say those weren't engine failures.

If the aircraft had flaps deployed (the crash site photos look like it), flight controls working (no indications they weren't), and the thrust levers pushed full forwards, there is very very little that will cause it to sink other than lack of thrust.
Brilliant, now what is your point? Are you suggesting a double engine failure, a roll back to idle thrust or an incorrectly set AAI causing VNAV level off and a thrust reduction. You can only choose one.

For the team pointing to the RAT out as a failure indicator, it could have been deployed by the crew after the initial reduction in climb performance. I am not convinced it is deployed but it really does not make a convincing argument for any type of failure.

For the children on holiday, yes I fly transport category jets, current on two types.
​​​​​​​
In reply to you, I am solely stating that it's a thrust-side problem. I think I somewhat misinterpreted your post as it looks like you might have been saying that anyway.

In general, I think it's looking like dual engine failure/shutdown cutting electrics. I agree that why it occurred is very unclear. Outside chance of total electrical failure causing dual engine failure rather than the other way around, but that would perhaps be even more concerning a design failure.

Similar to Jeju, we also have what is looking increasingly like a loss of ADS-B data at the moment things went wrong, not just a loss of coverage.

That gives:
  • Sound of RAT
  • Visible RAT
  • (edit: APU door open implies APU autostart)
  • Loss of ADS-B out
  • Near-total loss of thrust.
The alternate theories seem to be a) flaps (basically discounted), b) suction feed failed after total electrical failure, or c):
  • A/T rolled engines back
  • Crew interpreted this as dual engine failure
  • Crew didn't push throttles forward
  • Crew did switch each engine off & on again and maybe deployed RAT manually as well.

Originally Posted by Icarus2001
Assuming GE receive data from these engines in flight, a massive failure would prompt a swift communication from GE. Or a massive electrical issue could put Boeing on edge and also prompt urgent inspections on their aircraft.
I think it has been suggested that the upload only happens every 30 minutes or so.

Last edited by Someone Somewhere; 15th Jun 2025 at 08:21 .
Chuck Canuck
2025-06-15T08:22:00
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Post: 11902223
Originally Posted by bakutteh
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners’ imagination.😖🥴😬

This is a very plausible scenario. Above 400 ‘ AGL, memory items.

4 users liked this post.

amsm01
2025-06-15T08:54:00
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Post: 11902253
Originally Posted by bakutteh
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel switches to OFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners\x92 imagination.😖🥴😬
(Sorry, Airbus here and not familiar with Boeing) Flap 5 to 1 reduction on the Boeing triggers autothrust reduction, is that correct? If so, are there any other conditions that need to be met for this to happen like being in some kind of takeoff mode? Just thinking whether this would have potential otherwise in other regimes to cause issues, discontinued approach perhaps.

Am slightly puzzled as to why if flap reduction triggering climb thrust is part of the standard logic (and presumably clean-up technique) then partial dual thrust loss wouldn\x92t be immediately recognised as the classic symptom of gear / flap retraction handling error? I presume Boeing pilots / air India are just as aware of this it as everyone else, strikes me as odd that one would immediately go into full dual EF mode. My instinctive reaction without knowing the Boeing would be to firewall both TLs, would this have worked in the early flap retraction logic scenario? Many thanks all