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DaveReidUK
2025-06-14T16:07:00 permalink Post: 11901611 |
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
But certainly loss of engines or electrics that caused deployment of the RAT (if that was the case) would be accompanied by a bunch of load-shedding, which would in all likelihood include the transponder. Edit: Your own reply beat me to it ... 1 user liked this post. |
andihce
2025-06-14T16:37:00 permalink Post: 11901634 |
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC) I guess you have to make a post on just this one item to get it noticed! But I agree that this piece of data deserves close attention, and is potentially confirmatory of certain scenarios which lead to electrical power loss. I'm no expert on Flight Aware's ADS-B data, but other posts here show other flights taking off on this runway happily reporting data further down the runway and (well) after takeoff. How else do you explain the cessation of ADS-B data from this flight from shortly after takeoff until the crash? |
Someone Somewhere
2025-06-14T17:35:00 permalink Post: 11901681 |
What concerns me a little bit is if indeed AC power is lost, would the suction feed inlets in the wing tanks provide enough fuel flow to maintain TO thrust?
I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation... Could this cause a degradation of thrust? Even the slightest decrease..
I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?
more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC) There's a list of equipment operable on battery/RAT here, but I'm not sure which (if any) is the transponder (26:10): If you had gear pins and an engine loss, I could maybe see climb rate being zero or slightly negative. Not the brick impression we see here.
There have been a couple comments regarding the tilt of the bogies not corresponding to the landing configuration which have taken this as an indicator for an attempted (but failed) retraction.
I don't think anybody has so far confirmed which of the two positions the bogie would have without hydraulic pressure, but I would strongly think it is the one used in the retraction/extension cycle and not the landing configuration, for the simple reason that otherwise the gravity drop would potentially not work (I assume it is tilted for the stowing because it would otherwise not fit). Maybe someone with concrete knowledge can confirm this? This would then only confirm that the bogies were unpressurized (likely because of loss of hydraulics, but of course could also still be a partial retraction that stopped for some reason) 2 users liked this post. |
1stspotter
2025-06-14T18:27:00 permalink Post: 11901706 |
1. there are multiple frames of the video showing ' something' at the position where the RAT is located under the fuselage 2. the sound in the video which is very similar to a deployed RAT 3. the sound analysis posted here by multiple people last but not least 4. the aircraft stopped transmitting ADSB data shortly after the rotating. This indicates an electrical failure. Other aircraft ADSB data was picked up by FR24 receivers indication there is a good reception of the signal in that area. 8 users liked this post. |
MaybeItIs
2025-06-14T21:40:00 permalink Post: 11901866 |
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. 4 users liked this post. |
ILS27LEFT
2025-06-14T22:05:00 permalink Post: 11901881 |
Indeed
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. 1 user liked this post. |
MaybeItIs
2025-06-14T22:08:00 permalink Post: 11901884 |
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 .. Anyway, let's say we know what's supposed to happen when an engine-driven generator (or its GCS) quits. (Which incident do you refer to?) That's what all the redundancy is designed to address. And maybe that's exactly what did happen - a generator / GCS failed at high load in a high ambient temperature. But possibly the failure then highlighted a pre-existing but undetected fault in the switching system itself. With the generator working normally for (months?), everything seemed fine. Sadly, there are always possibilities that the designers don't consider, or are too hard (too expensive, etc) to address. 1 user liked this post. |
directsosij
2025-06-14T22:17:00 permalink Post: 11901896 |
Imaginations are running wild for some people here. Major electrical fault that leads to double engine failure at v2? Really? If that were the case the 787 fleet would be grounded by now given the black box has almost certainly been examined.
8 users liked this post. |
njc
2025-06-14T22:19:00 permalink Post: 11901899 |
I'm still sticking with "Major Electrical Fault" as my most likely cause, and this adds to my suspicions.
[snip] 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. 2 users liked this post. |
BugBear
2025-06-14T22:24:00 permalink Post: 11901903 |
OK, but even if we do assume that there was a major electrical fault which brought down the main supplies: multiple posts in this thread have already asserted that this would not cause the shutdown of the engines, and that even if the fuel pumps failed, suction would keep the engines running.
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njc
2025-06-14T22:29:00 permalink Post: 11901908 |
You mean if #2 failed (fire?) and the fire handle was pulled for #1? Then yes for sure that'd leave the plane without thrust but (a) that seems totally unconnected to the electrical failure hypothesis under discussion and (b) seems likely to have produced some visible "smoke" trails from the engines (not seen on video).
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Shep69
2025-06-14T22:45:00 permalink Post: 11901916 |
We`ll just have to wait a bit until some facts come out. Not ready to shelve the flap/RTOW probability quite yet. Or even deliberate (or inadvertent) actuation of the FCSs. Incapication, etc. 2 users liked this post. |
LTC8K6
2025-06-14T23:04:00 permalink Post: 11901939 |
The 787 is far more heavily dependent on electrical power than previous Boeing designs. |
Toruk Macto
2025-06-14T23:44:00 permalink Post: 11901965 |
There have been conflicting reports about the call to ATC. Original reports quoted the Captain saying "Mayday...no thrust, losing power, cannot lift". But I've seen reports today stating the call was simply "Mayday, Mayday" and then no further response.
Difficult to confirm so I wouldn't put too much weight behind it until something more official is released. 2 users liked this post. |
Someone Somewhere
2025-06-15T02:36:00 permalink Post: 11902060 |
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 ...
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. 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.
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.
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. ![]() 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...
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. 1 user liked this post. |
MaybeItIs
2025-06-15T04:00:00 permalink Post: 11902086 |
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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... |
Smooth Airperator
2025-06-15T04:47:00 permalink Post: 11902101 |
3 users liked this post. |
Icarus2001
2025-06-15T05:02:00 permalink 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...
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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 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 permalink 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 permalink Post: 11902135 |
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. ​​​​​​​ 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? |