Page Links: First Previous 1 2 3 4 5 6 Next Last Index Page
Icarus2001
2025-06-15T06:31:00 permalink 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? 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 permalink Post: 11902154 |
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". 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. |
MaybeItIs
2025-06-15T06:47:00 permalink Post: 11902155 |
I hate to disappoint you, but the people (like me) who design, test, and certify aircraft are not idiots. We design for failures. Yes, on rare occasion, something gets missed (e.g. MCAS), but we know that aircraft power systems sometimes fail (or suffer short term interuptions) and we design for that. EVERY VALVE IN THE FUEL SYSTEM MUST BE POWERED TO CHANGE STATE!!!! If electrical power is lost, they just stay where they are. The engine fuel valve must be powered open, and it must be powered closed. Same with the spar valve. The pilot moves a switch, that provides electrical signals to the spar valve and the engine fuel valve to open or close. It's
not
complicated and has been in use for decades.
TCMA (not TCAM) - Thrust Control Malfunction Accommodation - is a FADEC based system. It's resident in the engine FADEC (aka EEC) - the ONLY inputs from the aircraft that go into the TCMA is air/ground (to enable) and thrust lever position (to determine if the engine is doing what it's being commanded to do. The FADEC has the ability to shutdown the engine via the N2 overspeed protection system - this is separate from the aircraft run/cutoff signal, although it uses the same HPSOV to effect the shutdown. That same system is used by TCMA to shutoff fuel if it determines the engine is 'running away'. Hint, you might try going back a few pages and reading where all this has been posted previously. I hope I never suggested you guys are idiots! I very much doubt that indeed. You cannot be idiots. Planes fly, very reliably. That's evidence enough. Maybe my analysis is simplistic, but for someone who knows as little about the nuts and bolts that are your profession, I think I'm not doing too badly. I believe I have made a number of worthy contributions to this thread. Maybe I'm deluded. Too bad. Fact is, over the history of modern aviation, there have been a number of serious design stuff ups that "shouldn't have happened". As far as I'm concerned, the crash of AF447 is bloody good evidence of not considering a very simple, fundamental failure, and should NEVER have happened. The thing is, that would have been sooo easy to avoid. So please, don't get on too high a horse over this. Thanks for your information about all the fuel control valves. That's cool. Yes, my cars have numerous such systems, from the radiator grilles backward. And you misunderstand what I meant about "complicates things". Was that deliberate? What I meant was it complicates understanding how a major electrical failure could cause the Fuel Cutoff valves to close, that's all. The valves don't close if unpowered, but if the control is via the FADEC, then what could have caused them to close? Your explanation of how the Fuel Valves are controlled is rather simplistic too. "The pilot moves a switch, that provides electrical signals to the spar valve and the engine fuel valve to open or close." Seriously? Am I an idiot then? Is it a single pole, single throw switch? Is the valve driven by a stepper motor, or what? A DC Motor and worm drive? Does it have an integral controller? How does the valve drive know when to stop at end of travel? Would you mind elaborating, please? 1 user liked this post. |
Someone Somewhere
2025-06-15T06:56:00 permalink Post: 11902163 |
Expect all the alarms, too. 1 user liked this post. |
maddog2872
2025-06-15T07:01:00 permalink Post: 11902166 |
The 320 starts even if you forget to turn on fuel pumps. Don't ask how I know.
22 users liked this post. |
Compton3fox
2025-06-15T07:34:00 permalink Post: 11902190 |
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 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 . 12 users liked this post. |
Icarus2001
2025-06-15T07:57:00 permalink Post: 11902205 |
The better quality video does show something. It certainly could be the RAT. Automatic or manual deployment?
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. Since here we are two days after the EAFR was found then either both the aircraft manufacturer and the engine manufacturer know they are off the hook. That can only be for one of two reasons. They know there was a maintenance issue with this aircraft ( no IFE and call buttons?) or they know it was a handling error. Of course, tonight we may get urgent bulletins from Boeing or GE but the longer that does not happen, as Bloggs wisely stated, then we are left with a grim reality. Send in the clowns. 5 users liked this post. |
Someone Somewhere
2025-06-15T08:08:00 permalink Post: 11902212 |
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". 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. 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 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:
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 . |
das Uber Soldat
2025-06-15T08:34:00 permalink Post: 11902234 |
Could be that the gear is quite clearly in the forward tilt position (indicating initial gear retraction has commenced), but then the gear never goes up. How does that occur? The gear in the 787 is driven in retraction by the center hydraulic system. How is the center hydraulic system powered? Electrically, via C1 and C2 EMP's. How are those EMP's supplied with power? Engine 1 and 2 (via a bootstrap from L1/2 R1/2 gens). The rat also connects to the center hydraulic system, but importantly, it does not supply hydraulic power to the gear. Only a select number of flight control surfaces. So, my question to you is, given you're claiming there is zero evidence of electrical failure, how did the gear move into the forward tilt position, but then not retract? 4 users liked this post. |
Screamliner
2025-06-15T08:58:00 permalink Post: 11902261 |
So one thing to keep in mind, the RAT can be deployed manually, but also comes automatically when certain conditions arise, everybody here is assuming it\x92s only on dual engine failure but there are 4 more conditions that trigger the RAT,
- all three hydraulic system pressures are low - loss of all electrical power to the captain and first officers flight instruments - loss of all four EMP\x92s (electro motor driven pump) and faults in the flight controls system occur during arrival - loss of all four EMP\x92s and an engine fails during take off. This all comes directly from B787 FCOM, If we assume that what our survivor saw is correct, maybe it was an electrical failure, the aircraft had electrical issues in Delhi during departure and I checked the crash video again, I don\x92t see the strobe lights (neither wing or tail) and also no Anti collision light either. this might also explain the self starting APU on loss of the electrics (engine driven generators). That could also result in a loss of situational awareness with the speed, because of no indication, even the HUD would not work. The mayday call would still be doable because the radios work from the battery. |
Aerospace101
2025-06-15T11:42:00 permalink Post: 11902398 |
I see the YouTube influencers are now shifting their speculation to the RAT deployment and loss of thrust theory.
we have to look at the limited evidence and stop speculating on things that have no evidence yet (like the flaps). Aside from RAT deployment the other red flag here is the partial gear retraction. On the 787-8 the bogey will tilt forwards first, before gear doors opens. Not to be confused with the -9 and -10 variants where the gear doors automatically open after liftoff. This is an important distinction because the Center hydraulics which is solely electrically pump driven (not engine) only had enough power to tilt the bogey, not open the doors. so the question is, did the electrical failure (and loss of Center hydraulics power) happen before or after loss of thrust? 4 users liked this post. |
LTC8K6
2025-06-15T13:10:00 permalink Post: 11902453 |
Cognitive failure: the brain confuses one motor skill with another. You don’t confuse the switch/knob/lever, rather when you mean to complete one action (say, raise the gear) your brain erroneously decides to complete another motor-action that it knows, ie to raise the Flaps! Nothing to do with similar or adjacent selectors!
I think this was a major electrical failure most likely due to the engines quitting. The 787 is far more heavily dependent on electrical power to run it's systems than previous Boeing planes. It requires about 1.5 megawatts of power according to Wiki. 5X more than previous designs. Things that were done by engine driven pumps/compressors and engine bleed air are all done electrically on the 787. Flight cointrols that were moved hydraulically or pneumatically are moved by electric actuators. Etc. 2 users liked this post. |
JG1
2025-06-15T13:30:00 permalink Post: 11902476 |
A little bit tangential here, thinking about this Mayday call (the exact contents of which haven't been verified, but have been variously reported as "no power", or "lost power" ) , if in front of you on the PFD, in large red letters, you have the words ENG FAIL, why would you say, "no power"? Seems a bit strange. Why not say "engine failure" or "no thrust"?
Could it be that "No power" may have meant the whole cockpit went dark? ie. A total electrical failure or huge short (survivor's bang) initiating RAT deployment and apu autostart. Doesn't explain loss of thrust explicitly but if there was a massive electrical issue, and critical data was lost (thinking air/ground switch position and other fundamentals), would dual engine shutdown be a possibility? Simultaneous FADEC failure? Exceptionally remote possibility perhaps, but by definition these accidents are exceptionally remote. If the RAT deployed we know there was definitely an electrical issue - how bad was it, though? Thinking about the possibility of an electrical failure causing an engine (and instrumentation) failure rather than the other way around. Over to the experts on this. Last edited by JG1; 15th Jun 2025 at 14:20 . |
Icarus2001
2025-06-15T13:42:00 permalink Post: 11902480 |
Could it be that "No power" may have meant the whole cockpit went dark? ie. A total electrical failure, initiating RAT deployment and apu autostart. Doesn't explain loss of thrust explicitly but if there was a massive electrical issue, and critical data was lost (thinking air/ground switch position and other fundamentals), would dual engine shutdown be a possibility? Simultaneous FADEC failure? Exceptionally remote possibility perhaps, but by definition these accidents are exceptionally remote. Over to the experts on this.
The engines will just keep running despite total electrical failure. FADEC units are self powered and independent. Even a completely “dark” flight deck still has the ISIS. 3 users liked this post. |
Someone Somewhere
2025-06-15T13:43:00 permalink Post: 11902481 |
Sorry I am not a pilot but I did spend three years filming a TV series at Boeing for pBS/Channel 4 about the design and construction of the 777, and my response is not a technical one anyway. Do airfields have high definition video coverage of all takeoffs and landings? If so, they should be public domain and there would not be hundreds of posts about grainy over-magnified smartphone footage. If they don't, a 6-cam setup on each runway (3 either side of runway, one back, one across and one forward) could record continuously to hard disk or cloud. If airfields don't have this, shouldn't it be made mandatory?
I have been really wondering what single point of failure could take out both engines simultaneously as seems to be the case here. One single main bus contactor closing in error seems to possibly be such a single point fault.
Online/running generators connected together by accident/fault will cause a HUGE load on everything, electric connections, generator itself and the shafts and gears driving the generators. Heck, I wouldnt be surprised if the generator could disintegrate due to such an electromagnetic shock load. So, the question is if there is something between the generators that could limit the electric current. A VFD possibly would as the VFD maybe would not be able to pass the current required for shearing the drive shaft for example. But then again, electronic switches like IGBT/MOSFET and such are able to pass an incredibly large over current for some milliseconds before exploding. Possibly 50 to 100 times the nominal current. So I am not sure if a VFD really would save the rest of the system in a situation with two generators connected together in error. So, where is the VFD part installed, directly on each generator or somewhere else in the system? Are there physical interlocks on the contactors or only electric interlocks? VFDs are for frequency conversion to drive the motors (CAC/pumps/engine start). They won't be carrying the full generator load for galleys and anti-ice; that will be handled by cross-ties, which is a big black box on the 787. Fast fuses can be faster acting than circuit breakers, but are one-shot. I'm not sure how fast-acting and effective the generator contactors/controllers are; conventional ACBs/MCCBs will blow open magnetically under sufficient fault current regardless of what the trip unit or close coil commands. I wouldn't really expect electrical reconfiguration to happen on climbout, and I wouldn't expect it to be the first time this contactor gets used since maintenance - everything should get a good workout during sequential APU/engine starts.
No system would be designed to parallel two frequency wild generators. The output from each would be rectified to dc and conditioned before application to the load, but could be paralleled at dc level if required for redundancy. These are quarter megawatt generators, where an out of phase connection could shear drive shafts, destroy the drive train, or worse.
In a very simple main-tie-main arrangement you can close any two of three breakers and still keep the sources separate. It gets much more complicated when you have ten different sources. I suspect the 'large motor power centre' might parallel the rectified output of some generators.
I no longer believe in the no flaps / flaps raised early theory.
I think this was a major electrical failure most likely due to the engines quitting. The 787 is far more heavily dependent on electrical power to run it's systems than previous Boeing planes. It requires about 1.5 megawatts of power according to Wiki. 5X more than previous designs. Things that were done by engine driven pumps/compressors and engine bleed air are all done electrically on the 787. Flight controls that were moved hydraulically or pneumatically are moved by electric actuators. Etc. 1.5MW is the figure for all six generators; only four can be used at once. There's no indication they had any flight control issues.
Seems to be funny that no-one has mentioned the Battery, which because of its age could have failed either Short-circuit or Open-circuit.
Maybe some Boeing Electro Techs, could explain what role the battery has in this circumstance. The simultaneous failure of both engines points towards an electrical problem, unless the high temperature had adversely affected the fuel flow. 1 user liked this post. |
EGPI10BR
2025-06-15T14:27:00 permalink Post: 11902507 |
A little bit tangential here, thinking about this Mayday call (the exact contents of which haven't been verified, but have been variously reported as "no power", or "lost power" ) , if in front of you on the PFD, in large red letters, you have the words ENG FAIL, why would you say, "no power"? Seems a bit strange. Why not say "engine failure" or "no thrust"?
Could it be that "No power" may have meant the whole cockpit went dark? ie. A total electrical failure or huge short (survivor's bang) initiating RAT deployment and apu autostart. Doesn't explain loss of thrust explicitly but if there was a massive electrical issue, and critical data was lost (thinking air/ground switch position and other fundamentals), would dual engine shutdown be a possibility? Simultaneous FADEC failure? Exceptionally remote possibility perhaps, but by definition these accidents are exceptionally remote. If the RAT deployed we know there was definitely an electrical issue - how bad was it, though? Thinking about the possibility of an electrical failure causing an engine (and instrumentation) failure rather than the other way around. Over to the experts on this. Misty. 1 user liked this post. |
Iron Duck
2025-06-15T14:49:00 permalink Post: 11902519 |
2 users liked this post. |
nachtmusak
2025-06-15T16:00:00 permalink Post: 11902589 |
Let's postulate that engine rollback and subsequent complete electrical failure coincided with selection of gear up. The recorders will tell you that happened, and in consequence that the flight was unrecoverable, but they probably won't tell you why, especially if the event was the result of an interaction between a latent design weakness, a maintenance error or errors, and/or an unusual control input. The recorders
will
clear up the control inputs, most importantly whether the engines were deliberately shut down. If there was no unusual control input the cause
must
be a design weakness, a maintenance error, or more likely a combination of the two, the error exposing the weakness.
To put it another way: if pilot action isn't the root cause, then what exactly is the investigation supposed to say right now other than the utterly redundant "well this is a headscratcher, and we're going to take a while to figure it out"? Are they supposed to turn into Chicken Little screaming that the sky is falling with no evidence-based justification? To be fair, you could perhaps argue that they should come out and "clear" the pilots' names, but that implies an obligation to social media hucksters and mobs that I don't think should exist. Also we should be wary of treating it like an either/or; poor crew response to a manageable fault stemming from a design weakness or maintenance issue is also an option. See e.g. the Swirijaya crash that was initiated by a faulty autothrottle, but the resulting upset was quite preventable and also recoverable even after it had developed. 4 users liked this post. |
Nick H.
2025-06-15T20:56:00 permalink Post: 11902826 |
I'm surprised nobody is discussing a possible electrical failure in the context of Boeing's quality problems and whistleblowers and so on. Would that be against the PPRUNE rules? If anyone's interested, here's an article to get you started
https://prospect.org/economy/2025-06...hed-air-india/
3 users liked this post. |
LTC8K6
2025-06-15T21:01:00 permalink Post: 11902835 |
I'm surprised nobody is discussing a possible electrical failure in the context of Boeing's quality problems and whistleblowers and so on. Would that be against the PPRUNE rules? If anyone's interested, here's an article to get you started
https://prospect.org/economy/2025-06...hed-air-india/
|