Posts about: "Electrical Failure" [Posts: 124 Pages: 7]

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.

Hi tdracer, and thanks for your comments.

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?

I'm not sure if the engines would start , but once they were running, suction/gravity feed into the engine-driven high-pressure fuel pumps would keep the engine running, just like in an electrical failure.

Expect all the alarms, too.

The 320 starts even if you forget to turn on fuel pumps. Don't ask how I know.

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.

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.

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.

I think it has been suggested that the upload only happens every 30 minutes or so.

Well, could be that. Or...

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?

Me too. Including the 787-8. Do you fly the 787-8?

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.

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?

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 cointrols that were moved hydraulically or pneumatically are moved by electric actuators. Etc.

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.

No please read above.

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.

This discussion happened after Jeju. I note that one of the video sources here is actually leaked (camera-pointed-at-screen) airport CCTV. Do not mistake airport CCTV not being publicly available for it not existing.

We'd need to know the impedance/available fault current of the generators. 50x would be unusually high in an industrial setting.

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.

Not designed to parallel, but you still need to switch each generator on/off buses and tie or separate buses.

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.

The 787 flight controls remain almost entirely hydraulic except for stab trim and two spoiler pairs. The centre system is now electric- or RAT-only with no ADP backup. Left and Right systems are still driven by EDPs and will remain pressurised as long as there's fluid and the engines turn.

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.

Battery is essentially unused in normal operations other than to start the APU and keep the clocks running. It's there for emergencies (like after the engines fail). And yes, been discussed.

BAW38 didn\x92t give an engine failure notification either. Neither engine produced the required power when demanded.

Misty.

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.

That is exactly what I am saying - that the only cause that can be positively identified at this point is pilot action whether accidental or deliberate. It's the only thing that can be conclusively ruled either in or out by now. However the tone of several of the messages here is that everything else has conclusively been ruled out because it has been three days, which makes no logical sense to me.

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.

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/

We are primarily interested in the info we can get from the evidence we have. That being a couple of videos, photos of the crash scene, and the testimony of a survivor.