2025-06-13T12:13:00
permalink Post: 11900427
One thing which could cause simultaneous unexpected idle power is the autothrottle. I'm thinking about this, leading to a crew too startled to retract the gear and too distracted to push the thrust levers forward, as a possible cause. As others have said, the RAT could have been manually deployed - an action which would make sense to pilot convinced that he was about to lose both engine driven generators.
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2025-06-13T12:48:00
permalink Post: 11900479
Question is why both engines lost power . Foreign object ingestion , contaminated fuel or both cutoff levels operated ? We do not know .
Any autothrust discussion is misleading since every pilot in that situation will firewall the levers whatever thrust reduction was selected for TO . the same is true for the RAT discussion- if enough hydraulic pressure was generated or not . The plane pitched up last second so there obviously was control until the end . Of course , without energy pulling alone will not bring you anywhere .
Why did both engines fail the same second as they would be cut off ???
Any autothrust discussion is misleading since every pilot in that situation will firewall the levers whatever thrust reduction was selected for TO . the same is true for the RAT discussion- if enough hydraulic pressure was generated or not . The plane pitched up last second so there obviously was control until the end . Of course , without energy pulling alone will not bring you anywhere .
Why did both engines fail the same second as they would be cut off ???
The "gear-up" places additional load on the hydraulic pumps and the result of that is step increase of load on the generators. Was this the trigger of the failures?
2025-06-13T13:18:00
permalink Post: 11900511
Out of interest about when did the RAT include a hydraulic pump, not that it would be sufficient to retract the gear anyway.
2025-06-13T23:43:00
permalink Post: 11901006
1 user liked this post.
2025-06-13T23:49:00
permalink Post: 11901007
Speaking as a B787 Captain..... There is so much rubbish and stupid suggestion being written here.
This aircraft was airborne for a grand total of 22 seconds, half of which was climbing to no more than 150' aal.
- No Flaps? Due to the setup of the ECL it is physically impossible to go down the runway without some sort of take-off flap set. The T/o config warning would have been singing it's head off. Despite assertions to the contrary I have seen no video clear enough to detect a lack of flaps.
- RAT out? Almost impossible, I have seen no quality footage that definitively witnesses the RAT being out. Those who think they car hear a RAT type noise might be listening to a motorcycle passing or similar. It takes a triple hydraulic failure or a double engine failure to trigger RAT deploment. They happily went through V1 without a hint of rejected take off so as they rotated the aircraft was serviceable. These are big engines, they take a long time to wind down when you shut them down. I have never tried it however engine failure detection takes 30s or for the aircraft to react and they were not even airborne that long.
- Flaps up instead of gear? The B787 flaps are slow both in and out. Given that the 'Positive rate' call is not made the second the wheels leave the ground, a mis-selection of flaps up would not cause any loss of lift for at least 20 seconds, by which time they had already crashed. I believe the gear remained down not because of mis-selection but because of a major distraction on rotate.
Discounting the impossible, two hypotheses remain:
1. Invalid derate set through incorrect cross-checking. Trundling down the runway takes very little power to reach Vr. It is only when you rotate that you create more drag and discover that you do not have sufficient thrust vs. drag to sustain a climb. Or....
2. Put 200' as the altitude target in the FCU. Immediate ALT capture and all the power comes off. PF is still hand flying trying to increase pitch but is already way behind the aircraft.
It could be after this that Boeing are forced to review the B787 practice of exploring the very edges of the performance envelope.
This aircraft was airborne for a grand total of 22 seconds, half of which was climbing to no more than 150' aal.
- No Flaps? Due to the setup of the ECL it is physically impossible to go down the runway without some sort of take-off flap set. The T/o config warning would have been singing it's head off. Despite assertions to the contrary I have seen no video clear enough to detect a lack of flaps.
- RAT out? Almost impossible, I have seen no quality footage that definitively witnesses the RAT being out. Those who think they car hear a RAT type noise might be listening to a motorcycle passing or similar. It takes a triple hydraulic failure or a double engine failure to trigger RAT deploment. They happily went through V1 without a hint of rejected take off so as they rotated the aircraft was serviceable. These are big engines, they take a long time to wind down when you shut them down. I have never tried it however engine failure detection takes 30s or for the aircraft to react and they were not even airborne that long.
- Flaps up instead of gear? The B787 flaps are slow both in and out. Given that the 'Positive rate' call is not made the second the wheels leave the ground, a mis-selection of flaps up would not cause any loss of lift for at least 20 seconds, by which time they had already crashed. I believe the gear remained down not because of mis-selection but because of a major distraction on rotate.
Discounting the impossible, two hypotheses remain:
1. Invalid derate set through incorrect cross-checking. Trundling down the runway takes very little power to reach Vr. It is only when you rotate that you create more drag and discover that you do not have sufficient thrust vs. drag to sustain a climb. Or....
2. Put 200' as the altitude target in the FCU. Immediate ALT capture and all the power comes off. PF is still hand flying trying to increase pitch but is already way behind the aircraft.
It could be after this that Boeing are forced to review the B787 practice of exploring the very edges of the performance envelope.
Even though these are big engines with plenty of inertia, when you select engine shut off they spool down very quickly if on load. IE, The generators, two per engine and hydraulic pumps, etc, being driven by the (relatively) small mass of the N2 rotor will drag the speed down very quickly, the gennies will trip offine in seconds, the pumps will quickly reduce flow and pressure.
As for what went wrong.
If the engines have stopped working there has to be a common failure mode, fuel is one but as has been said, no other aircraft has had a problem, as far as we know. FOD? It would have to be something major to shut down two GeNX engines and there would be debris all over the runway, we would know by now.
I have no idea if the RAT has deployed, I can't see it in the video and the noise could be something else.
We shall see.
There is compelling evidence that flaps are set correctly and not retracted inadvertently.
I await further evidence.
Edit to add. LAE 40 years, type rated on 737 to 787 with lots of others in between.
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2025-06-14T00:00:00
permalink Post: 11901015
1 user liked this post.
2025-06-14T00:19:00
permalink Post: 11901019
Do you recall a 787 made an emergency landing in Louisiana on a revenue flight Houston/Newark in 2012? Your Post referenced an abnormal that may lend credence to a major power loss in this wreck.
Never expected to see any surviving tail cone or Empennage structure. Quite a find
Forgive the intrusion sir
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2025-06-14T01:17:00
permalink Post: 11901057
Turin, your name appeared on a thread I was researching regarding generator control units, 787.
Do you recall a 787 made an emergency landing in Louisiana on a revenue flight Houston/Newark in 2012? Your Post referenced an abnormal that may lend credence to a major power loss in this wreck.
Never expected to see any surviving tail cone or Empennage structure. Quite a find
Forgive the intrusion sir
Do you recall a 787 made an emergency landing in Louisiana on a revenue flight Houston/Newark in 2012? Your Post referenced an abnormal that may lend credence to a major power loss in this wreck.
Never expected to see any surviving tail cone or Empennage structure. Quite a find
Forgive the intrusion sir
Boeing 787 Makes Emergency Landing
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2025-06-14T01:37:00
permalink Post: 11901066
AD validity
Still valid Dave. That AD was raised circa post #248 (Search thread for \x93AD\x94)
All four Variable Frequency Generators (2 per engine) going offline at once is too much of a coincidence not to mention that AD.
RAT deployment has been substantiated, which occurs automatically, extension of which takes about 6 secs & would be heard by pax in the cabin as a loud \x93bang\x94 as the leg locks into place.
The sole on-board survivor quote regarding flickering green/white lights (Emergency Exit lights) directly adjacent to his seat 11A, speaks to electrical disruption during the takeoff phase.
If the double engine failure or electrical bus/distribution failure causing loss of thrust occurred for a reason other than the AD mentioned above, the cause will need to be established without delay lest the void is filled with mis-information, fear, uncertainty, & doubt.
The current level of trust in the manufacturer is fragile for good reason.
.
This occurrence will have operators & regulators around the world reviewing their risk assessment models, especially regarding Master Minimum Equipment List (MMEL)/ Defect Deferral Guide (DDG) maintenance relief.
Compliance & maintenance come at a cost.
Lack thereof comes at a far greater & heavier cost.
All four Variable Frequency Generators (2 per engine) going offline at once is too much of a coincidence not to mention that AD.
RAT deployment has been substantiated, which occurs automatically, extension of which takes about 6 secs & would be heard by pax in the cabin as a loud \x93bang\x94 as the leg locks into place.
The sole on-board survivor quote regarding flickering green/white lights (Emergency Exit lights) directly adjacent to his seat 11A, speaks to electrical disruption during the takeoff phase.
If the double engine failure or electrical bus/distribution failure causing loss of thrust occurred for a reason other than the AD mentioned above, the cause will need to be established without delay lest the void is filled with mis-information, fear, uncertainty, & doubt.
The current level of trust in the manufacturer is fragile for good reason.
.
This occurrence will have operators & regulators around the world reviewing their risk assessment models, especially regarding Master Minimum Equipment List (MMEL)/ Defect Deferral Guide (DDG) maintenance relief.
Compliance & maintenance come at a cost.
Lack thereof comes at a far greater & heavier cost.
3 users liked this post.
2025-06-14T03:05:00
permalink Post: 11901101
Miscellaneous comments:
I have seen in manuals for other airliners that because the bogie tilt is by a hydraulic actuator, gravity deploying the gear means the gear doesn't tilt to landing position.
With the loss of centre-system pressure*, would you expect the bogies to tilt naturally? I.e. spring pressure holds the gear in the stowed tilt, a hydraulic cylinder pushes the gear to the landing tilt. No pressure means the gear returns to the 'stowed' tilt.
The tilt actuator is designed to be overridden when the bogie hits the ground, so perhaps it has some kind of intentional bypass and doesn't stay in place without continually applied hydraulic pressure.
If so, that would also point towards total loss of electrics and no attempt to raise the gear.
* 787 centre system is powered by two electric pumps, plus the RAT. The RAT hydraulic pump only powers flight controls, not the landing gear.
Electric loss:
Surely even total AC power loss shouldn't result in engine loss, even if the RAT doesn't come online. The FADECs have their own alternators, bare minimum flight control computers and actuators are available on battery (though probably result in some equivalent of Direct Law), and boost pumps are unnecessary at low altitude. Left/right EDPs will remain active if the engines are running at any serious speed; providing flight controls.
Poor crew reaction to ending up in direct law is possible but it's hard to see the electrical issues as a cause, not a symptom.
Anti-terrorism squad looks to be doing an excellent job (/s) and recovered a convenience-store-grade CCTV recorder, probably from somewhere on the campus it crashed into:
https://economictimes.indiatimes.com.../121823103.cms
With the loss of centre-system pressure*, would you expect the bogies to tilt naturally? I.e. spring pressure holds the gear in the stowed tilt, a hydraulic cylinder pushes the gear to the landing tilt. No pressure means the gear returns to the 'stowed' tilt.
The tilt actuator is designed to be overridden when the bogie hits the ground, so perhaps it has some kind of intentional bypass and doesn't stay in place without continually applied hydraulic pressure.
If so, that would also point towards total loss of electrics and no attempt to raise the gear.
* 787 centre system is powered by two electric pumps, plus the RAT. The RAT hydraulic pump only powers flight controls, not the landing gear.
Electric loss:
Surely even total AC power loss shouldn't result in engine loss, even if the RAT doesn't come online. The FADECs have their own alternators, bare minimum flight control computers and actuators are available on battery (though probably result in some equivalent of Direct Law), and boost pumps are unnecessary at low altitude. Left/right EDPs will remain active if the engines are running at any serious speed; providing flight controls.
Poor crew reaction to ending up in direct law is possible but it's hard to see the electrical issues as a cause, not a symptom.
https://economictimes.indiatimes.com.../121823103.cms
2025-06-14T07:22:00
permalink Post: 11901193
(I screwed up earlier and had a 767 image here...)
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system.
Compromising both engines inherently compromises the electrical system: dropping below idle N2 (plus some safety margin) disconnects generators.
Last edited by Someone Somewhere; 14th Jun 2025 at 17:57 .
2 users liked this post.
2025-06-14T07:36:00
permalink Post: 11901205
Only on the electrically-powered centre system (which does gear and flaps). Left and right have engine-driven pumps which will provide plenty of power for flight controls provided the engines remain above maybe 30-40% N2.
Compromising both engines inherently compromises the electrical system: dropping below idle N2 (plus some safety margin) disconnects generators.
Compromising both engines inherently compromises the electrical system: dropping below idle N2 (plus some safety margin) disconnects generators.
3 users liked this post.
2025-06-14T12:24:00
permalink Post: 11901432
The B787 is a way way different and much more complex and sophisticated plane than your Gulfie. The B787's two outermost (left & right) hydraulic systems are primarily driven by the engines, mechanically driving the hydraulic pumps. The center hydraulics are primarily electrically driven, and power the main flight controls, amongst other things like the gear. The left and right ones power the main flight controls as well, some of the less important flight control surfaces like spoilers and thrust reversers -- pardon me for not having the exact list of things. They also have a backup/supplementary electric pump each. Each of the two main engines has redundancy for the power plant a.k.a. VFSG (and motor-driven pump?) in its own right as well. All three hydraulic systems work together in a redundant fashion when it comes to the primary flight controls. The RAT can provide both electrical and mechanical sources of hydraulic support, if I'm not mistaken. The flight instrument and information systems can also be powered from two backup batteries, the APU power plant itself, and/or the RAT.
The Global Express has 4 engine driven generators, one APU generator, one RAT generator that provide AC and DC power to the aircraft's systems. On the hydraulic side, the aircraft has 3 fully independent and redundant hydraulic systems which power all flight control surfaces the exception being, the slats and flaps are AC power driven and are available even with only the RAT providing power. The 3 hydraulic systems are powered from each engine backed up by 2 EDPs (system 1 and 2) and system 3 is powered by 2 EDPs only. The RAT powers system 3 via one of its EDPs. In the event of a dual engine failure the RAT would deploy automatically and power the AC essential plus DC essential busses and one EDP on system 3. The APU is available to you up to FL450 and will supply full AC power but bleed air only up to FL300.
5 users liked this post.
2025-06-14T12:48:00
permalink Post: 11901455
Sorry but before you make a statement like this, you better read up on the "complexity and sophistication" of the latest business jets like the Gulfstreams and Global Express.
The Global Express has 4 engine driven generators, one APU generator, one RAT generator that provide AC and DC power to the aircraft's systems. On the hydraulic side, the aircraft has 3 fully independent and redundant hydraulic systems which power all flight control surfaces the exception being, the slats and flaps are AC power driven and are available even with only the RAT providing power. The 3 hydraulic systems are powered from each engine backed up by 2 EDPs (system 1 and 2) and system 3 is powered by 2 EDPs only. The RAT powers system 3 via one of its EDPs. In the event of a dual engine failure the RAT would deploy automatically and power the AC essential plus DC essential busses and one EDP on system 3. The APU is available to you up to FL450 and will supply full AC power but bleed air only up to FL300.
The Global Express has 4 engine driven generators, one APU generator, one RAT generator that provide AC and DC power to the aircraft's systems. On the hydraulic side, the aircraft has 3 fully independent and redundant hydraulic systems which power all flight control surfaces the exception being, the slats and flaps are AC power driven and are available even with only the RAT providing power. The 3 hydraulic systems are powered from each engine backed up by 2 EDPs (system 1 and 2) and system 3 is powered by 2 EDPs only. The RAT powers system 3 via one of its EDPs. In the event of a dual engine failure the RAT would deploy automatically and power the AC essential plus DC essential busses and one EDP on system 3. The APU is available to you up to FL450 and will supply full AC power but bleed air only up to FL300.
Elsewhere, there is a picture of the tail wreckage showing what looks likethe APU door partially open. The panel is otherwise undamaged indicating not caused by post-impact. I’ll try to poach it
its here, but wrong file extension on the photo
https://www.nytimes.com/interactive/...smid=url-share
Last edited by galaxy flyer; 14th Jun 2025 at 13:52 .
2025-06-14T15:33:00
permalink Post: 11901579
It\x92s the elephant in the room regarding the audio, isn\x92t it, but I am not prepared to say either way. There simply is too much city background noise/ambience to discern this from the engine noise from a landing 787.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
Of course one taking off would have a different signature. If anyone can point point to one taking off with the rat out we could compare.
What I find interesting is that I don\x92t see any evidence in the audio of the engine spooling down, which would leave a recogniseable pattern in the audio one should think. So either it is down so much that the fan rpm is down to windmilling already, or it is simply low enough in volume to be already masked by the ambience.
So taking this and moving into speculative territory for a moment, I think I read somewhere that the video with audio starts 17 seconds after the wheels left the ground.
Provided the engines were windmilling the video audio since I haven\x92t been able to find any obvious spool down, can anyone say anything meaningful on how long it takes for the engines to spool down to windmilling rpm?
we can then backtrack from the point the video starts. How does that timing then coincide with the ADS-B data ceasing to transmit, for instance?
Putting back in the more strictly data-driven hat, I am not prepared to say so far anything about the engine working or not. You guys know more anout why the rat is out.
2025-06-14T15:55:00
permalink Post: 11901596
2 users liked this post.
2025-06-14T21:50:00
permalink Post: 11901869
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 ...
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 ...
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 ..
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.
2025-06-14T22:11:00
permalink Post: 11901886
There was banging prior the failed generator in the 787 Emergency landing....plus loss of altitude, direction, and EE Does all elec load go to the opposite engine? Because if it does and that engine either fails or gets shut down mistakenly ....OOPS no Thrust, no Electrical power, only instruments from APU. If the APU started on climb, we know exactly what occurred....
2025-06-14T22:56:00
permalink Post: 11901928
There was banging prior the failed generator in the 787 Emergency landing....plus loss of altitude, direction, and EE Does all elec load go to the opposite engine? Because if it does and that engine either fails or gets shut down mistakenly ....OOPS no Thrust, no Electrical power, only instruments from APU. If the APU started on climb, we know exactly what occurred....