June 17, 2025, 23:14:00 GMT
permalink Post: 11904751
Could someone post an authoritative list of the inputs to the EAFR\x92s? By \x93authoritative\x94, I mean the actual wiring diagram excerpt of the aircraft model and engine configuration (and hopefully mod state...), that labels each input.
I\x92m confidently assuming that it will, for example, include an input monitoring the state of the input controlling the fuel shut off valves in the wing roots. But does it monitor, separately, each and every one of the switches and systems that can change the input controlling the fuel shut off valves? I'm hoping and assuming \x91yes\x92, but hope and assumptions can be unhelpful and misguided.
As we know, there are some things the pilots can do that will result in fuel shut off, but other things will result in fuel shut off without pilot intervention.
Of course, it may be that the recorded data will indicate that there was no change in the state of the inputs controlling the fuel shut off valves during the short flight. Hopefully \x96 yes hopefully \x96 that will be confirmed one way or other, soon. Along with another dozen questions....
I was struck by a comment in this or the earlier thread that I cannot now find. It was to the effect \x96 I\x92m paraphrasing \x96 that fuel shut off results in an almost immediate cessation of thrust. (Please correct my paraphrasing if I\x92m off track.) I was also struck by how quiet the aircraft was in the original video, except for the RAT. (Or was it a motorcycle? Sorry couldn\x92t resist. Just joking\x85)
Someone earlier asked how the aircraft could have kept climbing if both engines stopped very late in the take-off roll or shortly after take-off. My answer: Momentum. A bullet fired into the air loses thrust immediately after \x91take off\x92 but continues climbing for a while. And my understanding of the expert opinion on the available, reliable information is that the aircraft didn\x92t climb very far.
I\x92m confidently assuming that it will, for example, include an input monitoring the state of the input controlling the fuel shut off valves in the wing roots. But does it monitor, separately, each and every one of the switches and systems that can change the input controlling the fuel shut off valves? I'm hoping and assuming \x91yes\x92, but hope and assumptions can be unhelpful and misguided.
As we know, there are some things the pilots can do that will result in fuel shut off, but other things will result in fuel shut off without pilot intervention.
Of course, it may be that the recorded data will indicate that there was no change in the state of the inputs controlling the fuel shut off valves during the short flight. Hopefully \x96 yes hopefully \x96 that will be confirmed one way or other, soon. Along with another dozen questions....
I was struck by a comment in this or the earlier thread that I cannot now find. It was to the effect \x96 I\x92m paraphrasing \x96 that fuel shut off results in an almost immediate cessation of thrust. (Please correct my paraphrasing if I\x92m off track.) I was also struck by how quiet the aircraft was in the original video, except for the RAT. (Or was it a motorcycle? Sorry couldn\x92t resist. Just joking\x85)
Someone earlier asked how the aircraft could have kept climbing if both engines stopped very late in the take-off roll or shortly after take-off. My answer: Momentum. A bullet fired into the air loses thrust immediately after \x91take off\x92 but continues climbing for a while. And my understanding of the expert opinion on the available, reliable information is that the aircraft didn\x92t climb very far.
June 17, 2025, 23:37:00 GMT
permalink Post: 11904770
I was struck by a comment in this or the earlier thread that I cannot now find. It was to the effect – I’m paraphrasing – that fuel shut off results in an almost immediate cessation of thrust. (Please correct my paraphrasing if I’m off track.) I was also struck by how quiet the aircraft was in the original video, except for the RAT. (Or was it a motorcycle? Sorry couldn’t resist. Just joking…)
Someone earlier asked how the aircraft could have kept climbing if both engines stopped very late in the take-off roll or shortly after take-off. My answer: Momentum.
Someone earlier asked how the aircraft could have kept climbing if both engines stopped very late in the take-off roll or shortly after take-off. My answer: Momentum.
Slamming the throttles back is a lot slower as the FCU (on a traditional engine)/FADEC spins down the engine slowly - I suppose to make sure that the airflow through the engine remains stable.
Regarding the momentum: As the first few seconds of the climb were normal compared to previous T/Os of the same flight (speed & altitude, confirmed by comparison of the RAW ADS-B data) I don't believe the engine failure happened before or on lift-off.
June 18, 2025, 00:08:00 GMT
permalink Post: 11904784
One good thing from reading the full thread is I learned the 78 hydraulic system is essentially the same as the 777 !
While I appreciate the excellent analysis of some regarding the RAT I`m still not completely convinced of its deployment much less why it depoloyed. Sounds like the auto-deploy is identical to 777 (less the transfer bus deal which is replaced by the electrics on the 78 system), but it can be manually deployed as well by boinking the button.
I very much respect the survivors testimony. It will be very helpful. And all he went through. However, one must realize that under stress and injury (whether pilot or pax) ones memory is severely affected by physiological factors and retrograde symptoms of a traumatic event which varies by individual.
While I appreciate the excellent analysis of some regarding the RAT I`m still not completely convinced of its deployment much less why it depoloyed. Sounds like the auto-deploy is identical to 777 (less the transfer bus deal which is replaced by the electrics on the 78 system), but it can be manually deployed as well by boinking the button.
I very much respect the survivors testimony. It will be very helpful. And all he went through. However, one must realize that under stress and injury (whether pilot or pax) ones memory is severely affected by physiological factors and retrograde symptoms of a traumatic event which varies by individual.
June 18, 2025, 00:09:00 GMT
permalink Post: 11904785
also see in the final moments of desperation, reaching down and turning the Fuel Control Switches, OFF-THEN-ON, in the hope that an engine will come to life, if they believed that the engine was dead. This may be the reason the RAT extended? Just thinking out loud.
June 18, 2025, 04:38:00 GMT
permalink Post: 11904900
But likewise, the engines can't have failed much before rotation:
The aircraft climb rate decreases, it descends, it crashes. Maybe the RAT was out. That is all we know.
Last edited by Senior Pilot; 18th June 2025 at 07:09 . Reason: Remove quote from deleted post plus throttle comment
June 18, 2025, 08:46:00 GMT
permalink Post: 11905031
Most? The Airbus I'm familiar with is 100' AGL or 5s after liftoff and I think this is common to all Airbus FBW. The B787 & B777 appear to be 200' AGL but I'm taking this from online FCOM extracts. The
B737
does appear to be 400'. Company limitations may be higher.
As mentioned elsewhere both EK and Air NZ have had messy low level mis-set altitude capture incidents with the B777, but in isolation, obviously, this wouldn't cause RAT extension.
About airport cameras. Someone pointed out on the other thread that airports have more coverage than they would necessarily advertise. Presumably available to investigators but not to the public or press.
As mentioned elsewhere both EK and Air NZ have had messy low level mis-set altitude capture incidents with the B777, but in isolation, obviously, this wouldn't cause RAT extension.
About airport cameras. Someone pointed out on the other thread that airports have more coverage than they would necessarily advertise. Presumably available to investigators but not to the public or press.
The ideas of mis-set MCP, AT modes, etc. were worth exploring but by this point, like the gear/flap/performance ones, there is enough convincing evidence now that a) the takeoff was normal until it suddenly wasn\x92t and b) none of the above would cause RAT deployment and a glide into the ground.
June 18, 2025, 11:50:00 GMT
permalink Post: 11905173
Hi all,
Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.
I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.
So, my questions is related to T/O performance.
Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?
By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect…. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?
Thanks for the help !
Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.
I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.
So, my questions is related to T/O performance.
Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?
By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect…. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?
Thanks for the help !
June 18, 2025, 12:13:00 GMT
permalink Post: 11905186
Hi all,
Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.
I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.
So, my questions is related to T/O performance.
Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?
By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect\x85. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?
Thanks for the help !
Disclaimer: I read this thread from hour 1, still scratching my head regarding perf though.
I know sound analysis points to higher odds being a dual engine failure with RAT deployed, however I still have some questions if anyone is available to enlighten.
So, my questions is related to T/O performance.
Is it possible on the 787 to calculate perf in the OPT for F15/20 T/O, and to enter F5 T/O speed on the FMC ?
By that I mean do normal procedure, but at the point where you are suppose to enter flaps, CG speed ect\x85. You, out of habit (if F5 is indeed a habit on the 787) enter F5, but F15/20 speeds ? Or would there be a warning that you have manually inputed speeds that are not correct for the selected flaps and conditions inputed in the FMC ?
Thanks for the help !
June 18, 2025, 14:29:00 GMT
permalink Post: 11905294
"Emergency power system"
"Emergency power system"
is the most awkward designation for the ram air turbine I've ever heard....
Last edited by Saab Dastard; 18th June 2025 at 15:54 . Reason: quoting deleted post
June 18, 2025, 14:50:00 GMT
permalink Post: 11905306
It could equally refer to the APU which some have suggested either started or was in the process of starting.
June 18, 2025, 15:17:00 GMT
permalink Post: 11905327
I'd like to stick my neck out and say what I think I know. And I do mean "know", not what I think "likely" or "possible".
1. The aircraft reached an altitude AGL rather more than one wingspan. This can be clearly seen in the still from the CCTV video posted by Cape Bloggs on 2025-06-18 at 0401. The 787-8 wingspan is 197+ ft. So it got at least 200 feet up in the air. (Info from CCTV screen shot.)
2. (a) Ground effect on lift essentially disappears on TO when the wheels are at screen height. (Info from an eminent colleague who performed the analysis.) I believe it follows that (b) he didn't get up to 200 ft by performing a zoom climb on unstick. It further follows that (c) there must have been some initially adequate lift out of GE to establish for a few seconds positive RoC.
3. The FR24 graphic posted by Musician shows that the aircraft became initially airborne "as usual", compared with other TO profiles. (Info from FR24.)
4. The aircraft lacked adequate thrust even to maintain altitude shortly after unstick.
5. Flaps 5 is minimal for TO. If you don't set it, you are told very clearly that you are misconfigured, well before TO roll. (Info from others.)
6. At Flaps 5 and likely loading (fuel, PAX, token sum for baggage) and in the atmospheric conditions pertaining, there is more than enough nominal thrust available to establish positive RoC. That obviously also holds for Flaps-more-than-5. (Info from others.)
I am not au fait with audio spectral analysis so, unlike some others here, including some whose views and experience I value highly, I am agnostic at this point about the RAT. (This is neither to deprecate those who performed this analysis, nor the views of those who know more about practical spectral analysis than I do and are convinced by it.)
Now for my personal inference so far from this.
Items 2 and 3 above suggest to me that the aircraft was adequately configured to conduct a normal TO and initially establish positive RoC for a second or two.
For me, the big question is: why wasn't there adequate thrust to maintain that? (We've been talking about those possibilities for some days now - I won't attempt to summarise.)
PBL
1. The aircraft reached an altitude AGL rather more than one wingspan. This can be clearly seen in the still from the CCTV video posted by Cape Bloggs on 2025-06-18 at 0401. The 787-8 wingspan is 197+ ft. So it got at least 200 feet up in the air. (Info from CCTV screen shot.)
2. (a) Ground effect on lift essentially disappears on TO when the wheels are at screen height. (Info from an eminent colleague who performed the analysis.) I believe it follows that (b) he didn't get up to 200 ft by performing a zoom climb on unstick. It further follows that (c) there must have been some initially adequate lift out of GE to establish for a few seconds positive RoC.
3. The FR24 graphic posted by Musician shows that the aircraft became initially airborne "as usual", compared with other TO profiles. (Info from FR24.)
4. The aircraft lacked adequate thrust even to maintain altitude shortly after unstick.
5. Flaps 5 is minimal for TO. If you don't set it, you are told very clearly that you are misconfigured, well before TO roll. (Info from others.)
6. At Flaps 5 and likely loading (fuel, PAX, token sum for baggage) and in the atmospheric conditions pertaining, there is more than enough nominal thrust available to establish positive RoC. That obviously also holds for Flaps-more-than-5. (Info from others.)
I am not au fait with audio spectral analysis so, unlike some others here, including some whose views and experience I value highly, I am agnostic at this point about the RAT. (This is neither to deprecate those who performed this analysis, nor the views of those who know more about practical spectral analysis than I do and are convinced by it.)
Now for my personal inference so far from this.
Items 2 and 3 above suggest to me that the aircraft was adequately configured to conduct a normal TO and initially establish positive RoC for a second or two.
For me, the big question is: why wasn't there adequate thrust to maintain that? (We've been talking about those possibilities for some days now - I won't attempt to summarise.)
PBL
Last edited by T28B; 18th June 2025 at 15:33 . Reason: slight formatting assist
June 18, 2025, 15:28:00 GMT
permalink Post: 11905332
The emergency system is known as a ram air turbine. It is a small propeller that drops from the bottom of the 787 Dreamliner\x92s fuselage to serve as a backup generator.
https://www.wsj.com/business/airline...QPg1BBGQ%3D%3D
June 18, 2025, 15:54:00 GMT
permalink Post: 11905352
I'd like to stick my neck out and say what I think I know. And I do mean "know", not what I think "likely" or "possible".
1. The aircraft reached an altitude AGL rather more than one wingspan. This can be clearly seen in the still from the CCTV video posted by Cape Bloggs on 2025-06-18 at 0401. The 787-8 wingspan is 197+ ft. So it got at least 200 feet up in the air. (Info from CCTV screen shot.)
2. (a) Ground effect on lift essentially disappears on TO when the wheels are at screen height. (Info from an eminent colleague who performed the analysis.) I believe it follows that (b) he didn't get up to 200 ft by performing a zoom climb on unstick. It further follows that (c) there must have been some initially adequate lift out of GE to establish for a few seconds positive RoC.
3. The FR24 graphic posted by Musician shows that the aircraft became initially airborne "as usual", compared with other TO profiles. (Info from FR24.)
4. The aircraft lacked adequate thrust even to maintain altitude shortly after unstick.
5. Flaps 5 is minimal for TO. If you don't set it, you are told very clearly that you are misconfigured, well before TO roll. (Info from others.)
6. At Flaps 5 and likely loading (fuel, PAX, token sum for baggage) and in the atmospheric conditions pertaining, there is more than enough nominal thrust available to establish positive RoC. That obviously also holds for Flaps-more-than-5. (Info from others.)
I am not au fait with audio spectral analysis so, unlike some others here, including some whose views and experience I value highly, I am agnostic at this point about the RAT. (This is neither to deprecate those who performed this analysis, nor the views of those who know more about practical spectral analysis than I do and are convinced by it.)
Now for my personal inference so far from this. Items 2 and 3 above suggest to me that the aircraft was adequately configured to conduct a normal TO and initially establish positive RoC for a second or two. For me, the big question is: why wasn't there adequate thrust to maintain that? (We've been talking about those possibilities for some days now - I won't attempt to summarise.)
PBL
1. The aircraft reached an altitude AGL rather more than one wingspan. This can be clearly seen in the still from the CCTV video posted by Cape Bloggs on 2025-06-18 at 0401. The 787-8 wingspan is 197+ ft. So it got at least 200 feet up in the air. (Info from CCTV screen shot.)
2. (a) Ground effect on lift essentially disappears on TO when the wheels are at screen height. (Info from an eminent colleague who performed the analysis.) I believe it follows that (b) he didn't get up to 200 ft by performing a zoom climb on unstick. It further follows that (c) there must have been some initially adequate lift out of GE to establish for a few seconds positive RoC.
3. The FR24 graphic posted by Musician shows that the aircraft became initially airborne "as usual", compared with other TO profiles. (Info from FR24.)
4. The aircraft lacked adequate thrust even to maintain altitude shortly after unstick.
5. Flaps 5 is minimal for TO. If you don't set it, you are told very clearly that you are misconfigured, well before TO roll. (Info from others.)
6. At Flaps 5 and likely loading (fuel, PAX, token sum for baggage) and in the atmospheric conditions pertaining, there is more than enough nominal thrust available to establish positive RoC. That obviously also holds for Flaps-more-than-5. (Info from others.)
I am not au fait with audio spectral analysis so, unlike some others here, including some whose views and experience I value highly, I am agnostic at this point about the RAT. (This is neither to deprecate those who performed this analysis, nor the views of those who know more about practical spectral analysis than I do and are convinced by it.)
Now for my personal inference so far from this. Items 2 and 3 above suggest to me that the aircraft was adequately configured to conduct a normal TO and initially establish positive RoC for a second or two. For me, the big question is: why wasn't there adequate thrust to maintain that? (We've been talking about those possibilities for some days now - I won't attempt to summarise.)
PBL
But you ask..... How can an aircraft possibly get airborne with a stalled wing? Look at Air France 7775 . At rotate the wing was already stalled (albeit for different reasons) but the airborne profile of the aircraft was rather similar to Air India.
June 18, 2025, 16:46:00 GMT
permalink Post: 11905393
Loss of all Hydraulics
I still consider the forward truck tilt is a massive clue to a C system Hydraulic failure prior to wheels-up, which must have been caused by loss of electrics (since C is solely electrically powered), so I am still wondering if hydraulic failure happened before or after the loss of thrust.
While thinking about the consequences of a total hydraulics failure around time of rotation (caused by a suspected dual engine failure), here is a new observation. I searched the previous threads to see if anyone lese had noticed it.
In the rooftop video, as it's just approaching the treeline, there are spoiler deflections visible just behind the engines on each wing.
With a total hydraulics failure, the pilots control column using direct wiring, will only control this spoiler pair and the stabiliser. The RAT does not control this spoiler pair (hydraulically), only the most inboard spoilers pair. Its an interesting observation because it means this spoiler pair were being deflected electrically, either by the battery or RAT. But if the RAT provides emergency C hydraulic power why didn't the RAT powered spoilers deflect instead? Does this mean the RAT was unable to provide emergency hydraulic at such low airspeed?
I think this also re-affirms the critical loss of power (dual engine failure), and rules out many other theories. It tragically lost all power, both engines, all hydraulics and electrics (apart from battery and RAT).
I am wondering if anyone else has noticed other flight control deflections?
(Tried posting link to youtube but unhelpfully frames entire video)
While thinking about the consequences of a total hydraulics failure around time of rotation (caused by a suspected dual engine failure), here is a new observation. I searched the previous threads to see if anyone lese had noticed it.
Observation/Question - in the accident video, the view from behind the aircraft as it pitches up seems to show inboard spoilers aft of the engines on both wings partially open - is that what I'm seeing? Pic at 99 above roof top video screen shot see here] also shows what I'm looking at... Spoilers, or markings on the wings maybe?
@ treadigraph
@ treadigraph
In the rooftop video, as it's just approaching the treeline, there are spoiler deflections visible just behind the engines on each wing.
With a total hydraulics failure, the pilots control column using direct wiring, will only control this spoiler pair and the stabiliser. The RAT does not control this spoiler pair (hydraulically), only the most inboard spoilers pair. Its an interesting observation because it means this spoiler pair were being deflected electrically, either by the battery or RAT. But if the RAT provides emergency C hydraulic power why didn't the RAT powered spoilers deflect instead? Does this mean the RAT was unable to provide emergency hydraulic at such low airspeed?
I think this also re-affirms the critical loss of power (dual engine failure), and rules out many other theories. It tragically lost all power, both engines, all hydraulics and electrics (apart from battery and RAT).
I am wondering if anyone else has noticed other flight control deflections?
(Tried posting link to youtube but unhelpfully frames entire video)
Last edited by Aerospace101; 18th June 2025 at 16:48 . Reason: Removed youtube video
June 18, 2025, 18:18:00 GMT
permalink Post: 11905444
To my mind, this points to a potential software issue. 787s have already suffered from 2 separate software issues in which the passage of time causes a major and possibly catastrophic failure - the need to reboot systems before 51 days and 248 days have elapsed, due to poorly-written software. Given that history, the probability of there being a third, previously-unidentified but broadly similar in nature software issue seems surprisingly high. They aren't independent variables.
Such a passage-of-time software issue wouldn't show up in most (or possibly any) testing scenarios. It is the sort of issue that robust QA and static code analysis are designed to catch. But in at least two separate systems on the 787 it has not been caught prior to software shipping. Meanwhile, every new technical post demonstrates the myriad ways in which non-software potential causes are mitigated by redundant design.
The odds of two (or more) redundant mechanical systems failing in precisely the same way at precisely the same moment are very, very small. The odds of identical software on two (or more) redundant systems reaching a passage-of-time bug at precisely the same moment are, by contrast, very much higher. True redundancy would require different software on each redundant sub-system.
Such a passage-of-time software issue wouldn't show up in most (or possibly any) testing scenarios. It is the sort of issue that robust QA and static code analysis are designed to catch. But in at least two separate systems on the 787 it has not been caught prior to software shipping. Meanwhile, every new technical post demonstrates the myriad ways in which non-software potential causes are mitigated by redundant design.
The odds of two (or more) redundant mechanical systems failing in precisely the same way at precisely the same moment are very, very small. The odds of identical software on two (or more) redundant systems reaching a passage-of-time bug at precisely the same moment are, by contrast, very much higher. True redundancy would require different software on each redundant sub-system.
Integer overflow is a specific type of issue common to many systems, but like you said - it is something that should be found with robust QA and analysis. The ability to shut down all generators at once from a single source seems like a risky design decision to me and I agree with your point about different software on 2 or more redundant sub systems.
My theory is that this was an accepted risk because the engine-driven fuel pumps would be more than enough in most phases of flight to keep the engines running, and you would still have 2 engines for redundancy. The APU would also restore AC power in lets say 30 seconds and you would then have electric fuel pumps as well.
I think there are several factors that could explain how loss of all AC power during takeoff could lead to a crash:
- The crash happened within 30 seconds - possibly too short for the APU to start, and the RAT doesn't power the AC electric fuel pumps
- The engine driven fuel pumps even if sufficient in level flight may have struggled during rotation - has Boeing tested an actual takeoff with only EDP feeding the engine while the fuel tanks are rotating and in extreme environments, or, have they only tested this statically?
- The takeoff was hot and heavy - combined with the landing gear stuck down and reduced thrust from loss of electric fuel pumps could this be enough?
Last edited by adfad; 18th June 2025 at 18:36 .
June 18, 2025, 19:10:00 GMT
permalink Post: 11905482
Perhaps two things might have exacerbated any electrical problems:
1) Electrical Grounding
Boeing whistleblower, Sam Salehpour claims that Boeing used improper techniques to ground electrical systems on the 787, which could lead to arcing, overheating, and potential fire hazards.
2) B787-9 RAT Certification
During B787-9 flight testing, The generator control unit in the RAT experienced a failure during flight testing. This failure led to a delay in the 787-9's certification, as the FAA needed to ensure the reliability and safety of the RAT system.
Based on my previous speculation regarding a BTB short, I wonder how aircraft engines might react in a situation where initially a transient power fault is followed by only battery power being available? As I understand it, there are no longer cable connections to the engines, given no valid inputs from the.thrust levers, what thrust mode would the FADEC's revert to?
1) Electrical Grounding
Boeing whistleblower, Sam Salehpour claims that Boeing used improper techniques to ground electrical systems on the 787, which could lead to arcing, overheating, and potential fire hazards.
2) B787-9 RAT Certification
During B787-9 flight testing, The generator control unit in the RAT experienced a failure during flight testing. This failure led to a delay in the 787-9's certification, as the FAA needed to ensure the reliability and safety of the RAT system.
Based on my previous speculation regarding a BTB short, I wonder how aircraft engines might react in a situation where initially a transient power fault is followed by only battery power being available? As I understand it, there are no longer cable connections to the engines, given no valid inputs from the.thrust levers, what thrust mode would the FADEC's revert to?
June 18, 2025, 19:15:00 GMT
permalink Post: 11905486
@syseng68k
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.
June 18, 2025, 19:37:00 GMT
permalink Post: 11905502
@
EDLB
No, we don't know if the fuel valves closed. Nor do we know if the RAT or APU started automatically.
No, we don't know if the fuel valves closed. Nor do we know if the RAT or APU started automatically.
Last edited by MarineEngineer; 18th June 2025 at 19:50 .
June 18, 2025, 21:30:00 GMT
permalink Post: 11905563
@syseng68k
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.
June 18, 2025, 22:38:00 GMT
permalink Post: 11905597
@syseng68k
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.
Consensus here is, that both engines where stopped by a closing fuel cut off valve, wich yields a fast loss of N2. The generators then shut down very quick as does the thrust in a few seconds. This is supported by the quick RAT extension which allowed the crew to control the flight. The APU did autostart too. A thrust changed with the thrust leaver to idle is much slower and would not result in the dramatic change in performance. Thrust set to idle will not engage the RAT since the electric generators would still work. So a thrust leaver changed to idle or any intervention by Autothrust (AT) would not yield to the RAT extension. Something or someone activated a fuel cut off. How and why that happened is the big question, the investigators have to answer.