njc
June 14, 2025, 15:06:00 GMT
permalink Post: 11901555

Quote:

Originally Posted by aeo

- The bogie could be explained by the Flap/Slat priority valve giving priority to the flaps if the PM suddenly realised his mistake and quickly put the flap lever back to the TO position and then selected the gear lever to UP. Those systems are both heavy hitters and would’ve sucked the life out of the CTR hydraulic system pumps.
- There is no way loss of AC (alleged RAT deployment) could've caused a spool down of both engines. Think QF A380 incident in SIN - The entire #1 engine wiring harness in the wing was completely severed and yet it continued (by design) to run at its previous thrust setting. They had to shut it down using a fire truck!
- History and design would dictate that a big 180 minutes ETOP’s twin such as the 787 having a dual engine failure or significant power loss at such a critical phase of flight would be a billion to one chance at best. Only the Airbus A400 had a software issue causing all 4 engine fuel shutoff valves to close causing it to crash killing the flight test crew - But this was during its development and flt testing.
- Wide body twin’s delivering in the region of 60,000 to 115,000 lbs of thrust at TO rarely , if at all, flame out from multiple bird strike(s) like the baby Bus’s and Boeing’s. If anyone has seen the frozen chickens at TO power video would know what I’m talking about. And the Fan Blade being ‘blown off’ as well. In both cases the engine was was able to maintain full TOGA thrust for significantly longer than the AI aircraft.

I can see that you are rejecting some hypotheses but I'm not totally clear if there's a hypothesis that you support. Pilot error? (I've also reviewed your other posts in the thread.)
As for history and design making a dual-engine failure a billion to one chance: I'd be more inclined to agree that it's unlikely to be what happened if the actual manufacturing of planes (Boeings in particular) and the maintenance procedures were both carried out "by the book" at all times by the manufacturer and the airlines... This is clearly not the case though.

Last edited by Saab Dastard; 14th June 2025 at 19:35 . Reason: reference to deleted posts removed

AndyJS
June 14, 2025, 15:46:00 GMT
permalink Post: 11901586

Quote:

Originally Posted by MaybeItIs

The existence of the video taken from a building near the flight path adds a lot of weight, to me.

Think about living next to a flight path. I do. I never take videos of passing planes. I doubt this video-taker did either.

But something incited him to pick up his phone (I guess) and start videoing, even before he could see the plane, which is out of view at the start. I suggest that he heard the RAT coming, knew it was totally out of the ordinary and thought it worth filming.

Why else would you film just another passing plane?

Also, looking at that video, I can see a "shadow" where the RAT would be. The RAT is very small compared with the landing gear, but there's something there. Largely lost to video compression, but it adds up.

And I can hear it, but not on every copy of that video. Try slowing the video down, but I don't know if that's reliable.

Maybe he was a plane-spotter and was filming a lot of take-offs. We don't know this was the only one he filmed, (unless it has already been established that this was the only take-off he videoed).

njc
June 14, 2025, 16:04:00 GMT
permalink Post: 11901609

Quote:

Originally Posted by Sailvi767

Thrust loss from a loss of fuel flow is near instantaneous.

I believe the point being made by the person you quoted was that the noise of the engines might have become much quieter before the start of the video with the possible RAT noise (the one where the plane passes almost overhead).

DaveReidUK
June 14, 2025, 16:07:00 GMT
permalink Post: 11901611

Quote:

Originally Posted by deltafox44

I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ?

There could be other reasons not connected with the aircraft systems,

But certainly loss of engines or electrics that caused deployment of the RAT (if that was the case) would be accompanied by a bunch of load-shedding, which would in all likelihood include the transponder.

Edit: Your own reply beat me to it ...

CharlieMike
June 14, 2025, 16:21:00 GMT
permalink Post: 11901619

Quote:

Originally Posted by OPENDOOR

During the nearly two years that elapsed between AF 447 disappearing and the recovery of the flight data recorders nobody suggested that the PF might have, unwittingly, flown the aircraft, stalled, into the ocean.
AI 171 may prove to also have a totally unpredicted cause.

This was my thinking too. Extending this thinking, the technical aspect is generally quite predictable, the human element not so.

I\x92m absolutely not speculating this is the case here, but could you not achieve the effect this flight suffered by just switching off the fuel control switches at 100ft on takeoff?

There are now so many assumptions based on the assumed state of flap, RAT etc that it\x92s becoming pointless speculation.

Kraftstoffvondesibel
June 14, 2025, 16:31:00 GMT
permalink Post: 11901627

Quote:

Originally Posted by Chu Chu

Is there any chance the sound on the video could be from a damaged engine? Not suggesting that's likely -- just seems like the least improbable alternative explanation.

No, it would have looked very different in the analysis.

About the engine spool down not present in the audio:
I did not know engines spooled down that quickly if shut down in the air, I am not an aerodynamicist, but it makes sense it would happen with all the drag. I had a mental sound in my head from normal shutdowns, and action movies I guess.
That means my point about it being no spool down detectable in the audio really doesn\x92t matter.

Is there known numbers for timing RAT deployment or spool up? Because there is no sign of that either in the audio.

I will have a go at a few after take-off videos and use some alternative comparison techniques to see if I can say anything with certainty about any engine power being present or not.

My hunch, after analyzing a few landing videos with and without the RAT with the standard audio analyzers tells me the engines were at similar or below rpm/noise making level/thrust compared to a normal landing, and that they had already completely spooled down(which you guys suggest is to be expected to happen much more quickly than I thought, so maybe doesn\x92t say much) when the video with audio starts.

deltafox44
June 14, 2025, 16:35:00 GMT
permalink Post: 11901632

Quote:

Originally Posted by Jonty

I have tried a couple of times but it keeps getting removed as some sort of "AI construct" by the moderators.
This is a screen shot taken from the Video thats posted on the BBC Verify website, that they have verified as authentic.
https://www.bbc.co.uk/news/articles/c626y121rxxo
I still can't see a RAT deployed.

Given the quality of the video you cannot see that the RAT is NOT deployed either

Jonty
June 14, 2025, 16:41:00 GMT
permalink Post: 11901643

Quote:

Originally Posted by deltafox44

Given the quality of the video you cannot see that the RAT is NOT deployed either

I disagree. I think the lines of the underneath of the aircraft are quite obvious and its clear there's no RAT. Given it drops on the wing to body fairing just behind the main landing gear on the starboard side of the aircraft, it should be very obvious in this photo.

sorvad
June 14, 2025, 16:56:00 GMT
permalink Post: 11901658

Quote:

Originally Posted by Jonty

How about here….

aeo
June 14, 2025, 17:01:00 GMT
permalink Post: 11901660

Fair point Pip.

I just saw a picture of the tail (taken from above) and the APU door is partially open?

I believe the 787 has a similar APU automatic start function with loss of AC power just like the 777. It looks like the APU door was starting to open to allow for an auto start.. Similar situation to that BA 777 that landed short in LHR due to fuel icing.

Its looking more and more like an AC power loss.

Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment.

galaxy flyer
June 14, 2025, 17:02:00 GMT
permalink Post: 11901661

Here’s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side.

DaveReidUK
June 14, 2025, 17:07:00 GMT
permalink Post: 11901665

Quote:

Originally Posted by Jonty

The status of the engines/hydraulics/electrics/RAT is likely to be one of the first findings when the FDR is read.

So get the arguments in quick as we'll probably know definitively within a couple of days.

Kbboca
June 14, 2025, 17:12:00 GMT
permalink Post: 11901667

Quote:

Originally Posted by aeo

Fair point Pip.

Its looking more and more like an AC power loss.

Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment.

Thank you for commenting on the DGAC order. I'm just a lowly SLF, but it struck me that the DGAC seemed to be focusing initially on fuel and power issues. I've been surprised there's been so little comment.

Someone Somewhere
June 14, 2025, 17:35:00 GMT
permalink Post: 11901681

Quote:

Originally Posted by aeo

What concerns me a little bit is if indeed AC power is lost, would the suction feed inlets in the wing tanks provide enough fuel flow to maintain TO thrust?

I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation...

Could this cause a degradation of thrust? Even the slightest decrease..

A slight decrease in two engines is still far better than a loss of one engine, and that has to be manageable.

Quote:

Originally Posted by deltafox44

787 has four main AC buses. Cannot find information on the standby/emergency buses but I would probably expect two.

There's a list of equipment operable on battery/RAT here, but I'm not sure which (if any) is the transponder (26:10):

Quote:

Originally Posted by stn

Is that with the B787? Because all buses can fly without APU. Those days at work are ####ty, tho

I think the post you replied to was in the context of mandating APU on for takeoff. Could just say "on if available", though.

Quote:

Originally Posted by A0283

Have been going through the thread but cannot remember if we discussed and excluded the gear pins? There seems to have been more than enough turnaround time.

I can't see how gear pins would stop you doing anything more than raising the gear. They don't cause engine failure, RAT extension, or uncommanded flap retraction.

If you had gear pins and an engine loss, I could maybe see climb rate being zero or slightly negative. Not the brick impression we see here.

Quote:

Originally Posted by TehDehZeh

There have been a couple comments regarding the tilt of the bogies not corresponding to the landing configuration which have taken this as an indicator for an attempted (but failed) retraction.
I don't think anybody has so far confirmed which of the two positions the bogie would have without hydraulic pressure, but I would strongly think it is the one used in the retraction/extension cycle and not the landing configuration, for the simple reason that otherwise the gravity drop would potentially not work (I assume it is tilted for the stowing because it would otherwise not fit).
Maybe someone with concrete knowledge can confirm this?

This would then only confirm that the bogies were unpressurized (likely because of loss of hydraulics, but of course could also still be a partial retraction that stopped for some reason)

I did raise this earlier... FCOMs say that the bogies remain in the stowed tilt after a gravity drop, but I don't know if that's because the gear has springs to hold it that way without hydraulics, or just they close the valves on the hydraulics so it stays in the last commanded position without pressure.

HumbleDeer
June 14, 2025, 17:37:00 GMT
permalink Post: 11901683

Quote:

Originally Posted by galaxy flyer

Here\x92s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side.

Considering everything that's possibly to be found in the vicinity of the plane in the picture, I don't think we can conclusively say that's the RAT deployed.

Compton3fox
June 14, 2025, 17:53:00 GMT
permalink Post: 11901693

Quote:

Originally Posted by Kraftstoffvondesibel

I have seen your previous posts about this, and I happen to agree. Visually, as a lay man non visuals expert, I am in your \xabcamp.\xbb

However, the rat is small, and the artifacts are plentiful. Small sensor, compressed video, compressed upload, zoom, it is in short an awful source.

However, the RAT is a much better noisemaker, and the audio signature is much more obvious than it\x92s visual appearance in this case, and though the recording isn\x92t fantastic quality, there was more than enough information there to objectively conclude the RAT is out. And that is my professional, on the weekend, opinion.

I want to ask a pretty frank question for all of you, and I hope it is ok, from an audio specialist non-pilot:
Provided the engines spooled down. Provided the RAT is out. (There are no explosions, no bird strikes.)
Isn\x92t software and previous electrical failures a red herring too?Would anything but a complete fuel shut off lead to this result? That still leaves everything from the Fate is the Hunter plot, to Airbus A350 center consoles and Alaska 2059 open as root causes.

That leads to the next question.. Is there any system on the 787 that CAN shutdown the engines. We know there is at least one... But the A/C needs to be ground mode. However, if would not be the 1st time a system that should not deploy when the A/C is airborne, does! LaudaAir out from BKK is one example...

Compton3fox
June 14, 2025, 18:01:00 GMT
permalink Post: 11901698

Quote:

Originally Posted by Jonty

We can debate over a poor quality photo but the audio evidence presented earlier today is pretty conclusive.. The RAT was out.

lighttwin2
June 14, 2025, 18:04:00 GMT
permalink Post: 11901699

There are a few comments along the lines of "it is incredibly unlikely that..." this is selection bias in reverse. Something incredibly unlikely has happened, and it's contained in this sample set.

To summarise some known facts about the TCMA system:

1) TCMA will shut down an engine if:

It believes via multiple redundant sensors indicate the aircraft is on the ground
It detects engine power in excess of that set by the thrust levers - subject to a margin to account for engine performance variation - that is determined to be a runaway condition

2) In 2019 an ANA pilot was able to confuse the TCMA by rapidly moving the thrust levers into reverse, to forward and back into reverse again. This caused both engines to shutdown.

3) Since then the TCMA should have been updated/fixed (and indeed the software will have been updated by SB since the a/c was delivered, to detect a wider range of runaway conditions)

And speculation:

4) It may be possible - given the close timings - that a TCMA activation occurred as the a/c was leaving the ground, with kinetic energy and spool down time getting the a/c from the ground to its peak height

In the recent BA LGW incident the PF reduced thrust to idle at V1, then added thrust back, then committed to a RTO. I wonder if something similar could have occurred:

In error, PF reduces power to idle at a speed approaching V1
Engines begin reducing power, but n1 reduces more slowly than the TCMA system is expecting (perhaps because the TCMA margin is calculated when the a/c is stationary, but at 170kt a turbofan will spool down more slowly due to the ram air / windmill effect)
TCMA detects a runaway condition - while a/c is on the ground - and cuts off fuel via the relay circuit
PF decides to commit to takeoff and rotates, not knowing that TCMA has already activated
10-15s after rotation, n1 has now dropped below minimums for electrical generation. Electrics fail, final transponder signal is sent, and RAT is deployed

Obviously this should not be possible, and there are other possibilities.

jimtx
June 14, 2025, 18:06:00 GMT
permalink Post: 11901700

Quote:

Originally Posted by galaxy flyer

Here\x92s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side.

I don't think you can infer no hyd pressure from the spoiler "float. I've read elsewhere that they are biased up slightly to be used in slow speed roll control.

appruser
June 14, 2025, 18:11:00 GMT
permalink Post: 11901703

Quote:

Originally Posted by xetroV

Or he may have heard the RAT spooling up. Valuable as a witness account may be, we\x92ll have to wait for FDR and CVR data and/or wreckage analysis before drawing conclusions.

Good point. In the survivor's narrative, the sequence is: 5-10s after takeoff -> plane seemed stuck in the air -> green & white light came on -> they "gave race for more takeoff" (revved up) -> entered straight into (hostel).

njc June 14, 2025, 15:06:00 GMT permalink Post: 11901555	Quote: Originally Posted by aeo - The bogie could be explained by the Flap/Slat priority valve giving priority to the flaps if the PM suddenly realised his mistake and quickly put the flap lever back to the TO position and then selected the gear lever to UP. Those systems are both heavy hitters and would’ve sucked the life out of the CTR hydraulic system pumps. - There is no way loss of AC (alleged RAT deployment) could've caused a spool down of both engines. Think QF A380 incident in SIN - The entire #1 engine wiring harness in the wing was completely severed and yet it continued (by design) to run at its previous thrust setting. They had to shut it down using a fire truck! - History and design would dictate that a big 180 minutes ETOP’s twin such as the 787 having a dual engine failure or significant power loss at such a critical phase of flight would be a billion to one chance at best. Only the Airbus A400 had a software issue causing all 4 engine fuel shutoff valves to close causing it to crash killing the flight test crew - But this was during its development and flt testing. - Wide body twin’s delivering in the region of 60,000 to 115,000 lbs of thrust at TO rarely , if at all, flame out from multiple bird strike(s) like the baby Bus’s and Boeing’s. If anyone has seen the frozen chickens at TO power video would know what I’m talking about. And the Fan Blade being ‘blown off’ as well. In both cases the engine was was able to maintain full TOGA thrust for significantly longer than the AI aircraft. I can see that you are rejecting some hypotheses but I'm not totally clear if there's a hypothesis that you support. Pilot error? (I've also reviewed your other posts in the thread.) As for history and design making a dual-engine failure a billion to one chance: I'd be more inclined to agree that it's unlikely to be what happened if the actual manufacturing of planes (Boeings in particular) and the maintenance procedures were both carried out "by the book" at all times by the manufacturer and the airlines... This is clearly not the case though. Last edited by Saab Dastard; 14th June 2025 at 19:35 . Reason: reference to deleted posts removed
AndyJS June 14, 2025, 15:46:00 GMT permalink Post: 11901586	Quote: Originally Posted by MaybeItIs The existence of the video taken from a building near the flight path adds a lot of weight, to me. Think about living next to a flight path. I do. I never take videos of passing planes. I doubt this video-taker did either. But something incited him to pick up his phone (I guess) and start videoing, even before he could see the plane, which is out of view at the start. I suggest that he heard the RAT coming, knew it was totally out of the ordinary and thought it worth filming. Why else would you film just another passing plane? Also, looking at that video, I can see a "shadow" where the RAT would be. The RAT is very small compared with the landing gear, but there's something there. Largely lost to video compression, but it adds up. And I can hear it, but not on every copy of that video. Try slowing the video down, but I don't know if that's reliable. Maybe he was a plane-spotter and was filming a lot of take-offs. We don't know this was the only one he filmed, (unless it has already been established that this was the only take-off he videoed).
njc June 14, 2025, 16:04:00 GMT permalink Post: 11901609	Quote: Originally Posted by Sailvi767 Thrust loss from a loss of fuel flow is near instantaneous. I believe the point being made by the person you quoted was that the noise of the engines might have become much quieter before the start of the video with the possible RAT noise (the one where the plane passes almost overhead).
DaveReidUK June 14, 2025, 16:07:00 GMT permalink Post: 11901611	Quote: Originally Posted by deltafox44 I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ? There could be other reasons not connected with the aircraft systems, But certainly loss of engines or electrics that caused deployment of the RAT (if that was the case) would be accompanied by a bunch of load-shedding, which would in all likelihood include the transponder. Edit: Your own reply beat me to it ...
CharlieMike June 14, 2025, 16:21:00 GMT permalink Post: 11901619	Quote: Originally Posted by OPENDOOR During the nearly two years that elapsed between AF 447 disappearing and the recovery of the flight data recorders nobody suggested that the PF might have, unwittingly, flown the aircraft, stalled, into the ocean. AI 171 may prove to also have a totally unpredicted cause. This was my thinking too. Extending this thinking, the technical aspect is generally quite predictable, the human element not so. I\x92m absolutely not speculating this is the case here, but could you not achieve the effect this flight suffered by just switching off the fuel control switches at 100ft on takeoff? There are now so many assumptions based on the assumed state of flap, RAT etc that it\x92s becoming pointless speculation.
Kraftstoffvondesibel June 14, 2025, 16:31:00 GMT permalink Post: 11901627	Quote: Originally Posted by Chu Chu Is there any chance the sound on the video could be from a damaged engine? Not suggesting that's likely -- just seems like the least improbable alternative explanation. No, it would have looked very different in the analysis. About the engine spool down not present in the audio: I did not know engines spooled down that quickly if shut down in the air, I am not an aerodynamicist, but it makes sense it would happen with all the drag. I had a mental sound in my head from normal shutdowns, and action movies I guess. That means my point about it being no spool down detectable in the audio really doesn\x92t matter. Is there known numbers for timing RAT deployment or spool up? Because there is no sign of that either in the audio. I will have a go at a few after take-off videos and use some alternative comparison techniques to see if I can say anything with certainty about any engine power being present or not. My hunch, after analyzing a few landing videos with and without the RAT with the standard audio analyzers tells me the engines were at similar or below rpm/noise making level/thrust compared to a normal landing, and that they had already completely spooled down(which you guys suggest is to be expected to happen much more quickly than I thought, so maybe doesn\x92t say much) when the video with audio starts.
deltafox44 June 14, 2025, 16:35:00 GMT permalink Post: 11901632	Quote: Originally Posted by Jonty I have tried a couple of times but it keeps getting removed as some sort of "AI construct" by the moderators. This is a screen shot taken from the Video thats posted on the BBC Verify website, that they have verified as authentic. https://www.bbc.co.uk/news/articles/c626y121rxxo I still can't see a RAT deployed. Given the quality of the video you cannot see that the RAT is NOT deployed either
Jonty June 14, 2025, 16:41:00 GMT permalink Post: 11901643	Quote: Originally Posted by deltafox44 Given the quality of the video you cannot see that the RAT is NOT deployed either I disagree. I think the lines of the underneath of the aircraft are quite obvious and its clear there's no RAT. Given it drops on the wing to body fairing just behind the main landing gear on the starboard side of the aircraft, it should be very obvious in this photo.
sorvad June 14, 2025, 16:56:00 GMT permalink Post: 11901658	Quote: Originally Posted by Jonty I disagree. I think the lines of the underneath of the aircraft are quite obvious and its clear there's no RAT. Given it drops on the wing to body fairing just behind the main landing gear on the starboard side of the aircraft, it should be very obvious in this photo. How about here….
aeo June 14, 2025, 17:01:00 GMT permalink Post: 11901660	Fair point Pip. I just saw a picture of the tail (taken from above) and the APU door is partially open? I believe the 787 has a similar APU automatic start function with loss of AC power just like the 777. It looks like the APU door was starting to open to allow for an auto start.. Similar situation to that BA 777 that landed short in LHR due to fuel icing. Its looking more and more like an AC power loss. Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment.
galaxy flyer June 14, 2025, 17:02:00 GMT permalink Post: 11901661	Here’s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side.
DaveReidUK June 14, 2025, 17:07:00 GMT permalink Post: 11901665	Quote: Originally Posted by Jonty I disagree. I think the lines of the underneath of the aircraft are quite obvious and its clear there's no RAT. Given it drops on the wing to body fairing just behind the main landing gear on the starboard side of the aircraft, it should be very obvious in this photo. The status of the engines/hydraulics/electrics/RAT is likely to be one of the first findings when the FDR is read. So get the arguments in quick as we'll probably know definitively within a couple of days.
Kbboca June 14, 2025, 17:12:00 GMT permalink Post: 11901667	Quote: Originally Posted by aeo Fair point Pip. Its looking more and more like an AC power loss. Interestingly, the DGAC order for AI maintenance to check those random 787 systems are all associated in some way to an automatic RAT deployment. Thank you for commenting on the DGAC order. I'm just a lowly SLF, but it struck me that the DGAC seemed to be focusing initially on fuel and power issues. I've been surprised there's been so little comment.
Someone Somewhere June 14, 2025, 17:35:00 GMT permalink Post: 11901681	Quote: Originally Posted by aeo What concerns me a little bit is if indeed AC power is lost, would the suction feed inlets in the wing tanks provide enough fuel flow to maintain TO thrust? I know the system is designed to achieve this in a situation where all of the AC powered boost pumps are lost. But what about in a real situation... Could this cause a degradation of thrust? Even the slightest decrease.. A slight decrease in two engines is still far better than a loss of one engine, and that has to be manageable. Quote: Originally Posted by deltafox44 I did read and search this thread, but I found nothing about ADS-B loss just before the end of the runway and at 71 ft high, according to FR24. ADS-B coverage is poor on the ground on the north-east part of the airfield (hence the fake news about taking off from the intersection) but I don't think it would be lost once airborne, except if it has been shut off... electrical failure ? more precisely, loss of the two Main AC buses (ADS-B not powered by Standby AC) 787 has four main AC buses. Cannot find information on the standby/emergency buses but I would probably expect two. There's a list of equipment operable on battery/RAT here, but I'm not sure which (if any) is the transponder (26:10): You Tube Quote: Originally Posted by stn Is that with the B787? Because all buses can fly without APU. Those days at work are ####ty, tho I think the post you replied to was in the context of mandating APU on for takeoff. Could just say "on if available", though. Quote: Originally Posted by A0283 Have been going through the thread but cannot remember if we discussed and excluded the gear pins? There seems to have been more than enough turnaround time. I can't see how gear pins would stop you doing anything more than raising the gear. They don't cause engine failure, RAT extension, or uncommanded flap retraction. If you had gear pins and an engine loss, I could maybe see climb rate being zero or slightly negative. Not the brick impression we see here. Quote: Originally Posted by TehDehZeh There have been a couple comments regarding the tilt of the bogies not corresponding to the landing configuration which have taken this as an indicator for an attempted (but failed) retraction. I don't think anybody has so far confirmed which of the two positions the bogie would have without hydraulic pressure, but I would strongly think it is the one used in the retraction/extension cycle and not the landing configuration, for the simple reason that otherwise the gravity drop would potentially not work (I assume it is tilted for the stowing because it would otherwise not fit). Maybe someone with concrete knowledge can confirm this? This would then only confirm that the bogies were unpressurized (likely because of loss of hydraulics, but of course could also still be a partial retraction that stopped for some reason) I did raise this earlier... FCOMs say that the bogies remain in the stowed tilt after a gravity drop, but I don't know if that's because the gear has springs to hold it that way without hydraulics, or just they close the valves on the hydraulics so it stays in the last commanded position without pressure.
HumbleDeer June 14, 2025, 17:37:00 GMT permalink Post: 11901683	Quote: Originally Posted by galaxy flyer Here\x92s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side. Considering everything that's possibly to be found in the vicinity of the plane in the picture, I don't think we can conclusively say that's the RAT deployed.
Compton3fox June 14, 2025, 17:53:00 GMT permalink Post: 11901693	Quote: Originally Posted by Kraftstoffvondesibel I have seen your previous posts about this, and I happen to agree. Visually, as a lay man non visuals expert, I am in your \xabcamp.\xbb However, the rat is small, and the artifacts are plentiful. Small sensor, compressed video, compressed upload, zoom, it is in short an awful source. However, the RAT is a much better noisemaker, and the audio signature is much more obvious than it\x92s visual appearance in this case, and though the recording isn\x92t fantastic quality, there was more than enough information there to objectively conclude the RAT is out. And that is my professional, on the weekend, opinion. I want to ask a pretty frank question for all of you, and I hope it is ok, from an audio specialist non-pilot: Provided the engines spooled down. Provided the RAT is out. (There are no explosions, no bird strikes.) Isn\x92t software and previous electrical failures a red herring too?Would anything but a complete fuel shut off lead to this result? That still leaves everything from the Fate is the Hunter plot, to Airbus A350 center consoles and Alaska 2059 open as root causes. That leads to the next question.. Is there any system on the 787 that CAN shutdown the engines. We know there is at least one... But the A/C needs to be ground mode. However, if would not be the 1st time a system that should not deploy when the A/C is airborne, does! LaudaAir out from BKK is one example...
Compton3fox June 14, 2025, 18:01:00 GMT permalink Post: 11901698	Quote: Originally Posted by Jonty I disagree. I think the lines of the underneath of the aircraft are quite obvious and its clear there's no RAT. Given it drops on the wing to body fairing just behind the main landing gear on the starboard side of the aircraft, it should be very obvious in this photo. We can debate over a poor quality photo but the audio evidence presented earlier today is pretty conclusive.. The RAT was out.
lighttwin2 June 14, 2025, 18:04:00 GMT permalink Post: 11901699	There are a few comments along the lines of "it is incredibly unlikely that..." this is selection bias in reverse. Something incredibly unlikely has happened, and it's contained in this sample set. To summarise some known facts about the TCMA system: 1) TCMA will shut down an engine if: It believes via multiple redundant sensors indicate the aircraft is on the ground It detects engine power in excess of that set by the thrust levers - subject to a margin to account for engine performance variation - that is determined to be a runaway condition 2) In 2019 an ANA pilot was able to confuse the TCMA by rapidly moving the thrust levers into reverse, to forward and back into reverse again. This caused both engines to shutdown. 3) Since then the TCMA should have been updated/fixed (and indeed the software will have been updated by SB since the a/c was delivered, to detect a wider range of runaway conditions) And speculation: 4) It may be possible - given the close timings - that a TCMA activation occurred as the a/c was leaving the ground, with kinetic energy and spool down time getting the a/c from the ground to its peak height In the recent BA LGW incident the PF reduced thrust to idle at V1, then added thrust back, then committed to a RTO. I wonder if something similar could have occurred: In error, PF reduces power to idle at a speed approaching V1 Engines begin reducing power, but n1 reduces more slowly than the TCMA system is expecting (perhaps because the TCMA margin is calculated when the a/c is stationary, but at 170kt a turbofan will spool down more slowly due to the ram air / windmill effect) TCMA detects a runaway condition - while a/c is on the ground - and cuts off fuel via the relay circuit PF decides to commit to takeoff and rotates, not knowing that TCMA has already activated 10-15s after rotation, n1 has now dropped below minimums for electrical generation. Electrics fail, final transponder signal is sent, and RAT is deployed Obviously this should not be possible, and there are other possibilities.
jimtx June 14, 2025, 18:06:00 GMT permalink Post: 11901700	Quote: Originally Posted by galaxy flyer Here\x92s another screen shot from an unknown source showing both the RAT and a bit of symmetric spoiler float due to lack of hydraulic pressure to close side. I don't think you can infer no hyd pressure from the spoiler "float. I've read elsewhere that they are biased up slightly to be used in slow speed roll control.
appruser June 14, 2025, 18:11:00 GMT permalink Post: 11901703	Quote: Originally Posted by xetroV Or he may have heard the RAT spooling up. Valuable as a witness account may be, we\x92ll have to wait for FDR and CVR data and/or wreckage analysis before drawing conclusions. Good point. In the survivor's narrative, the sequence is: 5-10s after takeoff -> plane seemed stuck in the air -> green & white light came on -> they "gave race for more takeoff" (revved up) -> entered straight into (hostel).

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