2025-06-13T09:03:00
permalink Post: 11900213
https://assets.publishing.service.go...211_G-POWN.pdf
One example of fuel contamination causing a significant loss of thrust on both engines at low altitude.
But it seems extremely unlikely for contaminated fuel to impact both engines at exactly the same time, with no asymmetry and no surges or smoke.
What can cause a sudden catastrophic loss of thrust on both engines at exactly the same time?
Birds (but no apparent surges)
Inadvertent movement of the fuel cut off switches (which would be an incredible error but I suppose it could conceivably be muscle memory having done so recently after the last leg…weirder things have happened. Remember the 767 events of the late 80s)
Intentional shutdown of the engines (pilot suicide has happened before)
Some catastrophic electrical/FADEC/engine interface failure (which I highly doubt is feasible in a modern 1309 aircraft)
I can’t think of any others…
One example of fuel contamination causing a significant loss of thrust on both engines at low altitude.
But it seems extremely unlikely for contaminated fuel to impact both engines at exactly the same time, with no asymmetry and no surges or smoke.
What can cause a sudden catastrophic loss of thrust on both engines at exactly the same time?
Birds (but no apparent surges)
Inadvertent movement of the fuel cut off switches (which would be an incredible error but I suppose it could conceivably be muscle memory having done so recently after the last leg…weirder things have happened. Remember the 767 events of the late 80s)
Intentional shutdown of the engines (pilot suicide has happened before)
Some catastrophic electrical/FADEC/engine interface failure (which I highly doubt is feasible in a modern 1309 aircraft)
I can’t think of any others…
I cant think of any reason for electrical failure and "no thrust" (as per statements) without any visual cues other than (a) suicide, or (b) starvation. Is there any electrical failure that can cause fuel valves to close? I dont fly Boeing, so can any Dreamliner driver explain what conditions could trigger an overspeed and auto engine shutdown (quote from Google below)? Would short runway, and hot/low QNH do it? Also, what happened to the order demanding a full power down/recycle every 51 days?
The EEC has build in protections to protect the engine. One of these protections is the Engine Overspeed Protection, when the core engine exceeds 120% the EEC shuts off the fuel to the applicable engine.
Last edited by Arrowhead; 13th Jun 2025 at 09:46 .
2025-06-13T11:32:00
permalink Post: 11900388
One has to assume that, given the seeming lack of lateral deviation from the flight path, and with no obvious yawing or rudder input visible on the videos, there's only two realistic conclusions here? Simultaneous dual engine failure of unknown cause if the RAT was indeed deployed; or flaps reduced too early leading to a stall if the RAT wasn't deployed.
Evidence in this thread would lean me toward the RAT deployed and therefore dual engine out scenario. As for the cause of that, well, only a couple of likely scenarios exist that could cause simultaneous shutdown of both engines, including mistaken or intentional use of the fuel cutoff levers.
Evidence in this thread would lean me toward the RAT deployed and therefore dual engine out scenario. As for the cause of that, well, only a couple of likely scenarios exist that could cause simultaneous shutdown of both engines, including mistaken or intentional use of the fuel cutoff levers.
2025-06-13T18:58:00
permalink Post: 11900812
OK, another hour spent going through all the posts since I was on last night...
I won't quote the relevant posts as they go back ~15 pages, but a few more comments:
TAT errors affecting N1 power set: The FADEC logic (BTW, this is pretty much common on all Boeing FADEC) will use aircraft TAT if it agrees with the dedicated engine inlet temp probe - but if they differ it will use the engine probe . The GE inlet temp probe is relatively simple and unheated, so (unlike a heated probe) a blocked or contaminated probe will still read accurately - just with greater 'lag' to actual temperature changes.
TCMA - first off, I have to admit that this does look rather like an improper TCMA activation, but that is very, very unlikely. For those who don't know, TCMA is a system to shutdown a runaway engine that's not responding to the thrust lever - basic logic is an engine at high power with the thrust lever at/near idle, and the engine not decelerating. However, TCMA is only active on the ground (unfamiliar with the 787/GEnx TCMA air/ground logic - on the 747-8 we used 5 sources of air/ground - three Radio Altimeters and two Weight on Wheels - at least one of each had to indicate ground to enable TCMA). TCMA will shutdown the engine via the N2 overspeed protection - nearly instantaneous. For this to be TCMA, it would require at least two major failures - improper air ground indication or logic, and improper TCMA activation logic (completely separate software paths in the FADEC). Like I said, very, very unlikely.
Fuel contamination/filter blockage: The fuel filters have a bypass - if the delta P across the filter becomes excessive, the filter bypasses and provides the contaminated fuel to the engine. Now this contaminated fuel could easy foul up the fuel metering unit causing a flameout, but to happen to two engines at virtually the same time would be tremendous unlikely.
Auto Thrust thrust lever retard - the TO lockup in the logic makes this very unlikely (it won't unlock below (IIRC) 400 ft., and even that requires a separate pilot action such as a mode select change or thrust lever movement). And if it did somehow happen, all the pilot needs to do is push the levers back up.
Engine parameters on the FDR: I don't know what exactly is on the 787 FDR with regards to engine parameters, but rest assured that there is plenty of engine data that gets recorded - most at one/second. Getting the FDR readout from a modern FDR is almost an embarrassment of riches. Assuming the data is intact, we'll soon have a very good idea of what the engines were doing
I won't quote the relevant posts as they go back ~15 pages, but a few more comments:
TAT errors affecting N1 power set: The FADEC logic (BTW, this is pretty much common on all Boeing FADEC) will use aircraft TAT if it agrees with the dedicated engine inlet temp probe - but if they differ it will use the engine probe . The GE inlet temp probe is relatively simple and unheated, so (unlike a heated probe) a blocked or contaminated probe will still read accurately - just with greater 'lag' to actual temperature changes.
TCMA - first off, I have to admit that this does look rather like an improper TCMA activation, but that is very, very unlikely. For those who don't know, TCMA is a system to shutdown a runaway engine that's not responding to the thrust lever - basic logic is an engine at high power with the thrust lever at/near idle, and the engine not decelerating. However, TCMA is only active on the ground (unfamiliar with the 787/GEnx TCMA air/ground logic - on the 747-8 we used 5 sources of air/ground - three Radio Altimeters and two Weight on Wheels - at least one of each had to indicate ground to enable TCMA). TCMA will shutdown the engine via the N2 overspeed protection - nearly instantaneous. For this to be TCMA, it would require at least two major failures - improper air ground indication or logic, and improper TCMA activation logic (completely separate software paths in the FADEC). Like I said, very, very unlikely.
Fuel contamination/filter blockage: The fuel filters have a bypass - if the delta P across the filter becomes excessive, the filter bypasses and provides the contaminated fuel to the engine. Now this contaminated fuel could easy foul up the fuel metering unit causing a flameout, but to happen to two engines at virtually the same time would be tremendous unlikely.
Auto Thrust thrust lever retard - the TO lockup in the logic makes this very unlikely (it won't unlock below (IIRC) 400 ft., and even that requires a separate pilot action such as a mode select change or thrust lever movement). And if it did somehow happen, all the pilot needs to do is push the levers back up.
Engine parameters on the FDR: I don't know what exactly is on the 787 FDR with regards to engine parameters, but rest assured that there is plenty of engine data that gets recorded - most at one/second. Getting the FDR readout from a modern FDR is almost an embarrassment of riches. Assuming the data is intact, we'll soon have a very good idea of what the engines were doing
2025-06-13T21:33:00
permalink Post: 11900929
Something I've been wondering about this accident is the phase of the flight where the apparent power loss happened. It seems like the engines were running normally through the takeoff, until the aircraft lifted off the ground. After that the loss of power seemed to happen very quickly.
Could there be a scenario where aircraft's fuel supply is interrupted by change in aircraft's attitude (for example faulty pumps, partially contaminated fuel)? Frankly I have no idea how 787's fuel pumps operate, or if fuel contamination could happen in a way that blocks the flow only when aircraft reaches certain nose-up attitude.
Could there be a scenario where aircraft's fuel supply is interrupted by change in aircraft's attitude (for example faulty pumps, partially contaminated fuel)? Frankly I have no idea how 787's fuel pumps operate, or if fuel contamination could happen in a way that blocks the flow only when aircraft reaches certain nose-up attitude.
2025-06-13T21:51:00
permalink Post: 11900947
The probability of something (or maybe several somethings) being a primary cause of this crash is near unity. The question, what possible causes are likely?
To take a specific item of speculation that might case dual engine rollback, fuel contamination was suggested. I don't remember all the points made in this context, but some were: no other aircraft presumably using the same fuel supply had issues; why would both engines apparently fail near simultaneously?; why would they fail just after rotation?; and so on. The consensus seemed to be, not impossible, but unlikely (presumably in the sense I just described).
Accidental (or even deliberate) fuel shutoff was also suggested. Again, the consensus seemed to be, possible, but unlikely for this type, since previous ergonomic causes of such accidental shutoff had long since been addressed.
2025-06-14T01:16:00
permalink Post: 11901055
Trying repeatedly to follow the whole thread plus updates but loading on the iPhone constantly jumps backwards and forwards making it a struggle to cover everything.
Two points which may or may not have relevance. One is just before the final crash, a dark-looking cover(?) flies up into the air. Could this be the first contact with sound that the surviving passenger alleges he heard?
Secondly the cost of aviation fuel seems to be comparatively more expensive in India than either Japan (leg before) or the UK (following leg). Would this effect refuelling procedures within India, supposing a company directive to save when possible?
(Frequent long-haul passenger.)
Two points which may or may not have relevance. One is just before the final crash, a dark-looking cover(?) flies up into the air. Could this be the first contact with sound that the surviving passenger alleges he heard?
Secondly the cost of aviation fuel seems to be comparatively more expensive in India than either Japan (leg before) or the UK (following leg). Would this effect refuelling procedures within India, supposing a company directive to save when possible?
(Frequent long-haul passenger.)
But let’s run with it. Less fuel = lighter load. So…how does that make lift off/climb a more difficult procedure??? It shouid have been easier. How does that result in rapid loss of lift? Did they finish their tablespoon of fuel?
Or - if you are hinting at fuel contamination by being “watered down” somehow…why were no other aircraft affected? You might wish to consider Cathay Pacific flight 780, which suffered a serious fuel contamination incident. The problem was not initialiy detectable, but some engine underperformance was noted in one engine fairly early into the flght. The problems compounded during the flght from Surabaya to Hong Kong, culminating in complete engine shutdown. Fortunately, due to the experience and skill of Captain and Copilot, they just - only just - managed to land safely in Hong Kong. Point is - a crash scenario did not unfold in seconds.
Last edited by Blake777; 14th Jun 2025 at 01:48 .
2025-06-14T03:12:00
permalink Post: 11901105
Ex petroleum lab technician and tank farm sampler here. We would occasionally get fuel samples from crashed aircraft to test for contamination. One test was for water and sediment/microorganism sludge.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it’s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it’s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
6 users liked this post.
2025-06-14T03:35:00
permalink Post: 11901109
Ex petroleum lab technician and tank farm sampler here.
Jetstar Boeing 787-8 VH-VKJ General Electric GEnx-1B Engine Biocide Serious Incident near Kansai
On 29 March 2019 the No 1 General Electric GEnx-1B engine of Jetstar Airways Boeing 787-8 VH-VKJ , flying from Cairns , Australia to Osaka Kansai Internationa l, Japan, fell below idle during the descent at an altitude of about 16,000 ft for 8 seconds. The No 2 engine then fell below idle too for 81 seconds. The aircraft safely landed at Kansai International less than 30 minutes later.2025-06-14T04:00:00
permalink Post: 11901123
Ex petroleum lab technician and tank farm sampler here. We would occasionally get fuel samples from crashed aircraft to test for contamination. One test was for water and sediment/microorganism sludge.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
Fuel contamination is certainly a valid theory. The main thing working against it is that it would seem from the aircraft's flight path is that both engines failed at exactly the same time and lost thrust simultaneously. The chances of this are non zero, but remote. I say that as there appears to be no yaw, or other controlling of the aircraft - either by pilot or automation - that would suggest an asymmetric thrust scenario, even for a few seconds.
Yes, Jetstar had the biocide issue but did not immediately hit both engines within seconds of each other.
It's my understanding that both engines draw fuel from independent sources during that time (which may be fed from a common source (eg central tank). But again, the odds of both failing at the exact same instant is low, but not zero.
2025-06-14T06:31:00
permalink Post: 11901163
Ex petroleum lab technician and tank farm sampler here. We would occasionally get fuel samples from crashed aircraft to test for contamination. One test was for water and sediment/microorganism sludge.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
In this accident, fuel contamination continues to be dismissed as a cause, because no other aircraft have reported issues. But there has been no discussion regarding the airport's fuel storage, transfer, or filtration systems. Water and sediment naturally settles at the bottom of fuel storage tanks. If this aircraft received fuel drawn from the bottom of a storage tank, in the absence of a proper filtration system, it\x92s possible that it was contaminated. The next aircraft may have received fuel from a different storage tank with good fuel.
Also, for them to fail at exactly the same time with near full tanks (as evidenced from the explosion) doesn't give much credence to the contaminated fuel theory in my opinion.
2025-06-14T07:18:00
permalink Post: 11901188
A summary of the more certain things we know about the accident so far:
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction. What exactly caused the engine/electrical issues remains speculative. An action slip mistaking flaps for gear seems much less likely as due to the above, the correct selection was probably made.
From the videos of the last moments, there is strong evidence that the RAT was deployed, which has a very short list of possible triggers. The sole eye witness from inside describes power issues which lends credence.
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else. Its seems at least one FDR has been recovered so depending on where they take it for read-out, we should get some initial facts fairly shortly.
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction. What exactly caused the engine/electrical issues remains speculative. An action slip mistaking flaps for gear seems much less likely as due to the above, the correct selection was probably made.
From the videos of the last moments, there is strong evidence that the RAT was deployed, which has a very short list of possible triggers. The sole eye witness from inside describes power issues which lends credence.
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else. Its seems at least one FDR has been recovered so depending on where they take it for read-out, we should get some initial facts fairly shortly.
14 users liked this post.
2025-06-14T07:51:00
permalink Post: 11901217
How is misselected flap still being discussed? Misselected flap does not cause gear retraction to cease nor cause the RAT to deploy. Both of which are (subjectively) evidenced in the videos. What is the supporting evidence for misselected flap?
Yes absolutely. 100% catastrophic loss of power when getting airborne. No evidence for bird strikes\x85no severe eng damage symptoms in the videos, no mention of birds in the mayday\x85
they\x92ve gone TO power all the way to rotate, no power issues, no eng fuel issues, but as soon as its wheels off they lose all power. That can\x92t be coincidental. TCMA certainly fits this scenario especially with ground/air logic.
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else.
they\x92ve gone TO power all the way to rotate, no power issues, no eng fuel issues, but as soon as its wheels off they lose all power. That can\x92t be coincidental. TCMA certainly fits this scenario especially with ground/air logic.
1 user liked this post.
2025-06-14T08:30:00
permalink Post: 11901251
A summary of the more certain things we know about the accident so far:
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction. What exactly caused the engine/electrical issues remains speculative. An action slip mistaking flaps for gear seems much less likely as due to the above, the correct selection was probably made.
From the videos of the last moments, there is strong evidence that the RAT was deployed, which has a very short list of possible triggers. The sole eye witness from inside describes power issues which lends credence.
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else. Its seems at least one FDR has been recovered so depending on where they take it for read-out, we should get some initial facts fairly shortly.
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction. What exactly caused the engine/electrical issues remains speculative. An action slip mistaking flaps for gear seems much less likely as due to the above, the correct selection was probably made.
From the videos of the last moments, there is strong evidence that the RAT was deployed, which has a very short list of possible triggers. The sole eye witness from inside describes power issues which lends credence.
Taken together, it seems that there was an event (or events) shortly after rotation that compromised both engines and the electrical system. There is no evidence yet of birdstrikes and continued engine operation *should* not be affected by the aircraft electrical system as they are independently/internally powered, so logic would have the engines failing first leading to a cascade of other problems. Something that affects all engines pretty much simultaneously is a rare beast but it has happened in the past; outside of a deliberate selection of the fuel and/or fire switches for both power plants there is fuel contamination, FOD and not much else. Its seems at least one FDR has been recovered so depending on where they take it for read-out, we should get some initial facts fairly shortly.
This indeed is the best summary till now
3 users liked this post.
2025-06-14T08:43:00
permalink Post: 11901266
I’m not a 787 driver so for fear of looking dumb in front of those that are this still confuses me. Even IF they’ve mis-selected the flap setting (I still don’t think it’s been cemented on here that there is in fact a FMS/flap setting disagreement warning but i believe there is), had the wrong de-rated take off settings, selected flaps instead of gear up the 787 with massive high bypass engines, FBW and full envelope protections surely cannot let itself be put in such a low energy/high alpha regime as we saw in the videos IF it has both fans functioning normally, surely?
the pilots may have messed up royally and numerous times so those holes lined up but the plane is the final block in the chain and a 21st century all digital entirely clean sheet design was sold as being immune to such catastrophic outcomes from a few minor (consequential yes) and fairly common errors- aren’t all the protections and our procedures designed after decades of mistakes?
im having a hard time squaring how a fully functioning modern bird like this could allow for this outcome and almost whatever the pilots did outside of unbelievable inputs and the pilots are are a bit of a red herring IMO
Dale Winsley
@Winsleydale
No. The LE slats are deployed therefore the flaps are as well. This is an automatic linkage. The flaps are set at Take-Off. Hard to see from the angle but they are...if slats are out (easy to see) then flaps are set. Looks like Flaps 5. Also, the 787 has the highest Thrust-to-Weight ratio of any airliner on Earth. The change in Alpha and lift is a trifling matter for it, at these settings (1-5). It will fly out of it easily, even at that density altitude. The attitude change is - in the circumstances I describe, consistent with a massive power loss (both sides). I believe based on probability that simultaneous mechanical failure is not the cause. Fuel contamination or starvation is likewise unlikely based on the 787 fuel system. The common element is the FADEC/Autothrottle/TOGO. However, each engine FADEC is dual redundant two channels. So any such common failure must happen further upstream. From a design perspective, that would be unthinkable. But this is Boeing. Given what I can see with my own eyes, I believe the flap issue is a non-starter. Also, re the landing gear: Clearly the Positive Rate challenge would be met based on normal rotation and fly-off at V2. But since we know the flaps were set correctly, that rules out an "oopsie" moment. Just as likely there was at the challenge moment an indication that something was amiss, and the Gear Up call was not made. They see both N1s unwinding and it takes a second to get past the WFT factor. They cross-check and see the airspeed also unwinding. Then they unload the Alpha and pitch to gear down Vy. And they had another 6 seconds. Whatever it was, it was not a flap, mechanical or fuel issue. We will know soon enough. But this is Boeing. My gut says "software". All 787s worldwide need to be grounded, now.
6:10 AM \xb7 Jun 14, 2025
\xb7
53.8K
Views
Last edited by Senior Pilot; 14th Jun 2025 at 09:04 . Reason: Add X quote
2025-06-14T09:23:00
permalink Post: 11901300
Double power loss causality
A summary of the more certain things we know about the accident so far:
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction .
The takeoff run was from the full length and appeared normal, even after comparing with the same flight on previous days. This very much reduces the likelihood of it being a performance issue, e.g. wrong flaps, derate, ZFW/TOW, etc.
Shortly after takeoff, the gear started retracting but stopped in an early intermediate position. At the same time the aircraft climb rate dropped off, then it started a shallow descent. This is consistent with a loss of electrical power causing a loss of hydraulic pressure and total engine thrust from both engines reducing below that generated by one engine at the takeoff setting. The position reporting also went offline at that moment, indicating that it was likely load shed due to an electrical malfunction .
I personally think this is a good summary of what we can ascertain at this point from the evidence we have.
I am not a 787 driver by any means but with a fair bit of aviation experience. I would be interested in any thoughts on this suggestion regarding loss of thrust:
If we take it as a reasonable assumption as above that it is almost simultaneous loss of significant thrust, and for the good reasons already discussed, it is pretty unlikely that from what we can see/analyse, that the cause of this would be bird strike (expect to see some signs on video if it's significant enough to cause double engine failure) nor fuel contamination (reasons as above re: likelihood, other ac affected and simultaneous nature). TCMA I don't know enough about but it seems that the sensor redundancy/logic protection is so high it would not be the sole cause.
On this basis, should we perhaps consider the causality of a total electrics failure of some kind first, leading to deployment of the RAT, gear retraction cease etc. Clearly the independent FADEC power generation systems would mean this doesn't on its own prevent thrust control of the engines but could we then be looking at cascading faults (possibly exacerbated by latent faults below the MEL/defect threshold) that contribute to dual power loss and sensor/system issues in throttle response not resulting in FADEC commands to the engines to increase thrust. So even at that point 'firewalling' the throttles could tragically not recover the situation?
Very happy to be corrected by those with much more experience and understanding of big jets operations and systems!
2025-06-14T16:39:00
permalink Post: 11901637
The complex software.
Can anyone familiar with the 787 built in overspeed protections comment on what could possibly override a pilots TOGA button command or fire walling the throttles?
I am presuming that at some point just prior to the mayday call the pilots would have just commanded \x91full\x92 thrust and received no or a significantly mild response.
I don\x92t think fuel contamination, birds or anything else external to the aircraft affected this crash. There is no evidence of it.
could some combination of already MEL items and one or more faulty inputs to the computers cause the aircraft to \x91protect\x92 itself into the ground? Regardless of throttle position?
I am thinking - ground/air logic, faulty airspeed sense, faulty AoA sense or other.
I am presuming that at some point just prior to the mayday call the pilots would have just commanded \x91full\x92 thrust and received no or a significantly mild response.
I don\x92t think fuel contamination, birds or anything else external to the aircraft affected this crash. There is no evidence of it.
could some combination of already MEL items and one or more faulty inputs to the computers cause the aircraft to \x91protect\x92 itself into the ground? Regardless of throttle position?
I am thinking - ground/air logic, faulty airspeed sense, faulty AoA sense or other.
2025-06-15T01:21:00
permalink Post: 11902026
I can buy the AC power loss, but TCMA activation as well - That\x92s a stretch. TCMA is available on the ground and on approach and will activate if the engine thrust doesn\x92t follow the Thrust Lever command. On the ground it will shut the engine down (think RTO with engine stuck at T/O). On approach it will reduce the thrust if the engine doesn\x92t respond to the Thrust Lever command ala Cathay Pacific A330 (CMB - HKG) with the fuel contamination incident.
5 users liked this post.
2025-06-15T04:47:00
permalink Post: 11902101
3 users liked this post.
2025-06-15T06:25:00
permalink Post: 11902143
So are we now saying total loss of AC power for the RAT activation and activation of TCMA on two very independent engines for the power loss? What are the chances..
I can buy the AC power loss, but TCMA activation as well - That\x92s a stretch. TCMA is available on the ground and on approach and will activate if the engine thrust doesn\x92t follow the Thrust Lever command. On the ground it will shut the engine down (think RTO with engine stuck at T/O). On approach it will reduce the thrust if the engine doesn\x92t respond to the Thrust Lever command ala Cathay Pacific A330 (CMB - HKG) with the fuel contamination incident.
I can buy the AC power loss, but TCMA activation as well - That\x92s a stretch. TCMA is available on the ground and on approach and will activate if the engine thrust doesn\x92t follow the Thrust Lever command. On the ground it will shut the engine down (think RTO with engine stuck at T/O). On approach it will reduce the thrust if the engine doesn\x92t respond to the Thrust Lever command ala Cathay Pacific A330 (CMB - HKG) with the fuel contamination incident.
1 user liked this post.
2025-06-15T12:18:00
permalink Post: 11902422
There's some possible fuel contamination mechanisms which would only affect one aircraft
- The fuel truck’s water-absorbing “monitor” element breaks up, the first aircraft after the break gets the bead slug; later uplifts may be clear once the hose is flushed. The beads jam metering valves almost immediately.
- After pipe maintenance, the first few hundred litres can carry residual cleaning surfactant that strips protective films and causes filter-monitor “soap lock”.
- Biofilm growth happens inside one aircraft’s wing tanks when it sits in humid conditions or does short hops with warm fuel. On the next flight the biofilm shears off, blocks strainers,
- The fuel truck’s water-absorbing “monitor” element breaks up, the first aircraft after the break gets the bead slug; later uplifts may be clear once the hose is flushed. The beads jam metering valves almost immediately.
- After pipe maintenance, the first few hundred litres can carry residual cleaning surfactant that strips protective films and causes filter-monitor “soap lock”.
- Biofilm growth happens inside one aircraft’s wing tanks when it sits in humid conditions or does short hops with warm fuel. On the next flight the biofilm shears off, blocks strainers,
2 users liked this post.