June 21, 2025, 15:24:00 GMT
permalink Post: 11907841
Resubmitting following some Mod Feedback and a significant re-write. Yes, it is speculative
I have a theory that I'd like to share. It brings together various pieces of known information, along with 30+ years of my experience as an aircraft engineer that forms a plausible (IMO) explanation of what may have happened.
We Know - From the Video's and the ADSB Data:
That up to and for the first few seconds after take-off appears relatively normal.
The AC appears to lose thrust without e.g. birdstrike or other spectacular smoke /fire producing event.
That the RAT deployed.
That the pilot reported 'Thrust not achieved' [Edit - We dont 'know' this - it is heavily reported]
We can see that the AC had a relatively busy schedule in the few days prior to the accident flight, so there was no significant downtime for maintenance activities that could have caused incident.
The AC flew DEL-CDG on 11 Jun with quite a racy turnaround in CDG of 1h12m. The centre tank would have been empty at CDG on arrival, and would have been partially filled for the return CDG-DEL.
CDG-DEL Arrived 01:47 am IST. Again the Centre Tank would have been empty. But quite a bit of fuel in the wings.
8 Hrs later, at 09:48 am IST the AC departed DEL-AMD. For such a short-hop, Fuel upload would have been minimal, merely a 'topping up' if at all. Certainly nothing into the Centre Tank.
DEL That night was fairly hot and humid - 57% at 02:30, 54% at 05:30, 44% at 08:30. That wing tank fuel could have picked up a fair amount of water.
The flight DEL-AMD would have only used the wing pumps. Thus any water in that 'overnight' fuel would have been vigorously stirred and evenly suspended. At concentrations that would cause no ill-effect at all.
The AC was on the ground at AMD for 2 Hrs, from 11:17am to 1:17 pm IST. The AC would have re-fuelled, first filling up the wing tanks to the top, then filling the centre-tank to whatever quantity necessary. There was enough time for water in the wing tanks to settle out.
The B787 Fuel system has pumps in the wing tanks, and pumps in the centre tanks. The Centre Tank pumps are also known as 'override' pumps because they output a higher pressure than the wing tank pumps, thus ensuring that with all pumps running, the centre tank fuel is used first.
Should the centre tank pumps stop, due to either filure or running out of fuel to pump, the wing tank pumps then produce the pressure.
In the event that all pumps stop running (e.g. an electrical failure), the engines will suck the fuel from the wing tanks. The 'sucked' fuel comes from a dedicated pipe in each tank through the 'Suction Feed Check Valve' (so that pumped fuel doesn't just exit through the suction tube). The suction tube pickup is in a slightly different position to the wing pump pickups.
It is conceivable to me that the suction tube pickup could have been immersed in water, settled out from the fuel in the wing tanks.
Then - at start-up of the aircraft in AMD, The engines would have been supplied with fuel from the centre tank. Fresh Fuel. All OK. Wing pumps running and doing not much. But, I speculate, the suction pick-ups immersed in water. Waiting.
Start up and taxi out was all normal. Runway acceleration up to v1 appears normal. V1 - Rotate - (positive rate - Gear up? - Not my debate).
But somewhere around that time, I speculate that a significant electrical failure occurred. Enough for the RAT to deploy. Enough for the fuel pumps to stop. I'll not speculate on the cause. We know that it can occur, that's why the RAT was designed to operate.
The engines at that point were at TOGA thrust. In a significant electrical failure, the engines will keep on doing what they were last told. Keep that thrust stable. So the AC climbed for a few seconds more. The pilots did what they were trained to do for a power failure, manage that, thankfully the engines were still going well...
But there was only so much 'good' fuel in the lines. The engines sucking fuel themselves, the fuel would now be coming from the suction pickups, a different supply. A supply likely heavily water contaminated. It would take a few seconds for that contaminated fuel to actually reach the engines, but when that contaminated fuel hit, Thrust would have been significantly reduced. The EEC's would have been doing their best to maintain the thrust, firewalling the throttles would probably have little effect at that exact moment. The engines would have likely worked through that bad fuel in a shortish period of time, but a period of time that our crew did not have. A fully loaded aircraft producing less than take-off thrust, is not sustaining enough thrust for continued flight. The rest - is down to the skill of the crew in deciding exactly where to hit the ground within the very narrow range of choice they had.
I have a theory that I'd like to share. It brings together various pieces of known information, along with 30+ years of my experience as an aircraft engineer that forms a plausible (IMO) explanation of what may have happened.
We Know - From the Video's and the ADSB Data:
That up to and for the first few seconds after take-off appears relatively normal.
The AC appears to lose thrust without e.g. birdstrike or other spectacular smoke /fire producing event.
That the RAT deployed.
That the pilot reported 'Thrust not achieved' [Edit - We dont 'know' this - it is heavily reported]
We can see that the AC had a relatively busy schedule in the few days prior to the accident flight, so there was no significant downtime for maintenance activities that could have caused incident.
The AC flew DEL-CDG on 11 Jun with quite a racy turnaround in CDG of 1h12m. The centre tank would have been empty at CDG on arrival, and would have been partially filled for the return CDG-DEL.
CDG-DEL Arrived 01:47 am IST. Again the Centre Tank would have been empty. But quite a bit of fuel in the wings.
8 Hrs later, at 09:48 am IST the AC departed DEL-AMD. For such a short-hop, Fuel upload would have been minimal, merely a 'topping up' if at all. Certainly nothing into the Centre Tank.
DEL That night was fairly hot and humid - 57% at 02:30, 54% at 05:30, 44% at 08:30. That wing tank fuel could have picked up a fair amount of water.
The flight DEL-AMD would have only used the wing pumps. Thus any water in that 'overnight' fuel would have been vigorously stirred and evenly suspended. At concentrations that would cause no ill-effect at all.
The AC was on the ground at AMD for 2 Hrs, from 11:17am to 1:17 pm IST. The AC would have re-fuelled, first filling up the wing tanks to the top, then filling the centre-tank to whatever quantity necessary. There was enough time for water in the wing tanks to settle out.
The B787 Fuel system has pumps in the wing tanks, and pumps in the centre tanks. The Centre Tank pumps are also known as 'override' pumps because they output a higher pressure than the wing tank pumps, thus ensuring that with all pumps running, the centre tank fuel is used first.
Should the centre tank pumps stop, due to either filure or running out of fuel to pump, the wing tank pumps then produce the pressure.
In the event that all pumps stop running (e.g. an electrical failure), the engines will suck the fuel from the wing tanks. The 'sucked' fuel comes from a dedicated pipe in each tank through the 'Suction Feed Check Valve' (so that pumped fuel doesn't just exit through the suction tube). The suction tube pickup is in a slightly different position to the wing pump pickups.
It is conceivable to me that the suction tube pickup could have been immersed in water, settled out from the fuel in the wing tanks.
Then - at start-up of the aircraft in AMD, The engines would have been supplied with fuel from the centre tank. Fresh Fuel. All OK. Wing pumps running and doing not much. But, I speculate, the suction pick-ups immersed in water. Waiting.
Start up and taxi out was all normal. Runway acceleration up to v1 appears normal. V1 - Rotate - (positive rate - Gear up? - Not my debate).
But somewhere around that time, I speculate that a significant electrical failure occurred. Enough for the RAT to deploy. Enough for the fuel pumps to stop. I'll not speculate on the cause. We know that it can occur, that's why the RAT was designed to operate.
The engines at that point were at TOGA thrust. In a significant electrical failure, the engines will keep on doing what they were last told. Keep that thrust stable. So the AC climbed for a few seconds more. The pilots did what they were trained to do for a power failure, manage that, thankfully the engines were still going well...
But there was only so much 'good' fuel in the lines. The engines sucking fuel themselves, the fuel would now be coming from the suction pickups, a different supply. A supply likely heavily water contaminated. It would take a few seconds for that contaminated fuel to actually reach the engines, but when that contaminated fuel hit, Thrust would have been significantly reduced. The EEC's would have been doing their best to maintain the thrust, firewalling the throttles would probably have little effect at that exact moment. The engines would have likely worked through that bad fuel in a shortish period of time, but a period of time that our crew did not have. A fully loaded aircraft producing less than take-off thrust, is not sustaining enough thrust for continued flight. The rest - is down to the skill of the crew in deciding exactly where to hit the ground within the very narrow range of choice they had.
Last edited by GroundedSpanner; 21st June 2025 at 17:52 . Reason: Thrust not achieved comment is not proven.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ADSB Centre Tank Electrical Failure Fuel (All) RAT (All) RAT (Deployment) TOGA V1
June 21, 2025, 17:11:00 GMT
permalink Post: 11907910
Yes - Yes it does.
However, that water scavenge works by picking up fluid from just next to at aft boost pump inlet, and dripping it into the aft boost pump inlet. Powered by the motive flow of the aft boost pump.
Whereas the suction feed inlet, is - although not far away - in a different location that could itself be sitting in water.
After a good look at the SDS - It seems like the system is assuming a small amount of water, with fuel flowing.
But when the centre tank override pumps are doing all the supply, its the same fluid being circulated in the same bay. If there is a 'lot' of water, then the aft boost pump is just circulating water (or very water rich fuel).
I think the key point of my post was that in an significant power failure, when the pumps stop working, the fuel supply is changed from centre to wing tanks, that it will take a few seconds from after the pumps stop working, to the fuel being received at the engines to be coming from a different source. That source being the bottom of the wing tanks. If the fuel quality is very different in the 2 different locations, the engines are going to struggle.
However, that water scavenge works by picking up fluid from just next to at aft boost pump inlet, and dripping it into the aft boost pump inlet. Powered by the motive flow of the aft boost pump.
Whereas the suction feed inlet, is - although not far away - in a different location that could itself be sitting in water.
After a good look at the SDS - It seems like the system is assuming a small amount of water, with fuel flowing.
But when the centre tank override pumps are doing all the supply, its the same fluid being circulated in the same bay. If there is a 'lot' of water, then the aft boost pump is just circulating water (or very water rich fuel).
I think the key point of my post was that in an significant power failure, when the pumps stop working, the fuel supply is changed from centre to wing tanks, that it will take a few seconds from after the pumps stop working, to the fuel being received at the engines to be coming from a different source. That source being the bottom of the wing tanks. If the fuel quality is very different in the 2 different locations, the engines are going to struggle.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Centre Tank Fuel (All)
June 22, 2025, 00:15:00 GMT
permalink Post: 11908173
I don't want to refute your theory, but given your 30 years of experience---presuming it is relevant--I'd ask you to clarify a few things.
First, water in fuel is not a novel concept and I would presume that the designers of the 787 knew about it. You've simply stated that water might collect and settle out, but how much water might you expect under those conditions (57% humidity doesn't seem terribly high to me) and what features and procedures are already there to mitigage water contamination issues? Your theory would imply that there basically aren't any. IDK how the tank venting system works, but the idea that some huge amount of water could have condensed in the tank from the outside seems preposterous.
Second, how much water do you think it would take to cause a sustained flameout in one of those engines? Remember that they have automatic continous relight, so you're going to have to sustain your flame suppression long enough for them to wind down completely. I think those engines were probably using something like 2 gallons per second of fuel along with 250lbs of air heated to over 1100F. Any fuel in the mix would burn and the water would be converted to steam so you'd need mostly water for a long time. So if you think a hundred gallons of water could have gotten into each tank then perhaps I'd buy your theory--which, btw, does fit the known facts pretty well. But I think that short of some woeful neglect, Boeing and AI already know about and have methods of dealing with water contamination. At least I hope so.
First, water in fuel is not a novel concept and I would presume that the designers of the 787 knew about it. You've simply stated that water might collect and settle out, but how much water might you expect under those conditions (57% humidity doesn't seem terribly high to me) and what features and procedures are already there to mitigage water contamination issues? Your theory would imply that there basically aren't any. IDK how the tank venting system works, but the idea that some huge amount of water could have condensed in the tank from the outside seems preposterous.
Second, how much water do you think it would take to cause a sustained flameout in one of those engines? Remember that they have automatic continous relight, so you're going to have to sustain your flame suppression long enough for them to wind down completely. I think those engines were probably using something like 2 gallons per second of fuel along with 250lbs of air heated to over 1100F. Any fuel in the mix would burn and the water would be converted to steam so you'd need mostly water for a long time. So if you think a hundred gallons of water could have gotten into each tank then perhaps I'd buy your theory--which, btw, does fit the known facts pretty well. But I think that short of some woeful neglect, Boeing and AI already know about and have methods of dealing with water contamination. At least I hope so.
Experience. Without wishing to dox myself, I've worked in engineering at a major airline from apprentice through (in no particular order) Line Maintenance, Heavy and Light Maintenance, to technical support and maintenance control on both Boeing and Airbus products, with various qualifications and authorisations along the way. [Hmm - Scrap this sentence?]On the day 9/11 occurred, I should have been making modifications inside a fuel tank instead of staring at the TV with mouth on the floor.
However, I would describe my experience as broad, yet shallow in respect to this incident. Some of my fleet I know every rivet. Some of my fleet I've only ever seen from a distance. I don't touch airplanes for a living any more. B787 though - is not my area of specialty. I'll dig in, but am not the expert. I am not a systems design engineer, so precise numbers and flow rates, are not what I do. But what the systems do, how they operate, what they look like, smell and taste like... yeah, I'm not a muggle. And I do have access to all the manuals and know how to use them. And - let me be clear, I am speculating. I was advancing a theory. It WILL be some flavour of wrong. The investigation will reveal all.
I Agree, Water in fuel is not a novel concept. Aircraft fuel tanks attract water - fact. How much? It varies. I've sumped tanks and got no water, I've seen drops of water beading about in the bottom of a gallon jug, I've seen gallons of water. I've been so covered in fuel I cant smell it or think straight and taken gallon after gallon not being able to tell if its fuel or water. I also agree that 57% humidity doesn't seem particularly high - its not south east Asian jungle levels - but I'm not an expert at humidity, 32Deg c at 57% humidity at 02:30 am is not going to be comfortable for me though. I looked at recent weather in DEL, and those values were at the higher end of the range.
Further, I believe the prevailing weather conditions on the ground are less important when it comes to the volume of water getting in. Fuel is cold, or gets damn cold during a 9 Hr flight. Fuel Temperature Management is an issue for our Drivers. So as the fuel is used at altitude, Air enters the tank through NACA Ducts in the outboard end of the wing. Its beneficial to maintain a slight positive pressure, amongst other things to reduce evaporation. (Added complication, there is also the Nitrogen Enrichment system due to TWA800 - but that's more about processing the air in the tank to change the properties and make it non-explosive). Then as the aircraft descends, more air enters as the air pressure increases. Its the humidity of that air in the descent that is going to determine the volume of water entering the tank and potentially the fuel. The water in the air condenses on the sides of the tank because of the cold post-flight fuel. It doesn't dissolve into the fuel, but sinks to the bottom. Ground temperature / humidity and time will likely affect how much water condenses out of that air while on the ground. There won't be a huge amount of air exchange on the ground. Likely if the AC landed at 2am, then from sunrise as the tank warmed up, there would actually be a flow out of the vents.
What Features and procedures are there to mitigate Water? I apologise if my post gave the impression that there are no mitigation processes. There are. Water is well understood in the industry.
Well for a start, Features / Design. The Aircraft has a water scavenge system. Water doesn't mix with fuel, it sinks to the bottom being about 20% denser than fuel, so at the very lowest point in the tank, the water scavenge system (Powered by the Aft Fuel Pump through a jet pump, a venturi like system) will suck up the 'fluid' at the very lowest point, where the water would collect and in Boeings words 'drip' that fluid into the path of the pump pickup inlet (but I'd describe it more as a 'squirt'). The idea being that a small amount of water injected into the fuel will be consumed by the engines harmlessly.
There is also agitation. The wing tank pumps are pretty much running constantly, from before engine startup to after engine shutdown. The pumps are quite violent to the fuel and supply more pressure then the engine could ever need. Any excess pressure is dumped right back into the tank, quite close to the pump, in a direction that would further stir up the fuel and help break up any water into suspended droplets.
This all works if there is a small amount of water in the fuel. The water scavenge pickup is right next to the pump inlet, but a bit lower. Little bits of water get managed. Looking at the pictures of the system, I'd say a couple of gallons of water would do no harm at all.
But if there was significantly more water in that tank. Guessing 10-30 + gallons, then the pump would be circulating water, or highly water rich fuel.
Then there's the suction pickup. Its in the same 'bay' as the aft fuel pump and located a little 'higher' than the pump inlet and water scavenge inlet. But also located between stringers that can separate out the settled water ( I wish I could share the pictures, but more than my job is worth ) I can imagine the suction pickup being in a pool of 'stagnant' water.
I also saw a post from Metcha about the scavenge system blocking with Algae - I don't know about that (B787 not my fleet). But possible that could aggravate things. There's also the reports of the Indian AAIB looking at the Titan Biocide incident. Its possible that might be related and could modify the theory.
Procedures - There's the (at my airline weekly I think) procedure to 'sump' the tanks. There are drain points in the tank. Valves that you can push in with a tool and fluid drains. As described earlier (and videos exist on YouTube), you drain about a gallon of fluid and examine it for water. Most often in temperate climates (my experience), there's a few 'beads' of water in the bottom of the jug, moving about like mercury. Except when there's more. Sometimes there's a clear line in the jug, half water, fuel above. And sometimes a gallon of water, that smells like fuel. You drain it until you are sure there's no water.
Could 'that much' water have condensed in the tank? Well - There's the question. I guess the basis of the theory is that on descent into DEL, the wing tanks picked up some very humid air, which settled water into the tanks through the night. Then, as the theory I posited must work, the wing pumps must have circulated and suspended that water into the fuel.
By design, the water from the CDG-DEL arrival should have been consumed in the DEL-AMD Sector. But desperately clinging to defending my theory (I appreciate this is a hole), lets assume that at DEL the pumps were running for a long time. Lets assume that the pumps allowed the water to be dispersed within the tank prior to being used through the engines. Then - in the DEL-AMD sector, the wing tanks could have picked up more water.
How much water would cause a sustained flameout? I never posited a sustained flameout. I posited a significant reduction in thrust. Listening back to the rooftop video, which at first we were all listening for evidence of RAT, there's also a rhythmic pop-pop-pop of engines struggling. I think the engines were running, albeit badly. Heavily water contaminated fuel will do that. It doesn't have to be 100% water. Just enough water to make the engine lose thrust. Your 2 gallons per second figure assumes the engine running at full flow. I'm not a figures man, I'll not challenge that, I do recall flowmeters at max thrust spin like crazy. But an engine struggling due to a high perrcentage of contamination, is that using 2 gal/sec? or just trying to? What happens if there is e.g. 20% water in the fuel?
There are also reported incidents of engine flameout / thrust reduction that have all happened at altitude. Incidents that have been recovered due to the altitude and time available. I Posited that the engines would have eventually regained full thrust once the contamination worked though. But 30 seconds of rough engine is very different at 40,000 feet than it is at 100 feet.
The theory also relies on a second part - the electrical failure. That the electrical failure causes the fuel supply to switch, a few seconds after the failure. We go, at the point of electrical failure from a pumped centre tank supply to a sucked wing tank supply. It takes time for that different fuel to reach the engine.
Ive written enough and am tired. Must stop now.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) Centre Tank Electrical Failure Engine Failure (All) Engine Shutdown Fuel (All) RAT (All) RAT (Deployment) Relight
June 29, 2025, 18:51:00 GMT
permalink Post: 11913174
Engine Shutdown vs running poorly
Listen to the rooftop video in Capn Bloggs excellent Side-By-Side video . Ignore the RAT. Try and focus on all the sound that is not RAT.
I think I can hear a pulsing, a chunk-chunk-chunk' sound.
Do we think that is the engines struggling to work?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): RAT (All)
June 29, 2025, 21:33:00 GMT
permalink Post: 11913248
Its possible that the RAT was deployed for other reasons, prior to the engines losing thrust. So, leaving the RAT out of the equation for a bit, do we think there is a sound of engines TRYING to run?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators RAT (All) RAT (Deployment)
June 30, 2025, 21:18:00 GMT
permalink Post: 11913900
It would go against every aspect of training for a professional crew to deploy the rat below 400 feet. Further if you put 100 crewmembers in a simulator on takeoff and said deploy the rat manually I would bet not a single crew member could find the rat deploy switch and activate it in under 5 seconds and maybe 2 or 3 in 10 seconds.
It can auto-deploy in a significant electrical failure.
The theory I'm working is that, given the configuration of the aircraft, if there is a significant electrical failure (sufficient for the RAT to auto-deploy). The aircraft fuel pumps are lost. Approx. 7ish seconds after those fuel pumps are lost (if the engines are at TOGA), the fuel being received by the engines is arriving from a different source, a potentially contaminated source. I believe that the engine failure is a secondary result of the power loss (with specific circumstances).
But this all hinges on whether the engines were trying to run, or commanded off. Hence the request for interpretation of the sound.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Electrical Failure Engine Failure (All) Fuel (All) RAT (All) TOGA
June 30, 2025, 22:21:00 GMT
permalink Post: 11913922
OK - Fair Challenges - good post, I'll have a go at answering and simultaneously expanding my own thoughts. In fact I'm not having a go at you, I'm more working my theory....
Experience. Without wishing to dox myself, I've worked in engineering at a major airline from apprentice through (in no particular order) Line Maintenance, Heavy and Light Maintenance, to technical support and maintenance control on both Boeing and Airbus products, with various qualifications and authorisations along the way. [Hmm - Scrap this sentence?]On the day 9/11 occurred, I should have been making modifications inside a fuel tank instead of staring at the TV with mouth on the floor.
However, I would describe my experience as broad, yet shallow in respect to this incident. Some of my fleet I know every rivet. Some of my fleet I've only ever seen from a distance. I don't touch airplanes for a living any more. B787 though - is not my area of specialty. I'll dig in, but am not the expert. I am not a systems design engineer, so precise numbers and flow rates, are not what I do. But what the systems do, how they operate, what they look like, smell and taste like... yeah, I'm not a muggle. And I do have access to all the manuals and know how to use them. And - let me be clear, I am speculating. I was advancing a theory. It WILL be some flavour of wrong. The investigation will reveal all.
I Agree, Water in fuel is not a novel concept. Aircraft fuel tanks attract water - fact. How much? It varies. I've sumped tanks and got no water, I've seen drops of water beading about in the bottom of a gallon jug, I've seen gallons of water. I've been so covered in fuel I cant smell it or think straight and taken gallon after gallon not being able to tell if its fuel or water. I also agree that 57% humidity doesn't seem particularly high - its not south east Asian jungle levels - but I'm not an expert at humidity, 32Deg c at 57% humidity at 02:30 am is not going to be comfortable for me though. I looked at recent weather in DEL, and those values were at the higher end of the range.
Further, I believe the prevailing weather conditions on the ground are less important when it comes to the volume of water getting in. Fuel is cold, or gets damn cold during a 9 Hr flight. Fuel Temperature Management is an issue for our Drivers. So as the fuel is used at altitude, Air enters the tank through NACA Ducts in the outboard end of the wing. Its beneficial to maintain a slight positive pressure, amongst other things to reduce evaporation. (Added complication, there is also the Nitrogen Enrichment system due to TWA800 - but that's more about processing the air in the tank to change the properties and make it non-explosive). Then as the aircraft descends, more air enters as the air pressure increases. Its the humidity of that air in the descent that is going to determine the volume of water entering the tank and potentially the fuel. The water in the air condenses on the sides of the tank because of the cold post-flight fuel. It doesn't dissolve into the fuel, but sinks to the bottom. Ground temperature / humidity and time will likely affect how much water condenses out of that air while on the ground. There won't be a huge amount of air exchange on the ground. Likely if the AC landed at 2am, then from sunrise as the tank warmed up, there would actually be a flow out of the vents.
What Features and procedures are there to mitigate Water? I apologise if my post gave the impression that there are no mitigation processes. There are. Water is well understood in the industry.
Well for a start, Features / Design. The Aircraft has a water scavenge system. Water doesn't mix with fuel, it sinks to the bottom being about 20% denser than fuel, so at the very lowest point in the tank, the water scavenge system (Powered by the Aft Fuel Pump through a jet pump, a venturi like system) will suck up the 'fluid' at the very lowest point, where the water would collect and in Boeings words 'drip' that fluid into the path of the pump pickup inlet (but I'd describe it more as a 'squirt'). The idea being that a small amount of water injected into the fuel will be consumed by the engines harmlessly.
There is also agitation. The wing tank pumps are pretty much running constantly, from before engine startup to after engine shutdown. The pumps are quite violent to the fuel and supply more pressure then the engine could ever need. Any excess pressure is dumped right back into the tank, quite close to the pump, in a direction that would further stir up the fuel and help break up any water into suspended droplets.
This all works if there is a small amount of water in the fuel. The water scavenge pickup is right next to the pump inlet, but a bit lower. Little bits of water get managed. Looking at the pictures of the system, I'd say a couple of gallons of water would do no harm at all.
But if there was significantly more water in that tank. Guessing 10-30 + gallons, then the pump would be circulating water, or highly water rich fuel.
Then there's the suction pickup. Its in the same 'bay' as the aft fuel pump and located a little 'higher' than the pump inlet and water scavenge inlet. But also located between stringers that can separate out the settled water ( I wish I could share the pictures, but more than my job is worth ) I can imagine the suction pickup being in a pool of 'stagnant' water.
I also saw a post from Metcha about the scavenge system blocking with Algae - I don't know about that (B787 not my fleet). But possible that could aggravate things. There's also the reports of the Indian AAIB looking at the Titan Biocide incident. Its possible that might be related and could modify the theory.
Procedures - There's the (at my airline weekly I think) procedure to 'sump' the tanks. There are drain points in the tank. Valves that you can push in with a tool and fluid drains. As described earlier (and videos exist on YouTube), you drain about a gallon of fluid and examine it for water. Most often in temperate climates (my experience), there's a few 'beads' of water in the bottom of the jug, moving about like mercury. Except when there's more. Sometimes there's a clear line in the jug, half water, fuel above. And sometimes a gallon of water, that smells like fuel. You drain it until you are sure there's no water.
Could 'that much' water have condensed in the tank? Well - There's the question. I guess the basis of the theory is that on descent into DEL, the wing tanks picked up some very humid air, which settled water into the tanks through the night. Then, as the theory I posited must work, the wing pumps must have circulated and suspended that water into the fuel.
By design, the water from the CDG-DEL arrival should have been consumed in the DEL-AMD Sector. But desperately clinging to defending my theory (I appreciate this is a hole), lets assume that at DEL the pumps were running for a long time. Lets assume that the pumps allowed the water to be dispersed within the tank prior to being used through the engines. Then - in the DEL-AMD sector, the wing tanks could have picked up more water.
How much water would cause a sustained flameout? I never posited a sustained flameout. I posited a significant reduction in thrust. Listening back to the rooftop video, which at first we were all listening for evidence of RAT, there's also a rhythmic pop-pop-pop of engines struggling. I think the engines were running, albeit badly. Heavily water contaminated fuel will do that. It doesn't have to be 100% water. Just enough water to make the engine lose thrust. Your 2 gallons per second figure assumes the engine running at full flow. I'm not a figures man, I'll not challenge that, I do recall flowmeters at max thrust spin like crazy. But an engine struggling due to a high perrcentage of contamination, is that using 2 gal/sec? or just trying to? What happens if there is e.g. 20% water in the fuel?
There are also reported incidents of engine flameout / thrust reduction that have all happened at altitude. Incidents that have been recovered due to the altitude and time available. I Posited that the engines would have eventually regained full thrust once the contamination worked though. But 30 seconds of rough engine is very different at 40,000 feet than it is at 100 feet.
The theory also relies on a second part - the electrical failure. That the electrical failure causes the fuel supply to switch, a few seconds after the failure. We go, at the point of electrical failure from a pumped centre tank supply to a sucked wing tank supply. It takes time for that different fuel to reach the engine.
Ive written enough and am tired. Must stop now.
Experience. Without wishing to dox myself, I've worked in engineering at a major airline from apprentice through (in no particular order) Line Maintenance, Heavy and Light Maintenance, to technical support and maintenance control on both Boeing and Airbus products, with various qualifications and authorisations along the way. [Hmm - Scrap this sentence?]On the day 9/11 occurred, I should have been making modifications inside a fuel tank instead of staring at the TV with mouth on the floor.
However, I would describe my experience as broad, yet shallow in respect to this incident. Some of my fleet I know every rivet. Some of my fleet I've only ever seen from a distance. I don't touch airplanes for a living any more. B787 though - is not my area of specialty. I'll dig in, but am not the expert. I am not a systems design engineer, so precise numbers and flow rates, are not what I do. But what the systems do, how they operate, what they look like, smell and taste like... yeah, I'm not a muggle. And I do have access to all the manuals and know how to use them. And - let me be clear, I am speculating. I was advancing a theory. It WILL be some flavour of wrong. The investigation will reveal all.
I Agree, Water in fuel is not a novel concept. Aircraft fuel tanks attract water - fact. How much? It varies. I've sumped tanks and got no water, I've seen drops of water beading about in the bottom of a gallon jug, I've seen gallons of water. I've been so covered in fuel I cant smell it or think straight and taken gallon after gallon not being able to tell if its fuel or water. I also agree that 57% humidity doesn't seem particularly high - its not south east Asian jungle levels - but I'm not an expert at humidity, 32Deg c at 57% humidity at 02:30 am is not going to be comfortable for me though. I looked at recent weather in DEL, and those values were at the higher end of the range.
Further, I believe the prevailing weather conditions on the ground are less important when it comes to the volume of water getting in. Fuel is cold, or gets damn cold during a 9 Hr flight. Fuel Temperature Management is an issue for our Drivers. So as the fuel is used at altitude, Air enters the tank through NACA Ducts in the outboard end of the wing. Its beneficial to maintain a slight positive pressure, amongst other things to reduce evaporation. (Added complication, there is also the Nitrogen Enrichment system due to TWA800 - but that's more about processing the air in the tank to change the properties and make it non-explosive). Then as the aircraft descends, more air enters as the air pressure increases. Its the humidity of that air in the descent that is going to determine the volume of water entering the tank and potentially the fuel. The water in the air condenses on the sides of the tank because of the cold post-flight fuel. It doesn't dissolve into the fuel, but sinks to the bottom. Ground temperature / humidity and time will likely affect how much water condenses out of that air while on the ground. There won't be a huge amount of air exchange on the ground. Likely if the AC landed at 2am, then from sunrise as the tank warmed up, there would actually be a flow out of the vents.
What Features and procedures are there to mitigate Water? I apologise if my post gave the impression that there are no mitigation processes. There are. Water is well understood in the industry.
Well for a start, Features / Design. The Aircraft has a water scavenge system. Water doesn't mix with fuel, it sinks to the bottom being about 20% denser than fuel, so at the very lowest point in the tank, the water scavenge system (Powered by the Aft Fuel Pump through a jet pump, a venturi like system) will suck up the 'fluid' at the very lowest point, where the water would collect and in Boeings words 'drip' that fluid into the path of the pump pickup inlet (but I'd describe it more as a 'squirt'). The idea being that a small amount of water injected into the fuel will be consumed by the engines harmlessly.
There is also agitation. The wing tank pumps are pretty much running constantly, from before engine startup to after engine shutdown. The pumps are quite violent to the fuel and supply more pressure then the engine could ever need. Any excess pressure is dumped right back into the tank, quite close to the pump, in a direction that would further stir up the fuel and help break up any water into suspended droplets.
This all works if there is a small amount of water in the fuel. The water scavenge pickup is right next to the pump inlet, but a bit lower. Little bits of water get managed. Looking at the pictures of the system, I'd say a couple of gallons of water would do no harm at all.
But if there was significantly more water in that tank. Guessing 10-30 + gallons, then the pump would be circulating water, or highly water rich fuel.
Then there's the suction pickup. Its in the same 'bay' as the aft fuel pump and located a little 'higher' than the pump inlet and water scavenge inlet. But also located between stringers that can separate out the settled water ( I wish I could share the pictures, but more than my job is worth ) I can imagine the suction pickup being in a pool of 'stagnant' water.
I also saw a post from Metcha about the scavenge system blocking with Algae - I don't know about that (B787 not my fleet). But possible that could aggravate things. There's also the reports of the Indian AAIB looking at the Titan Biocide incident. Its possible that might be related and could modify the theory.
Procedures - There's the (at my airline weekly I think) procedure to 'sump' the tanks. There are drain points in the tank. Valves that you can push in with a tool and fluid drains. As described earlier (and videos exist on YouTube), you drain about a gallon of fluid and examine it for water. Most often in temperate climates (my experience), there's a few 'beads' of water in the bottom of the jug, moving about like mercury. Except when there's more. Sometimes there's a clear line in the jug, half water, fuel above. And sometimes a gallon of water, that smells like fuel. You drain it until you are sure there's no water.
Could 'that much' water have condensed in the tank? Well - There's the question. I guess the basis of the theory is that on descent into DEL, the wing tanks picked up some very humid air, which settled water into the tanks through the night. Then, as the theory I posited must work, the wing pumps must have circulated and suspended that water into the fuel.
By design, the water from the CDG-DEL arrival should have been consumed in the DEL-AMD Sector. But desperately clinging to defending my theory (I appreciate this is a hole), lets assume that at DEL the pumps were running for a long time. Lets assume that the pumps allowed the water to be dispersed within the tank prior to being used through the engines. Then - in the DEL-AMD sector, the wing tanks could have picked up more water.
How much water would cause a sustained flameout? I never posited a sustained flameout. I posited a significant reduction in thrust. Listening back to the rooftop video, which at first we were all listening for evidence of RAT, there's also a rhythmic pop-pop-pop of engines struggling. I think the engines were running, albeit badly. Heavily water contaminated fuel will do that. It doesn't have to be 100% water. Just enough water to make the engine lose thrust. Your 2 gallons per second figure assumes the engine running at full flow. I'm not a figures man, I'll not challenge that, I do recall flowmeters at max thrust spin like crazy. But an engine struggling due to a high perrcentage of contamination, is that using 2 gal/sec? or just trying to? What happens if there is e.g. 20% water in the fuel?
There are also reported incidents of engine flameout / thrust reduction that have all happened at altitude. Incidents that have been recovered due to the altitude and time available. I Posited that the engines would have eventually regained full thrust once the contamination worked though. But 30 seconds of rough engine is very different at 40,000 feet than it is at 100 feet.
The theory also relies on a second part - the electrical failure. That the electrical failure causes the fuel supply to switch, a few seconds after the failure. We go, at the point of electrical failure from a pumped centre tank supply to a sucked wing tank supply. It takes time for that different fuel to reach the engine.
Ive written enough and am tired. Must stop now.
Last edited by Senior Pilot; 30th June 2025 at 23:01 . Reason: Quote from a week ago; this is not a Hamsterwheel thread, thanks!
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) Centre Tank Electrical Failure Engine Failure (All) Engine Shutdown Fuel (All) RAT (All) RAT (Deployment)
July 01, 2025, 06:24:00 GMT
permalink Post: 11914037
THE important bit is - Electrical Bang + some seconds = fuel is from a different source.
Mods have removed my post text and replaced it. Annoying, as it was revised from a week ago. I don't have all the answers,
Do they still use Bowsers in India? I thought most airports used underground pipes feeding pots on the stands.
...
...
But they do use bowsers at at DEL...... and there is evidence of 'interference'.
A story about a very recently busted fuel Theft syndicate at DEL
EDIT - There's some good conversation going on about whether the Centre pumps are actually running at takeoff. If it can be proven that they are not running at takeoff, then the whole theory is based on a massive incorrect assumption and I will respectfully withdraw it.
Last edited by GroundedSpanner; 1st July 2025 at 07:36 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Thread Moderation
July 11, 2025, 21:51:00 GMT
permalink Post: 11919859
One item in the report is the position of the LG Lever - Down.
Given the lack of a full transcript, and in trying to defend the crewmembers intentions , Is it possible that at the point of "Positive Rate - Gear Up" - PM Brain farted, and performed a different muscle memory action? Thus they would deny moving the Switches - and take a few seconds to compute what they just did?
Given the lack of a full transcript, and in trying to defend the crewmembers intentions , Is it possible that at the point of "Positive Rate - Gear Up" - PM Brain farted, and performed a different muscle memory action? Thus they would deny moving the Switches - and take a few seconds to compute what they just did?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Muscle Memory
July 11, 2025, 22:05:00 GMT
permalink Post: 11919876
The landing gear lever is forward and up on the centre instrument panel, adjacent to the PFD. The two fuel control switches are aft and low, on the thrust pedestal. There's no reasonable way to confuse one for the other in terms of position, hand movement or 'muscle memory'.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches Gear Lever Muscle Memory
July 12, 2025, 20:09:00 GMT
permalink Post: 11920799
Question - For those of you with good simulator access.
What - Exactly - are the Flight Deck Effects that would be seen (and in what order?) in the scenario that PM Operated #1 then #2 to cutoff, whilst in flight with APU not running?
e.g. - What screens would blank? for how long? Master Caution? EICAS Messages? Chimes/Aural Alerts?
Intent behind this question is, If PF Does not see the switches operated, what reasonably is the amount of time it would take to look at those switches? Where is the attention initially directed?
What - Exactly - are the Flight Deck Effects that would be seen (and in what order?) in the scenario that PM Operated #1 then #2 to cutoff, whilst in flight with APU not running?
e.g. - What screens would blank? for how long? Master Caution? EICAS Messages? Chimes/Aural Alerts?
Intent behind this question is, If PF Does not see the switches operated, what reasonably is the amount of time it would take to look at those switches? Where is the attention initially directed?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU EICAS Fuel (All) Fuel Cutoff Switches
July 13, 2025, 11:49:00 GMT
permalink Post: 11921258
Some facts
From the Manuals AMM - IPD - WDM - CMM - Avoiding speculation in this post. Just Facts.
Cutoff Switch
Each switch has 14 pins - 4 sets of contacts
Designation | Cutoff | Common | Run
A | 1 | 2 | 3
B | 4 | 5 | 6
C | 7 | 8 | 9
D | 10 | 11 | 12
Pins 13 and 14 power the LED - Powered by Capt Instrument bus 28vdc - signal from common core sys
A Contacts feed an RDC
B Contacts feed a different RDC
C Leads to Engine Fuel Control Relay 2(L or R)
D Leads to Engine Fuel Control Relay 1(L or R) AND Engine Fuel Relay 1
The common pins are all GND. Positive voltage is suppled to the cutoff and run pins.
The relays - do various things. I cant detail everywhere they lead to.
The AMM States that the manufacturer for the engine fuel control switches has determined that you should not replace the switches on-wing, and that you should replace the thrust control module instead.
Thrust Control Module
This LRU (replaced twice per the interim report) - contains the cutoff switches.
The CMM for the Thrust Control Module does not call out a test of the locking feature that I can find. It does perform various tests of the switch function.
Cutoff Switch
Each switch has 14 pins - 4 sets of contacts
Designation | Cutoff | Common | Run
A | 1 | 2 | 3
B | 4 | 5 | 6
C | 7 | 8 | 9
D | 10 | 11 | 12
Pins 13 and 14 power the LED - Powered by Capt Instrument bus 28vdc - signal from common core sys
A Contacts feed an RDC
B Contacts feed a different RDC
C Leads to Engine Fuel Control Relay 2(L or R)
D Leads to Engine Fuel Control Relay 1(L or R) AND Engine Fuel Relay 1
The common pins are all GND. Positive voltage is suppled to the cutoff and run pins.
The relays - do various things. I cant detail everywhere they lead to.
The AMM States that the manufacturer for the engine fuel control switches has determined that you should not replace the switches on-wing, and that you should replace the thrust control module instead.
Thrust Control Module
This LRU (replaced twice per the interim report) - contains the cutoff switches.
The CMM for the Thrust Control Module does not call out a test of the locking feature that I can find. It does perform various tests of the switch function.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches
July 13, 2025, 20:50:00 GMT
permalink Post: 11921641
My thoughts are that the thrust levers are something that 'were' moved by foreign objects (unlike all the silly speculation wrt the switches). That foreign object being the EICAS Screen/instrument panel/windscreen support structure AT impact.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EICAS
July 13, 2025, 21:34:00 GMT
permalink Post: 11921685
SAIB NM-18-33 Interpretation
Reading
SAIB NM-18-33
My Interpretation/reading:
Some 737 Operators reported incorrect/broken locking features on cutoff switches - PN 766AT613-3D
If you have PN 766AT61 3 -3D installed - Replace it with 766AT61 4 -3D, which includes an improved locking feature.
The other Aircraft listed - have switches with similar design. In the case of the B787, switch PN 4TL837-3D. Check those AC to ensure locking is OK, and if you do happen to find something odd, let us (the FAA) know.
No-one, has ever found anything wrong with any of those other switches, or there would be AD's.
Thus there is not a problem with 787 Fuel Switch locking features.
My Interpretation/reading:
Some 737 Operators reported incorrect/broken locking features on cutoff switches - PN 766AT613-3D
If you have PN 766AT61 3 -3D installed - Replace it with 766AT61 4 -3D, which includes an improved locking feature.
The other Aircraft listed - have switches with similar design. In the case of the B787, switch PN 4TL837-3D. Check those AC to ensure locking is OK, and if you do happen to find something odd, let us (the FAA) know.
No-one, has ever found anything wrong with any of those other switches, or there would be AD's.
Thus there is not a problem with 787 Fuel Switch locking features.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FAA Fuel (All) Fuel Cutoff Switches SAIB NM-18-33 Special Airworthiness Information Bulletin
July 14, 2025, 21:09:00 GMT
permalink Post: 11922503
Again, not familiar with the specifics of the 787, but on the 747-400/-8, one pole of the fuel switch feeds EICAS - which uses it in various message logic - and sends it out to any other aircraft systems that use it. There is "Digital Flight Data Acquisition Unit) DFDAU .... that takes all the various system digital signals, sorts them and provides them to the DFDR and QAR. The 787 has something similar to the DFDAU but I don't recall what it's called.
The other 2 contact sets feed latching relays (again driven each coil independently by dropping to GND at the switch) that then drive spar valves and reset signals to the FADEC Channels. (and more).
So - for the benefit of those that hang on to the 'possibility' of electrical gremlins and 'ghost' switch signals.
Each switch has 4 mechanically separated 'channels' - 2 of which do electromechanical things to the engines through separate paths, the other 2 feed through independent paths the FDR and the rest of the computer systems. The results of the electromechanical actions also feed back to the FDR.
Thus the readout from the EAFR will PROVE that the switches MUST have been PHYSICALLY MOVED.
And - I'm nervous to challenge you tdracer - there's quite the authority gradient and I know I'm at the bottom end, but I can't let this fly...
Its 'Deefer Doo'. Fight me.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Authority Gradient DFDR Digital Flight Data Acquisition Unit EAFR EICAS FADEC FDR Fuel (All) Fuel Cutoff Switches Spar Valves
July 14, 2025, 21:47:00 GMT
permalink Post: 11922533
I cant speak for how long it would take to connect the dots though.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EICAS RAT (All) RAT (Deployment)
July 15, 2025, 00:15:00 GMT
permalink Post: 11922588
But we will be able to say we've inspected.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches
July 15, 2025, 23:24:00 GMT
permalink Post: 11923343
Moving the conversation forward - What can we do?
I refuse to use the phrase that involves small rodents and circular exercise machines. But this conversation has to move forward.
If we take it that the preliminary report is true (or true enough). switches were moved by human hands, and is thus a Human Factors incident with very little that we can learn technically about the aircraft design...
How is this community going to learn from this incident? What are we going to do as a community to improve safety?
Accident investigation - IMO - is about examining all the facts. Looking at those facts, in the most unfiltered light, and working out the TRUE causes, regardless of the prevailing opinions of the time. Any aviation death is one too many. Every aviation death should be used to improve safety for those that follow. Sometimes the results are technical / design philosophy changes, sometimes its about humans.
Regardless of whether this incident was action slip, absent mindedness, intrusive thoughts manifested, or murder-suicide. The common theme is mental health.
What - really - is the state of mental health awareness in the pilot/aviation community? How much does it vary across geographic locations / cultures and communities? I don't know. I'm an engineer in a single location. I have never been in a CRM training session (plenty of HF Training though), I have no business getting involved in your business . Yet I have observed from the outside over the years pilots going from outright ridicule of CRM concepts as a flash-in-the-pan management consultancy theory, to being 'a bit interesting', to being 'a useful tool', to it being baked in as a fundamental concept of what you do.
But CRM is about the interpersonal aspects of working with each other. About assessing the competency and capability of your team mates, and utilising each others skills and capabilities for the best outcome. CRM is about interacting with others? But what about interacting with your self? How open can you be? - Really?
I've seen this thread, this forum, and the moderation team deny the discussion of pilot suicide (and even action slip) as 'unprofessional' talk, slander against professional pilots. Is that not suggestive of a community that is not (as a group) ready to acknowledge the possibilities? If so - Why? Is there a fear that acknowledgement of mental health issues will lead to personal disadvantage?
Me - As an engineer. My company is starting to 'talk the talk' about mental health awareness. There's mental health awareness week. There's leaflets and presentations and hotlines to call. But do I believe really that if I seek help, my company has got my back? No of course not! There is fear. Fear that should I take advantage of the 'services' then a 30 minute conversation could balloon into the loss of my career, income, ability to pay the mortgage and feed the family.
And you guys and gals - have Licences to maintain. Lose that and you are off the job. How much pressure do you have to pass your medicals? at any cost?. I've been watching a PPL on YouTube recently - reddit link containing a video and discussion who lost their licence because they sought help for a relatively minor issue, in a modern western 'enlightened' society. They have a YouTube career to fall back on, and they are young. A lot of us have only done aviation all our lives, are paid well for it and have nothing to fall back on.
I don't know the answers. I don't have a magic solution. I don't know how the pilot (or aviation as a whole) community can solve the next big challenge. How do WE the aviation professional community address mental health in a way that works for safety as a whole, whilst protecting the needs of the individuals and the needs of our employers?
A lot of questions and no answers. Sorry.
If we take it that the preliminary report is true (or true enough). switches were moved by human hands, and is thus a Human Factors incident with very little that we can learn technically about the aircraft design...
How is this community going to learn from this incident? What are we going to do as a community to improve safety?
Accident investigation - IMO - is about examining all the facts. Looking at those facts, in the most unfiltered light, and working out the TRUE causes, regardless of the prevailing opinions of the time. Any aviation death is one too many. Every aviation death should be used to improve safety for those that follow. Sometimes the results are technical / design philosophy changes, sometimes its about humans.
Regardless of whether this incident was action slip, absent mindedness, intrusive thoughts manifested, or murder-suicide. The common theme is mental health.
What - really - is the state of mental health awareness in the pilot/aviation community? How much does it vary across geographic locations / cultures and communities? I don't know. I'm an engineer in a single location. I have never been in a CRM training session (plenty of HF Training though), I have no business getting involved in your business . Yet I have observed from the outside over the years pilots going from outright ridicule of CRM concepts as a flash-in-the-pan management consultancy theory, to being 'a bit interesting', to being 'a useful tool', to it being baked in as a fundamental concept of what you do.
But CRM is about the interpersonal aspects of working with each other. About assessing the competency and capability of your team mates, and utilising each others skills and capabilities for the best outcome. CRM is about interacting with others? But what about interacting with your self? How open can you be? - Really?
I've seen this thread, this forum, and the moderation team deny the discussion of pilot suicide (and even action slip) as 'unprofessional' talk, slander against professional pilots. Is that not suggestive of a community that is not (as a group) ready to acknowledge the possibilities? If so - Why? Is there a fear that acknowledgement of mental health issues will lead to personal disadvantage?
Me - As an engineer. My company is starting to 'talk the talk' about mental health awareness. There's mental health awareness week. There's leaflets and presentations and hotlines to call. But do I believe really that if I seek help, my company has got my back? No of course not! There is fear. Fear that should I take advantage of the 'services' then a 30 minute conversation could balloon into the loss of my career, income, ability to pay the mortgage and feed the family.
And you guys and gals - have Licences to maintain. Lose that and you are off the job. How much pressure do you have to pass your medicals? at any cost?. I've been watching a PPL on YouTube recently - reddit link containing a video and discussion who lost their licence because they sought help for a relatively minor issue, in a modern western 'enlightened' society. They have a YouTube career to fall back on, and they are young. A lot of us have only done aviation all our lives, are paid well for it and have nothing to fall back on.
I don't know the answers. I don't have a magic solution. I don't know how the pilot (or aviation as a whole) community can solve the next big challenge. How do WE the aviation professional community address mental health in a way that works for safety as a whole, whilst protecting the needs of the individuals and the needs of our employers?
A lot of questions and no answers. Sorry.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Action slip Human Factors Mental Health Preliminary Report Thread Moderation
July 16, 2025, 23:47:00 GMT
permalink Post: 11924060
The switch is directly connected to the coils of a latching relay. That latching relay is directly connected to the coils of the spar valve. There is no digital logic device in the way,
The position of the switch is monitored (through a different set of contacts) by the EAFR (twice). The position of the spar valve is monitored by the EAFR.
Thus the recorder sees (twice) that the switch is moved, and that the valve moved in response.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR Fuel (All) Fuel Cutoff Fuel Cutoff Switches Spar Valves
July 17, 2025, 23:02:00 GMT
permalink Post: 11924737
"There has been no defect reported pertaining to the fuel control switch since 2023 on VT-ANB." - This will have been verified by the investigation team fairly rapidly. Verified reportable fact, included in the preliminary report.
Yes in the final report they would be in a position to make a statement like that. But in the preliminary - No.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR Fuel (All) Fuel Cutoff Switches Preliminary Report