SQ-368 (engine & wing on fire) final report out
If there was no known fuel leak there is no need to shutdown. In this case crew seem to be unaware of fuel leak, later PR teams tried to spin it as ~10 gallons of hidden oil.
Look at the fire photo posted, evenly intense to the tip.take a close look at the flame pattern.
My theory and speculation is the fuel leaked during fuel jettison from the wing tip jettison.
Perhaps the wing filled the empty cavities with fuel during the fuel jettison approx 35 tons guessing. That is 17.5 tons each wing jettison point dumped in 20 minutes.
The ignition was on selecting idle reverse thrust.
Fire services at Singapore are definitely world class as is the airport.
If the fire services reported fire is "under control " within the first minutes.
It is hard to believe but possible especially if that fire went out after a short time, expending all the pooled fuel.
"No fire" means no evacuation after the first 2 minutes.
Just a theory but worth considering for those who speculate prior to investigation release.
Look at the fire photo posted, evenly intense to the tip.take a close look at the flame pattern.
My theory and speculation is the fuel leaked during fuel jettison from the wing tip jettison.
Perhaps the wing filled the empty cavities with fuel during the fuel jettison approx 35 tons guessing. That is 17.5 tons each wing jettison point dumped in 20 minutes.
The ignition was on selecting idle reverse thrust.
Fire services at Singapore are definitely world class as is the airport.
If the fire services reported fire is "under control " within the first minutes.
It is hard to believe but possible especially if that fire went out after a short time, expending all the pooled fuel.
"No fire" means no evacuation after the first 2 minutes.
Just a theory but worth considering for those who speculate prior to investigation release.
It's about SQ training and standards, and decision making. Or lack of.
What would you do, Lonewolf, if you did an autoland and the aircraft started to bank and drift off to the left?
Sit on your hands and wait for the autopilot to fix itself, or disconnect the autopilot and land yourself/go around?
This incident is why I don't fly with SQ. It's just a slightly polished version of Asiana.
What would you do, Lonewolf, if you did an autoland and the aircraft started to bank and drift off to the left?
Sit on your hands and wait for the autopilot to fix itself, or disconnect the autopilot and land yourself/go around?
This incident is why I don't fly with SQ. It's just a slightly polished version of Asiana.
Only half a speed-brake
A little devil's advocate: Once you jettison, your chances of identifying a fuel leak are effectively zero. If it had started as a small one, within the normal variation of fuel indications, but progressively increased in flow while the crew managed the return and later opened the overboards ...
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What would you do, Lonewolf, if you did an autoland and the aircraft started to bank and drift off to the left?
TOGA pressed when wheels are planted.
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https://www.youtube.com/watch?v=VRtSEbf7Iac
SQ is capable of calling out the fire trucks before landing and capable of considering evac via slides as shown in this incident. Fire indication in aft cargo hold and emergency landing.
SQ is capable of calling out the fire trucks before landing and capable of considering evac via slides as shown in this incident. Fire indication in aft cargo hold and emergency landing.
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Main Fuel/Oil Heat Exchanger failure (Known fault on GE engines)
Higher presssure fuel enters the oil system and circulates around the oil system - hence the oil system parameters changing.
Fuel/oil vapour/mist vents out the central vent system and to atmosphere.
Due to cold stream airflow/forward speed of the aircraft nothing happens.
Flaps down on approach and lowering airspeed, venting fuel/oil vapour impinges on the lower wing surface.
Selecting reverse thrust plus decaying forward speed due to landing, no more airflow to draw the vapour away.
Engine central vent system vapour ignites and spreads to the contaminated lower surface.
Even after engine shutdown, system still pressurised and venting adding to problem.
Higher presssure fuel enters the oil system and circulates around the oil system - hence the oil system parameters changing.
Fuel/oil vapour/mist vents out the central vent system and to atmosphere.
Due to cold stream airflow/forward speed of the aircraft nothing happens.
Flaps down on approach and lowering airspeed, venting fuel/oil vapour impinges on the lower wing surface.
Selecting reverse thrust plus decaying forward speed due to landing, no more airflow to draw the vapour away.
Engine central vent system vapour ignites and spreads to the contaminated lower surface.
Even after engine shutdown, system still pressurised and venting adding to problem.
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Simple answer, 'notapilot15' - There was no issue with the fuel dumping/jettison system which never caught fire.
The engine and wing caught alight after landing..
As someone earlier posted about the NGS system being installed, this aircraft has it fitted.
ATA 47 if you are interested.
The engine and wing caught alight after landing..
As someone earlier posted about the NGS system being installed, this aircraft has it fitted.
ATA 47 if you are interested.
post 632
But why the quantity? as the big difference in this event?. Else there would have been earlier fires in the data bank.
What's the postulated lesson learned here? or is this just a theory?
Even after engine shutdown, system still pressurised and venting adding to problem.
What's the postulated lesson learned here? or is this just a theory?
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Lomapaseo,
I have no idea about the full facts and figures from the fuel and oil systems and haven't seen them.
I believe you know (from past postings) the engine oil system is still pressurised up to 10 minutes after shutdown.
So the theory is until then, the contaminated oil system by being pressurised and venting could be feeding the fire.
If there was another issue to compound the problem, IE a fuel leak in the pylon, that I do not know.
I have no idea about the full facts and figures from the fuel and oil systems and haven't seen them.
I believe you know (from past postings) the engine oil system is still pressurised up to 10 minutes after shutdown.
So the theory is until then, the contaminated oil system by being pressurised and venting could be feeding the fire.
If there was another issue to compound the problem, IE a fuel leak in the pylon, that I do not know.
Theory is external leak in jettison system. Copy from FCTM follows
"
Significant fuel leaks, although fairly rare, are difficult to detect. The Fuel Leak NNC includes steps for a leak that is between the front spar and the engine (an “engine fuel leak”) or a leak from the tank to the outside (a “tank leak”). The NNC for the 777-200 non-ER airplane includes steps for a leak into the center wing dry bay area. An engine fuel leak is the most common type of fuel leak since fuel lines are exposed in the strut. Most other fuel lines, such as a crossfeed manifold, are contained within the tanks. A significant fuel leak directly from a tank to the outside is very rare due to the substantial wing structure that forms the tanks.
There is no specific fuel leak annunciation on the flight deck. A leak must be detected by discrepancies in the fuel log, by visual confirmation, or by some annunciation that occurs because of a leak. Any unexpected change in fuel quantity or fuel balance should alert the crew to the possibility of a leak. If a leak is suspected, it is imperative to follow the NNC.
The NNC leads the crew through steps to determine if the fuel leak is from the strut or the engine area. If an engine fuel leak is confirmed, the NNC directs the crew to shutdown the affected engine. There are two reasons for the shutdown. The first is to close the spar valve, which stops the leak. This prevents the loss of fuel which could result in a low fuel state. The second reason is that the fire potential is increased when fuel is leaking around the engine. The risk of fire increases further when the thrust reverser is used during landing. The thrust reverser significantly changes the flow of air around the engine which can disperse fuel over a wider area.
"
Significant fuel leaks, although fairly rare, are difficult to detect. The Fuel Leak NNC includes steps for a leak that is between the front spar and the engine (an “engine fuel leak”) or a leak from the tank to the outside (a “tank leak”). The NNC for the 777-200 non-ER airplane includes steps for a leak into the center wing dry bay area. An engine fuel leak is the most common type of fuel leak since fuel lines are exposed in the strut. Most other fuel lines, such as a crossfeed manifold, are contained within the tanks. A significant fuel leak directly from a tank to the outside is very rare due to the substantial wing structure that forms the tanks.
There is no specific fuel leak annunciation on the flight deck. A leak must be detected by discrepancies in the fuel log, by visual confirmation, or by some annunciation that occurs because of a leak. Any unexpected change in fuel quantity or fuel balance should alert the crew to the possibility of a leak. If a leak is suspected, it is imperative to follow the NNC.
The NNC leads the crew through steps to determine if the fuel leak is from the strut or the engine area. If an engine fuel leak is confirmed, the NNC directs the crew to shutdown the affected engine. There are two reasons for the shutdown. The first is to close the spar valve, which stops the leak. This prevents the loss of fuel which could result in a low fuel state. The second reason is that the fire potential is increased when fuel is leaking around the engine. The risk of fire increases further when the thrust reverser is used during landing. The thrust reverser significantly changes the flow of air around the engine which can disperse fuel over a wider area.
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Input from insider
The following from a friend in the industry:
"Some more info. Probably not the greatest idea to use it for reverse. Fuel Oil cooler failed internally Oil pressure dropped oil quantity also erratic. Engine return to idle for last 2 hours of the flight.
Pilot lands but applies full reverse thrust. Engine burst into flames and heat melts fuel tank access panels. More fire than can be handled by on board systems PAX sit and watch the show."
Photos in following post.
"Some more info. Probably not the greatest idea to use it for reverse. Fuel Oil cooler failed internally Oil pressure dropped oil quantity also erratic. Engine return to idle for last 2 hours of the flight.
Pilot lands but applies full reverse thrust. Engine burst into flames and heat melts fuel tank access panels. More fire than can be handled by on board systems PAX sit and watch the show."
Photos in following post.
Last edited by Minimbah; 16th Jul 2016 at 05:44. Reason: Typo
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Probably not the greatest idea to use it for reverse.
This is a topic that has both divided opinion & ignorance. I've worked for various airlines; only 1 had an SOP of NOT to use T/R on and engine with a fire warning. Some had a 'beware' 'consider' philosophy. Some had never thought about it. None of the FCTM addressed the problem. Given that T/R's are a bonus in the stopping calculations IMHO it would be good airmanship not to use T/R with a Fire RTO nor to use T/R with a damaged running engine for RTO or landing.
My point is that there is so little guidance, and in this day where in-depth airmanship is a diminishing element under the onslaught of rigid SOP's, lack of guidance can lead to lax and dormant thinking in NNC's.
This is a topic that has both divided opinion & ignorance. I've worked for various airlines; only 1 had an SOP of NOT to use T/R on and engine with a fire warning. Some had a 'beware' 'consider' philosophy. Some had never thought about it. None of the FCTM addressed the problem. Given that T/R's are a bonus in the stopping calculations IMHO it would be good airmanship not to use T/R with a Fire RTO nor to use T/R with a damaged running engine for RTO or landing.
My point is that there is so little guidance, and in this day where in-depth airmanship is a diminishing element under the onslaught of rigid SOP's, lack of guidance can lead to lax and dormant thinking in NNC's.
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Photos from Minimbah are very interesting!
http://www.pprune.org/rumours-news/5...ml#post9441497
Two photos clearly show that it was the wing that was on fire, sooting the fuselage. Tyres are fine so absolutely no reason to keep pax on board in this case, and total luck that the fire crews happened to be there.
I need to repeat the earlier statement: You can not say that this was a good decision because noone got hurt.
Keeping people in anything that burns is never a good idea. Best case scenario is that they get lucky because of circumstances (like wind direction), but mostly they are not that lucky. Be it boats, helis, airplanes, cars or houses. There is a reason you evacuate your house if the forest fire flames are touching your windows.
http://www.pprune.org/rumours-news/5...ml#post9441497
Two photos clearly show that it was the wing that was on fire, sooting the fuselage. Tyres are fine so absolutely no reason to keep pax on board in this case, and total luck that the fire crews happened to be there.
I need to repeat the earlier statement: You can not say that this was a good decision because noone got hurt.
Keeping people in anything that burns is never a good idea. Best case scenario is that they get lucky because of circumstances (like wind direction), but mostly they are not that lucky. Be it boats, helis, airplanes, cars or houses. There is a reason you evacuate your house if the forest fire flames are touching your windows.
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I've worked for various airlines; only 1 had an SOP of NOT to use T/R on and engine with a fire warning. Some had a 'beware' 'consider' philosophy. Some had never thought about it.
Just for my info, is it "no reverse" or "not more then idle"?
I have concerns about using assymetric reverse thrust on an emergency return to land. It adds more pressure on the pilot in an already stressful situation.
I would rather put the mitigation priority on this postulated cause towards addressing the amount of fuel leaked.
I would rather put the mitigation priority on this postulated cause towards addressing the amount of fuel leaked.
