BA 777 returned to LHR with gear trouble
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Nobody hurt, but nearly 100 tonnes of fuel into the sea.
As a layman, reading the report, it just confirms how fiendishly complicated these aircraft are, and how many things there are to go wrong. The fact that they rarely do is a tribute to the engineers.
As a layman, reading the report, it just confirms how fiendishly complicated these aircraft are, and how many things there are to go wrong. The fact that they rarely do is a tribute to the engineers.
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As a layman, reading the report, it just confirms how fiendishly complicated these aircraft are, and how many things there are to go wrong. The fact that they rarely do is a tribute to the engineers.
Yes, they are fiendishly complex, but as an Engineer, I am embarrassed that some poor sod forgot to secure a panel in the fuel cell, and left the screws hanging there in a parts bag! We are paid to ensure things like this do not happen. This easily could have had a horrible ending.
Yes, they are fiendishly complex, but as an Engineer, I am embarrassed that some poor sod forgot to secure a panel in the fuel cell, and left the screws hanging there in a parts bag! We are paid to ensure things like this do not happen. This easily could have had a horrible ending.
Ich bin ein Prooner.
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Sad to say that the Televisual media was getting into "Aircrash" mode when reporting this. An on-the-spot reporter (outside the railings at H/row) was spouting the "facts", and ended his report by saying that "this kind of thing" (the hole in the tank leaking fuel) was exactly what caused the Paris Concorde crash.
Innacurate, irresponsible reporting IMHO.
Innacurate, irresponsible reporting IMHO.
A couple of queries:
1. With a reported serious fuel leak, why burn down to MLW? is this not a case for an overweight landing?
2. Why taxy the aircraft to the stand after landing following a serious fuel leak?
1. With a reported serious fuel leak, why burn down to MLW? is this not a case for an overweight landing?
2. Why taxy the aircraft to the stand after landing following a serious fuel leak?
They didn't BURN down to MLW, they dumped. With sufficient fuel to continue flight it's what I'd have done. Could there have been a fire and centre tank explosion? - possibly but unlikely. Heavyweight landing = hot brakes.
No leakage reported by Fire and Rescue Service who presumably accompanied the aircraft and stood by.
Sounds to me like a number of command decisions were made - that's what we're paid for.
No one hurt - rejoice!
No leakage reported by Fire and Rescue Service who presumably accompanied the aircraft and stood by.
Sounds to me like a number of command decisions were made - that's what we're paid for.
No one hurt - rejoice!
Noah, The quote referring to the Concorde incident was exactly the same as given by a senior BA quality manager at a management briefing just after the event.
As has been said in a previous post, There for the grace of......etc.
As has been said in a previous post, There for the grace of......etc.
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1. With a reported serious fuel leak, why burn down to MLW? is this not a case for an overweight landing?
1. Quite a lot of time had passed...
2. A lot of fuel had leaked...
If the doomsday scenario had not yet occurred (i.e. ignition) I would have thought "stabilise" the situation and not rush into anything. A hastily arranged return and congfiguration could have provided that ignition source.
I'm pretty sure the AAIB report said the crew had diagnosed a CFT leak, so dumping presumably emptied that tank and elimated the bulk of the problem. Sounds well handled by my book... well, the flying side of it anyway <G>
Further to above... roughly what I said.
With approximately 4,000 kg of fuel remaining in the centre tank, an ILS approach was made to Runway 27L. There were no reports of any fuel leaking during the approach and the landing was made with minimum braking in order to keep the brake units as cool as possible. The Airfield Fire and Rescue Service met the aircraft and reported some vapour emanating from the left main landing gear wheel unit but no apparent fuel leaks. As a precaution, the left engine was shutdown and the aircraft was taxied back to a stand where the passengers were disembarked normally
NoD
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1. With a fuel leak I would not quickly decide if I would go and dump some more.
2. An overweight landing is basically not a problem if it does not combine adversely with braking and/or flight control problems.
3. As far as I know; if the dumping system is U/S it’s not a no-go.
4. Landing a B 777 at MTOW on a 3000 m runway will not cause any serious braking problems if you do it in an intelligent way i.e. make use of max reversers and use the whole runway to decelerate.
2. An overweight landing is basically not a problem if it does not combine adversely with braking and/or flight control problems.
3. As far as I know; if the dumping system is U/S it’s not a no-go.
4. Landing a B 777 at MTOW on a 3000 m runway will not cause any serious braking problems if you do it in an intelligent way i.e. make use of max reversers and use the whole runway to decelerate.
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Interesting thoughts CAP 56.
Lets assume you are the commander, with the fuel leaking during the initial climb you level off at 4000 feet.
You keep the speed back to Vref 80 and as you know the attitude will be about 1 degree nose up so the fuel stops leaking.
Without any further action you return for an overweight landing.
During the flare the attitude is such that the fuel is now gushing out again, all around the u/c bay.
You select reverse and keep it in until very low speed. You remember (too late) the layout of the reversers and fuel soaked gear bay (very close)... its the last thing you ever do.
This commander however, not knowing what the problem was, apart from visual reports of a fuel leak (and reducing centre tank contents) decided to dump down to MLW and return.
I would have done the same, as would many other type rated 777 commanders.
Lets assume you are the commander, with the fuel leaking during the initial climb you level off at 4000 feet.
You keep the speed back to Vref 80 and as you know the attitude will be about 1 degree nose up so the fuel stops leaking.
Without any further action you return for an overweight landing.
During the flare the attitude is such that the fuel is now gushing out again, all around the u/c bay.
You select reverse and keep it in until very low speed. You remember (too late) the layout of the reversers and fuel soaked gear bay (very close)... its the last thing you ever do.
This commander however, not knowing what the problem was, apart from visual reports of a fuel leak (and reducing centre tank contents) decided to dump down to MLW and return.
I would have done the same, as would many other type rated 777 commanders.
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Woodpecker
I was merely thinking while writing, but you are right, it’s not a clear cut case as long as you do not know where the leak is.
If the leak was know to be in the centre tank then, provided enough fuel was carried in the wing, I agree that emptying the centre was a good idea.
I do not have the figures but irrespective of MLW I would then probably have landed with full wings, to cope with the fact that I may have gotten it wrong on the exact location of the leak, if that brings me over the MLW so be it. I would be looking for a good compromise that is defendable.
I would then be left with 3000 m to land, thinking that a hot brake is worse than the use of the rev and assuming the worst case scenario of the leak still being there.
Basically that would mean an average deceleration of 1 m/s*s a very low value that you can get from the rev only with only a little braking. Not many people look at the deceleration/acceleration indicator.
1. (a=v*v/2*d) using 160 kts and 3000 m a= 1 m/s*s
2. example: arrow indicates + 20 kts over next 10 sec = 2 kt/1 s*s = 1 m/s*s = +/- 1.5 cm arrow
I am not aware of a limitation/caution on the use of rev in this case (QRH ?)
So the question really is? What do I consider the most important?
I think that any reasoning that is reasonably defendable is therefore acceptable. There is no absolute yes or no.
Interesting issue and good exchange of ideas.
Thanks.
PS: I really do not know about reversers and fuel leak combining adversely. Surely the fuel will be dispersed by the rev BEFORE it can enter the engine. If it does do so, the concentration will be quite low. But I must say I really do not know and am interested in why Airbus came up with the idea to caution doing so. Surely, Boeing must have thought about this after so many years of building these aircraft?
I was merely thinking while writing, but you are right, it’s not a clear cut case as long as you do not know where the leak is.
If the leak was know to be in the centre tank then, provided enough fuel was carried in the wing, I agree that emptying the centre was a good idea.
I do not have the figures but irrespective of MLW I would then probably have landed with full wings, to cope with the fact that I may have gotten it wrong on the exact location of the leak, if that brings me over the MLW so be it. I would be looking for a good compromise that is defendable.
I would then be left with 3000 m to land, thinking that a hot brake is worse than the use of the rev and assuming the worst case scenario of the leak still being there.
Basically that would mean an average deceleration of 1 m/s*s a very low value that you can get from the rev only with only a little braking. Not many people look at the deceleration/acceleration indicator.
1. (a=v*v/2*d) using 160 kts and 3000 m a= 1 m/s*s
2. example: arrow indicates + 20 kts over next 10 sec = 2 kt/1 s*s = 1 m/s*s = +/- 1.5 cm arrow
I am not aware of a limitation/caution on the use of rev in this case (QRH ?)
So the question really is? What do I consider the most important?
I think that any reasoning that is reasonably defendable is therefore acceptable. There is no absolute yes or no.
Interesting issue and good exchange of ideas.
Thanks.
PS: I really do not know about reversers and fuel leak combining adversely. Surely the fuel will be dispersed by the rev BEFORE it can enter the engine. If it does do so, the concentration will be quite low. But I must say I really do not know and am interested in why Airbus came up with the idea to caution doing so. Surely, Boeing must have thought about this after so many years of building these aircraft?
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woodpecker:
Interesting thread... I'm surprised reverser use should be quite so deprecated; I was under the impression that (on modern big fans at least) reversers used only 'cold' (relatively) fan air, not the hot core gas stream.
Certainly that's the case on all fans I'm aware of; if I had a 'fuel soaked gear bay' I suspect I'd choose cold air over very hot brakes!
What do the books say?
R1
You select reverse and keep it in until very low speed. You remember (too late) the layout of the reversers and fuel soaked gear bay (very close)... its the last thing you ever do.
Certainly that's the case on all fans I'm aware of; if I had a 'fuel soaked gear bay' I suspect I'd choose cold air over very hot brakes!
What do the books say?
R1
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Quite right, the "big fans" only use the "cold" air in the reverse mode but the exhaust (at 600C) from the core is still coming out ther back!
My point is that it only takes one spark ( or contact with this core stream) to set the whole lot off. The effect of the reversers at slow speed is to pick up everything (including in this case whatever was around the leak area) and deflect it forwards.
If you look at the 777 fire at Denver (on the ground) it was not initially direct contact between the leaking fuel connection and the engine exhaust cone but fuel vapour which then spread to the leak.
Back to the topic, they did a good job, any comments should be directed to those involved some fifty odd sectors earlier.
My point is that it only takes one spark ( or contact with this core stream) to set the whole lot off. The effect of the reversers at slow speed is to pick up everything (including in this case whatever was around the leak area) and deflect it forwards.
If you look at the 777 fire at Denver (on the ground) it was not initially direct contact between the leaking fuel connection and the engine exhaust cone but fuel vapour which then spread to the leak.
Back to the topic, they did a good job, any comments should be directed to those involved some fifty odd sectors earlier.
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Woodpecker
If you have a fuel leak there are two issues to look at:
1. It comes somewhere downstream of the spar shut of valve
2. it does not
In case 1 you shut down the # and the story ends in a (n-1) approach, in case 2 you use as much fuel as possible from the leaking tank respecting the unbalance limits. If it’s the center tank you may consider dumping it if you think it’s a safer option.
Respecting these limits, requires you to know what the limiting factors are. On most jets this is a one engine configuration with high flap setting limiting the moment produced by the ailerons to counter the roll induced.
If the tank leaks you better get on the ground quickly. To avoid any complications you do not want to have any hot spots, read hot brakes and therefore will try to avoid overheating the brakes using the max reverse allowed.
Until now I have no information that this is unacceptable and I do not expect that it will pop up.
I will however inform myself on the flash temperatures of the fuel used however from my ATLP courses I recall from memory that it’s not such a big problem under normal pressures and temperatures.
What I do remember very clearly is that my teacher who had a Masters in this stuff told us that you could throw a match in this kind of fuel without any problem. Needless to say that we were all surprised.
So in this case you land, use rev till 100 kts, then brakes and shut down the engines while you are on the APU. I know this last paragraph has a touch of hindsight and I would probably not have gone that far in my analysis but what is the problem if the fire brigade is standing next to you and your aircraft is cold.
If you have a fuel leak there are two issues to look at:
1. It comes somewhere downstream of the spar shut of valve
2. it does not
In case 1 you shut down the # and the story ends in a (n-1) approach, in case 2 you use as much fuel as possible from the leaking tank respecting the unbalance limits. If it’s the center tank you may consider dumping it if you think it’s a safer option.
Respecting these limits, requires you to know what the limiting factors are. On most jets this is a one engine configuration with high flap setting limiting the moment produced by the ailerons to counter the roll induced.
If the tank leaks you better get on the ground quickly. To avoid any complications you do not want to have any hot spots, read hot brakes and therefore will try to avoid overheating the brakes using the max reverse allowed.
Until now I have no information that this is unacceptable and I do not expect that it will pop up.
I will however inform myself on the flash temperatures of the fuel used however from my ATLP courses I recall from memory that it’s not such a big problem under normal pressures and temperatures.
What I do remember very clearly is that my teacher who had a Masters in this stuff told us that you could throw a match in this kind of fuel without any problem. Needless to say that we were all surprised.
So in this case you land, use rev till 100 kts, then brakes and shut down the engines while you are on the APU. I know this last paragraph has a touch of hindsight and I would probably not have gone that far in my analysis but what is the problem if the fire brigade is standing next to you and your aircraft is cold.
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Woodpecker,
I was merely refering to the philosophy of the QRH in case of fuel leak.
Of course, in case of a fuel leak in the centre tank the QRH would not lead you into shutting down an engine and nor did I make any such statement.
Cheers
I was merely refering to the philosophy of the QRH in case of fuel leak.
Of course, in case of a fuel leak in the centre tank the QRH would not lead you into shutting down an engine and nor did I make any such statement.
Cheers
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May I ask whether this area in the Main Gear compartment is accessible for checking, and indeed is it a requirement to check it for damage at all during post/pre-flights.
According to the AIB report on G-YMME it had flown 53 sectors with this panel off and had only leaked because 43.000Kg of fuel had been put in, enough to leak during climb out.
After any tank work I always used to completely fill the tank in question for leak checking, but that was in the military and the tanks were only 9000Lbs max. This tank I believe can hold 80-90,000kgs
Thanks
According to the AIB report on G-YMME it had flown 53 sectors with this panel off and had only leaked because 43.000Kg of fuel had been put in, enough to leak during climb out.
After any tank work I always used to completely fill the tank in question for leak checking, but that was in the military and the tanks were only 9000Lbs max. This tank I believe can hold 80-90,000kgs
Thanks
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You can only see this area of the gear bay with the door open - not something that is usually done unless there is specific maintenance that needs to access that area.
Part of the problem with this incident was that the removal of the panel was unrecorded - hence there was nothing in the paperork to tell the engineers who did the leak check on the lower access panels that any other panels had been taken off.
Part of the problem with this incident was that the removal of the panel was unrecorded - hence there was nothing in the paperork to tell the engineers who did the leak check on the lower access panels that any other panels had been taken off.