Another 787 Fuel Leak
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Here is a quick and dirty definition per the FAA Part 121 Regs. There are a couple of alternatives this but it's not worth going into those under this particular discussion. I'm sure there are equivalent requirements under most regulatory organizations.
FUEL REQUIRED TO:
FUEL REQUIRED TO:
(1) To fly to and land at the airport to which it is released;
(2) After that, to fly for a period of 10 percent of the total time required to fly from the airport of departure to, and land at, the airport to which it was released;
(3) After that, to fly to and land at the most distant alternate airport specified in the flight release, if an alternate is required; and
(4) After that, to fly for 30 minutes at holding speed at 1,500 feet above the alternate airport (or the destination airport if no alternate is required) under standard temperature conditions.
(2) After that, to fly for a period of 10 percent of the total time required to fly from the airport of departure to, and land at, the airport to which it was released;
(3) After that, to fly to and land at the most distant alternate airport specified in the flight release, if an alternate is required; and
(4) After that, to fly for 30 minutes at holding speed at 1,500 feet above the alternate airport (or the destination airport if no alternate is required) under standard temperature conditions.
Last edited by Spooky 2; 14th Jan 2013 at 11:13.
Per Ardua ad Astraeus
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Thanks - we in the UK call that contingency and it is 'normally' 5% - whether that changes for Ultra Long Haul I do not know. Where does 'FLAG' come from?
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US Supplemental or Scheduled International carrier that fly the US Flag on the airplane. (Decal of course). Kind of old school but the term is still used and refered to as such.
BOAC:
Maybe I can help, maybe I can't.
In Laker, CAA rules required a 5% contingency to be carried for the part of the route where no enroute alternates existed. So, for a DC-10 flying from LGW to JFK we were required, in effect, to carry 5% of the fuel burn between SNN and YQX which amounted to about 2,000 lbs.
When I flew identical DC-10s for a US Flag carrier (Part 121), we were required to carry 10% of the entire fuel burn from LGW to JFK.
This simply could not be done whilst carrying a decent (identical) payload so we used the Reclear Flightplan System. The ATC flight plan would be filed from LGW to YQX with full reserves. We also carried a flight plan for the entire trip to JFK.
So, approaching YQX, if the fuel on board equalled the fuel required to make the non-stop flight (IE: you now only needed 10% of the burn from YQX to JFK then the flight could continue after being recleared by the despatcher.
If not, then we would reclear to BGR and, ultimately, to BOS by which time all that was required was 10% of the burn from BOS to JFK.
It was an unwieldy system but it worked. I never failed to make the direct flight.
Incidentally, if it was a Supplemental Flight (Part 135) then the captain could make the decision to reclear without consulting the despatcher.
Maybe I can help, maybe I can't.
In Laker, CAA rules required a 5% contingency to be carried for the part of the route where no enroute alternates existed. So, for a DC-10 flying from LGW to JFK we were required, in effect, to carry 5% of the fuel burn between SNN and YQX which amounted to about 2,000 lbs.
When I flew identical DC-10s for a US Flag carrier (Part 121), we were required to carry 10% of the entire fuel burn from LGW to JFK.
This simply could not be done whilst carrying a decent (identical) payload so we used the Reclear Flightplan System. The ATC flight plan would be filed from LGW to YQX with full reserves. We also carried a flight plan for the entire trip to JFK.
So, approaching YQX, if the fuel on board equalled the fuel required to make the non-stop flight (IE: you now only needed 10% of the burn from YQX to JFK then the flight could continue after being recleared by the despatcher.
If not, then we would reclear to BGR and, ultimately, to BOS by which time all that was required was 10% of the burn from BOS to JFK.
It was an unwieldy system but it worked. I never failed to make the direct flight.
Incidentally, if it was a Supplemental Flight (Part 135) then the captain could make the decision to reclear without consulting the despatcher.
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Individual Operators can request relief as you have described. This then becomes a part of their OpsSpecs. Obviously going from KLAX to EGLL and carrying the 10% is a significant penalty if applied for the whole, say eleven hours as opposed to the coast out, coast in segment.
Keep in mind that we are talking about 10% of the time in minutes and not 10% of the fuel in LBS/KGS.
Keep in mind that we are talking about 10% of the time in minutes and not 10% of the fuel in LBS/KGS.
Last edited by Spooky 2; 14th Jan 2013 at 14:41.
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In Long-haul operations fuel planning as you described is not unusual. It can often cause some considerable head scratching for those used to the more simplistic short-haul operations. The easiest way to view it is that at all times enroute the aircraft will have sufficient fuel to reach AN airport suitable for landing (with its associated requirements such as Wx holding etc) plus 10%, plus normal fixed reserves. However that airport may not, and initially almost certainly on ultra-long haul ops won't, be the destination airport. The latter will only become the airport suitable for landing plus 10% during the later stages of the flight. Different operators will then have varying requirements with regard alternate carriage, but that's another story. Without a similar fuel policy, ultra-long haul operations would be effectively impossible.
As a matter of interest, what is the 787s fuel average burn in tonnes/hr?
As a matter of interest, what is the 787s fuel average burn in tonnes/hr?
As a matter of interest, what is the 787s fuel average burn in tonnes/hr?
Pprune-B787 Performance
It was reported on Avweb this morning that Reuters reports that JAL says (talk about third hand info!) that the reason for the BOS fuel spill was an uncommanded activation of a fuel transfer valve which allowed fuel pumped from a "belly" tank (I thought Boeing called them "center" tanks) to overfill a wing tank. Upon arrival back in Tokyo, the same aircraft spilled fuel on the ramp after a valve used to defuel the aircraft opened. JAL has grounded that particular airplane until the cause of these fuel system malfunctions is identified and corrected.
A couple of observations and opinions:
Okay, the xfer valve thing at BOS I can understand. For some unknown reason a xfer valve opened and a wing tank was overfilled causing fuel to exit via the vent. I've seen this happen a couple of times when a crewmember tried to pack the wings and didn't stop in time. In this case JAL is quoted as stating that the valve operated "uncommanded" and are looking for the cause. Makes sense.
But the fuel spill after arrival in Tokyo is less clear. A "defueling" valve is traditionally used to allow defueling of the aircraft through the single point refueling receptacle. I'd be interested to know how a "defueling valve being open can cause a fuel spill. An open "jettison" valve is an entirely different matter though! I'll be interested to see whether something was lost in the translation in the reporting of this incident or perhaps the function of a defueling valve has been redefined.
A couple of observations and opinions:
Okay, the xfer valve thing at BOS I can understand. For some unknown reason a xfer valve opened and a wing tank was overfilled causing fuel to exit via the vent. I've seen this happen a couple of times when a crewmember tried to pack the wings and didn't stop in time. In this case JAL is quoted as stating that the valve operated "uncommanded" and are looking for the cause. Makes sense.
But the fuel spill after arrival in Tokyo is less clear. A "defueling" valve is traditionally used to allow defueling of the aircraft through the single point refueling receptacle. I'd be interested to know how a "defueling valve being open can cause a fuel spill. An open "jettison" valve is an entirely different matter though! I'll be interested to see whether something was lost in the translation in the reporting of this incident or perhaps the function of a defueling valve has been redefined.
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Should be an answer here somewhere...
Pprune-B787 Performance
Pprune-B787 Performance
Yes a failure of a valve/electronics associated with the fuel system would make sense. "Operator error" on the other hand does not.
Squawk-7600, quotes...
Yesterday:
"Chris I'd suggest you're speaking of a bygone era. I can honestly say I've never had to dick around with the refuelling system of any modern jet I've flown. I have no idea of how it works on the 787, but I can pretty much guarantee it's all fully automatic."
Today (1):
"Yes a failure of a valve/electronics associated with the fuel system would make sense."
Quite: that's when you may have to "dick around" with the system, and that's when it's all too easy to make a mistake.
Today (2):
" 'Operator error' on the other hand does not [make sense]."
Joint effort, perhaps?
Yesterday:
"Chris I'd suggest you're speaking of a bygone era. I can honestly say I've never had to dick around with the refuelling system of any modern jet I've flown. I have no idea of how it works on the 787, but I can pretty much guarantee it's all fully automatic."
Today (1):
"Yes a failure of a valve/electronics associated with the fuel system would make sense."
Quite: that's when you may have to "dick around" with the system, and that's when it's all too easy to make a mistake.
Today (2):
" 'Operator error' on the other hand does not [make sense]."
Joint effort, perhaps?
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Competence, preparation, procedures.....
Backing away from operations by crew, line, or builder does not inspire confidence.
When did it become more important who was left holding the bag?
That used to be roundly condemned, not supported.
Fix it.
Backing away from operations by crew, line, or builder does not inspire confidence.
When did it become more important who was left holding the bag?
That used to be roundly condemned, not supported.
Fix it.
None but a blockhead
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Has data been gathered on what fuel's actually remaining on landing? A decent statistical analysis on a good sample of normal flights that complete without incident might be a good counterpoint to the assumptions implicit in regulatory and company policy. Could also help identify routes, operators or a/c type which consistently edge towards a less safe regime. Evidence-based aviation, and all that...
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Chris I hear what you're saying, and while I'm also not familiar with the 787 aircraft, on other contemporary aircraft I fly the fuel simply doesn't work as I think you believe. It's not like the "old" days where the refueler determines how much fuel will go in different tanks. These days neither the refueler nor the pilots determine how much fuel goes where, the aircraft decides that for itself. I've done countless flights where fuel has become trapped in areas we don't want it, but that's just tough luck. The only manual input on behalf of the refueler is to preselect the required fuel. Based on the information that has been released, it's almost certain that a valve or associated control has failed as part of that automatic process. I'm not sure why you seem to be constantly trying to implicate operator error. If the aircraft had a failure such that manual intervention of the refuelling distribution was required, assuming that is even possible without determined engineering intervention, it would also almost certainly make that a no-go item given the subsequent affect on the fuel system. That is just the way the fuel systems in modern aircraft work; brilliant and completely idiot proof when it works, wheeled back into the hangar when it doesn't.
Squawk-7600,
I'm not trying to implicate the operator, the manufacturer, or anyone else. I'm pointing out that there is a multitude of possibilities. You, on the other hand, seem to be implying that the fault can only be 100% Boeing.
(You also imply that I know nothing about the refuelling of modern a/c, and have never done it. Isn't that somewhat presumptious?)
If you've deliberately got airborne with fuel that "has become trapped in areas we don't want it", I don't call that "just tough luck". But I can think of other ways of describing it.
On the other hand, to suggest that any need for manual intervention in the refuelling process (because the automatics have hiccupped) would invariably mean its being "wheeled back into the hangar" is plain nonsense.
I'm not trying to implicate the operator, the manufacturer, or anyone else. I'm pointing out that there is a multitude of possibilities. You, on the other hand, seem to be implying that the fault can only be 100% Boeing.
(You also imply that I know nothing about the refuelling of modern a/c, and have never done it. Isn't that somewhat presumptious?)
If you've deliberately got airborne with fuel that "has become trapped in areas we don't want it", I don't call that "just tough luck". But I can think of other ways of describing it.
On the other hand, to suggest that any need for manual intervention in the refuelling process (because the automatics have hiccupped) would invariably mean its being "wheeled back into the hangar" is plain nonsense.
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Oh goodness me, Chris let it go! You win, happy now? 
Nice attempt at a swipe, but your comments about the trapped fuel indicates you clearly know nothing about how some modern aircraft's fuel systems work, but whatever you say. I simply pointed out the most likely scenario.
PS ... and no I 'm not being presumptuous. Having gone through a generational change of aircraft I thought I'd respectfully point out how things have changed with the recent crop of aircraft. Meanwhile this is how you described yourself
Nice attempt at a swipe, but your comments about the trapped fuel indicates you clearly know nothing about how some modern aircraft's fuel systems work, but whatever you say. I simply pointed out the most likely scenario.
PS ... and no I 'm not being presumptuous. Having gone through a generational change of aircraft I thought I'd respectfully point out how things have changed with the recent crop of aircraft. Meanwhile this is how you described yourself
As a retired ex-A320 driver (1988 - 2001) ...
Last edited by Squawk-7600; 16th Jan 2013 at 00:31.
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@Squawk-7600:
You might want to reconsider giving Chris a hard time. He may have finished his career commanding short-haul types, but that does not preclude him being an F/O on long-haul types (including modern types) prior to 1988.
Now - as far as I can tell Chris has said nothing more than it would be wise to keep an open mind until more information becomes available, and I have a tough time finding anything wrong with that statement.
[EDIT : As someone who has been (wrongly) accused of "shilling for Airbus" in the past, and bearing in mind your post #9, please realise that I'm not in this for manufacturer politics!]
You might want to reconsider giving Chris a hard time. He may have finished his career commanding short-haul types, but that does not preclude him being an F/O on long-haul types (including modern types) prior to 1988.
Now - as far as I can tell Chris has said nothing more than it would be wise to keep an open mind until more information becomes available, and I have a tough time finding anything wrong with that statement.
[EDIT : As someone who has been (wrongly) accused of "shilling for Airbus" in the past, and bearing in mind your post #9, please realise that I'm not in this for manufacturer politics!]
Last edited by DozyWannabe; 16th Jan 2013 at 00:49.
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Sigh 
Dozy I'm not trying to give anyone a hard time, however what goes around comes around.
This was what was said
Having been through that myself I can empathise. However, once again, I was simply pointing out that the latest generation of aircraft are NOT normally refuelled like that anymore. Instead of operator error, the most likely scenario was a failure of either a valve or its controller. Low and behold this statement was subsequently made
I'm sorry if I have dented any egos in how the operation of contemporary aircraft may have changed in respect to how we used to do things. However I did not appreciate the oblique swipe regarding taking off with trapped fuel. For that member's information, on the particular aircraft I was referring to "shunting fuel around" is very much an engineering function and I have never witnessed a flight delayed as a result of requiring trapped fuel to be repositioned by the engineers.
Now, maybe we can get back on topic?
Dozy I'm not trying to give anyone a hard time, however what goes around comes around.
This was what was said
It may not be relevant to this case, but as a former pilot I can remember sometimes getting slightly confused with the complexities of valve operation during some refuelling operations on various airliners. (Do I hear sniggers from former F/Es?) Although 2-pilot aircraft have automatic fuel distribution during refuelling, there are times when adjustments have to be made. These may involve using defuelling valves and tank pumps to shunt the fuel around. And then there have been occasions when crews have tried to squeeze a bit of extra fuel in by one means or another, when range is being pushed to the limit...
... the reason for the BOS fuel spill was an uncommanded activation of a fuel transfer valve which allowed fuel pumped from a "belly" tank (I thought Boeing called them "center" tanks) to overfill a wing tank.
Now, maybe we can get back on topic?