AAIB BA38 B777 Initial Report Update 23 January 2008
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The term "freezing point" for Jet-A1 is maybe somewhat misleading. It's basically the temperature below where the normally "transparent" fuel shows its first traces of "milkiness". Diesel guys refer to this as the Cloud Point. The flow is not impaired at this temperature.
This also increases the likelihood that freezing will be detected before it starts to cause a problem.
gonebutnotforgotten (post#185), the only thing you have not covered in your discussion of the descent from TOD to 600ft is the denouement.
Is it plausible that the 'plug of wax' (which you liken to an embolus) could affect both engines, when they are being fed from separate autonomous tanks? If not, there would have to be two plugs of wax evolving separately and independently.
Plausible enough, but is it likely that they would each migrate to the two engines and cause their separate failures at an interval of only 8 seconds?
You don't believe it either, do you?
Chris
Is it plausible that the 'plug of wax' (which you liken to an embolus) could affect both engines, when they are being fed from separate autonomous tanks? If not, there would have to be two plugs of wax evolving separately and independently.
Plausible enough, but is it likely that they would each migrate to the two engines and cause their separate failures at an interval of only 8 seconds?
You don't believe it either, do you?
Chris
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Re-post
I first posted this ten days ago, but I just love repeating myself....
It will be fuel contamination
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China has a $2,000,000,0000 a year industry making fakes. Lest you think this is just the odd Rolex or Gucci bag for a laugh the China PLC inventory includes millions of fake car and truck parts not caring one whit how many people are killed thereby. More sinister is the the fake pharmaceuticals which often are not simply benign white chalk pills but random chemicals found out back in the garage, once again not caring one whit who or how many die.
In the case at hand the only other remotely possible explanations are a multiple bird strike of epic proportions or fuel exhaustion. Give credence to the former if you like, to the latter, well, you will need a lower opinion of BA aircrew than is common.
No, someone will have passed off a few million litres of doctored diesel fuel as jet fuel. This fake fuel of course is not tested for fuel freezing. Fuel freezing will then have occurred during the lengthy flight from China (not ice formation, but wax components of the fuel reverting to solid) and this slurry sank to the bottom of the tanks. On final with perhaps 4 tons or so sloshing around in near-as-empty tanks this fuel willl have been ingested.
Eh Voila
Have some faith in your hardware is what 10,000 hours on the 777 has taught me. There will be human skulduggery at root here somewhere
It will be fuel contamination
--------------------------------------------------------------------------------
China has a $2,000,000,0000 a year industry making fakes. Lest you think this is just the odd Rolex or Gucci bag for a laugh the China PLC inventory includes millions of fake car and truck parts not caring one whit how many people are killed thereby. More sinister is the the fake pharmaceuticals which often are not simply benign white chalk pills but random chemicals found out back in the garage, once again not caring one whit who or how many die.
In the case at hand the only other remotely possible explanations are a multiple bird strike of epic proportions or fuel exhaustion. Give credence to the former if you like, to the latter, well, you will need a lower opinion of BA aircrew than is common.
No, someone will have passed off a few million litres of doctored diesel fuel as jet fuel. This fake fuel of course is not tested for fuel freezing. Fuel freezing will then have occurred during the lengthy flight from China (not ice formation, but wax components of the fuel reverting to solid) and this slurry sank to the bottom of the tanks. On final with perhaps 4 tons or so sloshing around in near-as-empty tanks this fuel willl have been ingested.
Eh Voila
Have some faith in your hardware is what 10,000 hours on the 777 has taught me. There will be human skulduggery at root here somewhere
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Embolism?
Chris - I was just trying to make sense of the previous posts, and yes, it is pretty unlikely/unprecedented, but same fuel, same temperatures, and very nearly identical tanks (one hydraulic heat exchanger versus two) means that the independence may not be what it seems. As has been pointed out earlier, the fact that there was a small differnece in the reactions of the two engines means that the electronic explanations may be less likely than the 'mechanical' ones. In the end I'm as baffled as everyone else, this is a fascinating puzzle but it feels we may be zeroing in on the answer.
Gentlemen. The AAIB are zeroing in on the answers, probably a combination of several factors if history teaches us anything. You (the speculators rather than the sensible ' hang on a minute' ones) are waffling to pass an idle moment.
If by some bizarre coincidence one of you happens to be right, please don't expect me to place any trust in your opinion next time.
If by some bizarre coincidence one of you happens to be right, please don't expect me to place any trust in your opinion next time.
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Fitter 2: You (the speculators rather than the sensible ' hang on a minute' ones) are waffling to pass an idle moment.
NSEU: This also increases the likelihood that freezing will be detected before it starts to cause a problem.
Stilton: Ok then, why did no other China originating aircraft have problems
gonebutnotforgotten: Yes, thats about what I am supposing - but like anyone else, I have no idea really. I dont like the word "plug". I know that when I used to do the test in the lab, the wax crystals settled out. Maybe it was both ice and wax. Maybe it was water. Maybe it wasn't fuel at all. I just don't know. Its just one of a number of hypotheses. All I am saying is, the facts that we know argue more strongly for it than against it.
Pinkman
China has a $2,000,000,0000 a year industry making fakes. Lest you think this is just the odd Rolex or Gucci bag for a laugh the China PLC inventory includes millions of fake car and truck parts not caring one whit how many people are killed thereby. More sinister is the the fake pharmaceuticals which often are not simply benign white chalk pills but random chemicals found out back in the garage, once again not caring one whit who or how many die.
In the case at hand the only other remotely possible explanations are a multiple bird strike of epic proportions or fuel exhaustion. Give credence to the former if you like, to the latter, well, you will need a lower opinion of BA aircrew than is common.
In the case at hand the only other remotely possible explanations are a multiple bird strike of epic proportions or fuel exhaustion. Give credence to the former if you like, to the latter, well, you will need a lower opinion of BA aircrew than is common.
I can think of all sorts of other reasons the engines might not have responded, for example, differential expansion of fuel control componentry which was apparently at the root of the B737 rudder problem.
Could we please wait and see?
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I found the following elsewhere:
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=comm...
http://preview.tinyurl.com/2p2tgy
"Sources close to the investigation also tell The DAILY that British
Airways engineers have been collecting fuel samples from every flight
emanating from China. The sample collection, plus comments from the
AAIB indicating the aircraft had "adequate" fuel remaining on board at
the time of the crash, is believed to point toward suspicions of a
heavier-than-fuel contaminant being present. Theories propounded by
crew include the possible presence of water in the tanks that, having
become frozen during the intense cold-soak period of the flight,
partially melted and formed a slush that could have partially blocked
the fuel lines.
Sources also tell The DAILY that upper air temperatures over Russia
and northern Europe were extremely cold on the day of the accident.
Information from other crews coming from Asia on Jan. 17 encountered
extremely low temperatures in the -70 to -75 degrees C. range,
resulting in fuel temperatures dipping into the -40s. European upper
air temperatures also indicate the last 6.5 hours of the inbound China
flight would have been flown at an outside air temperature of -60 deg.
C. or lower. Although this would have resulted in fuel temperatures on
approach in the -35 degrees C range, this would not normally
constitute a problem unless, potentially, contaminants were present."
And it's been said (not by me) that "Sources close to the investigation" means a leak from the AAIB investigation. True? Likely? Or just yet more speculation & rumour-mongering?
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=comm...
http://preview.tinyurl.com/2p2tgy
"Sources close to the investigation also tell The DAILY that British
Airways engineers have been collecting fuel samples from every flight
emanating from China. The sample collection, plus comments from the
AAIB indicating the aircraft had "adequate" fuel remaining on board at
the time of the crash, is believed to point toward suspicions of a
heavier-than-fuel contaminant being present. Theories propounded by
crew include the possible presence of water in the tanks that, having
become frozen during the intense cold-soak period of the flight,
partially melted and formed a slush that could have partially blocked
the fuel lines.
Sources also tell The DAILY that upper air temperatures over Russia
and northern Europe were extremely cold on the day of the accident.
Information from other crews coming from Asia on Jan. 17 encountered
extremely low temperatures in the -70 to -75 degrees C. range,
resulting in fuel temperatures dipping into the -40s. European upper
air temperatures also indicate the last 6.5 hours of the inbound China
flight would have been flown at an outside air temperature of -60 deg.
C. or lower. Although this would have resulted in fuel temperatures on
approach in the -35 degrees C range, this would not normally
constitute a problem unless, potentially, contaminants were present."
And it's been said (not by me) that "Sources close to the investigation" means a leak from the AAIB investigation. True? Likely? Or just yet more speculation & rumour-mongering?
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In Journalist-speak, "sources close to the investigation" can also mean anybody the AAIB has had any dealings with including the mini cab driver who overheard some gossip driving the investigator to LHR.
"Sources WITHIN the investigation" might be slightly more interesting as weasel words...but that's not the case here.
Bobbsy
"Sources WITHIN the investigation" might be slightly more interesting as weasel words...but that's not the case here.
Bobbsy
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British Airways engineers have been collecting fuel samples from every flight emanating from China.
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Low temperature operation
Speaking as a non driver (at least for the last 50 years), but who spent many years trying to make various bits of A/C equipment work at -60 and beyond. May I ask what other equipment is in the fuel lines, apart from filters. Are there turbine type flowmeters for example. and rotational type valves. What has to happen to increase fuel flow.
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In Journalist-speak, "sources close to the investigation" can also mean anybody the AAIB has had any dealings with including the mini cab driver who overheard some gossip driving the investigator to LHR.
"Sources WITHIN the investigation" might be slightly more interesting as weasel words...but that's not the case here.
Bobbsy
"Sources WITHIN the investigation" might be slightly more interesting as weasel words...but that's not the case here.
Bobbsy
Paxing All Over The World
PROJECT MECH
Do you mean when a major event took place only the previous day? As you will understand, an important Service Letter would have been prepared carefully over many days and it was purely coincidental that such an unfortunate incident took place the previous day. Boeing and all it's staff are working assiduously ... etcetera.
Isn't it just deliciously ironic that Boeing brought out a Service Letter reference worldwide Fuel Specifications on the 18/01/08?
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Why did no other China operating aircraft have problems?
There's a simple solution you've all missed. Sure China is notorious for counterfeits. But why just the fuel? Take a very close look at that B777. Can you be sure it hasn't been replaced with an ALMOST PERFECT REPLICA while on the ground in China? And if it hadn't been for that pesky fuel system they'd have gotten away with it too...
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Glide performance of 777?
So as to avoid any speculation on a probable cause, I'd like to find out more about the glide performance of the 777.
Can a 777 pilot please comment...
Most machines I've flown (737 the biggest) have glide ratios of between 2 and 3 nm per 1000 ft in the clean configuration.
Fully configured this normally halves.
Argument: When the engines failed to respond (or thrust decreased) the aircraft was at 600' and 2nm.
If the glide performance of a configured 777 is say 1.5nm per 1000' (Im guessing!) the aircraft would have flown another 0.9nm (and obviously not made it)
Above assumes that the aircraft was already at glide speed and any extra speed would obviously send it farther (but I doubt all the way to the airfield).
We do however know that the engines were turning and it seems obvious that they were producing some amount of thrust till touchdown.
Could a 777 pilots perhaps comment on what amount of power would be needed to get the 777 to go 2nm from 600' in the landing config?
I understand that knowing a rough power setting is not really relevant to the incident, but it will certainly help pass the time while we wait on the AAIB
PP
Can a 777 pilot please comment...
Most machines I've flown (737 the biggest) have glide ratios of between 2 and 3 nm per 1000 ft in the clean configuration.
Fully configured this normally halves.
Argument: When the engines failed to respond (or thrust decreased) the aircraft was at 600' and 2nm.
If the glide performance of a configured 777 is say 1.5nm per 1000' (Im guessing!) the aircraft would have flown another 0.9nm (and obviously not made it)
Above assumes that the aircraft was already at glide speed and any extra speed would obviously send it farther (but I doubt all the way to the airfield).
We do however know that the engines were turning and it seems obvious that they were producing some amount of thrust till touchdown.
Could a 777 pilots perhaps comment on what amount of power would be needed to get the 777 to go 2nm from 600' in the landing config?
I understand that knowing a rough power setting is not really relevant to the incident, but it will certainly help pass the time while we wait on the AAIB
PP