BA038 (B777) Thread
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I did hear that recently an ADIRU fault on a bmi A320 was positively fixed by changing an oven in the forward galley. If the cause was some kind of interference then it could have come from the most unlikely sources.
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Why the Fuss
Re: Gordon Brown? If his motorcade/Aircraft/Jaguar had anything to do with the incident, (HIGHLY unlikely), it was inadvertent, sloppy, witless. This isn't to say that if the PM was not present or even tangentially involved, that something like what is being discussed couldn't have happened any other way. There seem to be two camps; Brown's retinue downed the flight, or nothing like it happened or could have happened. In the middle is enough room to drive a twelve tonne lorry. Jammer, MW, hostile elements; there is room for all manner of conspiracy, why stop at Brown or Vapor Lock? Curiouser and curiouser. The only changes I've noticed is a minor change in fueling protocol by two yank Legacies, if there were something that could affect the Fleet, it would be common knowledge. Right, AAIB?
OK. I'll bite.
Don't fly 'planes or design them. Good at Physics though.
One cause, two possibilities, one result.
Cause. The fuel got too cold and separated to constituent parts. One or more of which didn't like pumps.
Possibilities. Either there was a software warning that was ignored; or there was not a software warning and fuel temperature was therefore not known to the crew.
Result. Engines didn't do the expected.
If I'm wrong I'll buy a personal title. If I'm right I'll buy a personal title.
One cause, two possibilities, one result.
Cause. The fuel got too cold and separated to constituent parts. One or more of which didn't like pumps.
Possibilities. Either there was a software warning that was ignored; or there was not a software warning and fuel temperature was therefore not known to the crew.
Result. Engines didn't do the expected.
If I'm wrong I'll buy a personal title. If I'm right I'll buy a personal title.
pls88x
Certainly on the temperature.
Gradient, possibly a factor earlier in the flight although I'd expect that the smallest amount of turbulence would mix the fuel in a part full tank later in the trip. So even if the gradient 'hid' the true temp, the true figure would have been measured after a slosh or two.
My point is that the fuel temp was not spotted, either by the software or the crew.
Certainly on the temperature.
Gradient, possibly a factor earlier in the flight although I'd expect that the smallest amount of turbulence would mix the fuel in a part full tank later in the trip. So even if the gradient 'hid' the true temp, the true figure would have been measured after a slosh or two.
My point is that the fuel temp was not spotted, either by the software or the crew.
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Vapour lock= OutaGas
Boguing.
....I dont think mixing is guaranteed by smooth flight sloshing .In a seperate discipline we are warned not to rely on it to mix oil and petrol for 2 strokes.
.
...Now Mr Physics, tell us how much the boiling (gassing) point of hydrocarbon liquids goes down if its freezing(waxing) point has been Orientally cunningly reduced from -47 to -57 ?....Would it be as low as say +10 or +11 centigrade ?
...The same discipline warns us of the Vapour lock problems with usage of winter road fuel above around 7000ft.
Does the in flight fuel temp indicate prominently all the time ?(Seperate from TAT leading edge temp) or is there just a warning show at a value that has been preset according to the crews understanding of the specification of the uplifted fuel?
....I dont think mixing is guaranteed by smooth flight sloshing .In a seperate discipline we are warned not to rely on it to mix oil and petrol for 2 strokes.
.
...Now Mr Physics, tell us how much the boiling (gassing) point of hydrocarbon liquids goes down if its freezing(waxing) point has been Orientally cunningly reduced from -47 to -57 ?....Would it be as low as say +10 or +11 centigrade ?
...The same discipline warns us of the Vapour lock problems with usage of winter road fuel above around 7000ft.
Does the in flight fuel temp indicate prominently all the time ?(Seperate from TAT leading edge temp) or is there just a warning show at a value that has been preset according to the crews understanding of the specification of the uplifted fuel?
Controversial, moi?
Does the in flight fuel temp indicate prominently all the time?
Fuel freeze point is entered manually on the PERF INIT page of the FMC. In BA it defaults to -40°C but is overwritten as appropriate. This figure is used by the aeroplane systems to generate the FUEL TEMP LOW warning should the fuel temperature reach withing 3°C of the entered value.
Second Law
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Vapour Pressure
wilyflier:
I have the greatest of respect for the quality of the postings in this thread, let's see if this one is vaguely up to scratch.
It's the Vapour Pressure of the mixture that's changing with sinoadditives and it's that that drives any change in Boiling Point, a pedantic point but one that's crucial in this "vapour lock = outa gas" hypothesis.
Stick out neck time.
Fuel stratification and subsequent cavitation did get my vote - it fits the evidence beautifully , but ....... we ain't heard a thing from AAIB.
The hypothesis is eminently testable and (i) I would be amazed if they hadn't had a go at it already and (ii) if the numbers stacked up in a repeatable way and the model "worked" (iii) we'd have heard by now.
I know, call me naive. Fire away.
CW
I have the greatest of respect for the quality of the postings in this thread, let's see if this one is vaguely up to scratch.
It's the Vapour Pressure of the mixture that's changing with sinoadditives and it's that that drives any change in Boiling Point, a pedantic point but one that's crucial in this "vapour lock = outa gas" hypothesis.
Stick out neck time.
Fuel stratification and subsequent cavitation did get my vote - it fits the evidence beautifully , but ....... we ain't heard a thing from AAIB.
The hypothesis is eminently testable and (i) I would be amazed if they hadn't had a go at it already and (ii) if the numbers stacked up in a repeatable way and the model "worked" (iii) we'd have heard by now.
I know, call me naive. Fire away.
CW
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Vapor Pressure
Chris, this is a popular theory, though it brings up unfortunate implications. (See posts #261 and #602). Fuel Exhaustion is "ostensibly" ruled out, Fuel Starvation has been obliquely addressed, Engine Response is on the Record, Fuel contamination has gotten little buzz. (Notwithstanding the public disclosure of Fuel "testing" absent conclusion as to causation or even postulate). The Fuel "tests" were left unaddressed, and the public does what it always does, "assume" that means the Fuel is cleared. Not so. Everything points to Fuel issues, storage, transit, pumping, temperature, Engine response, etc. even quality. My fear is that the longer the investigative authority takes to update, the more it will overemphasize the ultimate outcome of the investigation. (I hope "Sinoadditve" does not become a new word in the Dictionary, for many reasons.)
Second Law
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Vapour Pressure (2)
airfoilmod
I've read every post on this thread but had forgotten 261 and 602. I blame being born in the 40s plus Scotch .......
I absolutely agree with you, fuel fits best. My caveats obviously obscured that central point.
But but it's very straightforward to do mass spec et al, n times on fuel samples so........... it's back to either my naivity that no news means they've found zip or ........we're looking at something more sinister over possible (temporary?) information suppression.
Yes I know AAIB needs no political clearance etc ad nauseum, if however we don't get a damaging fuel report until after the Olympics we may want to revise that view.
From naive to cynic in one bound!
........... and my apologies for "Sinoadditives", I liked it at the time.
CW
I've read every post on this thread but had forgotten 261 and 602. I blame being born in the 40s plus Scotch .......
I absolutely agree with you, fuel fits best. My caveats obviously obscured that central point.
But but it's very straightforward to do mass spec et al, n times on fuel samples so........... it's back to either my naivity that no news means they've found zip or ........we're looking at something more sinister over possible (temporary?) information suppression.
Yes I know AAIB needs no political clearance etc ad nauseum, if however we don't get a damaging fuel report until after the Olympics we may want to revise that view.
From naive to cynic in one bound!
........... and my apologies for "Sinoadditives", I liked it at the time.
CW
Controversial, moi?
Has it been restricted?
Concorde had an, arguable, design fault which could have led to another catastrophe. When the reason for the BAW38 accident is known a decision can be made.
If the worldwide fleet is grounded or restricted now what reasons would be given? If no cause of the accident is found then would those 600+ aircraft remain grounded?
Groundings are temporary restrictions against the original issue type certificate while it is being brought into compliance with the original specification.
From what I have read there is no varriance identified against the type certificate. For all we know this could be purely an operational problem and nothing wrong with the design.
If you support grounding, then just how far do you go? All recently certified aircraft from all manufacturers? Or do you feel there is supportable evidence to limit it to one manufacturer?, one aircraft type?, one model year?, one or two line numbers? or one operator's fleet?
When all is said and done what corrective action will place this large piece of capital ownership back into service in what time frame?
Certainly any of you can play a ouija board and decide to ground yourselves from flying anytime you choose, but I prefer to abide by a process of a rational approach.
From what I have read there is no varriance identified against the type certificate. For all we know this could be purely an operational problem and nothing wrong with the design.
If you support grounding, then just how far do you go? All recently certified aircraft from all manufacturers? Or do you feel there is supportable evidence to limit it to one manufacturer?, one aircraft type?, one model year?, one or two line numbers? or one operator's fleet?
When all is said and done what corrective action will place this large piece of capital ownership back into service in what time frame?
Certainly any of you can play a ouija board and decide to ground yourselves from flying anytime you choose, but I prefer to abide by a process of a rational approach.
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There *is* what appears to be a new interim bulletin on the AIB site - but my Adobe reader hangs when 95% of the .pdf has downloaded and freezes my comfuser so I don't know if it's "new" or one of the "old" bulletins. Anyone read it?
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Approx how much time is required to cause the cavitation damage within the pumps that is experienced here.
I would assume that it would take a long long time; much more than a few hours.
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I would assume that it would take a long long time; much more than a few hours.
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This is just a factual outline
The cavitation issue may never have been known if this accident never happened. Although it was not causative, we all must agree that it was unexpected. Perhaps several hundred lives were just saved twenty years from now as a result of this incident. The problem with cavitation is kind of like the difference between a styrofoam cup and a glass. The cavitation can cause the liquid (in this case fuel) to become aerated.
The other issue with cavitation relates to debris. The cavities (no matter how small) can not form unless something is lost or disintegrated. While the fuel flow was not impeded, the combination of the aeration and potential debris from the cavitation may have had some impact.
The other issue with cavitation relates to debris. The cavities (no matter how small) can not form unless something is lost or disintegrated. While the fuel flow was not impeded, the combination of the aeration and potential debris from the cavitation may have had some impact.
RR will know the cavitation history from examination of the Trent engines previously returned to them for repair/inspection/overhaul over the years.
Secondly, it is now 2 months since G-MMMY undershot, the AAIB are obliged to issue a report after 30 days which they have done, but are they obliged to issue a report every 30 days?
Secondly, it is now 2 months since G-MMMY undershot, the AAIB are obliged to issue a report after 30 days which they have done, but are they obliged to issue a report every 30 days?
Last edited by Oldlae; 17th Mar 2008 at 16:37. Reason: Clarity