BA038 (B777) Thread
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Ground and/or air test? Next bulletin already written?
Warning: I'm non-professional; not crew, not engineer - just scientist guest and thanks.
Seems Andy Pasztor was right in his article in WSJ, post 908. No surprise, afterall why would David King (AAIB) talk to a journalist if he was not preparing the ground for a further release of information.
Reference has been made in a recent post to dubious Chinese manufacturing practices and related these to the adulteration of fuel on BA038. I think we can safely assume that the fuel has been fully tested, found to be good and was not adulterated. That is, it performs within required standards and does not contain sub-standard substances. As an aside, it is possible the fuel was not Chinese but maybe Russian. In anycase, the question of origin is redundant given that the AAIB are satisified with it.
AAIB satisfaction in the standardisation of the fuel is crucial to understanding the rest of the special bulletin. No doubt initially the AAIB would have been hoping that they could show the fuel was sub-standard. The result would have been - phew!, wipe brows and proceed to the publication of a definitive cause.
As it is, the AAIB, RR and Boeing, are left with a mystery. They strongly suspect the fuel was degraded in some manner, due to the exceptional environmental circumstances of the flight, but cannot yet prove it or, at least, demonstrate that this is the most likely cause of the accident.
So, without a simple cause, e.g. adulteration of fuel or some mechanical defect/malfunction, the authorities are left with testing and research and preparing the public, governments and airlines for operational changes that may be issued in a following bulletin. The AAIB are preparing the ground.
But how to test? Can Boeing fully test the fuel in tanks equivalent in volume and dimensions to those in a 777, at the right temperature and barometric pressure and also push through the test system vibrations generated and experienced by G-YMMM? Does anyone know?
I suspect, but hope to be wrong, that a ground testing system, as described above, does not exist anywhere.
Possibly the AAIB/Boeing et al will commission a test 777. Time is critical: the authorities need an answer before the northern hemisphere winter arrives, but commissioning a test flying 777 will take months and, even assuming they act quickly, the only test area available now is Antarctica! Anyone seen a strange 777 in southern Chile/Argentina??
So, I'm assuming the present testing/research will be inconclusive and the AAIB will issue another bulletin towards the end of 2008 that will contain operational changes (actually, I expect that a draft of this bulletin has already been written). In other words, the precautionary principle will be
applied:-
1) avoid prolonged flight in very cold air masses
2) if 1) cannot be followed then loiter, in some way, until fuel is warmed.
And, if I was a pilot, I'd spool up the engines on descent a couple of times - just to make sure! Better to discover a problem with a few thousand feet to spare rather than 720.
Regards, Tanimbar
PS. I love a mystery and I am enjoying reading and writing on this thread but once in a while I remember, with some embarrassment, that my enjoyment is predicated on the lucky survival of the souls on BA038. In other words, I would not contribute if they had died. Their luck did not run out but what of the next occurence! We here write for enjoyment, the AAIB to save lives. We must remember that.
Seems Andy Pasztor was right in his article in WSJ, post 908. No surprise, afterall why would David King (AAIB) talk to a journalist if he was not preparing the ground for a further release of information.
Reference has been made in a recent post to dubious Chinese manufacturing practices and related these to the adulteration of fuel on BA038. I think we can safely assume that the fuel has been fully tested, found to be good and was not adulterated. That is, it performs within required standards and does not contain sub-standard substances. As an aside, it is possible the fuel was not Chinese but maybe Russian. In anycase, the question of origin is redundant given that the AAIB are satisified with it.
AAIB satisfaction in the standardisation of the fuel is crucial to understanding the rest of the special bulletin. No doubt initially the AAIB would have been hoping that they could show the fuel was sub-standard. The result would have been - phew!, wipe brows and proceed to the publication of a definitive cause.
As it is, the AAIB, RR and Boeing, are left with a mystery. They strongly suspect the fuel was degraded in some manner, due to the exceptional environmental circumstances of the flight, but cannot yet prove it or, at least, demonstrate that this is the most likely cause of the accident.
So, without a simple cause, e.g. adulteration of fuel or some mechanical defect/malfunction, the authorities are left with testing and research and preparing the public, governments and airlines for operational changes that may be issued in a following bulletin. The AAIB are preparing the ground.
But how to test? Can Boeing fully test the fuel in tanks equivalent in volume and dimensions to those in a 777, at the right temperature and barometric pressure and also push through the test system vibrations generated and experienced by G-YMMM? Does anyone know?
I suspect, but hope to be wrong, that a ground testing system, as described above, does not exist anywhere.
Possibly the AAIB/Boeing et al will commission a test 777. Time is critical: the authorities need an answer before the northern hemisphere winter arrives, but commissioning a test flying 777 will take months and, even assuming they act quickly, the only test area available now is Antarctica! Anyone seen a strange 777 in southern Chile/Argentina??
So, I'm assuming the present testing/research will be inconclusive and the AAIB will issue another bulletin towards the end of 2008 that will contain operational changes (actually, I expect that a draft of this bulletin has already been written). In other words, the precautionary principle will be
applied:-
1) avoid prolonged flight in very cold air masses
2) if 1) cannot be followed then loiter, in some way, until fuel is warmed.
And, if I was a pilot, I'd spool up the engines on descent a couple of times - just to make sure! Better to discover a problem with a few thousand feet to spare rather than 720.
Regards, Tanimbar
PS. I love a mystery and I am enjoying reading and writing on this thread but once in a while I remember, with some embarrassment, that my enjoyment is predicated on the lucky survival of the souls on BA038. In other words, I would not contribute if they had died. Their luck did not run out but what of the next occurence! We here write for enjoyment, the AAIB to save lives. We must remember that.
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I followed a BA 777 across Poland/Germany to London a few nights ago. He asked for descent when over Berlin to FL340. When asked by Berlin for the reason, the reply was, 'Fuel Temperature' so I guess new procedures are already in force. Any BA 777 drivers care to enlighten us?
If the failure had occurred to only one engine, then there could be myriad reasons why this happened.
The fact that both failed at the same time points to the only common factor and that is fuel.
I think the AAIB have it right and spending endless hours and bandwidth on even more speculation and second guessing seems a particularly pointless exercise.
If the failure had occurred to only one engine, then there could be myriad reasons why this happened.
The fact that both failed at the same time points to the only common factor and that is fuel.
I think the AAIB have it right and spending endless hours and bandwidth on even more speculation and second guessing seems a particularly pointless exercise.
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tanimbar,
Thanks a lot for your post. It was interesting reading. I'd like to comment on a few minor points.
(my emphasis)
To be nitpicking, the AAIB quoted the meteorological services as saying that the conditions encountered by BA038 were "unusual", but "not exceptional".
I'm curious to see if they're going to go that far.
Here we may have a problem. According to the recorded data, the fuel still was relatively warm. So there would have been no need to get it warmed any more.
Lowest recorded fuel temperature was -34C, so 23 degrees above the measured freezing point, and still 13 degrees above the specified freezing point for Jet-A1, and 18 degrees above the specified freezing point for the Chinese fuel type they were actually carrying. If left unchanged the warning would have been triggered at -37C, 3C above freezing point for Jet-A. They were still even above that.
Descents for low fuel temperature are normal, when the temperature reaches the threshold (at least 3 degrees above fuel freezing point)
The Manual advises that when that happens, to either descent to a lower (warmer) altitude or to increase cruise mach to increase TAT. Both carries a fuel consumption penalty, and I guess the decision is the PIC's.
Bernd
Thanks a lot for your post. It was interesting reading. I'd like to comment on a few minor points.
Originally Posted by tanimbar
As it is, the AAIB, RR and Boeing, are left with a mystery. They strongly suspect the fuel was degraded in some manner, due to the exceptional environmental circumstances of the flight, but cannot yet prove it or, at least, demonstrate that this is the most likely cause of the accident.
To be nitpicking, the AAIB quoted the meteorological services as saying that the conditions encountered by BA038 were "unusual", but "not exceptional".
Possibly the AAIB/Boeing et al will commission a test 777. Time is critical: the authorities need an answer before the northern hemisphere winter arrives, but commissioning a test flying 777 will take months and, even assuming they act quickly, the only test area available now is Antarctica! Anyone seen a strange 777 in southern Chile/Argentina??
So, I'm assuming the present testing/research will be inconclusive and the AAIB will issue another bulletin towards the end of 2008 that will contain operational changes (actually, I expect that a draft of this bulletin has already been written). In other words, the precautionary principle will be
applied:-
1) avoid prolonged flight in very cold air masses
2) if 1) cannot be followed then loiter, in some way, until fuel is warmed.
applied:-
1) avoid prolonged flight in very cold air masses
2) if 1) cannot be followed then loiter, in some way, until fuel is warmed.
Lowest recorded fuel temperature was -34C, so 23 degrees above the measured freezing point, and still 13 degrees above the specified freezing point for Jet-A1, and 18 degrees above the specified freezing point for the Chinese fuel type they were actually carrying. If left unchanged the warning would have been triggered at -37C, 3C above freezing point for Jet-A. They were still even above that.
Originally Posted by rubik101
I followed a BA 777 across Poland/Germany to London a few nights ago. He asked for descent when over Berlin to FL340. When asked by Berlin for the reason, the reply was, 'Fuel Temperature' so I guess new procedures are already in force.
The Manual advises that when that happens, to either descent to a lower (warmer) altitude or to increase cruise mach to increase TAT. Both carries a fuel consumption penalty, and I guess the decision is the PIC's.
Bernd
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Assuming that the engine fuel feeding system is symmetrical and was isolated between the two of them, I can presume we have only one anomaly that was replicated between the 2 existing engines; IMHO I believe that if this 777 had 4 engines all of them would have suffered the same problem (whatever it may be), and I would guess that the timing between failures would be very close.
This anomaly exists, it’s real, and if it has the ability to affect 2 separate engine/tank systems in the very same time-frame, it’s possible to replicate it for testing purposes. It will happen again.
This anomaly exists, it’s real, and if it has the ability to affect 2 separate engine/tank systems in the very same time-frame, it’s possible to replicate it for testing purposes. It will happen again.
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Saturn V:
Again, I would say that the Chinese have become quite adept at making their various counterfeits pass known bench tests, such as the stir/optical fuel freeze test mentioned in the thread, so seeing some GCMS results is the point when this concern will finally be put out of my own mind.
GD&L:
Exactly. That very slight difference in behaviour of the two engines that was noted in this incident may be a real keystone in the investigation, if the piping is essentially, but not exactly, the same on both sides, with the laggardly engine being plumbed to the most vulnerable routing...
Another thought... what if the water content was 'acceptable', but certainly not zero.... the 777 has some piping that is prone to internal icing, but was not previously known (i.e. a very hard angle, in a relatively more exposed area...).... this area forms an ice 'seed', and agglomeration begins... more ice as water flows by slowly (near idle) and is frozen on contact, and/or 'waxing'... while, at relatively high flows this behaviour is staved off due to more new warmer fuel washing over the area of vulnerability... but with the right odd mixture of fuel... right water content... right pre-cooling... right lower fuel flow volume for sufficient period of time.... could be just the precise but unlikely combination needed...
In reality, what the heck is left?
[from quoted source]...the 777's fuel contained additives designed to prevent it from freezing under such conditions...
GD&L:
Assuming that the engine fuel feeding system is symmetrical and was isolated between the two of them, I can presume we have only one anomaly that was replicated between the 2 existing engines...
Another thought... what if the water content was 'acceptable', but certainly not zero.... the 777 has some piping that is prone to internal icing, but was not previously known (i.e. a very hard angle, in a relatively more exposed area...).... this area forms an ice 'seed', and agglomeration begins... more ice as water flows by slowly (near idle) and is frozen on contact, and/or 'waxing'... while, at relatively high flows this behaviour is staved off due to more new warmer fuel washing over the area of vulnerability... but with the right odd mixture of fuel... right water content... right pre-cooling... right lower fuel flow volume for sufficient period of time.... could be just the precise but unlikely combination needed...
In reality, what the heck is left?
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From the report: "In addition, work has commenced on developing a more complete understanding of the dynamics of the fuel as it flows from the fuel tank to the engine."
This may suggest a restriction due to fluidic resonance in a tuned circuit. If the conditions are exactly right and there is some initiating event, a resonance can occur in a pipe that will restrict fluid flow. Given two near identical tuned circuits and operating conditions, the resonance and the resulting fluid restriction will be virtually identical in both circuits. The report mentions near identical engine thrust restriction.
In a structure with two separate systems with near identical geometry and operating conditions, resonance in one system can induce resonance in the other system by mechanical coupling through the structure. Under these conditions, the typical delay between the initial resonance of the first system and the induced resonance of the second system is on the order of 2 to 20 seconds. The report mentions a 7 second delay between the first and the second engine thrust restriction. Note that very little resonant energy needs to be coupled through the structure to induce a resonance in a near identical circuit.
Such a resonance is likely to be at a very low frequency and it should be relatively audible to the ear. However, it is not certain if a resonance of this frequency would be recorded by any of the flight data recorders. Typical audio recorders in aircraft eliminate low frequencies to improve speech intelligibility and the mechanical vibration of the resonance is too small and too fast to be detected as a variation of flight parameters.
I believe that witnesses reported that the aircraft made an unusual sound as it approached the airport. While witnesses tend to be unreliable, some weight might be given to this observation as witnesses who work at airports tend to have experience with typical aircraft noise.
An investigation to include or exclude this possibility would be an extremely difficult and time consuming process.
This may suggest a restriction due to fluidic resonance in a tuned circuit. If the conditions are exactly right and there is some initiating event, a resonance can occur in a pipe that will restrict fluid flow. Given two near identical tuned circuits and operating conditions, the resonance and the resulting fluid restriction will be virtually identical in both circuits. The report mentions near identical engine thrust restriction.
In a structure with two separate systems with near identical geometry and operating conditions, resonance in one system can induce resonance in the other system by mechanical coupling through the structure. Under these conditions, the typical delay between the initial resonance of the first system and the induced resonance of the second system is on the order of 2 to 20 seconds. The report mentions a 7 second delay between the first and the second engine thrust restriction. Note that very little resonant energy needs to be coupled through the structure to induce a resonance in a near identical circuit.
Such a resonance is likely to be at a very low frequency and it should be relatively audible to the ear. However, it is not certain if a resonance of this frequency would be recorded by any of the flight data recorders. Typical audio recorders in aircraft eliminate low frequencies to improve speech intelligibility and the mechanical vibration of the resonance is too small and too fast to be detected as a variation of flight parameters.
I believe that witnesses reported that the aircraft made an unusual sound as it approached the airport. While witnesses tend to be unreliable, some weight might be given to this observation as witnesses who work at airports tend to have experience with typical aircraft noise.
An investigation to include or exclude this possibility would be an extremely difficult and time consuming process.
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Fuel
Left with several questions following AAIB report. The plumbing of the heat exchanger would be interesting, also if there is bypass or if all fuel must flow through this "radiator".
1. The poor thrust result, being virtually equivalent means both engines experienced poor flow as a result of the same fault.
2. Lack of (starvation) or diminished quality (environmental) would have to have been homogeneous, given separate sources (tanks).
3. From the report, there was some quantity of water in the Fuel. Though not excessive, it isn't soluble in Jet, unless itself dissolved in fluid that is in turn soluble in Fuel (eg Alcohol)
4. The delay in "off-throttle" of seven seconds could be related to a slight difference in temperature of the Fuel, due to its source location.
5. The #1, Port engine draws from the Port Main Tank, which in that flight was on the sun side of the A/C, potentially raising Fuel Temp. slightly.
soem dood-
Your suggestion of Gas Chromatography and Mass Spectroscopy is a good one, I'll wager you're not the only one who's thought of it.
I don't think your questions Re; fuel from China are ill advised at all. Contamination can be caused by substances that "improve" the "quality" of Jet, but in certain circumstances may prove disastrous.
Airfoil
1. The poor thrust result, being virtually equivalent means both engines experienced poor flow as a result of the same fault.
2. Lack of (starvation) or diminished quality (environmental) would have to have been homogeneous, given separate sources (tanks).
3. From the report, there was some quantity of water in the Fuel. Though not excessive, it isn't soluble in Jet, unless itself dissolved in fluid that is in turn soluble in Fuel (eg Alcohol)
4. The delay in "off-throttle" of seven seconds could be related to a slight difference in temperature of the Fuel, due to its source location.
5. The #1, Port engine draws from the Port Main Tank, which in that flight was on the sun side of the A/C, potentially raising Fuel Temp. slightly.
soem dood-
Your suggestion of Gas Chromatography and Mass Spectroscopy is a good one, I'll wager you're not the only one who's thought of it.
I don't think your questions Re; fuel from China are ill advised at all. Contamination can be caused by substances that "improve" the "quality" of Jet, but in certain circumstances may prove disastrous.
Airfoil
Last edited by airfoilmod; 13th May 2008 at 16:57. Reason: spelling
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In the true spirit of PPRUNE I heard that the PM's ECM and or some other source of directed counter measures, was being investigated as a possible cause.
Not sure of his exact whereabouts at the time...
Not sure of his exact whereabouts at the time...
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Quote :-
In the true spirit of PPRUNE I heard that the PM's ECM and or some other source of directed counter measures, was being investigated as a possible cause.
Not sure of his exact whereabouts at the time...
unquote
Please read the latest special bulletin - it specifically rules out EMI
.
In the true spirit of PPRUNE I heard that the PM's ECM and or some other source of directed counter measures, was being investigated as a possible cause.
Not sure of his exact whereabouts at the time...
unquote
Please read the latest special bulletin - it specifically rules out EMI
.
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...the reply was, 'Fuel Temperature' so I guess new procedures are already in force. Any BA 777 drivers care to enlighten us?
HF (ex-777 driver)
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Shawk
Shawk : Like two champagne glasses filled the same, fingertip tone on one producing a harmonic vibration on the other? Or also, like Flutter?
Ever see the original Engine/Propellor fit on the Electra (P-3)? Add thrust on final and the propellor discs like to take the wings off. Flutter.
Identical mechanical layout and Fluid supply on ETOPS. I brought that up a long time ago. Something like needing to introduce anomalies into "duplicate systems" with ETOPS. Each system marching to a different drum.
However, the engines were on auto-throttle, a very precise system that would command exactly the same thrust from both, a precisely timed move. Neither engine would have necessarily reacted in advance of the other, hence no need for harmonics. In whatever fault mode, the Fuel could be expected to be exactly homogeneous, save for a slight difference in temp., as above. Shaken, not Stirred.
Ever see the original Engine/Propellor fit on the Electra (P-3)? Add thrust on final and the propellor discs like to take the wings off. Flutter.
Identical mechanical layout and Fluid supply on ETOPS. I brought that up a long time ago. Something like needing to introduce anomalies into "duplicate systems" with ETOPS. Each system marching to a different drum.
However, the engines were on auto-throttle, a very precise system that would command exactly the same thrust from both, a precisely timed move. Neither engine would have necessarily reacted in advance of the other, hence no need for harmonics. In whatever fault mode, the Fuel could be expected to be exactly homogeneous, save for a slight difference in temp., as above. Shaken, not Stirred.
Last edited by airfoilmod; 13th May 2008 at 17:43.
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PG:
I do appreciate what caused you to deadpan a response to a provocative entry, with:
And so, I can't believe I have to say this (I am literally gritting my teeth as I type, because I wish this kettle of fish were closed and staying that way) but, actually they technically did not do that. They said they found no evidence consistent with EMI. I doubt they are expending one erg of energy on it at this point, nor should we, but I just wanted to be strictly accurate, where we can.
I do appreciate what caused you to deadpan a response to a provocative entry, with:
Please read the latest special bulletin - it specifically rules out EMI
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Please read the latest special bulletin - it specifically rules out EMI
I'd appreciate if you could provide the reference....
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Mechanical Deformation
What about this possibility.
Pumping high volumes (caused by demand for thrust increase) of very cold viscous fuel (fuel still within specs of course), where some part of the fuel system plumbing (between the tanks and the HP pumps) starts to deform and narrow due to the suction presssure of said cold viscous fuel, thus creating a temporary restriction.
In other words, some part of the pipe work partially (and temporarily) collapses due to the suction pressure and the viscosity of the fuel, causing a restriction. This theory is not unheard of, but does require the pipe work to rebound after the suction pressure is removed (thus leaving no evidence of a restriction). This might also explain how it could happen on both sides of the airplane.
Pumping high volumes (caused by demand for thrust increase) of very cold viscous fuel (fuel still within specs of course), where some part of the fuel system plumbing (between the tanks and the HP pumps) starts to deform and narrow due to the suction presssure of said cold viscous fuel, thus creating a temporary restriction.
In other words, some part of the pipe work partially (and temporarily) collapses due to the suction pressure and the viscosity of the fuel, causing a restriction. This theory is not unheard of, but does require the pipe work to rebound after the suction pressure is removed (thus leaving no evidence of a restriction). This might also explain how it could happen on both sides of the airplane.
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I found no reference to EMI in any of the bulletins.. (S1-3)
I'd appreciate if you could provide the reference....
I'd appreciate if you could provide the reference....
There is no evidence of any anomalous behaviour of any of the aircraft or engine systems that suggests electromagnetic interference.
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Wierd and wonderful
All these wierd and wonderful conspiracy theories and fanciful senarios will all be proved wrong. I think one should just look a little closer to home. Most of these disasters end up being something really simple.
Lets just suppose that BA engineering staff who are required to stick check the fuel system every 24hrs. What if that check is never done, i'm talking years. The accumalation of water in the fuel will be massive. AAIB have confirmed presence of water in fuel.
I would just suggest the AAIB pull the CCTV at LHR for the times MMM was there. I guarantee that they will never find an engineer performing the required water fuel stick check. Though of course all the sheets will be stamped by their B licence guy.
To illustrate the strength of the thread, immediately following the crash, the whole BA fleet had fuel drain stick checks called. Its rumoured the amount of water found during this operation was enough to float the QE2, but then it must of got there in the last 24hrs!
But then this theory is too simple for all you bright sparks in here!
Lets just suppose that BA engineering staff who are required to stick check the fuel system every 24hrs. What if that check is never done, i'm talking years. The accumalation of water in the fuel will be massive. AAIB have confirmed presence of water in fuel.
I would just suggest the AAIB pull the CCTV at LHR for the times MMM was there. I guarantee that they will never find an engineer performing the required water fuel stick check. Though of course all the sheets will be stamped by their B licence guy.
To illustrate the strength of the thread, immediately following the crash, the whole BA fleet had fuel drain stick checks called. Its rumoured the amount of water found during this operation was enough to float the QE2, but then it must of got there in the last 24hrs!
But then this theory is too simple for all you bright sparks in here!
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Just to add to the collapse/rebound pipe work theory stated above. If this did happen, maybe there is some evidence such as some small remaining distortion, or paint or other coating with tiny wrinkles or fractures. I'd think you'd have to go looking for this kind of evidence though, to find it.
I also think this theory could explain all facts to date as we (Ppruners) know them, but the evidence of a pipe work collapse/rebound would have to be there to confirm it.
I also think this theory could explain all facts to date as we (Ppruners) know them, but the evidence of a pipe work collapse/rebound would have to be there to confirm it.
Last edited by Flight Safety; 13th May 2008 at 20:04.