BA038 (B777) Thread
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Tenacity - Phil Gollin
At the beginning of the thread, everybody looked at Fuel, of course. After it tested "in spec.", I continued to question the part Fuel may have played in the accident. I took some ridicule, no problem. Turns out, the fuel is part of the problem here, though not in the "traditional sense".
Phil you seem to continue to focus on Fuel issues as well as vulnerability of other types. As far as I'm concerned, I think that is most appropriate.
The posters who wrote "the Fuel is in spec., what's your beef"??, may be the same ones who may seem impatient with your persistence. I hope you continue your line of comment.
Cavitation?? What part of the wear on the pumps was cavitation damage, and what part the pumps part time job as ice crusher? Ice is solid, if granular, sticky, or otherwise, and can abrade pump lobes and other metal pieces, with a decline in efficiency.
Upstream pipework?? Before the engine type comes into play, there is substantial icing in the plumbing, by test. What percentage of safety remains after the other types deal with it, GE, PW??
Final Note, and the most troubling vis a vis the AD. The FOHE cools Oil. Does it heat Fuel? Yes, but is that its designed task? It also melts Ice, as a casual read of the AD supports.
Relying for the ultimate safety of a/c, crew, and passengers, by tasking an inappropriate system with work it was not designed to do, seems cavalier, ill advised, and frankly, dangerous, given the information delivered thus far.
The Thrust Increase to avoid Icing, and the Idle Thrust to melt it means that half of the AD is expected to fail. This leaves the FOHE as the only line of defense to accomplish safety, yet it is this structure being redesigned, to be refit?? This is not even logical.
AF
Phil you seem to continue to focus on Fuel issues as well as vulnerability of other types. As far as I'm concerned, I think that is most appropriate.
The posters who wrote "the Fuel is in spec., what's your beef"??, may be the same ones who may seem impatient with your persistence. I hope you continue your line of comment.
Cavitation?? What part of the wear on the pumps was cavitation damage, and what part the pumps part time job as ice crusher? Ice is solid, if granular, sticky, or otherwise, and can abrade pump lobes and other metal pieces, with a decline in efficiency.
Upstream pipework?? Before the engine type comes into play, there is substantial icing in the plumbing, by test. What percentage of safety remains after the other types deal with it, GE, PW??
Final Note, and the most troubling vis a vis the AD. The FOHE cools Oil. Does it heat Fuel? Yes, but is that its designed task? It also melts Ice, as a casual read of the AD supports.
Relying for the ultimate safety of a/c, crew, and passengers, by tasking an inappropriate system with work it was not designed to do, seems cavalier, ill advised, and frankly, dangerous, given the information delivered thus far.
The Thrust Increase to avoid Icing, and the Idle Thrust to melt it means that half of the AD is expected to fail. This leaves the FOHE as the only line of defense to accomplish safety, yet it is this structure being redesigned, to be refit?? This is not even logical.
AF
Last edited by airfoilmod; 13th Mar 2009 at 18:13.
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WHBM
"How can the engine design have been in service for 15 years before such incidents happened. What caused it to work fine on comparable flights until now?"
As the AAIB report states, for the BA038 flight the minimum fuel temperature was in the bottom 0.2% of recorded temperatures. So if the system has a problem it may have taken this long for it to show up. It seems that the Delta flight came also from China but I haven't seen a temperature profile to be able to tell if it sits in the same family. Has it been an excessively cold period over these routes?
AIRFOILMOD
"The Problem isn't Ice, it's water. "In Spec." Fuel has it and at very low temps it takes shape as granular microscopic particles. As such, it does no harm. At Cruise, in VERY low temp. over many hours, the ice melts and refreezes in the FOHE.
There is no evidence that the the the freezing took place at the FOHE. I think think most now agree that ice formed upstream and was released in a relatively large quantity to the engine. The FOHE is then a likely place for the ice to stick. As the reports state testing has shown that the FOHE will block with sufficient quantities of ice.
It may therefore be prudent to improve the FOHE's handling of large quantities of ice, if Boeing cannot prevent this from occurring, but will it be enough to prevent further events? As for who should be liable for the mod and subsequent rollover. In these events it seems the engine is being supplied with fuel containing a quantity of ice it wasn't certified to live with. This would suggest an aircraft issue but I suspect RR/Boeing will jointly foot the bill.
"How can the engine design have been in service for 15 years before such incidents happened. What caused it to work fine on comparable flights until now?"
As the AAIB report states, for the BA038 flight the minimum fuel temperature was in the bottom 0.2% of recorded temperatures. So if the system has a problem it may have taken this long for it to show up. It seems that the Delta flight came also from China but I haven't seen a temperature profile to be able to tell if it sits in the same family. Has it been an excessively cold period over these routes?
AIRFOILMOD
"The Problem isn't Ice, it's water. "In Spec." Fuel has it and at very low temps it takes shape as granular microscopic particles. As such, it does no harm. At Cruise, in VERY low temp. over many hours, the ice melts and refreezes in the FOHE.
There is no evidence that the the the freezing took place at the FOHE. I think think most now agree that ice formed upstream and was released in a relatively large quantity to the engine. The FOHE is then a likely place for the ice to stick. As the reports state testing has shown that the FOHE will block with sufficient quantities of ice.
It may therefore be prudent to improve the FOHE's handling of large quantities of ice, if Boeing cannot prevent this from occurring, but will it be enough to prevent further events? As for who should be liable for the mod and subsequent rollover. In these events it seems the engine is being supplied with fuel containing a quantity of ice it wasn't certified to live with. This would suggest an aircraft issue but I suspect RR/Boeing will jointly foot the bill.
Last edited by spilko; 14th Mar 2009 at 09:38.
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DeScally of BC:
As long as procedures are in place to prevent at least the EDIT: one in 100,000 /EDIT chance of a repeat occurrence, I doubt a grounding order will be issued.
Here's a sampling of current major RR-equipped 777 Operators:
American
Cathay
British Airways
Delta
El Al
Emirates
Singapore
Malaysian
Thai
As long as procedures are in place to prevent at least the EDIT: one in 100,000 /EDIT chance of a repeat occurrence, I doubt a grounding order will be issued.
Here's a sampling of current major RR-equipped 777 Operators:
American
Cathay
British Airways
Delta
El Al
Emirates
Singapore
Malaysian
Thai
Last edited by vapilot2004; 14th Mar 2009 at 23:58. Reason: Thanks to Lomapaseo for spotting my reversal of fortune
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Airfoilmod hit the nail on the head in post 2261. The FOHE isn't a fuel heater it is an oil cooler. The fuel system itself isn't a fail safe design.
Having established that the current design traps ice RR and Boeing have to go to the 737 design of the fuel system where there is a bypass with a fuel heater. Those of us who flew the 732 remember well cycling the fuel heater and watching the oil temperature rise as an indication of it working.
It might also be prudent to put the bypasses back on all aircraft in particular ETOPS twins that are flying longer sectors than envisaged when they were designed.
Having established that the current design traps ice RR and Boeing have to go to the 737 design of the fuel system where there is a bypass with a fuel heater. Those of us who flew the 732 remember well cycling the fuel heater and watching the oil temperature rise as an indication of it working.
It might also be prudent to put the bypasses back on all aircraft in particular ETOPS twins that are flying longer sectors than envisaged when they were designed.
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An heart attack brought down BA038 .... analogy!
Warning: I'm non-professional; not crew, not engineer - just scientist guest and thanks.
A light hearted start -
the similarity of this accident with a plaque induced heart attack is interesting. Energy giving substance (food/fuel) contains substances (fats/water) that can clog and narrow energy channels (arteries/fuel lines) with potentially damaging substances (plaque/ice). Under certain circumstances these substances can break free and block the delivery of the energy substance (blood/fuel) to the engine (heart/turbine).
Quite rightly, doctors do advise the avoidance, or limitation, of the damaging substance (fats etc.) from human diets because that is the right philosophical and practical approach. However, doctors also carry out remedial action (stent insertions etc.) to remove damaging blockages, this being the equivalent of the 777/RR FOHE ice melting action.
The point of this analogy is doctors do not just concentrate on the remedial action (stent) and ignore the harmful effects of ingesting fats etc.; they study the whole system and try to recommend actions that avoid the critical moment (heart attack/turbine roll-back).
Surely this is the philosophy that the aircraft industry should follow and it is this that the AAIB is strongly advocating. That is, launch research programmes to fully understand water/ice in fuel and then make sure future aircraft systems are safer.
Of course, there is always a tension between the guardians of safety and commercial organisations - it has ever been so - and this, it seems to me, is evident in the words the AAIB use in the latest interim report.
I do hope the industry makes the effort to use modern investigative tools to fully understand the fuel it uses, to find actions that remove the danger of blockage and not just rely on the life saving operation of melting the ice!
Which brings me to observe that a 777/RR could experience more than one ice blockage event in a single flight. I hope no 777/RR pilots have been given the impression that if they experience a roll back following the step climb etc. and then follow the new SOP to melt that ice, that they will not have a recurrence on the same flight. Nor should pilots assume that if there is no roll back, following the step climbs etc., that there will not be a future roll back during that flight. You may be shouting that the probability of such outcomes is very low - maybe, but my point is that no one knows, so don't assume anything!
My vote would be to ground the fleet until the FOHE fix is in place. Why? Because I'm a coward when it comes to using my statistical bravery to risk other people's lives!
Regards, Tanimbar
A light hearted start -
the similarity of this accident with a plaque induced heart attack is interesting. Energy giving substance (food/fuel) contains substances (fats/water) that can clog and narrow energy channels (arteries/fuel lines) with potentially damaging substances (plaque/ice). Under certain circumstances these substances can break free and block the delivery of the energy substance (blood/fuel) to the engine (heart/turbine).
Quite rightly, doctors do advise the avoidance, or limitation, of the damaging substance (fats etc.) from human diets because that is the right philosophical and practical approach. However, doctors also carry out remedial action (stent insertions etc.) to remove damaging blockages, this being the equivalent of the 777/RR FOHE ice melting action.
The point of this analogy is doctors do not just concentrate on the remedial action (stent) and ignore the harmful effects of ingesting fats etc.; they study the whole system and try to recommend actions that avoid the critical moment (heart attack/turbine roll-back).
Surely this is the philosophy that the aircraft industry should follow and it is this that the AAIB is strongly advocating. That is, launch research programmes to fully understand water/ice in fuel and then make sure future aircraft systems are safer.
Of course, there is always a tension between the guardians of safety and commercial organisations - it has ever been so - and this, it seems to me, is evident in the words the AAIB use in the latest interim report.
I do hope the industry makes the effort to use modern investigative tools to fully understand the fuel it uses, to find actions that remove the danger of blockage and not just rely on the life saving operation of melting the ice!
Which brings me to observe that a 777/RR could experience more than one ice blockage event in a single flight. I hope no 777/RR pilots have been given the impression that if they experience a roll back following the step climb etc. and then follow the new SOP to melt that ice, that they will not have a recurrence on the same flight. Nor should pilots assume that if there is no roll back, following the step climbs etc., that there will not be a future roll back during that flight. You may be shouting that the probability of such outcomes is very low - maybe, but my point is that no one knows, so don't assume anything!
My vote would be to ground the fleet until the FOHE fix is in place. Why? Because I'm a coward when it comes to using my statistical bravery to risk other people's lives!
Regards, Tanimbar
Just to be safe ...
It would be reassuring to know that the redesigned FOHE can cope with ice pellets delivered at a greater rate than the CWT fuel scavenge system can shoot water into the main tank.
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Is it possible that fuel from Chinese sources is more prone to icing than fuel from UK or US suppliers? Presumably, the investigators will have compared the molecular composition of fuels from various sources using mass spectrometers and found no differences. If so, it seems strange that both instances of roll-back occurred on flights FROM China and none have been reported on reciprocal flights TO China.
Mitigation of ice formation by redesigning pipework/FOHE is all very well but the real long-term answer is a fuel which is free from significant ice formation under all imaginable flight conditions.
Mitigation of ice formation by redesigning pipework/FOHE is all very well but the real long-term answer is a fuel which is free from significant ice formation under all imaginable flight conditions.
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Add to the list of RR 777 operators Kenya Airways.
The emotive wording of the US statement is interesting. They were much less so about 737 rudder problems and the urgency of a fix. Nothing to do with nationality of course.
The emotive wording of the US statement is interesting. They were much less so about 737 rudder problems and the urgency of a fix. Nothing to do with nationality of course.
It might also be prudent to put the bypasses back on all aircraft in particular ETOPS twins that are flying longer sectors than envisaged when they were designed.
More Research Required
It's interesting that pipes accumulate ice at relatively warm temperatures, and little when really cold.
So we either prevent ice accumulation by heating, coatings or additives, or have mechanisms to avoid clogging when the ice sloughs off in warmer temperatures.
Boeing's original procedures seemed directed to fuel waxing.
It's interesting to see that the "ice" lining the pipes is not pure water ice but a mixture of fuel and water.
The Chinese fuel may have a part to play as one of the fractions may have a low temperature affinity for water.
It would be interesting to know the fuel fractions incorporated in the "ice" lining the pipes.
So we either prevent ice accumulation by heating, coatings or additives, or have mechanisms to avoid clogging when the ice sloughs off in warmer temperatures.
Boeing's original procedures seemed directed to fuel waxing.
It's interesting to see that the "ice" lining the pipes is not pure water ice but a mixture of fuel and water.
The Chinese fuel may have a part to play as one of the fractions may have a low temperature affinity for water.
It would be interesting to know the fuel fractions incorporated in the "ice" lining the pipes.
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Two Phase materials
Combinations of two materials produce unique and sometimes unsuspected results. Not the least of which is mass, obviously. Without a phase affinity between Ice and Fuel, the size of the clog would be reduced. Or, clogs might not form at all.
I've mentioned before colloids, and slurries. If the Ice is particulate, it's effect on thickened Fuel may be to create this occlusive material. The picture of the Face of the FOHE with "Ice" suggests "Packed Snow" rather than block Ice. The use of the Phrase "Occluded Artery" came to mind, and I note tanimbars further metaphor.
On the One hand, further research is assumed, but secondarily and of utmost importance is providing safe Fuel Systems for the affected a/c NOW.
Simply because the Fault can be broadened into discussions of "Chinese Fuel", "political Issues", and Safety/Commercial infighting deflects the focus of what should be:
Why is the AD adhered to as a FIX? If it is, it has massive exposure to failure.
1. The FOHE is defective by occurrence and by test.
2. The AD "relies" on this defective unit to prevent and/or to mitigate something the unit has CAUSED in the First Place.
There is NO free lunch, utilizing a faulty mechanism to perform a task it was not designed to, to allow the Fleet to continue to Fly?
To answer a previous post about the difference between ETOPS and "Quads" : From my perspective....... TWO ENGINES.
AF
Spilko, refreezing is a given at the FOHE in the midst of Fault, by definition. Overcome by ICE, the "melting" feature of the unit is overwhelmed, temps drop, and the migratory Ice "Packs" and freezes at the tube ends. I see your point, and terminology is critical here. Since there is no "precedent" for this, vocabulary will wean itself of misunderstanding as the mechanism is explored.
I've mentioned before colloids, and slurries. If the Ice is particulate, it's effect on thickened Fuel may be to create this occlusive material. The picture of the Face of the FOHE with "Ice" suggests "Packed Snow" rather than block Ice. The use of the Phrase "Occluded Artery" came to mind, and I note tanimbars further metaphor.
On the One hand, further research is assumed, but secondarily and of utmost importance is providing safe Fuel Systems for the affected a/c NOW.
Simply because the Fault can be broadened into discussions of "Chinese Fuel", "political Issues", and Safety/Commercial infighting deflects the focus of what should be:
Why is the AD adhered to as a FIX? If it is, it has massive exposure to failure.
1. The FOHE is defective by occurrence and by test.
2. The AD "relies" on this defective unit to prevent and/or to mitigate something the unit has CAUSED in the First Place.
There is NO free lunch, utilizing a faulty mechanism to perform a task it was not designed to, to allow the Fleet to continue to Fly?
To answer a previous post about the difference between ETOPS and "Quads" : From my perspective....... TWO ENGINES.
AF
Spilko, refreezing is a given at the FOHE in the midst of Fault, by definition. Overcome by ICE, the "melting" feature of the unit is overwhelmed, temps drop, and the migratory Ice "Packs" and freezes at the tube ends. I see your point, and terminology is critical here. Since there is no "precedent" for this, vocabulary will wean itself of misunderstanding as the mechanism is explored.
Last edited by airfoilmod; 14th Mar 2009 at 16:56.
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Dark Man!
I am aware of your first point about GE Wales, but where do you get the above "quote" from...?
Dag
...this deal also saved the GE90 from extinction at that time.
Dag
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ETOPS
I am completely committed to ETOPS. It is a boon to the industry and displays elegant solutions to a number of old problems. I fear however, that the responsibles have lost sight of what makes ETOPS unique. A lofty commitment to zero failure and a disciplined and unforgiving posture toward engineering base line.
On the one hand, twins are vulnerable to OEI always, but eliminating mere redundancy involves a discipline of separation of systems. At some point in the concept, duplication of flight critical systems is inevitable. I don't think we're there yet, BA038 notwithstanding. 038 could have been avoided in a non ETOPS way, because what befell the flight wasn't a lack of redundancy, but a process that affects all formats, ICE. By that I mean the a/c was lacking in what should have been a priori engineering vis a vis ICE and its hazards.
The research thus far hasn't indicted ETOPS in any way. What is unfolding in front of the community is a lowering of standards, and a concomitant inconsistency of applying those standards. To save a penny, the authority is loosening its credibility by exposing a make do philosophy to the Public, rather than a no tolerance profile re; Safety itself. Who's in charge here.
On the one hand, twins are vulnerable to OEI always, but eliminating mere redundancy involves a discipline of separation of systems. At some point in the concept, duplication of flight critical systems is inevitable. I don't think we're there yet, BA038 notwithstanding. 038 could have been avoided in a non ETOPS way, because what befell the flight wasn't a lack of redundancy, but a process that affects all formats, ICE. By that I mean the a/c was lacking in what should have been a priori engineering vis a vis ICE and its hazards.
The research thus far hasn't indicted ETOPS in any way. What is unfolding in front of the community is a lowering of standards, and a concomitant inconsistency of applying those standards. To save a penny, the authority is loosening its credibility by exposing a make do philosophy to the Public, rather than a no tolerance profile re; Safety itself. Who's in charge here.
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air temperatures at cruise altitude?
vapilot2004:
Thanks for your insights and your list of airlines currently operating the RR-equipped 777-200ER. I note that Air New Zealand also operates this type/engine combination; eight of them I believe. Which brings me to a question I'm hoping some of you pilots can answer for me (I'm not a pilot and so thanks for allowing me to participate in this thread without hopefully generating too much eyerolling from you):
In terms of typical cruise altitudes and air temperatures at those altitudes, are there any significant differences between the northern routes on which the BA and Delta rollbacks occurred, and NZ's AKL-YVR cross-equatorial route which they fly non-stop with the 777? This is a 14-hour ETOPS route.
Thanks for your insights and your list of airlines currently operating the RR-equipped 777-200ER. I note that Air New Zealand also operates this type/engine combination; eight of them I believe. Which brings me to a question I'm hoping some of you pilots can answer for me (I'm not a pilot and so thanks for allowing me to participate in this thread without hopefully generating too much eyerolling from you):
In terms of typical cruise altitudes and air temperatures at those altitudes, are there any significant differences between the northern routes on which the BA and Delta rollbacks occurred, and NZ's AKL-YVR cross-equatorial route which they fly non-stop with the 777? This is a 14-hour ETOPS route.
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deScally
With respect, it's in here. Happy reading.
Further:
Be careful of "Fuel Heating". It is warmer temps that created the hazard, not "very cold" Fuel. (Though it was a precursor).
Location of FOHE? perhaps away from the Fan Shroud a bit.
Bypass, a no brainer. Though GE uses the concept to further cool the oil, in this case, a "recirculation" not strictly a "bypass".
The Bottom Line? The Fuel system as a whole on this combination wants to be a bit more complex, to include additional mitigating procedures and mechanicals. It always looked a little simplistic, turns out it is.
vapilot -It is always hazardous to rely on the unknown, or statistics. If what you mean is "one in one hundred thousand" of an additional occurence, think about how many months it takes the Fleet to hit 50,000 trips. At that point the chance? ONE in TWO. Let's see, 228 a/c, one trip a day, 1,000 every 4 days, twenty thousand every 80 days (Five to One), etc. See?
bernd - re:GE. The HP in front of the FOHE not only "Heats" a little, it makes any free floating ice/slurry into margaritas, "blending" the mix for the FOHE and subsequently for the nozzles. It is this architecture more than any other reason, in my opinion, that makes GE mounted 777's "immune" from "the Plug". GE-"Blended"..... TRENT-"on the rocks".
Further:
Be careful of "Fuel Heating". It is warmer temps that created the hazard, not "very cold" Fuel. (Though it was a precursor).
Location of FOHE? perhaps away from the Fan Shroud a bit.
Bypass, a no brainer. Though GE uses the concept to further cool the oil, in this case, a "recirculation" not strictly a "bypass".
The Bottom Line? The Fuel system as a whole on this combination wants to be a bit more complex, to include additional mitigating procedures and mechanicals. It always looked a little simplistic, turns out it is.
vapilot -It is always hazardous to rely on the unknown, or statistics. If what you mean is "one in one hundred thousand" of an additional occurence, think about how many months it takes the Fleet to hit 50,000 trips. At that point the chance? ONE in TWO. Let's see, 228 a/c, one trip a day, 1,000 every 4 days, twenty thousand every 80 days (Five to One), etc. See?
bernd - re:GE. The HP in front of the FOHE not only "Heats" a little, it makes any free floating ice/slurry into margaritas, "blending" the mix for the FOHE and subsequently for the nozzles. It is this architecture more than any other reason, in my opinion, that makes GE mounted 777's "immune" from "the Plug". GE-"Blended"..... TRENT-"on the rocks".
Last edited by airfoilmod; 14th Mar 2009 at 20:02.
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on the rocks
AFM,
after 2340 posts on this thread, this is the one that sums up the technical issues in a nut-shell from my point of view "GE-blended, Trent-on the rocks"
Thanks.
(I'll be interested to read bernd's take on this)
daved
after 2340 posts on this thread, this is the one that sums up the technical issues in a nut-shell from my point of view "GE-blended, Trent-on the rocks"
Thanks.
(I'll be interested to read bernd's take on this)
daved