BA038 (B777) Thread
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I'm a little disturbed by Boeing's AD.
As a purely precautionary document - three cheers (but does it add to anything more than last Autumn's FAA one ?).
However, it seems a little too intrusive into the inquiries being undertaken by the proper authorities.
However, most importantly, there is no indication in the Boeing inturruption as to how the unknown process managed to affect two separate systems so similarly in time and effect.
Too much seems to be being read into something which is too vague.
.
As a purely precautionary document - three cheers (but does it add to anything more than last Autumn's FAA one ?).
However, it seems a little too intrusive into the inquiries being undertaken by the proper authorities.
However, most importantly, there is no indication in the Boeing inturruption as to how the unknown process managed to affect two separate systems so similarly in time and effect.
Too much seems to be being read into something which is too vague.
.
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News management - a necessary strategy
Warning: I'm non-professional; not crew, not engineer - just scientist guest and thanks.
I suspect we are being given a lesson in global news management. I think it is a good and necessary lesson.
Investigators, Boeing and RR engineers etc. already know that the root cause of the BA038 incident is the state of the fuel in the tanks and pipes. For fuel temperatures below -18C the AAIB have stated,
"Below this temperature little is known about the properties of ice crystals in fuel and further research may be required to enable the aviation industry to more fully understand this behaviour."
Others here have agreed that the phrase 'little is known' is shocking. But, the industry cannot, and should not, allow that damning finding to be transmitted to the general public without first indicating that there are operational actions to hopefully avoid a recurrence, and a temporary engineering solution that can be retrofitted to a class of aircraft most susceptible to the problem, namely, Boeing 777s with RR engines.
Meanwhile, quietly, the industry concentrates its efforts on understanding what does happen to fuel on these long, high and cold flights and the more permanent solution to the globally pervasive problem.
This strategy is probably the only viable one to follow. I hope that the industry is actively trying to fill the hole in its knowledge, i.e. the behaviour of cold fuel.
I still think the fuel within the main tanks stratified in some form and that a pulse of "gloop", or slurry as Airfoilmod calls it (#2178), entered the delivery systems and partially blocked them.
Moving to tongue in cheek mode - Oh to be a fly-on-the-wall in the meeting room where RR are holding their forensic investigations into the decision stage on the FOHE design. Why that design, why not the GE or P&W one? Were the GE and P&W engineers just lucky or did they have knowledge that guided them, and if they did, was this available to RR? I've lots of follow-up questions but will spare you.
There is a lot to be learned about how the industry shares knowledge and, probably more crucially, the authorities must determine how it is that, this most technically advanced global industry, does not know how fuel behaves below -18C.
I'm still staggered by that.
Regards, Tanimbar
I suspect we are being given a lesson in global news management. I think it is a good and necessary lesson.
Investigators, Boeing and RR engineers etc. already know that the root cause of the BA038 incident is the state of the fuel in the tanks and pipes. For fuel temperatures below -18C the AAIB have stated,
"Below this temperature little is known about the properties of ice crystals in fuel and further research may be required to enable the aviation industry to more fully understand this behaviour."
Others here have agreed that the phrase 'little is known' is shocking. But, the industry cannot, and should not, allow that damning finding to be transmitted to the general public without first indicating that there are operational actions to hopefully avoid a recurrence, and a temporary engineering solution that can be retrofitted to a class of aircraft most susceptible to the problem, namely, Boeing 777s with RR engines.
Meanwhile, quietly, the industry concentrates its efforts on understanding what does happen to fuel on these long, high and cold flights and the more permanent solution to the globally pervasive problem.
This strategy is probably the only viable one to follow. I hope that the industry is actively trying to fill the hole in its knowledge, i.e. the behaviour of cold fuel.
I still think the fuel within the main tanks stratified in some form and that a pulse of "gloop", or slurry as Airfoilmod calls it (#2178), entered the delivery systems and partially blocked them.
Moving to tongue in cheek mode - Oh to be a fly-on-the-wall in the meeting room where RR are holding their forensic investigations into the decision stage on the FOHE design. Why that design, why not the GE or P&W one? Were the GE and P&W engineers just lucky or did they have knowledge that guided them, and if they did, was this available to RR? I've lots of follow-up questions but will spare you.
There is a lot to be learned about how the industry shares knowledge and, probably more crucially, the authorities must determine how it is that, this most technically advanced global industry, does not know how fuel behaves below -18C.
I'm still staggered by that.
Regards, Tanimbar
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Tanimbar
The Press Release causes more problems than it solves, in my opinion. I am not expert in fluid dynamics by any stretch, but logic suggests the following.
It is highly unlikely there was liquid water any where in the fuel system of 038 for hours prior to the flight. If present as ice, then a "picture" of the state of the tankage would suggest that it was present as what? Cocktail ice? large blocks clinging to aluminum? That doesn't jive with the temps experienced by the a/c overnight or well prior to launch from Beijing. Block ice won't pump, and fuel won't "freeze" at all ambient temps. surrounding the flight. If the a/c brought it with on the flight in, that's one thing, but logic again suggests the problem arose on uplift in China. In spec. fuel would be carrying some quantity of water (as ice) in the uplifted batch.
As the flight progressed, this ice would "concentrate" in progressively greater quantities as it settled lower in the fuel system. At some point the siphon starts pulling high enough quantities of particle ice with Fuel such that it migrates toward the engines. Passing into the engines it converts to Steam and causes no particular problem. It may even enhance thrust at some miniscule value. However, it also, as a solid, would "fall out" of suspension and deposit in variable flow areas (due to specific gravity difference) and eventually create flow reduction.
It isn't particularly difficult to imagine this occurring at essentially the same time in both engines, ETOPS isn't foolproof, especially when systems are homogeneous and filled with the (same) Fuel.
I can't imagine what "Unimagined quality" the Fuel possessed to remain so mysterious. Rather than mystifying its audience, perhaps Boeing and FAA should tell the complete tale. A year on with new Physics/Chemistry/Fluidics? Stretches credulity. Just sayin'.
AF
It is highly unlikely there was liquid water any where in the fuel system of 038 for hours prior to the flight. If present as ice, then a "picture" of the state of the tankage would suggest that it was present as what? Cocktail ice? large blocks clinging to aluminum? That doesn't jive with the temps experienced by the a/c overnight or well prior to launch from Beijing. Block ice won't pump, and fuel won't "freeze" at all ambient temps. surrounding the flight. If the a/c brought it with on the flight in, that's one thing, but logic again suggests the problem arose on uplift in China. In spec. fuel would be carrying some quantity of water (as ice) in the uplifted batch.
As the flight progressed, this ice would "concentrate" in progressively greater quantities as it settled lower in the fuel system. At some point the siphon starts pulling high enough quantities of particle ice with Fuel such that it migrates toward the engines. Passing into the engines it converts to Steam and causes no particular problem. It may even enhance thrust at some miniscule value. However, it also, as a solid, would "fall out" of suspension and deposit in variable flow areas (due to specific gravity difference) and eventually create flow reduction.
It isn't particularly difficult to imagine this occurring at essentially the same time in both engines, ETOPS isn't foolproof, especially when systems are homogeneous and filled with the (same) Fuel.
I can't imagine what "Unimagined quality" the Fuel possessed to remain so mysterious. Rather than mystifying its audience, perhaps Boeing and FAA should tell the complete tale. A year on with new Physics/Chemistry/Fluidics? Stretches credulity. Just sayin'.
AF
Moving to tongue in cheek mode - Oh to be a fly-on-the-wall in the meeting room where RR are holding their forensic investigations into the decision stage on the FOHE design. Why that design, why not the GE or P&W one? Were the GE and P&W engineers just lucky or did they have knowledge that guided them, and if they did, was this available to RR? I've lots of follow-up questions but will spare you.
There is a lot to be learned about how the industry shares knowledge and, probably more crucially, the authorities must determine how it is that, this most technically advanced global industry, does not know how fuel behaves below -18C.
There is a lot to be learned about how the industry shares knowledge and, probably more crucially, the authorities must determine how it is that, this most technically advanced global industry, does not know how fuel behaves below -18C.
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lomapaseo, airfoilmod
Iomapaseo, so my tongue-in-cheek comments were actually foot-in-mouth! Apologies to RR. Thanks for the correction.
Airfoilmod, to tell the complete tale would require an explanation the industry does not yet have and may not have for years as the research is conducted. At least, that is what this ignorant observer considers likely.
To coin a phrase, 'Better to shut up, if you can't put-up'.
Regards, Tanimbar
Airfoilmod, to tell the complete tale would require an explanation the industry does not yet have and may not have for years as the research is conducted. At least, that is what this ignorant observer considers likely.
To coin a phrase, 'Better to shut up, if you can't put-up'.
Regards, Tanimbar
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Likely
Not. The shut up part anyway. I don't buy the "unknown behaviour" bit.
You're welcome to it, to each his own. It is typical of the investigative authority to prolong its work; this is not unknown in government. This may raise howls of protest or a delete, but it is my opinion. M.Mouse suggested that there was knowledge of results given to BA and its pilots. That is fine by me. There is however another group with an investment in the "results" that would preclude "secrecy" from being practiced: Other pilots and the travelling public. When all is said and done, I wager the reluctance of the investigation (ers) will not be taken as having been prudent.
AF
You're welcome to it, to each his own. It is typical of the investigative authority to prolong its work; this is not unknown in government. This may raise howls of protest or a delete, but it is my opinion. M.Mouse suggested that there was knowledge of results given to BA and its pilots. That is fine by me. There is however another group with an investment in the "results" that would preclude "secrecy" from being practiced: Other pilots and the travelling public. When all is said and done, I wager the reluctance of the investigation (ers) will not be taken as having been prudent.
AF
Last edited by airfoilmod; 5th Feb 2009 at 01:18.
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AF, I'm willing to accept the explanation that good knowledge of cold fuel behavior is either not well or widely understood.
I think we always learn in aviation, for example take ditching an airliner. We've recently been reminded (again) that it can be done successfully. But how to do it? Probably only a fairly small number of aviators understood it very well prior to the Hudson River accident, while many aviators didn't think it was possible. So that knowledge existed, but wasn't widely known.
I think it may be similar regarding cold fuel behavior.
I think we always learn in aviation, for example take ditching an airliner. We've recently been reminded (again) that it can be done successfully. But how to do it? Probably only a fairly small number of aviators understood it very well prior to the Hudson River accident, while many aviators didn't think it was possible. So that knowledge existed, but wasn't widely known.
I think it may be similar regarding cold fuel behavior.
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Flight Safety
With respect, I would point out that ditching is a Pilot issue, Cold Fuel chemistry an engineering one. I have the belief that as a group, pilot's have a superior level of Intelligence and practical experience in their field relative to other less demanding pursuits, for very good reason. However, though a pilot may have a fine knowledge of engineering, it isn't a prerequisite for the certificate.
I have a keen interest in Fuel, my life, passengers and freight depend on quality; this quality is expected, and rightly so. I remain surprised at the less than emphatic response to a Chemical, Engineering, Production, and Quality "vacuum of knowledge".
Training and recurrent training emphasize failure, response, innovation, memory, and solution. Well enough two engines fail on a twin, an ETOPS a/c; on top of a rigorous solution and implementation, the consumers of a life dependent product must be patronised with "the great unknown"?
I don't necessarily believe FAA is doing anything unusual here, but when products are found to be life-threatening, generally the appropriate agency appears to act in a more immediate and appropriate time frame.
I have a keen interest in Fuel, my life, passengers and freight depend on quality; this quality is expected, and rightly so. I remain surprised at the less than emphatic response to a Chemical, Engineering, Production, and Quality "vacuum of knowledge".
Training and recurrent training emphasize failure, response, innovation, memory, and solution. Well enough two engines fail on a twin, an ETOPS a/c; on top of a rigorous solution and implementation, the consumers of a life dependent product must be patronised with "the great unknown"?
I don't necessarily believe FAA is doing anything unusual here, but when products are found to be life-threatening, generally the appropriate agency appears to act in a more immediate and appropriate time frame.
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I have a keen interest in Fuel, my life, passengers and freight depend on quality; this quality is expected, and rightly so.
I remain surprised at the less than emphatic response to a Chemical, Engineering, Production, and Quality "vacuum of knowledge".
...consumers of a life dependent product must be patronised with "the great unknown"?
As previously posited by another poster, it's likely that jet fuel at extreme low temperatures may become a non-newtonian fluid. The time has come for rheologists to study jet fuel at very low temperatures.
Such studies will require not only complex rigs to simulate the requisite conditions, but thousands of evaluations of the myriad possible combinations of jet fuels and additives.
Have a look here for some idea of world jet fuel specs and additives.
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Boeing final word /RR-Trents
oeing issues warning to 777 operators
A Delta Airlines 777-200ER was flying from Shanghai, China, to Atlanta last
November when its right engine suddenly lost thrust while the plane was
cruising at 39,000 feet over Montana.
The pilots followed flight manual procedures and descended to 31,000 feet,
where the Rolls-Royce engine recovered and responded normally. The flight,
with 15 crew members and 232 passengers, continued to Atlanta and landed
safely.
That incident would likely not have gotten much attention had the same kind
of Boeing jet, with Rolls-Royce engines, not lost all power in both engines
just before landing at London's Heathrow earlier in the year. The British
Airways 777 crash-landed short of the runway. Several passengers were
injured, but none seriously.
Safety experts eventually decided that the British Airways jet, also on a
flight from China, had flown through unusually cold weather at cruise
altitude and ice apparently formed in part of the engine and blocked the
fuel flow.
On Thursday, Boeing sent a notice to all operators of its 777s with Trent
engines made by Rolls-Royce, advising them that it now believes the Delta
and British Airways incidents appear to have been caused by the same thing –
ice blocking the fuel path.
A Boeing spokesman said Tuesday the "all operators" notice contains a series
of precautionary measures that pilots should take during flight to lessen
the chance ice could cause a sudden loss of engine power.
Eventually, the spokesman said, the FAA can be expected to order a
"permanent fix.'' That would likely mean a redesign of part of the Trent 777
engine.
Boeing would not release a copy of the letter it sent last week. The
spokesman said it is not a public document. But the industry magazine Flight
International obtained a copy and said the Boeing letter describes the Delta
and British Airways incidents as likely being caused by "similar factors.''
More than 700 Boeing 777s, a widebody jet that typically carries from 300 to
360 passengers, depending on the model, are in service with airlines around
the world. About 30 percent have Trent engines.
General Electric and Pratt & Whitney also make engines for the 777, but
those have a different design than the Trent engine from Rolls-Royce and are
not thought to be susceptible to the ice problem. The newest 777s built by
Boeing, the best-selling 777-300ER and the ultra-long-range 777-200LR, are
only powered with GE engines.
In September, the Federal Aviation Administration issued a formal
airworthiness directive that required changes in the way ground crews
prepare 777s with Trent engines and how pilots fly them in extreme cold
weather in response to what investigators found in studying the British
Airways crash in January. Shortly before the FAA issued its warning, Boeing
had sent out an "all operators" notice with a series of recommendations
developed to prevent a similar problem on its 777s with Trent engines.
Boeing recommended, for example, that pilots rev their engines when the fuel
temperature falls to 14 degrees Fahrenheit. That would conceivably dislodge
any ice that might be in the fuel line.
Another procedure recommended by Boeing, and ordered by the FAA, called for
the crew to advance the engine throttles to maximum thrust for 10 seconds
before descending on flights that have maintained the same altitude for at
least three hours, if the fuel temperature is below 14 degrees.
Those procedures have been revised in the Boeing bulletin sent last week,
following the Delta incident.
Boeing now recommends that pilots advance engine throttles to maximum thrust
before descending on flights that have maintained the same altitude for two
hours, not three.
Also in its latest notice, Boeing recommends that pilots, during the descent
for landing, reduce engine power to full idle for at least 30 seconds. By
reducing fuel flow, engine oil heat can melt any ice that may have
accumulated.
The FAA, as it did in September, is likely to make Boeing's latest
recommendations mandatory.
The 777 has never had a fatal crash since it entered service with United
Airlines in 1995. But the Delta and British Airways incidents have given
safety experts cause for concern, in large part because they are apparently
dealing with a previously unknown phenomenon.
The British Airways crash occurred Jan. 17, 2008, as the 777-200ER, with 152
passengers and crew members, approached Heathrow after a flight from
Beijing. Both engines failed to respond to autopilot commands for thrust as
the plane approached the airport.
It turned into one of the most puzzling aviation accidents in modern times.
The plane was badly damaged but was mostly intact, so investigators had all
the physical evidence in hand to look for clues. But one thing was missing –
the ice. The key piece of evidence had literally melted away.
Investigators now believe the problem is with the fuel-oil heat exchanger
system on the Trent 777 engine.
Boeing engineers, according to Flight International, have determined by
working in the laboratory that the heat generated by the Rolls-Royce
fuel-oil heat exchanger is not adequate to prevent moisture in the fuel from
freezing. When that happens, ice can form that blocks fuel to the exchanger,
"starving the engines,'' according to the magazine.
The General Electric and Pratt engines on the 777 have a different fuel
system architecture.
"Based on our knowledge of the system configurations, scenario studies and
laboratory test results, we do not believe that immediate action is
necessary or warranted for 777s powered by other engine types or non-777
airframes regardless of engine type,'' the Boeing letter sent to 777
operators last week states, according to Flight International.
A Delta Airlines 777-200ER was flying from Shanghai, China, to Atlanta last
November when its right engine suddenly lost thrust while the plane was
cruising at 39,000 feet over Montana.
The pilots followed flight manual procedures and descended to 31,000 feet,
where the Rolls-Royce engine recovered and responded normally. The flight,
with 15 crew members and 232 passengers, continued to Atlanta and landed
safely.
That incident would likely not have gotten much attention had the same kind
of Boeing jet, with Rolls-Royce engines, not lost all power in both engines
just before landing at London's Heathrow earlier in the year. The British
Airways 777 crash-landed short of the runway. Several passengers were
injured, but none seriously.
Safety experts eventually decided that the British Airways jet, also on a
flight from China, had flown through unusually cold weather at cruise
altitude and ice apparently formed in part of the engine and blocked the
fuel flow.
On Thursday, Boeing sent a notice to all operators of its 777s with Trent
engines made by Rolls-Royce, advising them that it now believes the Delta
and British Airways incidents appear to have been caused by the same thing –
ice blocking the fuel path.
A Boeing spokesman said Tuesday the "all operators" notice contains a series
of precautionary measures that pilots should take during flight to lessen
the chance ice could cause a sudden loss of engine power.
Eventually, the spokesman said, the FAA can be expected to order a
"permanent fix.'' That would likely mean a redesign of part of the Trent 777
engine.
Boeing would not release a copy of the letter it sent last week. The
spokesman said it is not a public document. But the industry magazine Flight
International obtained a copy and said the Boeing letter describes the Delta
and British Airways incidents as likely being caused by "similar factors.''
More than 700 Boeing 777s, a widebody jet that typically carries from 300 to
360 passengers, depending on the model, are in service with airlines around
the world. About 30 percent have Trent engines.
General Electric and Pratt & Whitney also make engines for the 777, but
those have a different design than the Trent engine from Rolls-Royce and are
not thought to be susceptible to the ice problem. The newest 777s built by
Boeing, the best-selling 777-300ER and the ultra-long-range 777-200LR, are
only powered with GE engines.
In September, the Federal Aviation Administration issued a formal
airworthiness directive that required changes in the way ground crews
prepare 777s with Trent engines and how pilots fly them in extreme cold
weather in response to what investigators found in studying the British
Airways crash in January. Shortly before the FAA issued its warning, Boeing
had sent out an "all operators" notice with a series of recommendations
developed to prevent a similar problem on its 777s with Trent engines.
Boeing recommended, for example, that pilots rev their engines when the fuel
temperature falls to 14 degrees Fahrenheit. That would conceivably dislodge
any ice that might be in the fuel line.
Another procedure recommended by Boeing, and ordered by the FAA, called for
the crew to advance the engine throttles to maximum thrust for 10 seconds
before descending on flights that have maintained the same altitude for at
least three hours, if the fuel temperature is below 14 degrees.
Those procedures have been revised in the Boeing bulletin sent last week,
following the Delta incident.
Boeing now recommends that pilots advance engine throttles to maximum thrust
before descending on flights that have maintained the same altitude for two
hours, not three.
Also in its latest notice, Boeing recommends that pilots, during the descent
for landing, reduce engine power to full idle for at least 30 seconds. By
reducing fuel flow, engine oil heat can melt any ice that may have
accumulated.
The FAA, as it did in September, is likely to make Boeing's latest
recommendations mandatory.
The 777 has never had a fatal crash since it entered service with United
Airlines in 1995. But the Delta and British Airways incidents have given
safety experts cause for concern, in large part because they are apparently
dealing with a previously unknown phenomenon.
The British Airways crash occurred Jan. 17, 2008, as the 777-200ER, with 152
passengers and crew members, approached Heathrow after a flight from
Beijing. Both engines failed to respond to autopilot commands for thrust as
the plane approached the airport.
It turned into one of the most puzzling aviation accidents in modern times.
The plane was badly damaged but was mostly intact, so investigators had all
the physical evidence in hand to look for clues. But one thing was missing –
the ice. The key piece of evidence had literally melted away.
Investigators now believe the problem is with the fuel-oil heat exchanger
system on the Trent 777 engine.
Boeing engineers, according to Flight International, have determined by
working in the laboratory that the heat generated by the Rolls-Royce
fuel-oil heat exchanger is not adequate to prevent moisture in the fuel from
freezing. When that happens, ice can form that blocks fuel to the exchanger,
"starving the engines,'' according to the magazine.
The General Electric and Pratt engines on the 777 have a different fuel
system architecture.
"Based on our knowledge of the system configurations, scenario studies and
laboratory test results, we do not believe that immediate action is
necessary or warranted for 777s powered by other engine types or non-777
airframes regardless of engine type,'' the Boeing letter sent to 777
operators last week states, according to Flight International.
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Something's missing
So the cold fuel transits the system, waits with liquid water in its composition so that it can freeze after entering the pylon and the enhanced heat of the HE? I think that isn't likely. Again, at the temps in the tanks, there would be no liquid water in the fuel. Something Capt. Cargill suggested covers more ground; an upstream "snowstorm" that caused cavitation at the engines. The "snow" (small granular water ice) would have formed as early as in the trucks (A/P tankage) prior to uplift.
Another problem with the Boeing memo as supplied. The assumption is the cavitation was caused by ice blocking proper flow to the HP pumps, if the blockage occurred at the HE does Boeing suggest the Fuel was flowing fine until the ice formed at the exchanger? I suppose the tests are ongoing relative to the FOHE and Boeings fully mocked up system. From the initial response of both engines one could assume that the exchangers were collecting a suspended (preformed) "precipitate" or subjected to the necking down of the exit aperture as ice quickly formed ahead of the exit.
It would be folly for Boeing to target only the RR if it suspected at all that the other engine types were in the least susceptible to the anomaly.
It would be likewise almost unthinkable for Boeing to allow a vulnerability to problems with the fuel to go unreported. This would appear to exonerate the fuel by default, the GE and Pratts as well. Let's not forget that rollbacks occurred well into the long flight, lending some suspicion to a greater concentration of particle ice with time aloft. Also, that on Delta, the rollback appears to have occurred without a demand for increased thrust, as on 038.
AF
Another problem with the Boeing memo as supplied. The assumption is the cavitation was caused by ice blocking proper flow to the HP pumps, if the blockage occurred at the HE does Boeing suggest the Fuel was flowing fine until the ice formed at the exchanger? I suppose the tests are ongoing relative to the FOHE and Boeings fully mocked up system. From the initial response of both engines one could assume that the exchangers were collecting a suspended (preformed) "precipitate" or subjected to the necking down of the exit aperture as ice quickly formed ahead of the exit.
It would be folly for Boeing to target only the RR if it suspected at all that the other engine types were in the least susceptible to the anomaly.
It would be likewise almost unthinkable for Boeing to allow a vulnerability to problems with the fuel to go unreported. This would appear to exonerate the fuel by default, the GE and Pratts as well. Let's not forget that rollbacks occurred well into the long flight, lending some suspicion to a greater concentration of particle ice with time aloft. Also, that on Delta, the rollback appears to have occurred without a demand for increased thrust, as on 038.
AF
Chicken or Egg?
Also, that on Delta, the rollback appears to have occurred without a demand for increased thrust, as on 038.
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Which came first on 038, the rollback or the demand for thrust?
Another question is : Did the Delta fuel pump show signs of cavitation afterward ?
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From the Flight Global article, it appears the GE and PW design recirculates some of the heated fuel back to the upstream face of the FOHE, thus preheating the new cold fuel approaching the upstream FOHE face (thus melting any water ice before reaching the FOHE). The Trent FOHE does not appear to have this warmed fuel recirculation feature, thus the fuel reaching the upstream face of the FOHE is colder than on the GE or PW designs
The question goes back to did GE and PW have previous knowledge of problems with ice, just returned the warmer fuel due to convenience of a place to return the fuel, or dumb luck?
Then again I would also wonder if other RR engines are plumbed in the exact manner of engines in question on the T7 and just not exposed to the long periods cold soaked conditions connected to the T7.
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Airfoilmod
So the cold fuel transits the system, waits with liquid water in its composition so that it can freeze after entering the pylon and the enhanced heat of the HE? I think that isn't likely. Again, at the temps in the tanks, there would be no liquid water in the fuel. Something Capt. Cargill suggested covers more ground; an upstream "snowstorm" that caused cavitation at the engines. The "snow" (small granular water ice) would have formed as early as in the trucks (A/P tankage) prior to uplift.
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I am still extremely disturbed that people are taking the (relatively unofficial) Boeing statement too seriously.
Any proper solution would need to explain the problem scientifically and (eventually) come up with a new set of rules both for Fuel Specification(s), for pipework/accessories installations and flight planning and operations.
THEN ALL aircraft, no matter what engine, would need to be checked against the new rules.
---------------
Two other things ;
(i) Still three cheers for any useful information.
(ii) Any real explanations for the BA flight having suffered a dual failure so almost simultaneously ?
------------------
Grasping at partial straws is not a solution.
.
Any proper solution would need to explain the problem scientifically and (eventually) come up with a new set of rules both for Fuel Specification(s), for pipework/accessories installations and flight planning and operations.
THEN ALL aircraft, no matter what engine, would need to be checked against the new rules.
---------------
Two other things ;
(i) Still three cheers for any useful information.
(ii) Any real explanations for the BA flight having suffered a dual failure so almost simultaneously ?
------------------
Grasping at partial straws is not a solution.
.
Any proper solution would need to explain the problem scientifically and (eventually) come up with a new set of rules both for Fuel Specification(s), for pipework/accessories installations and flight planning and operations.
THEN ALL aircraft, no matter what engine, would need to be checked against the new rules.
THEN ALL aircraft, no matter what engine, would need to be checked against the new rules.
We need to learn and avoid pointing fingers at persons/organizations and stop throwing stones inside a glass house that we are all inside.
Since it's obvious to me that the industry (regulators, engine and airframers )did not know of this combination beforehand it just happend to be a RR installation that first illustrated the weakeness in all our collected ignorance.
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Quote :-
......... Since it's obvious to me that the industry (regulators, engine and airframers )did not know of this combination beforehand it just happend to be a RR installation that first illustrated the weakeness in all our collected ignorance.
unquote
I knew someone intimately involved in the Kings Cross fire. There, both before during and after the official enquiry there were masses of misinformed criticism. Most people nowadays will say it was simplistically the combination of wooden treads and build-up of rubbish in the under-escalator area (plus poor emergency procedures).
Actually the main reason was the flash-over effect caused by the layout of the tunnels - something never expected and indeed "new" in terms of underground railway operation. The experts know what happened, the general public just have a simplistic view.
(The final costs of all the remedial works has been vast - and is only now being completed - I have a vague feeling the same might be a case here).
.
......... Since it's obvious to me that the industry (regulators, engine and airframers )did not know of this combination beforehand it just happend to be a RR installation that first illustrated the weakeness in all our collected ignorance.
unquote
I knew someone intimately involved in the Kings Cross fire. There, both before during and after the official enquiry there were masses of misinformed criticism. Most people nowadays will say it was simplistically the combination of wooden treads and build-up of rubbish in the under-escalator area (plus poor emergency procedures).
Actually the main reason was the flash-over effect caused by the layout of the tunnels - something never expected and indeed "new" in terms of underground railway operation. The experts know what happened, the general public just have a simplistic view.
(The final costs of all the remedial works has been vast - and is only now being completed - I have a vague feeling the same might be a case here).
.
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Actually there seems just as few facts in that piece as any other.
Still no information on where the "water" for the ice came from.
Still no information on the process whereby the ice formed and acted so regularly on two separate systems
Still no scientific/engineering explanations and new rules to cover ALL aircraft and ALL engine installations.
--------------------------------------
I have copied the piece below ;
Boeing issues warning to 777 operators
Below is a story I just filed, following up on the British Airways crash at Heathrow a year ago.
BY James Wallace
P-I aerospace reporter
A Delta Airlines 777-200ER was flying from Shanghai, China, to Atlanta last November when its right engine suddenly lost thrust while the plane was cruising at 39,000 feet over Montana.
The pilots followed flight manual procedures and descended to 31,000 feet, where the Rolls-Royce engine recovered and responded normally. The flight, with 15 crew members and 232 passengers, continued to Atlanta and landed safely.
That incident would likely not have gotten much attention had the same kind of Boeing jet, with Rolls-Royce engines, not lost all power in both engines just before landing at London's Heathrow earlier in the year. The British Airways 777 crash-landed short of the runway. Several passengers were injured, but none seriously.
Safety experts eventually decided that the British Airways jet, also on a flight from China, had flown through unusually cold weather at cruise altitude and ice apparently formed in part of the engine and blocked the fuel flow.
On Thursday, Boeing sent a notice to all operators of its 777s with Trent engines made by Rolls-Royce, advising them that it now believes the Delta and British Airways incidents appear to have been caused by the same thing – ice blocking the fuel path.
A Boeing spokesman said Tuesday the "all operators" notice contains a series of precautionary measures that pilots should take during flight to lessen the chance ice could cause a sudden loss of engine power.
Eventually, the spokesman said, the FAA can be expected to order a "permanent fix.'' That would likely mean a redesign of part of the Trent 777 engine.
Boeing would not release a copy of the letter it sent last week. The spokesman said it is not a public document. But the industry magazine Flight International obtained a copy and said the Boeing letter describes the Delta and British Airways incidents as likely being caused by "similar factors.''
More than 700 Boeing 777s, a widebody jet that typically carries from 300 to 360 passengers, depending on the model, are in service with airlines around the world. About 30 percent have Trent engines.
General Electric and Pratt & Whitney also make engines for the 777, but those have a different design than the Trent engine from Rolls-Royce and are not thought to be susceptible to the ice problem. The newest 777s built by Boeing, the best-selling 777-300ER and the ultra-long-range 777-200LR, are only powered with GE engines.
In September, the Federal Aviation Administration issued a formal airworthiness directive that required changes in the way ground crews prepare 777s with Trent engines and how pilots fly them in extreme cold weather in response to what investigators found in studying the British Airways crash in January. Shortly before the FAA issued its warning, Boeing had sent out an "all operators" notice with a series of recommendations developed to prevent a similar problem on its 777s with Trent engines.
Boeing recommended, for example, that pilots rev their engines when the fuel temperature falls to 14 degrees Fahrenheit. That would conceivably dislodge any ice that might be in the fuel line.
Another procedure recommended by Boeing, and ordered by the FAA, called for the crew to advance the engine throttles to maximum thrust for 10 seconds before descending on flights that have maintained the same altitude for at least three hours, if the fuel temperature is below 14 degrees.
Those procedures have been revised in the Boeing bulletin sent last week, following the Delta incident.
Boeing now recommends that pilots advance engine throttles to maximum thrust before descending on flights that have maintained the same altitude for two hours, not three.
Also in its latest notice, Boeing recommends that pilots, during the descent for landing, reduce engine power to full idle for at least 30 seconds. By reducing fuel flow, engine oil heat can melt any ice that may have accumulated.
The FAA, as it did in September, is likely to make Boeing's latest recommendations mandatory.
The 777 has never had a fatal crash since it entered service with United Airlines in 1995. But the Delta and British Airways incidents have given safety experts cause for concern, in large part because they are apparently dealing with a previously unknown phenomenon.
The British Airways crash occurred Jan. 17, 2008, as the 777-200ER, with 152 passengers and crew members, approached Heathrow after a flight from Beijing. Both engines failed to respond to autopilot commands for thrust as the plane approached the airport.
It turned into one of the most puzzling aviation accidents in modern times. The plane was badly damaged but was mostly intact, so investigators had all the physical evidence in hand to look for clues. But one thing was missing – the ice. The key piece of evidence had literally melted away.
Investigators now believe the problem is with the fuel-oil heat exchanger system on the Trent 777 engine.
Boeing engineers, according to Flight International, have determined by working in the laboratory that the heat generated by the Rolls-Royce fuel-oil heat exchanger is not adequate to prevent moisture in the fuel from freezing. When that happens, ice can form that blocks fuel to the exchanger, "starving the engines,'' according to the magazine.
The General Electric and Pratt engines on the 777 have a different fuel system architecture.
"Based on our knowledge of the system configurations, scenario studies and laboratory test results, we do not believe that immediate action is necessary or warranted for 777s powered by other engine types or non-777 airframes regardless of engine type,'' the Boeing letter sent to 777 operators last week states, according to Flight International.
============================================
Still no information on where the "water" for the ice came from.
Still no information on the process whereby the ice formed and acted so regularly on two separate systems
Still no scientific/engineering explanations and new rules to cover ALL aircraft and ALL engine installations.
--------------------------------------
I have copied the piece below ;
Boeing issues warning to 777 operators
Below is a story I just filed, following up on the British Airways crash at Heathrow a year ago.
BY James Wallace
P-I aerospace reporter
A Delta Airlines 777-200ER was flying from Shanghai, China, to Atlanta last November when its right engine suddenly lost thrust while the plane was cruising at 39,000 feet over Montana.
The pilots followed flight manual procedures and descended to 31,000 feet, where the Rolls-Royce engine recovered and responded normally. The flight, with 15 crew members and 232 passengers, continued to Atlanta and landed safely.
That incident would likely not have gotten much attention had the same kind of Boeing jet, with Rolls-Royce engines, not lost all power in both engines just before landing at London's Heathrow earlier in the year. The British Airways 777 crash-landed short of the runway. Several passengers were injured, but none seriously.
Safety experts eventually decided that the British Airways jet, also on a flight from China, had flown through unusually cold weather at cruise altitude and ice apparently formed in part of the engine and blocked the fuel flow.
On Thursday, Boeing sent a notice to all operators of its 777s with Trent engines made by Rolls-Royce, advising them that it now believes the Delta and British Airways incidents appear to have been caused by the same thing – ice blocking the fuel path.
A Boeing spokesman said Tuesday the "all operators" notice contains a series of precautionary measures that pilots should take during flight to lessen the chance ice could cause a sudden loss of engine power.
Eventually, the spokesman said, the FAA can be expected to order a "permanent fix.'' That would likely mean a redesign of part of the Trent 777 engine.
Boeing would not release a copy of the letter it sent last week. The spokesman said it is not a public document. But the industry magazine Flight International obtained a copy and said the Boeing letter describes the Delta and British Airways incidents as likely being caused by "similar factors.''
More than 700 Boeing 777s, a widebody jet that typically carries from 300 to 360 passengers, depending on the model, are in service with airlines around the world. About 30 percent have Trent engines.
General Electric and Pratt & Whitney also make engines for the 777, but those have a different design than the Trent engine from Rolls-Royce and are not thought to be susceptible to the ice problem. The newest 777s built by Boeing, the best-selling 777-300ER and the ultra-long-range 777-200LR, are only powered with GE engines.
In September, the Federal Aviation Administration issued a formal airworthiness directive that required changes in the way ground crews prepare 777s with Trent engines and how pilots fly them in extreme cold weather in response to what investigators found in studying the British Airways crash in January. Shortly before the FAA issued its warning, Boeing had sent out an "all operators" notice with a series of recommendations developed to prevent a similar problem on its 777s with Trent engines.
Boeing recommended, for example, that pilots rev their engines when the fuel temperature falls to 14 degrees Fahrenheit. That would conceivably dislodge any ice that might be in the fuel line.
Another procedure recommended by Boeing, and ordered by the FAA, called for the crew to advance the engine throttles to maximum thrust for 10 seconds before descending on flights that have maintained the same altitude for at least three hours, if the fuel temperature is below 14 degrees.
Those procedures have been revised in the Boeing bulletin sent last week, following the Delta incident.
Boeing now recommends that pilots advance engine throttles to maximum thrust before descending on flights that have maintained the same altitude for two hours, not three.
Also in its latest notice, Boeing recommends that pilots, during the descent for landing, reduce engine power to full idle for at least 30 seconds. By reducing fuel flow, engine oil heat can melt any ice that may have accumulated.
The FAA, as it did in September, is likely to make Boeing's latest recommendations mandatory.
The 777 has never had a fatal crash since it entered service with United Airlines in 1995. But the Delta and British Airways incidents have given safety experts cause for concern, in large part because they are apparently dealing with a previously unknown phenomenon.
The British Airways crash occurred Jan. 17, 2008, as the 777-200ER, with 152 passengers and crew members, approached Heathrow after a flight from Beijing. Both engines failed to respond to autopilot commands for thrust as the plane approached the airport.
It turned into one of the most puzzling aviation accidents in modern times. The plane was badly damaged but was mostly intact, so investigators had all the physical evidence in hand to look for clues. But one thing was missing – the ice. The key piece of evidence had literally melted away.
Investigators now believe the problem is with the fuel-oil heat exchanger system on the Trent 777 engine.
Boeing engineers, according to Flight International, have determined by working in the laboratory that the heat generated by the Rolls-Royce fuel-oil heat exchanger is not adequate to prevent moisture in the fuel from freezing. When that happens, ice can form that blocks fuel to the exchanger, "starving the engines,'' according to the magazine.
The General Electric and Pratt engines on the 777 have a different fuel system architecture.
"Based on our knowledge of the system configurations, scenario studies and laboratory test results, we do not believe that immediate action is necessary or warranted for 777s powered by other engine types or non-777 airframes regardless of engine type,'' the Boeing letter sent to 777 operators last week states, according to Flight International.
============================================