BA038 (B777) Thread
Approaching the issue from another angle, i would go for a combination of system selections (including interaction or possible interference with other systems) and characteristics.
A question that comes to mind would then be: which (sub) system components could (due to a yet undefined fault) migrate from commanded position without generating a fault indication to the flight crew but result in reduced fuel flow and cause engine rollback?
A question that comes to mind would then be: which (sub) system components could (due to a yet undefined fault) migrate from commanded position without generating a fault indication to the flight crew but result in reduced fuel flow and cause engine rollback?
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Well here's a potentially new twist, as I haven't read all the posts maybe it's been mentioned B4.
Mate of mine who flys the 777 made the same arrival into Heathrow from LAM a couple of hours B4 the stricken A/C. Now, aficionados correct me if I'm wrong, the 777 has both auto engine A/ice and auto Airframe A/ice systems. My mate had obviously seen operation of the engine a\ice system many times but never the auto airframe a\ice. That morning, apparently, the icing in the LAM hold was so severe that for the first time that he had seen the auto airframe a\ice system operated. He was so surprised that the fact was mentioned to ATC and later the ATIS was updated to mention severe icing.
He also mentioned that those huge Trents can have a problem with ''core icing'' but didn't elucidate on the matter!
Could severe icing during potentially a textbook CDA approach from the hold with the throttles almost closed right down to 600' produce a lack of response from the Trents as seen on the BA A/C?
I commend this question to the house!
Take care
Mate of mine who flys the 777 made the same arrival into Heathrow from LAM a couple of hours B4 the stricken A/C. Now, aficionados correct me if I'm wrong, the 777 has both auto engine A/ice and auto Airframe A/ice systems. My mate had obviously seen operation of the engine a\ice system many times but never the auto airframe a\ice. That morning, apparently, the icing in the LAM hold was so severe that for the first time that he had seen the auto airframe a\ice system operated. He was so surprised that the fact was mentioned to ATC and later the ATIS was updated to mention severe icing.
He also mentioned that those huge Trents can have a problem with ''core icing'' but didn't elucidate on the matter!
Could severe icing during potentially a textbook CDA approach from the hold with the throttles almost closed right down to 600' produce a lack of response from the Trents as seen on the BA A/C?
I commend this question to the house!
Take care
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mark exclamation,
I don't know if there's really a new twist.
Core icing in high-bypass turbofan engines has lately been the subject of some discussion, such as this PPRuNe thread, discussing a Wall Street Journal article, as well as a small article in the German Spiegel weekly magazine. But what I've read, the symptoms are usually flameouts, almost always with a quick relight.
From what I gather one of the problems is that core-icing at cruise altitudes has for a long time been thought impossible, but has recently been established as a likely cause for flameouts at altitude. The icing is apparently caused by very small ice particles and/or supercooled droplets.
This video mentions that drops above a certain size are normally deflected outward by the fan blades and do not enter the engine core. The very small size of the droplets/crystals in question may facilitate their entering the compressor and accumulating there under certain conditions, which, as of now, seem to be unknown. When larger chunks of that ice break free they may melt in the combustion chamber (or the later, hotter compressor stages) and cause a flameout, or even damage turbine blades.
Another thing that's peculiar about this form of ice accretion in the engine is that it may happen in conditions, under which the airframe does not suffer from ice accumulation.
To get back to the topic, in the case of BA038 there was no flameout, but "only" a failure to sustain a higher than "somewhat above flight idle" thrust. I'm still uncertain if there may be a connection. It seems unlikely, but then again, so does every possible explanation so far.
Bernd
I don't know if there's really a new twist.
Core icing in high-bypass turbofan engines has lately been the subject of some discussion, such as this PPRuNe thread, discussing a Wall Street Journal article, as well as a small article in the German Spiegel weekly magazine. But what I've read, the symptoms are usually flameouts, almost always with a quick relight.
From what I gather one of the problems is that core-icing at cruise altitudes has for a long time been thought impossible, but has recently been established as a likely cause for flameouts at altitude. The icing is apparently caused by very small ice particles and/or supercooled droplets.
This video mentions that drops above a certain size are normally deflected outward by the fan blades and do not enter the engine core. The very small size of the droplets/crystals in question may facilitate their entering the compressor and accumulating there under certain conditions, which, as of now, seem to be unknown. When larger chunks of that ice break free they may melt in the combustion chamber (or the later, hotter compressor stages) and cause a flameout, or even damage turbine blades.
Another thing that's peculiar about this form of ice accretion in the engine is that it may happen in conditions, under which the airframe does not suffer from ice accumulation.
To get back to the topic, in the case of BA038 there was no flameout, but "only" a failure to sustain a higher than "somewhat above flight idle" thrust. I'm still uncertain if there may be a connection. It seems unlikely, but then again, so does every possible explanation so far.
Bernd
Controversial, moi?
....a textbook CDA approach from the hold with the throttles almost closed right down to 600'....
Core icing is a known issue in certain defined conditions on the ground with Trent B777 engines and we have procedures to follow when it is a possibility.
In the air we have no knowledge or requirement for any procedures relating to core icing. As has been mentioned, it has now been discovered that it is possible in certain conditions but we have received no official communication on the subject.
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That bloody Carb Ice
ExclamationMark,
.......As a scenario it fits.
As I read it , core Icing when taxying in foggy conditions did not always lead to flameouts while running at low speed.If the engines had got any sort of ice in them you can bet your boots they would not be able to run properly or efficiently.Acceleration from idle revs would be bound to be somewhat reduced
.......This is the first I heard about severe icing in the LAM holding pattern before Final approach. Who says this? Whats his qualification to make the observation? Is it confirmable.Surely the AAIB interrogation would would have shown this up early on.
.......As a scenario it fits.
As I read it , core Icing when taxying in foggy conditions did not always lead to flameouts while running at low speed.If the engines had got any sort of ice in them you can bet your boots they would not be able to run properly or efficiently.Acceleration from idle revs would be bound to be somewhat reduced
.......This is the first I heard about severe icing in the LAM holding pattern before Final approach. Who says this? Whats his qualification to make the observation? Is it confirmable.Surely the AAIB interrogation would would have shown this up early on.
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Looks like the investigation is focusing on slush or ice in the fuel system as the root cause of the problem. Is there a redesign of the oil coolers in the near future?
The article follows....
Re-Evaluating Long, Cold Flights
Crash May Prompt
New Safety Rules
For Boeing's 777
By ANDY PASZTOR
April 25, 2008; Page B2
Prompted by the crash landing of a British Airways jetliner near London earlier this year, air-safety investigators are moving to recommend heightened cold-temperature safeguards for Boeing 777 aircraft flying long polar routes, according to people familiar with the details.
In a few weeks, these people said, investigators are likely to warn operators and pilots of Boeing Co.'s long-haul 777 models to take extra precautions when monitoring fuel temperatures on a growing number of extended flights over the North Pole. If temperatures creep too low, pilots can descend to warmer air or speed up to increase the heat generated by air friction against the plane's skin.
• The News: Investigators are moving to recommend cold-temperature safeguards for Boeing 777s on polar routes.
• Background: Slush or ice build-up in a British Airways 777 fuel system may have led to a Jan. 17 accident at London's Heathrow Airport.
• Outlook: Operational warnings or recommendations could come in the weeks ahead.
"It's a possibility" that such operational warnings or recommendations will be issued within the next few weeks, said David King, chief investigator for Britain's Air Accidents Investigation Branch, or AAIB, which is in charge of the probe. In an interview Thursday, Mr. King said safety experts are "looking at a wide range of things" affecting fuel management and environmental conditions on polar flights.
Though some are arguing for design changes, a team of U.S. and British investigators hasn't reached a consensus on whether to recommend modifications to make the fuel systems on some Boeing 777s more resistant to unusually frigid conditions. Such a move could be seen as a public relations blow to Boeing and Rolls-Royce PLC, which supplied the engines and related hardware on the accident aircraft.
A spokesman for Rolls-Royce, which has declined to comment on the accident or the status of the investigation, said Thursday that the company "remains committed to working with the AAIB and Boeing to establish the root cause of the event" and is cooperating with other participants. British Airways, Boeing, the Federal Aviation Administration and the U.S. National Transportation Safety Board all declined to comment.
Investigators suspect that the Jan. 17 accident at London's Heathrow Airport occurred because slush or ice built up in part of the fuel system of the British Airways 777 during a long polar flight from China in unusually cold outside temperatures. As the widebody jet descended toward London, remnants of icy particles likely clogged a portion of its fuel system, starving the Rolls-Royce engines and providing minimal power despite pilot commands for more thrust.
The plane slammed down 300 yards short of the runway. All 152 aboard survived. The probe has been closely watched partly because the root cause remains elusive and complex. The accident has garnered attention because it is believed to be the first such incident involving both of a plane's engines while maneuvering at such a low altitude in more than 14 million 777 flight-hours since 1995.
Some U.S. experts have advocated changing the design of the oil cooler used on some versions of the Boeing 777 powered by Rolls-Royce engines, arguing that that is where ice or slush may have blocked proper fuel flow. Taking the unusual step of disclosing details of a pending investigations, Mr. King said: "I don't believe there is anyone on my team that would argue for a redesign" of the oil cooler.
Investigators have ruled out engine or computer malfunctions, and pilot slip-ups, as well as systemic problems with fuel-tank design, fuel pumps or temperature sensors, according to people familiar with the details.
Write to Andy Pasztor at [email protected]
The article follows....
Re-Evaluating Long, Cold Flights
Crash May Prompt
New Safety Rules
For Boeing's 777
By ANDY PASZTOR
April 25, 2008; Page B2
Prompted by the crash landing of a British Airways jetliner near London earlier this year, air-safety investigators are moving to recommend heightened cold-temperature safeguards for Boeing 777 aircraft flying long polar routes, according to people familiar with the details.
In a few weeks, these people said, investigators are likely to warn operators and pilots of Boeing Co.'s long-haul 777 models to take extra precautions when monitoring fuel temperatures on a growing number of extended flights over the North Pole. If temperatures creep too low, pilots can descend to warmer air or speed up to increase the heat generated by air friction against the plane's skin.
• The News: Investigators are moving to recommend cold-temperature safeguards for Boeing 777s on polar routes.
• Background: Slush or ice build-up in a British Airways 777 fuel system may have led to a Jan. 17 accident at London's Heathrow Airport.
• Outlook: Operational warnings or recommendations could come in the weeks ahead.
"It's a possibility" that such operational warnings or recommendations will be issued within the next few weeks, said David King, chief investigator for Britain's Air Accidents Investigation Branch, or AAIB, which is in charge of the probe. In an interview Thursday, Mr. King said safety experts are "looking at a wide range of things" affecting fuel management and environmental conditions on polar flights.
Though some are arguing for design changes, a team of U.S. and British investigators hasn't reached a consensus on whether to recommend modifications to make the fuel systems on some Boeing 777s more resistant to unusually frigid conditions. Such a move could be seen as a public relations blow to Boeing and Rolls-Royce PLC, which supplied the engines and related hardware on the accident aircraft.
A spokesman for Rolls-Royce, which has declined to comment on the accident or the status of the investigation, said Thursday that the company "remains committed to working with the AAIB and Boeing to establish the root cause of the event" and is cooperating with other participants. British Airways, Boeing, the Federal Aviation Administration and the U.S. National Transportation Safety Board all declined to comment.
Investigators suspect that the Jan. 17 accident at London's Heathrow Airport occurred because slush or ice built up in part of the fuel system of the British Airways 777 during a long polar flight from China in unusually cold outside temperatures. As the widebody jet descended toward London, remnants of icy particles likely clogged a portion of its fuel system, starving the Rolls-Royce engines and providing minimal power despite pilot commands for more thrust.
The plane slammed down 300 yards short of the runway. All 152 aboard survived. The probe has been closely watched partly because the root cause remains elusive and complex. The accident has garnered attention because it is believed to be the first such incident involving both of a plane's engines while maneuvering at such a low altitude in more than 14 million 777 flight-hours since 1995.
Some U.S. experts have advocated changing the design of the oil cooler used on some versions of the Boeing 777 powered by Rolls-Royce engines, arguing that that is where ice or slush may have blocked proper fuel flow. Taking the unusual step of disclosing details of a pending investigations, Mr. King said: "I don't believe there is anyone on my team that would argue for a redesign" of the oil cooler.
Investigators have ruled out engine or computer malfunctions, and pilot slip-ups, as well as systemic problems with fuel-tank design, fuel pumps or temperature sensors, according to people familiar with the details.
Write to Andy Pasztor at [email protected]
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F111D says in part.....
Quote "Looks like the investigation is focusing on slush or ice in the fuel system as the root cause of the problem. Is there a redesign of the oil coolers in the near future?
The article follows"....End Quote.
Aviate quotes from the said article....
"Taking the unusual step of disclosing details of a pending investigations, Mr. King said: "I don't believe there is anyone on my team that would argue for a redesign" of the oil cooler."
Smoke and mirrors and speculative journalism from Andy Pasztor?
Quote "Looks like the investigation is focusing on slush or ice in the fuel system as the root cause of the problem. Is there a redesign of the oil coolers in the near future?
The article follows"....End Quote.
Aviate quotes from the said article....
"Taking the unusual step of disclosing details of a pending investigations, Mr. King said: "I don't believe there is anyone on my team that would argue for a redesign" of the oil cooler."
Smoke and mirrors and speculative journalism from Andy Pasztor?
Last edited by aviate1138; 25th Apr 2008 at 06:26. Reason: typo
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Perhaps one of the older generation:
Wiki quote "Also developed in 1949 was the Avro Jetliner, and although it never reached production, the term jetliner caught on as a generic term for all passenger jet aircraft"
The only other time I've heard it used is in an Arlo Guthrie song (?).
VnV
Wiki quote "Also developed in 1949 was the Avro Jetliner, and although it never reached production, the term jetliner caught on as a generic term for all passenger jet aircraft"
The only other time I've heard it used is in an Arlo Guthrie song (?).
VnV
The Reverend
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Ater my retirement from a legacy carrier on 747 aircraft equiped with RB211-524 engines, I operated a 747-100F with JT9D engines which had engine de-icing systems providing controlled heating of the fuel when manually activated if the fuel temperature indicator showed fuel temperature at the engine to be 0c or below, or when the fuel icing light illuminated. Heating was limited to a one minute heater operation or two minutes if No.1 tank temeperature was below -40c, for every 30 minute cycle. Kept the flight engineer pretty busy. The fuel heater was situated between the boost and high pressure stages of the engine driven fuel pump and heating was provided by 15th stage bleed air. As far as I know, fuel heating is automatic on all modern high performance powerplants but the problem of fuel icing is old hat and well known.
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Operational changes ahead ... and redesigns!
Warning: I'm non-professional; not crew, not engineer - just scientist guest and thanks.
Hello again,
Referring to the Andy Pasztor article in WSJ, post 908, and my post 751, 'What if no proof of cause - what does the AAIB do?' when I wrote:
"I've been wondering what would the AAIB do if they could not demonstrate to a high probability the cause of the accident. If, for example, the AAIB were convinced, but could not prove, that the fuel quality had been lowered by cold-soaking for an extended period of time and that this had lead, in some unknown way, to the accident, what would they do?
Presumably the AAIB would operate on the precautionary principle.
Might they:
1) Recommend/demand/regulate the avoidance of extended flight-time in very cold air masses;
2) Demand that if aircraft had experienced extended flight-time in very cold air masses then they must
loiter for some time in warmer air before descending for landing?"
I'm going to assume David King of AAIB is fairly certain that fuel degradation due to cold-soaking for extended periods of time is the root cause of the accident and that his quotes in the above article are accurate.
Then David King would seem to be trying to gather support in advance for a set of operational recommendations that he knows, or suspects, the industry will resist. Presumably he is not acting alone and, hopefully, will already have significant political support, albeit presently hidden below
the palisade.
Fact is that demonstrating by experimentation that fuel degradation was the result of operating conditions will take years. In the meantime, the industry should soberly reflect on the continuing lives of 152 souls and consider the accident a clear warning that, as has been the case so many times previously, and in most arenas of human endevour, we don't know it all!
So I think that in a few weeks there will be recommendations from the AAIB (and others) that operations in 'polar regions' must change.
And my predictions for the years ahead:
1) Fuel stratification will, by experimentation, be shown to be the direct cause of the accident (see post 241).
2) Aircraft will have systems (probably laser based) to detect ice/sludge etc. in fuel tanks. These may be retro-fitted to aircraft that fly ETOPS.
3) New fuel heating systems will be mandated for all new aircraft designs, that is, the fuel will be heated in the tanks and will not rely any longer on the downstream heat exchange systems returning the fuel to a non-degraded state.
Regards, Tanimbar
Hello again,
Referring to the Andy Pasztor article in WSJ, post 908, and my post 751, 'What if no proof of cause - what does the AAIB do?' when I wrote:
"I've been wondering what would the AAIB do if they could not demonstrate to a high probability the cause of the accident. If, for example, the AAIB were convinced, but could not prove, that the fuel quality had been lowered by cold-soaking for an extended period of time and that this had lead, in some unknown way, to the accident, what would they do?
Presumably the AAIB would operate on the precautionary principle.
Might they:
1) Recommend/demand/regulate the avoidance of extended flight-time in very cold air masses;
2) Demand that if aircraft had experienced extended flight-time in very cold air masses then they must
loiter for some time in warmer air before descending for landing?"
I'm going to assume David King of AAIB is fairly certain that fuel degradation due to cold-soaking for extended periods of time is the root cause of the accident and that his quotes in the above article are accurate.
Then David King would seem to be trying to gather support in advance for a set of operational recommendations that he knows, or suspects, the industry will resist. Presumably he is not acting alone and, hopefully, will already have significant political support, albeit presently hidden below
the palisade.
Fact is that demonstrating by experimentation that fuel degradation was the result of operating conditions will take years. In the meantime, the industry should soberly reflect on the continuing lives of 152 souls and consider the accident a clear warning that, as has been the case so many times previously, and in most arenas of human endevour, we don't know it all!
So I think that in a few weeks there will be recommendations from the AAIB (and others) that operations in 'polar regions' must change.
And my predictions for the years ahead:
1) Fuel stratification will, by experimentation, be shown to be the direct cause of the accident (see post 241).
2) Aircraft will have systems (probably laser based) to detect ice/sludge etc. in fuel tanks. These may be retro-fitted to aircraft that fly ETOPS.
3) New fuel heating systems will be mandated for all new aircraft designs, that is, the fuel will be heated in the tanks and will not rely any longer on the downstream heat exchange systems returning the fuel to a non-degraded state.
Regards, Tanimbar
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Smoke and mirrors and speculative journalism from Andy Pasztor?
Obvious contradiction with initial report where fuel quality was just fine.
Any Fuel Pressure Pump EICAS message type ?
Any Fuel Filter Clog EICAS message type ?
What about an AAIB official update ... is it better to first advise Mr Pasztor ?
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Yes - still
It takes a while to conjure up the necessary technical gobbledegook type spin to pad out a 1000 page report document which finally comes to the conclusion it was outa gas. 
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Core Icing
Core icing might expaln my previously expounded theory about rotating stall (which could be caused by failure of the airflow control system OR restriction into the IP compressor).
The theory on the part of the floor at Lloyd's (as of last week) is that it ain't the fuel that caused it, it's "RF interference". The theory goes that after George Brown was dropped off at Heathrow, his driver, or some other entity either deliberately or accidentally forgot to switch off their "jammer" and that the aforesaid vehicle on it's return journey may have gotten within "range" of the affected B777 and caused the mischief.
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I have a feeling that if there was any genuine weight to that theory then that wouldn't be the case. As it appears, the theory has only hung around as long as it has due to an uncorroborated posting on a US pilot board with absolutely nothing backing it up.
For random background, it was David King who oversaw putting the Lockerbie 747 back together and proved exactly where the bomb was placed, so it's not like he's unknown in the US, nor is he politically tied, having been the head honcho at the AAIB since long before the current administration (to use US terminology) was in charge. From what I've read the NTSB hold him in *extremely* high esteem.
For random background, it was David King who oversaw putting the Lockerbie 747 back together and proved exactly where the bomb was placed, so it's not like he's unknown in the US, nor is he politically tied, having been the head honcho at the AAIB since long before the current administration (to use US terminology) was in charge. From what I've read the NTSB hold him in *extremely* high esteem.
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Shall we speculate or shall we challenge?
It would seem to me, in this instance, we should take action to invigorate the AIRB and their associates in America, Boeing and RR to come clean with it. This has gone on too long and our fellow airmen and the people they are charged with carrying are either too much at risk or not to be bothered. Make your thougts known to those who might encourage the blokes along.
Those of us long retired can be a nusiance among them. On the other hand, if the gentlemen on the line begin to growl, maybe ...........
I have sent a number of messages to the US FAA, the NTSB and Boeing. Amazingly, in three weeks, not one of them has responded. The world wonders.............................
Tom
Those of us long retired can be a nusiance among them. On the other hand, if the gentlemen on the line begin to growl, maybe ...........
I have sent a number of messages to the US FAA, the NTSB and Boeing. Amazingly, in three weeks, not one of them has responded. The world wonders.............................
Tom
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Didn't all the geopolitical horse trading with that rogue regime of Muamar Ghadaffi make that Lockerbie tragedy seem a bit " convenient " and ' aha-ish "?
The icing and slush scenario is indeed plausible but to have it happened to both engines ( albeit with some seconds of time lag ) was a little bit too coincidental. Was there any indication that the auto engine anti ice had been activated on that BA038 flight?
The icing and slush scenario is indeed plausible but to have it happened to both engines ( albeit with some seconds of time lag ) was a little bit too coincidental. Was there any indication that the auto engine anti ice had been activated on that BA038 flight?