BA038 (B777) Thread
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Simple answer NO! BA038 was brought down due to ICE in the fuel system. Nothing more nothing less.
Must be great to be so sure in your own mind - do you work for London Airways (BA)
Must be great to be so sure in your own mind - do you work for London Airways (BA)
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Draughtsman, its not about being clear in ones mind, just read the AAIB report. Just they can't fathom were the water came from. Of course the answer is sure to be revealed in the near future.
I like your continual reference to London AIrways, maybe this should be a new thread. Is BA entitled to continue using British in their name when they have pulled out of all regional bases?
I guess you work for them out of GLA, sad day for you all. Lets hope your MP Sheridan and his motion in Parliament brings about a U turn.
Back on thread, ice brought down BA038, the Qantas flight cause is as yet unknown and totally unconnected.
I like your continual reference to London AIrways, maybe this should be a new thread. Is BA entitled to continue using British in their name when they have pulled out of all regional bases?
I guess you work for them out of GLA, sad day for you all. Lets hope your MP Sheridan and his motion in Parliament brings about a U turn.
Back on thread, ice brought down BA038, the Qantas flight cause is as yet unknown and totally unconnected.
Winter is upon us, so maybe we will see a repetition of BA 038. But then, maybe not. I have flown BA038's profile before without mishap, so why did that accident happen just once?
I do not support the fuel icing scenario. I reaffirm my hypothesis that on BA038's flight the fuel uplifted in Beijing had an unusually high gas content. This excess gas became trapped in the suction feed pickup in the wing tanks during flight, was pressurised in the descent (above normal levels) and was later injected into the fuel manifold at low altitude, as the trapped gas exceeded LP pump output pressure. The ejected gas restricted fuel flow to both engines (almost) simultaneously.
I do not support the fuel icing scenario. I reaffirm my hypothesis that on BA038's flight the fuel uplifted in Beijing had an unusually high gas content. This excess gas became trapped in the suction feed pickup in the wing tanks during flight, was pressurised in the descent (above normal levels) and was later injected into the fuel manifold at low altitude, as the trapped gas exceeded LP pump output pressure. The ejected gas restricted fuel flow to both engines (almost) simultaneously.
On one of my infrequent visits to Heathrow last week, I saw what I presume is G-YMMM sitting behind screens not far from its original location on the threshold of 27L.
Can someone tell me why the fin has been removed? A source of spare parts or an obstruction issue?
Can someone tell me why the fin has been removed? A source of spare parts or an obstruction issue?
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I can think of 2 better reasons. Firstly it was a gigantic vertical reminder of the event to those not fortunate enough to be armchair theorists on PPRuNe, secondly in high winds the ac was getting blown about.
Usual disclaimers apply!
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Can someone tell me why the fin has been removed? A source of spare parts or an obstruction issue?
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Trent Differences
It is my understanding that one of the main differences between the Trent engine installation and others is the design of the FOHE and the position it is plumbed on the trent. Perhaps one of our engineering buddies can confirm what the difference is.
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It is my understanding that one of the main differences between the Trent engine installation and others is the design of the FOHE and the position it is plumbed on the trent.
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I'm still very unhappy with all the findings so far and have little confidence in the ice theory.
This feeling will remain until a fully rigged 777 can be sat in a cold store to exactly similate the flight and bring about the same engine problems a number of times just like any other proper scientific experiment - demonstrable by REPEATABLE experiment.
Until then I shall habour deep suspicions that some dark conflict lies buried in the software with sharp teeth waiting to bite some other poor souls when they least expect it.
This feeling will remain until a fully rigged 777 can be sat in a cold store to exactly similate the flight and bring about the same engine problems a number of times just like any other proper scientific experiment - demonstrable by REPEATABLE experiment.
Until then I shall habour deep suspicions that some dark conflict lies buried in the software with sharp teeth waiting to bite some other poor souls when they least expect it.
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Until then I shall habour deep suspicions that some dark conflict lies buried in the software with sharp teeth waiting to bite some other poor souls when they least expect it.
You believe a software problem caused cavitation in the fuel pumps?
and what stopped the engines spooling up when the pilots advanced the throttles, isn't it a mechanical linkage in the 777?
The Fuel Metering Valves Opened Fully
I've read all the previous 2012 posts. Unless I missed something, it has been conclusively shown that the fuel metering valves moved to the full open position but there was no fuel to move through them. Since the valves opened, how could it be a software problem? The system responded to the movement of the throttles. The engines failed because of a scarcity of burnable materials to pass through that system. 
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This accident will eventually fall into the same category as the 747
centre wing tank saga. An accident or two followed by speculation
and investigation over many years. There is obviously a design
fault that could recur. But economic expediency by airlines, boeing
and the engine manufacturers means we all take a calculated risk
until the real problem is fixed. My bet is a small mod will be made
to the fuel system, a proceedure change to fuel management etc.
Just as the 747 problem unfolded, they will not acknowledge a
known design fault but will piecemeal create a fix. Why did they
change the centre wing pumps on the 747, why have they built
a nitrogen enrichment system into the latest 747s centre tank.
Different technically, but identical legally. I guess its all part
of human progress, we learn as we evolve, build technology.
centre wing tank saga. An accident or two followed by speculation
and investigation over many years. There is obviously a design
fault that could recur. But economic expediency by airlines, boeing
and the engine manufacturers means we all take a calculated risk
until the real problem is fixed. My bet is a small mod will be made
to the fuel system, a proceedure change to fuel management etc.
Just as the 747 problem unfolded, they will not acknowledge a
known design fault but will piecemeal create a fix. Why did they
change the centre wing pumps on the 747, why have they built
a nitrogen enrichment system into the latest 747s centre tank.
Different technically, but identical legally. I guess its all part
of human progress, we learn as we evolve, build technology.
Quote from Swedish Steve:
On the Trent, the Fuel passes through the FOHE first when it enters the engine. So there is a chance that any ice could block the passages in the heat exchanger. In the GE the fuel goes through the pumps first, so there is good chance that any ice will be broken up in the pump.
[Unquote]
If memory serves, that's news on this thread. If relevant, would it be practicable to re-position the FOHE, Steve? If so, would you expect the mod to be in the pipeline already (pun not intended).
Quote from Phlap1:
Just as the 747 problem unfolded, they will not acknowledge a known design fault but will piecemeal create a fix.
[Unquote]
In the event of that being necessary, let's hope they don't hang about too long in an effort to avoid it being too obvious to potential litigants. If they did, they could end up wasting one of the luckiest breaks in aviation history.
Quote from Smilin Ed:
...it has been conclusively shown that the fuel metering valves moved to the full open position but there was no fuel to move through them. Since the valves opened, how could it be a software problem?
[Unquote]
Looking at hypothetical software problems, could the fact that the position sensors indicated and recorded the valves fully open not be part of it?
Quote from Smilin Ed:
...the fuel metering valves moved to the full open position but there was no fuel to move through them.
[Unquote]
Considering a given engine: if the valve was indeed fully open, there was certainly a flow restriction elsewhere, as you say. Was that due to a foreign-object blockage (ice, for example), a loss of pressure (and/or suction) to shift it through, or the anomalous closure of another valve?
Quote from Smilin Ed:
I've read all the previous 2012 posts. Unless I missed something...
[Unquote]
Well... There's a thought.
On the Trent, the Fuel passes through the FOHE first when it enters the engine. So there is a chance that any ice could block the passages in the heat exchanger. In the GE the fuel goes through the pumps first, so there is good chance that any ice will be broken up in the pump.
[Unquote]
If memory serves, that's news on this thread. If relevant, would it be practicable to re-position the FOHE, Steve? If so, would you expect the mod to be in the pipeline already (pun not intended).
Quote from Phlap1:
Just as the 747 problem unfolded, they will not acknowledge a known design fault but will piecemeal create a fix.
[Unquote]
In the event of that being necessary, let's hope they don't hang about too long in an effort to avoid it being too obvious to potential litigants. If they did, they could end up wasting one of the luckiest breaks in aviation history.
Quote from Smilin Ed:
...it has been conclusively shown that the fuel metering valves moved to the full open position but there was no fuel to move through them. Since the valves opened, how could it be a software problem?
[Unquote]
Looking at hypothetical software problems, could the fact that the position sensors indicated and recorded the valves fully open not be part of it?
Quote from Smilin Ed:
...the fuel metering valves moved to the full open position but there was no fuel to move through them.
[Unquote]
Considering a given engine: if the valve was indeed fully open, there was certainly a flow restriction elsewhere, as you say. Was that due to a foreign-object blockage (ice, for example), a loss of pressure (and/or suction) to shift it through, or the anomalous closure of another valve?
Quote from Smilin Ed:
I've read all the previous 2012 posts. Unless I missed something...
[Unquote]
Well... There's a thought.
Quote from Chris Scott
Wouldn't the software which moves the fuel metering valves be different from the flight recorder software which monitors the valve position? Surely they are independent. Is there someone here who can answer that?
Quote from Smilin Ed:
...it has been conclusively shown that the fuel metering valves moved to the full open position but there was no fuel to move through them. Since the valves opened, how could it be a software problem?
[Unquote]
Looking at hypothetical software problems, could the fact that the position sensors indicated and recorded the valves fully open not be part of it?
...it has been conclusively shown that the fuel metering valves moved to the full open position but there was no fuel to move through them. Since the valves opened, how could it be a software problem?
[Unquote]
Looking at hypothetical software problems, could the fact that the position sensors indicated and recorded the valves fully open not be part of it?
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I believe Swedish Steve may have stumbled on the answer.
If the fuel flow through the FOHE became more & more partially blocked throughout this long cold flt,then a continuous descent at low pwr would not have changed anything, until more fuel was required at engine spool up at 1000ft. Then the ice would be sucked further into the FOHE causing a blockage, it would have melted with time but time was not what they had.
This in fact could explain the cavitation damage of the pumps, it had been happening to a lesser scale on other flts but the temporary "hicups" had not been noticed.
This had been a long very cold flt, with maybe a marginal fuel spec.
If the fuel flow through the FOHE became more & more partially blocked throughout this long cold flt,then a continuous descent at low pwr would not have changed anything, until more fuel was required at engine spool up at 1000ft. Then the ice would be sucked further into the FOHE causing a blockage, it would have melted with time but time was not what they had.
This in fact could explain the cavitation damage of the pumps, it had been happening to a lesser scale on other flts but the temporary "hicups" had not been noticed.
This had been a long very cold flt, with maybe a marginal fuel spec.
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It seems incredible to me that where there has been an obvious fault in an aircraft type whole fleets have been grounded until the problem is fixed or checked. Here we have a heavy, sophisticated aircraft that crashes for no expiclable reason and it just keeps on flying until, perhaps, it happens again! Can you imagine what must go through the mind of every 777 aircrew on finals? Surely the aviation authorities can do better than this or do we have the dreaded economic considerations outweighing the value of human lives?
Being inherently distrustful of computers I will always suspect 'wonky' software.
But just in case, why did we as Pilots accept losing total control of the fuel heat ?
From the 75 onward on Boeings (don't know about Airbus) not only do we have no control of such, but not even a way of monitoring its activation.
Bring back fuel heat switches !!
But just in case, why did we as Pilots accept losing total control of the fuel heat ?
From the 75 onward on Boeings (don't know about Airbus) not only do we have no control of such, but not even a way of monitoring its activation.
Bring back fuel heat switches !!
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I do NOT want to be too dogmatic as it has been so long since this (and the previous) thread started to remember all the details, let alone theories.
However, If I remember correctly, the engine thrust was increased and decreased several times during descent without problems. In addition, the actual problems occured at slightly different times but ended up at almost exactly the same amout of (lack of) thrust. It seems almost impossible that the conditions in each tank were such that the "icing" (OR WHATEVER) acted at different times but ended up with the almost exactly the same results.
People grasped at the cavitation damage because IF (AND IT IS A BIG IF) the cavitation meant that pumps would work at x% capacity and this would show why the thrust fell to the levels that actually concerned. HOWEVER, as no definitive statements accompanied the last AAIB report it is questionable as to whether this is possible, or not.
It seems odd that nothing has arisen in the more than 9 months since the accident (and especially since the Northern Hemisphere Winter is near enough here) to actually guide airlines in possible ways to minimise a re-occurance of such an incident.
(Sorry for the CAPITALS - but people do have a tendency to go off on tangents if you don't spell things out).
.
However, If I remember correctly, the engine thrust was increased and decreased several times during descent without problems. In addition, the actual problems occured at slightly different times but ended up at almost exactly the same amout of (lack of) thrust. It seems almost impossible that the conditions in each tank were such that the "icing" (OR WHATEVER) acted at different times but ended up with the almost exactly the same results.
People grasped at the cavitation damage because IF (AND IT IS A BIG IF) the cavitation meant that pumps would work at x% capacity and this would show why the thrust fell to the levels that actually concerned. HOWEVER, as no definitive statements accompanied the last AAIB report it is questionable as to whether this is possible, or not.
It seems odd that nothing has arisen in the more than 9 months since the accident (and especially since the Northern Hemisphere Winter is near enough here) to actually guide airlines in possible ways to minimise a re-occurance of such an incident.
(Sorry for the CAPITALS - but people do have a tendency to go off on tangents if you don't spell things out).
.