BA038 (B777) Thread
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Now you are doing it.
The 777 has built up a good safety record. The process leading to this failure has only been seen on this flight. Selective emphasis describes this as unique then suggests complacency within the investigation by asking for evidence of uniqueness.
The investigators will obviously look at what was different about this flight. They will also look into all the history - of this aircraft type and of all past accidents - to see whether anything already known about might have contributed here. As the investigation proceeds factual evidence and careful testing will eliminate some possibilities, and may reveal new factors to be considered and eliminated in turn.
This process has to be undertaken by specialists who understand aircraft, who know how accidents happen, and who are as dispassionate as it is possible to be in sometimes harrowing circumstances.
Air travel is as safe as human endeavour can make it - and that is very safe.
And that doesn't sell newspapers.
The 777 has built up a good safety record. The process leading to this failure has only been seen on this flight. Selective emphasis describes this as unique then suggests complacency within the investigation by asking for evidence of uniqueness.
The investigators will obviously look at what was different about this flight. They will also look into all the history - of this aircraft type and of all past accidents - to see whether anything already known about might have contributed here. As the investigation proceeds factual evidence and careful testing will eliminate some possibilities, and may reveal new factors to be considered and eliminated in turn.
This process has to be undertaken by specialists who understand aircraft, who know how accidents happen, and who are as dispassionate as it is possible to be in sometimes harrowing circumstances.
Air travel is as safe as human endeavour can make it - and that is very safe.
And that doesn't sell newspapers.
I understand the investigation process. I am an engineer myself and although I don't work in Aviation the fundamental process is common to any machine / structural investigation.
Please remember I was replying to a previous post.
All I asked was how is it possible to assume that the causal factors surrounding BA038 are UNIQUE to that aircraft and flight? i.e. No implications to other of the type or operator.
If the cause is unknown anything is possible and this may therefore also affect other aircraft of the same type or operator once the cause is known.
Engines do not just Roll Back; Something caused the event to happen. Most of the tabled possibilities are indeed EXTREMELY unlikely but the very fact they have cause one event means that without change a reoccurrence could happen.
If the cause is already known then that opens up other (also unlikely) possibilities.
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I have been informed by a collegue in Flight Safety, who has contacts with the AAIB, that they are currently running with the idea that there was fuel starvation to both engines. It seems that only 10% of the fuel required was making it to the engines causing them to wind down. The problem however is identiying the part of the fuel system at fault.
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RF is certainly a possibility and one that rarely leaves any tangible evidence for investigators to see. Most internal RF will be preventable due to electrical systems and wiring being shielded to prevent leakage affecting a neighbouring system, but external RF is a problem and can affect A/C in a perplexing manor of ways. I believe that it is rare for a fuel system to be compromised by RF as there are mechanical systems as back-up, and I believe there are 2 FCU’s on the aircraft, one for each engine. For both to be affected by RF would be unusual. I dare to speculate that it may just be a fuel flow problem due to contamination of the fuel, most of which was dumped onto the runway post landing! Time will tell.
I have been informed by a collegue in Flight Safety, who has contacts with the AAIB, that they are currently running with the idea that there was fuel starvation to both engines. It seems that only 10% of the fuel required was making it to the engines causing them to wind down. The problem however is identiying the part of the fuel system at fault.
from the AAIB initial report, Feb. 2008:
Data also revealed that the fuel metering valves on both engines correctly moved to the fully open position to schedule an increase in fuel flow. Both fuel metering units were tested and examined, and revealed no pre-existing defects.
Detailed examination of both the left and right engine high pressure fuel pumps revealed signs of abnormal cavitation on the pressure-side bearings and the outlet ports. This could be indicative of either a restriction in the fuel supply to the pumps or excessive aeration of the fuel. The manufacturer assessed both pumps as still being capable of delivering full fuel flow.
Investigations are now underway in an attempt to replicate the damage seen to the engine high pressure fuel pumps, and to match this to the data recorded on the accident flight. In addition, comprehensive examination and analysis is to be conducted on the entire aircraft and engine fuel system; including the modelling of fuel flows taking account of the environmental and aerodynamic effects.
At the risk of getting labelled a spotter I would observe that with any aircraft incident:
1. The mechanical engineer thinks the cause is mechanical failure.
2. The Electrical engineer thinks the problem is electrical.
3. The radio ham thinks it's RF interference.
4. The computer programmer thinks the cause is software problems.
5. The chemist thinks it's the fuel.
.........and so on, as this thread conclusively demonstrates.
To put it another way, everyone examines things through the lens of their own experience.
The trouble is that while I'm sure the speculation is well meaning in most cases, very little of that experience has anything much to do with commercial aviation.
I'd rather wait for the experienced folk at AAIB and Boeing to tell all of us what they believe the probable cause is, because as an engineer who first was responsible for an oil terminal and airport jet fuel handling facility, then spent six years with an airline engineering division, followed by an aerospace/defence outfit, and flies little tiny aircraft, I'm buggered if I know what happened.
1. The mechanical engineer thinks the cause is mechanical failure.
2. The Electrical engineer thinks the problem is electrical.
3. The radio ham thinks it's RF interference.
4. The computer programmer thinks the cause is software problems.
5. The chemist thinks it's the fuel.
.........and so on, as this thread conclusively demonstrates.
To put it another way, everyone examines things through the lens of their own experience.
The trouble is that while I'm sure the speculation is well meaning in most cases, very little of that experience has anything much to do with commercial aviation.
I'd rather wait for the experienced folk at AAIB and Boeing to tell all of us what they believe the probable cause is, because as an engineer who first was responsible for an oil terminal and airport jet fuel handling facility, then spent six years with an airline engineering division, followed by an aerospace/defence outfit, and flies little tiny aircraft, I'm buggered if I know what happened.
Snanceki said:
Possibly because I am guilty of not answering it. An apology and explanation are in order.
Sorry.
Explanation:
I just hate the way some news media capitalise on natural human curiosity by sensationalising matters. They do so, in a subtle way, by using sensationalising words. A hand-made objet d'art can be unique, never to be repeated. Using the Unique word to describe an event is imprecise to say the least. I would grudgingly go along with 'hitherto unique'
If you are objecting to the word Unique, then I am agreeing and reiterating that point, prompted by rather than answering your rhetorical question.
Like you, I can't believe anybody is saying 'We know what caused it, and it can't happen again, so there's no need to publish it.' They wouldn't dare. My take on the silence so far is the investigators - a collective name for members of the AAIB, Boeing, RR, possibly other regulatory bodies and probably several component suppliers - still don't know what happened, so I presume they are still speculating (testing hypotheses). And none of this speculation has resulted in a convincing causal sequence they can publish - yet.
I can see three possible outcomes. The worst outcome is we don't know what happened. The best is we know what happened and we can stop it happening (at least in that way) on future flights. In the middle is we know what happened and the only way we know of stopping it happening again is to not fly.
As somebody said a long time ago, the final report is the one to read.
Sorry again. Please let me plead oversensitivity, caused by excessive exposure to spin and hyperbole.
Maybe I'm being difficult but I don't understand your answer. Maybe you are just reiterating what I said. Maybe not.
Sorry.
Explanation:
I just hate the way some news media capitalise on natural human curiosity by sensationalising matters. They do so, in a subtle way, by using sensationalising words. A hand-made objet d'art can be unique, never to be repeated. Using the Unique word to describe an event is imprecise to say the least. I would grudgingly go along with 'hitherto unique'
If you are objecting to the word Unique, then I am agreeing and reiterating that point, prompted by rather than answering your rhetorical question.
Like you, I can't believe anybody is saying 'We know what caused it, and it can't happen again, so there's no need to publish it.' They wouldn't dare. My take on the silence so far is the investigators - a collective name for members of the AAIB, Boeing, RR, possibly other regulatory bodies and probably several component suppliers - still don't know what happened, so I presume they are still speculating (testing hypotheses). And none of this speculation has resulted in a convincing causal sequence they can publish - yet.
I can see three possible outcomes. The worst outcome is we don't know what happened. The best is we know what happened and we can stop it happening (at least in that way) on future flights. In the middle is we know what happened and the only way we know of stopping it happening again is to not fly.
As somebody said a long time ago, the final report is the one to read.
Sorry again. Please let me plead oversensitivity, caused by excessive exposure to spin and hyperbole.
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I thank my fellow airman of discussion for their endeavored reply's ("RF" theory for BA B-777 #720), .
In long ago past service as a B-742 FE, I recall that every time the lead ground fueller (when in the cockpit) would key his radio phone (to communicate with his fueling partner at the wing), that my automatic pressurization outflow valves would drive closed.
In long ago past service as a B-742 FE, I recall that every time the lead ground fueller (when in the cockpit) would key his radio phone (to communicate with his fueling partner at the wing), that my automatic pressurization outflow valves would drive closed.
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Thanks Rightbase.
Appears we are in the same camp.
However! waiting for the final report would put Forums like this "out of business".
Postulating what might have happened (on inadequate and potentially incorrect information) is surely what Forums like this are all about.
Although trained as an engineering investigator (and therefore trained to have an open mind) I never cease to be amazed by the power of collective thinking and the unusual and sometimes bizarre suggesting that are made. Some are easy to dismiss, others propositions less so and some are definitely feasible.
The main benefit from my perspective is increased understanding of how systems with which an individual is not adequately familiar become clearer.
Whatever the outcome of this investigation the cause is going to be UNUSUAL/UNPRECEDENTED but not UNIQUE.
If its happened once, it can occur again, unless suitable changes take place
Although I appreciate that the AAIB wish to dot the I's and cross the T's before publishing any further report I'm surprised that more "informed" data hasn't hasn't leaked out.
Now in one sense this is exactly as it should be, but with so many interested parties involved and an intact aircraft I find it surprising that (virtually) no recommendations have come from the AAIB impacting other aircraft of the type / operator. This suggests to me that they currently have no recommendation to make.
So either the team has:
1. No idea what caused the accident in which case the extremely improbably theories need to be considered more seriously or
2. The findings are worrying with significant impact to other aircraft / operations (although likelyhood of a repeat is low based on experience to date) and any action must be thoroughly researched and backed up due to implied costs etc. of taking action. ETOPS?
I wonder which is nearer to being correct? I favour option 2.
Either way the situation is IMHO unprecedented!
A no cause identified outcome is IMHO not viable since the aircraft is largely intact.
Interesting.
Appears we are in the same camp.
However! waiting for the final report would put Forums like this "out of business".
Postulating what might have happened (on inadequate and potentially incorrect information) is surely what Forums like this are all about.
Although trained as an engineering investigator (and therefore trained to have an open mind) I never cease to be amazed by the power of collective thinking and the unusual and sometimes bizarre suggesting that are made. Some are easy to dismiss, others propositions less so and some are definitely feasible.
The main benefit from my perspective is increased understanding of how systems with which an individual is not adequately familiar become clearer.
Whatever the outcome of this investigation the cause is going to be UNUSUAL/UNPRECEDENTED but not UNIQUE.
If its happened once, it can occur again, unless suitable changes take place
Although I appreciate that the AAIB wish to dot the I's and cross the T's before publishing any further report I'm surprised that more "informed" data hasn't hasn't leaked out.
Now in one sense this is exactly as it should be, but with so many interested parties involved and an intact aircraft I find it surprising that (virtually) no recommendations have come from the AAIB impacting other aircraft of the type / operator. This suggests to me that they currently have no recommendation to make.
So either the team has:
1. No idea what caused the accident in which case the extremely improbably theories need to be considered more seriously or
2. The findings are worrying with significant impact to other aircraft / operations (although likelyhood of a repeat is low based on experience to date) and any action must be thoroughly researched and backed up due to implied costs etc. of taking action. ETOPS?
I wonder which is nearer to being correct? I favour option 2.
Either way the situation is IMHO unprecedented!
A no cause identified outcome is IMHO not viable since the aircraft is largely intact.
Interesting.
Quote from snanceki:
A no cause identified outcome is IMHO not viable since the aircraft is largely intact.
[Unquote]
It’s a wonderful situation, isn’t it? Pity all those electrons have rearranged, though. I like your analysis. It is a blessed irony that the very presence of the hardware must be a mixed blessing for the investigators. Don’t we have it easy…
A no cause identified outcome is IMHO not viable since the aircraft is largely intact.
[Unquote]
It’s a wonderful situation, isn’t it? Pity all those electrons have rearranged, though. I like your analysis. It is a blessed irony that the very presence of the hardware must be a mixed blessing for the investigators. Don’t we have it easy…
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Sunfish:
I recall a similar post previously regarding the speculation around BA38. Perhaps it was you? I resisted the temptation to comment on that occasion, but as it's been raised again, here goes ... 
What you say is right, but would you prefer it if the Mechanical Engineer started spouting about fuel chemistry?
Sunfish:
You see, unless the poster has experience of commercial aviation, you seem to infer that their contribution is of less value - ie you are asking them to stick to their field!
As I see it, it's entirely sensible that those with experience of other fields make a contribution, even if they don't have experience of commercial aviation. A link pin is a link pin, chemistry is chemistry, software has bugs
- aviation is another field, but it doesn't change the laws of the universe. If those with commercial aviation experience - who I'm sure are for the most part intellegent enough to understand the suggestion from other fields being put forward - can "through the lens of their own experience" spot a flaw in a posted suggestion, they should raise it to rebuf the argument and the poster should accept that. Unless they have a counter argument of course, that's how a debate works isn't it ?
Whilst there have been some truly terrible posts on this and other threads despite the moderators considerable efforts, I also see a lot of people being shot down when they make a suggestion, with the responder (who often has a valid point, but agressively made) seeming to have implied that the poster is saying "I categorically state this is what is happened" when in all but a few cases they haven't.
If only commercial aviator's opinions are of value, then make the forum closed or read-only. For my part I think the mix of interested engineers from many disciplines is a real strength of PPrune, albeit that there is a problem due to it being used by Journos - who don't understand engineering uncertainty - as gospel fact for a sensationalist headline.
That's been posted many times too. I read every one of the first 1000 or so posts on this subject, but drifted away from the thread when useful additions dried up (interesting diagrams of the fuel system were still being added until quite recently). As you see I pop back from time to time. But this is the thread for people wanting to speculate, postulate and question, so if you just want to wait for the AAIB report, surely it's best to "move along, nothing to see here ..." 
Yup, as an CEng MIET in Electronic Engineering and a software professional, I'm similarly buggered (though that's probably as expected because as you say I don't have professional experience of commerical aviation) , and am keen to see the AAIB report.
But let's not stop some of the current issues with the use of PPrune kill one of it's greatest strengths, namely the excellent experience of interested individuals across multiple engineering fields.
Just need to find a way to make them float to the top amongst the youngsters, innexperienced but wannabe engineers, and Journos trying to provoke a headline.
To put it another way, everyone examines things through the lens of their own experience
What you say is right, but would you prefer it if the Mechanical Engineer started spouting about fuel chemistry?
Sunfish:
The trouble is that while I'm sure the speculation is well meaning in most cases, very little of that experience has anything much to do with commercial aviation.
As I see it, it's entirely sensible that those with experience of other fields make a contribution, even if they don't have experience of commercial aviation. A link pin is a link pin, chemistry is chemistry, software has bugs
- aviation is another field, but it doesn't change the laws of the universe. If those with commercial aviation experience - who I'm sure are for the most part intellegent enough to understand the suggestion from other fields being put forward - can "through the lens of their own experience" spot a flaw in a posted suggestion, they should raise it to rebuf the argument and the poster should accept that. Unless they have a counter argument of course, that's how a debate works isn't it ? Whilst there have been some truly terrible posts on this and other threads despite the moderators considerable efforts, I also see a lot of people being shot down when they make a suggestion, with the responder (who often has a valid point, but agressively made) seeming to have implied that the poster is saying "I categorically state this is what is happened" when in all but a few cases they haven't.
If only commercial aviator's opinions are of value, then make the forum closed or read-only. For my part I think the mix of interested engineers from many disciplines is a real strength of PPrune, albeit that there is a problem due to it being used by Journos - who don't understand engineering uncertainty - as gospel fact for a sensationalist headline.
I'd rather wait for the experienced folk at AAIB and Boeing to tell all of us what they believe the probable cause is
because as an engineer who first was responsible for an oil terminal and airport jet fuel handling facility, then spent six years with an airline engineering division, followed by an aerospace/defence outfit, and flies little tiny aircraft, I'm buggered if I know what happened.
, and am keen to see the AAIB report.But let's not stop some of the current issues with the use of PPrune kill one of it's greatest strengths, namely the excellent experience of interested individuals across multiple engineering fields.
Just need to find a way to make them float to the top amongst the youngsters, innexperienced but wannabe engineers, and Journos trying to provoke a headline.
Snanceki
I also favor option 2. Similar to what we knew about TWA800 at the same time. I hate mysteries in investigating multiple probabilistic combinations when the actual chain is missing links which can not be verified easily. Yet the aviation comunity including the users awaits a definitive corrective action to make the outcome all go away. If the wrong recommendation is chosen it not only is costly but it also adds new unforseen risks of its own. Therfore one can not rush quickly into expressing a conclusion.
I usually am satisfied to put a close watch on the data stream information that the fleet has to offer relative to suspected contributing causes and see what theory is best supported by monitoring the continued airworthiness of the suspected product line..
An no I don't yet have in mind a definition of the suspected product line, be it Rolls, Boeing or the whole damn fleet. I am only drawn to the parallels following TWA800
So either the team has:
1. No idea what caused the accident in which case the extremely improbably theories need to be considered more seriously or
2. The findings are worrying with significant impact to other aircraft / operations (although likelyhood of a repeat is low based on experience to date) and any action must be thoroughly researched and backed up due to implied costs etc. of taking action. ETOPS?
I wonder which is nearer to being correct? I favour option 2.
1. No idea what caused the accident in which case the extremely improbably theories need to be considered more seriously or
2. The findings are worrying with significant impact to other aircraft / operations (although likelyhood of a repeat is low based on experience to date) and any action must be thoroughly researched and backed up due to implied costs etc. of taking action. ETOPS?
I wonder which is nearer to being correct? I favour option 2.
I usually am satisfied to put a close watch on the data stream information that the fleet has to offer relative to suspected contributing causes and see what theory is best supported by monitoring the continued airworthiness of the suspected product line..
An no I don't yet have in mind a definition of the suspected product line, be it Rolls, Boeing or the whole damn fleet. I am only drawn to the parallels following TWA800
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From a usually reliable source...update
The problem however is identiying the part of the fuel system at fault.
This specific flight was one (perhaps the only one) that did not descend into warmer air along the route, due to very cold ambient temperatures aloft.
Not necessarily the FD crews fault, it could well have been that the actual fuel tank(s) fuel temperatures were incorrectly displayed.
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Snanceki
You don't attribute your quotes, so I need to distinguish the perception that you made re: a "post" of mine.
It is plausible that AAIB do NOT have evidence of causation that would implicate other aircraft, because if a warning to the Fleet were necessary, it hasn't happened; being the responsible chaps they are, I assume they will not endanger the Fleet by being "coy" with important announcements.
Asking for clarification is appropriate, but if one so obviously misunderstands a Post, one should withold personal conclusion and further confusion. By and Large the comment here is excellent, it comes from a number of interesting sources and the tenor and respect is exquisite. I am curious as any, and refutation of possible conclusions is interesting also, but of course, much remains to be known. In the meantime, I will read your posts and others with great relish.
(411A your surmise is compelling, When others were descending, BA was Climbing)
It is plausible that AAIB do NOT have evidence of causation that would implicate other aircraft, because if a warning to the Fleet were necessary, it hasn't happened; being the responsible chaps they are, I assume they will not endanger the Fleet by being "coy" with important announcements.
Asking for clarification is appropriate, but if one so obviously misunderstands a Post, one should withold personal conclusion and further confusion. By and Large the comment here is excellent, it comes from a number of interesting sources and the tenor and respect is exquisite. I am curious as any, and refutation of possible conclusions is interesting also, but of course, much remains to be known. In the meantime, I will read your posts and others with great relish.
(411A your surmise is compelling, When others were descending, BA was Climbing)
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I'm already on record for a theory. I'll go a bit more.
The permanent fix is to change the gear ratio for a reduction in pump speed and an increase in pump size to maintain the flow capacity.
In the interim, if the fuel is already cold soaked, don't continue a long exposure to an extremely low OAT. Do what every other prudent pilot did that day; get down.
The permanent fix is to change the gear ratio for a reduction in pump speed and an increase in pump size to maintain the flow capacity.
In the interim, if the fuel is already cold soaked, don't continue a long exposure to an extremely low OAT. Do what every other prudent pilot did that day; get down.
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Clarification.
@airfoilmod
My quote was attributed to Rightbase Post 719.
Since it was only a couple of posts earlier I thought the connection was self evident. Obviously not.
Stuart
My quote was attributed to Rightbase Post 719.
Since it was only a couple of posts earlier I thought the connection was self evident. Obviously not.
Stuart
Kolossi, you make the point that everyone should contribute from their field, within their realm of competence, and I agree with you. However many of the posts on this thread completely discount the design expertise of the aircraft manufacturer and the skill and experience of the pilots who operate the aircraft and the engineers that maintain them. That to me is unwise.
By way of example, while I now have to admit that Occams razor suggests that fuel system design or the fuel itself is the culprit, the "water in the fuel" crowd do not appear to know that fuel quality is monitored daily and that the petroleum industry has been paranoid about jet fuel quality, especially water contamination, since at least 1980. Before the fuel reached the aircraft, it will have passed at a minimum three filter/coalescer units designed to remove any water or particulate contamination.
Similarly Boeing would be well aware of the risk and catered for it in its design, so how someone can blandly say on page one or page two of a thread "it's water contamination" is beyond me.
The same goes for RF interference. Do the proponents of this theory think Boeing has never heard of it, nor allowed for it's in it's detailed designs? Same for pump cavitation theorists, do you think the engine designers are idiots?
That's why people get irritated by some posters - because their helpful suggestions imply that the designers, pilots or maintainers of the aircraft were idiots.
By way of example, while I now have to admit that Occams razor suggests that fuel system design or the fuel itself is the culprit, the "water in the fuel" crowd do not appear to know that fuel quality is monitored daily and that the petroleum industry has been paranoid about jet fuel quality, especially water contamination, since at least 1980. Before the fuel reached the aircraft, it will have passed at a minimum three filter/coalescer units designed to remove any water or particulate contamination.
Similarly Boeing would be well aware of the risk and catered for it in its design, so how someone can blandly say on page one or page two of a thread "it's water contamination" is beyond me.
The same goes for RF interference. Do the proponents of this theory think Boeing has never heard of it, nor allowed for it's in it's detailed designs? Same for pump cavitation theorists, do you think the engine designers are idiots?
That's why people get irritated by some posters - because their helpful suggestions imply that the designers, pilots or maintainers of the aircraft were idiots.
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Irritation
My experience in discussion is that people who are "irritated" by information may have an agenda regarding the outcome or the "reputation" of those who may own a piece of the potential fault. I will admit that some content here does tip a certain naivete regarding Aerospace and Aviation in general, but isn't that to be expected in a Forum such as this? I strive to look for the useful in things I encounter, and encourage people in general to have a good time; this isn't rocket science, and I have found a sub-group of true professionals here. This is a fascinating investigation, no one was killed, and as has been pointed out, the Hull is intact and may end up at Embry-Riddle some day. Cheers and happy typing. Bill
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@ Sunfish Post 739
But I have to add that sometimes even FMECA Failure Mode and Effects Analysis (of which I am sure you are aware) and best design practice can miss certain possibilities.
Just as an example take the PH co-cylindical tailfin actuator - unpredicted behaviour due to dirt ingress on 737. Enough said.
Maybe a SINGLE temp thermistor in just one tank is not appropriate.
Maybe current min. fuel temp in combination with the way it gets measured, is not appropriate.
Although Occam indicates the likelyhood of the simplest potential cause it does not at this stage exclude the other "way out" possibilities such as EMI. Be tolerant. You can always claim you were right when others are finally proved wrong.
@ Airfoilmod
Cranfield might be more appropriate! It's certainly nearer.
Similarly Boeing would be well aware of the risk and catered for it in its design
Just as an example take the PH co-cylindical tailfin actuator - unpredicted behaviour due to dirt ingress on 737. Enough said.
Maybe a SINGLE temp thermistor in just one tank is not appropriate.
Maybe current min. fuel temp in combination with the way it gets measured, is not appropriate.
Although Occam indicates the likelyhood of the simplest potential cause it does not at this stage exclude the other "way out" possibilities such as EMI. Be tolerant. You can always claim you were right when others are finally proved wrong.
@ Airfoilmod
Cranfield might be more appropriate! It's certainly nearer.