Air crash investigations
Should be a fascinating episode....
The Air Accidents Investigation Branch (AAIB) has concluded that the 17 January crash-landing of a Boeing 777 at Heathrow was probably caused by "ice within the fuel feed system" which restricted flow to the engines. BA038 (G-YMMM), after a routine flight from Beijing, suffered reduced thrust in both engines while coming into …
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Someone in the know should answer this. Are we talking about low fuel on return TRIPS, or in return LINES? Because, my concern now is that if we are talking about low fuel on return trips, with more airlines reducing fuel loading to reduce weight and fuel consumption, could ice in the fuel become more of a problem?
Paris, becoming more of a problem.
"operation at low inlet pressure"
Which also commonly occurs when they fuel begins to run out! Seems more likely to me, especially as:
a) it gets warmer near the ground, and
b) what are the chances of the pumps on both sides of the plane having the same problem at the same moment?
I still think Gordon Brown's posse brought it down with their mobile phone jammers...
Read the report before introducing ludicrous conspiracy theories. They tested the aircraft systems with very high levels of EM interference without any harmful effects. And there were about 10 tonnes of fuel remaining after landing.
Paris is the nearest thing we've got to a 'dolt' icon.
>If they cant remove the water by other means why not just freeze the fuel before it leaves the refinery? If it forms ice there then surely that would get rid of it?
They could do this....but you should also remember that airports store massive amount of fuel which then get pumped into planes either directly or using a bowser....
And refueling can take place in all weathers and not all seals are 100% - so a bit of rain water or condensation could in theory get into the plane fuel tanks, even if the refinery got rid of any water beforehand.
Just seems like one of those things, coupled with an excessively cold region that the plane went through en route.....
Lessons hopefully will be learned....
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Almost all aircraft fuel contains water. The fuel often drops below freezing point and the water freezes. Planes almost never drop out of the sky as a result.
Therefore, saying that the water froze and blocked the fuel lines isn't any sort of explanation at all. An explanation would describe what was different this time that caused the lines to get blocked when normally they don't.
My worry is that something significant might have changed recently. That would mean the past isn't a good guide to the likelihood of this problem occurring again in future. Until you have a full explanation for the accident it is complacent to suppose it is a one-off.
Atypical merkin style cover up , but Boeing are fully versed in that because in the past they have actively covered up various passenger plane defects by design in more then one model starting with the first long distance passenger plane the twin engined 247 way back in the early thirties and curiously on the old forties built C97 it had a tendency to throw a prop into its fuselage under certain operational conditions and the exact same engine in the RB50 would catch fire in mid flight causing total loss of aircraft in mid flight (corrosion was said to be the culprit back then ?????).
With Boeing it is basically cover up by design , for after all they learned much from the later Comet Jet disaster and routinely apply the initial rule blame the pilots for judgmental errors not the plane for commercial reasons only as the general public rarely read the follow up incident reports and are guided by the media propaganda headlines and ignore the shallow story underneath rather then read the follow up real stories which ninety nines times out of a hundred are basically ignored by the worlds chain mass propaganda media !
Choices , given the fact that the fuel was of a superior standard to that which is sold in the UK or US ,thus it suffers from a credibility gap and it just gets worse like the ongoing stench of just another cover up to hide the real problems .
AAIB do *not* "make it up". If they have made a statement, it is because it is the truth as determined by the many immensely experienced investigators that work on these occurrences.
Go and read the latest interim report, it runs to 21 pages of A4 and covers a great deal of ground, explaining why other possibilities do not fit the established facts.
A complete search of the flight records (one of the few kinds I'm in favour of keeping) of 777 operations has shown that this is the only time that an incident of this nature has occurred without there being an alternative explanation. That is one occasion in 6.5 million flight hours.
Mine's the white coat with a copy of "Principles of Air Crash Investigation" in the pocket.
"the report also said that the planes fuel, when checked didn't have particularly high water content... in fact it was below average."
That could be because the bulk of the water had frozen out of the fuel into lumps of ice. The concentration of water remaining in the fuel will depend on the temperature of the fuel, if given enough time to reach eqillibrium. Lower temperature means lower remaining water concentration.
I would therefore think that fuel with average water content would not contain enough water to form a significant amount of ice, or reach such a low temperature that it's water concentration would abnormally low.
Ice is more dense than aviation fuel, so will not float on the surface, out of harms way.
My guess is someone pissed in the tank. Did they test for urea?
I am no expert.
The tests used in certifying aircraft control systems understandably tend to focus on the kind of circumstances which an aircraft engine control might realistically be expected to experience (normal operation, lightning strike, etc).
It seems extremely unlikely that an ECU undergoing EMC testing would be subjected to the very very very high levels of directed RF energy in specific frequency bands which are sometimes used by the spooks in order to prevent remote-controlled detonation of explosive devices when Important People are passing through an area. (for "extremely unlikely", please read "they don't test civil engines for this kind of thing", and they probably don't for military either).
That doesn't mean Gordon Bliar's countermeasures team are to blame in this incident, but it does mean you shouldn't dismiss the possibility quite so quickly, though how it would ever be proved either way is a bit interesting.
Yours, a former employee of the company that made the ECU in this picture.
When will the pilots admit that they forgot to engage their carburettor heaters?
Explanation for non-flyboys: Every student pilot has it dinned into him from the start of basic training - always switch on carby heat as you begin your final descent, to stop the carburettor(s) icing up.
<<Ice is more dense than aviation fuel, so will not float on the surface, out of harms way>>
The trouble is that doesn't happen with jet fuel (Avtur). The water content tends to stay suspended in the fuel, causing it to thicken as it freezes. Unlike petrol (Avgas), where the water generally sinks to the bottom and can be caught in the various sumps and drain points in the fuel system. From my experience, checking out an Avgas-fueled aircraft that's been standing in the rain for a few days, you generally find traces of water in a least one of the drain points. I haven't flown jets, but I think the pre-flight checks include draining a fuel sample and mixing it with a special water-detecting paste.
Interestingly, the original Boeing 707 was intended to run on petrol, for this reason. However, improvements in fuel refining led to a decision to use kerosene, which has a higher energy content.
It bothers me when all the reports say "one chance in a million".
We have ca. 2 million flights a year globally, & this is the first occurrence of this particular problem in ca. forty years. One in a billion?
Paris, because my chance of carnal knowledge with her is higher than a dual flame-out.
Dual flame-out with Paris )(&*LKH^%#$ljkh*&%pwieufbh_)_&)*(#$
No. Just no. They always take enough fuel to reach their destination with some left over. (The only case I know of where this didn't happen was a flight in Canada where they mixed up metric and imperial units.) If there is any chance of a plane running out (happens every so often with private Cessnas and Pipers) they will divert to the nearest airport. Most conclusively, if the tank was empty both engines would have cut out completely at almost the same time, not seven seconds apart. They continued to provide some thrust, so obviously there was some fuel left.
OH, yeah, Boeing is trying REAL HARD to cover up massive design flaws in the 777...oh, wait, they really don't crash all that much - in fact that was the first major failure of one.
So then, it MUST be EM jammers, because we all know that Brown was in the same vicinity...hmm, but only one airplane had problems. So that may not be that likely...
Why can't people just admit that shite happens, that this particular plane flew in some really COLD air, and they just got unlucky? Not very exciting that way though, is it???
While the explanation given doesn't seem at all unreasonable, I seriously doubt that Boeing, the US government, or it's UK subsidiary the British government would be too happy to disseminate the truth anyway should it turn out that the fuel pumps had failed after the design had been outsourced to a rather good bus mechanic in Gurgaon, India.
Business interests will always trump the truth.
Living on the flight path to Heathrow (close enough to have to turn up the tele when planes go over every 2 minutes). I can assure everyone on here that 777s among many other planes are taking off and landing all the time without problem.
Aircraft operated out of the UK have a very high standard of maintenance, mainly to keep them earning money, but also because they cost ALOT and have to last a good while.
The excerpts from this report strike me as very detailed, so i would think the whole report is also well detailed. This is the report for insurance people, health & safety and all the other organisations involved so its got to be credible and written by people who specialise in this. no conspriacies here, move along.
Your humble Turbo Diesel hatchback has a heated fuel line to prevent ice in the fuel. I cannot believe a Boeing 777 costing eleventy billion pounds doesn't have one too. Similarly I cannot believe (like the TD) it is engaged automatically when needed.
Therefore I reject this finding as a 'convenient fiction' . I think the penny pinching BA barsteward accountants (to cut weight and therefore fuel consumption) didn't put enough juice in it before they took off.
"Following the accident, 66 fuel samples were taken from the aircraft and the engines. A number of these samples were tested and critical properties such as the freezing point, density, flash point, viscosity, contamination, fuel additives and presence of water were tested against DEF STAN 91‑91 and ASTM D1655 requirements. The fuel samples complied fully with the fuel specifications for Jet A‑1. Additional tests were carried out to detect any unusual components that would not normally be found in aviation turbine fuels. No evidence of contamination was found."
If you choose to ignore all the evidence and persist in concocting implausible conspiracies, surely there are some wiki pages you could be editing?
I am sure that all in the AAIB would take great offence to assertion that they would bow to goverment pressure as not to offend the Chinese.
The AAIB is highly respected the world over for its technical excellence and independence. If the fuel was bad, they would say that the fuel was bad.
So, AFAICS, what we have so far is:
1. The report blames the crash on ice in the fuel (probably).
2. Previous comments from informed sources tell us that all jet fuel contains water, which freezes when cold enough.
3. Yet thousands of similar flights, at similar heights and temperatures, land without problems.
4. So there is no logical explanation yet of why this particular flight lost engine power.
Incidentally, the fact that no ice was found in the fuel is presumably meaningless. At ground level, it would have melted before there was time to measure it.
The thing that bothers me is: why, after such an extremely long flight, did the engines lose power right at the moment of landing approach, at low altitude and just as the surrounding temperature had risen considerably? One is tempted to invoke Murphy's Law, until it occurs that almost any other time and place would have been even worse. E.g. over the North Pole?
...but to me, reading the report, it seems that the low volume of fuel in the centre tank remained there for the majority of the aircraft's flight, and especially existed when the aircraft ventured through the coldest portion of the flight. All the air in the central tank would act as a wonderful insulator to the warmth of the cabin above, but being quite close to the skin of the aircraft, would have been especially cold (gravity pulling the fuel to the bottom of the plane and all).
Then they scrubbed the centre tank contents into the respective left and right-hand main tanks, pumping whatever ice-crystals had formed in the fuel with them. Being uniformly spread in the centre tank, the main tanks are now uniformly contaminated.
A descent from FL400 doesn't require a significant level of thrust, and so the fuel flow would not have been excessive enough to disrupt the suspended crystals. However, the approach to LHR requires the constant changing of the thrust (at times to high levels), which would have started to clog up the filters. And if you've seen what happens to your plug-hole when you get hair clogged up, you'll appreciate that ice clogging filters will only cause more ice to stick to it as it passes. In fact, an increased demand for fuel will actually causes more ice crystals to pass near the filters. Some of these will naturally join with those already on the filter. In a twist of irony, demanding more fuel may actually speed the problem rather than solve it.
Why did the engines fail around the same time, because both tanks would have been uniformly contaminated by the central tank, and layman math would suggest 7 seconds difference between failures would be perfectly reasonable.
But that's just my 2 inches of manifold pressure!
Read The F**** Report! before ignorantly commenting.
I have read (skimmed) the AAIB report. The report identifies that there is a fuel additive that has been used by the RAF, USAF & other militaries for the last 40 or so years (or was it 50 or so?) and is approved by Boeing for use on the 777. The use of this additive would have *completely* mitigated this accident. Yet no civilian operators use this additive on large transport aircraft; some use it on smaller types.
Sadly, the report does not bite the bullet to recommend to the certification authorities to mandate the use of this additive on the commercial operators. Shame on the AAIB (although this is an interim report, not final)
Yes, this incident is a 1 in 6.5 million flight hours occurrence. Rare, but worrying because nothing like this has been seen before and had been assumed to be so improbable as to not be worth designing extra fuel heating to cope with.
Clearly the fuel/oil heat exchanger on the inlet side of the engine LP fuel pump is insufficient in this one very unusual circumstance. It may not be adequate in other engines on the 777, not just the Trent. They are worried enough about this to issue a safety recommendation that it be investigated.
What is clear is that, from reading the report, on this occasion the fuel flows in general were lower than on other flights because less power was used for the slower than usual step climbs en route, and less power than many other flights used was applied to level for the hold at Lambourne. This may have been the reason that, when power was then finally applied at a significant level for the final approach, the sudden increase in fuel flow was able to dislodge the build up of ice that appears to have to been present whereas if it had been gradually dislodged before by higher fuel flows en route and during the descent the ice would not have arrived all in a rush and blocked the pipes nearer or in the engines.
As for other suggestions of cover up and conspiracy, no I don't think so. This is something so unusual as to not have been recognised if it ever occurred in the past. It probably didn't, definitely not on the 777 because there are records to prove that last fact.
AAIB will get to the bottom of this one, but it will quite likely take another year or more due to the work that will be needed to identify the real culprit.
I suspect that there will eventually be a modification to ensure that the pipes from the wing tanks to the engines cannot cold soak to the extent that ice build up can occur to the extent it must have done to cause this effect.
Might not be be so bad over the north pole as the air craft would be in a low drag configuration and could stay in the air with the reduced thrust or descend very slowly in which case the fuel might have time to defrost. With plenty of altitude they could probably reach a suitable runway.
As for the coincidence of the problem occurring just as landing: During cruise and descent throttle setting is normally low so in fact the maybe blockage could have been there from much earlier in the flight and only become a problem when increased thrust was needed on approach.
I guess there will some effort to avoid this in future, fuel heating systems? Don't some aircraft dump AirCon wast heat into certain fuel tanks?
I am not an expert, I just hope the people looking into it are experts and are able to call a spade a spade and get the design of the spade improved.... hmm starting to sound like a manfrommars!
Plane flew through an unusually cold area: Could this mean more ice or more densely packed ice or a single slab of ice in the tank as opposed to bits ?
Why when landing: From cruising to landing throttle is moved back, in the report at 720ft they attempted to throttle up thus sucking harder on the fuel tank, could this have pulled the bigger than usual bits of ice into the pipes?
Further: If the ice had formed a large slab/iceberg during decent the temperature would have changed an the ice would probably have broken apart (See global warming for a working example:))
So the "changed" factor is the duration of flight in a colder than normal climate. The only problem is it can't be proven.
BTW: is not the correct British date format January 17th 2008 ?
"Quick Miss Hilton, we need an excuse as to why the plain crashed, people are getting impationt"
"uuurrrhhhhh emmmm ummmmmmmm ICE!"
"Thanks Miss Hilton, Ice will do nicely"
"Right so we have concluded out investigations, and even though there was below average water in the fuel and also this has never happened before, we believe that ice _might_ have formed in the fuel lines"
There was approximately 10 tonnes of fuel left, definately not fuel starvation, the requirement is to carry a minium of 105% of the required fuel, 10 tonnes sounds a lot, but it's not, in fact it's quite close to the minimum for this aircraft over this distance (a 777 burns 6-8 tonnes an hour), there's a lots of mummurings going on from pilots about being forced to carry the bare minimum fuel (http://business.timesonline.co.uk/tol/business/industry_sectors/transport/article4641399.ece).
So, if (a big IF) more and more planes are flying with low (but safe) levels of fuel then maybe it's making the more unusual conditions more likely, perhaps a combination of low (but safe) levels of fuel, unusually low temperatures and perhaps other "unusual" factors affecting fuel heaters, water sumps, the pressure change back to 1 atmos (and the ratio of fumes to fuel in the tank), maybe even engine design, perhaps a single engine failure happens more commonly but it's not a problem unless both happen to fail simultaniously and maybe not logged with any similar significance even if it's detected on one engine?
To answer no 3 and 4 "Scrutiny of data from about 141,000 other Boeing 777 flights has thrown up no evidence of similar conditions on previous flights." the conditions were exceptionally unusual (very cold for a very long time).
The source here is the full 20+ page AAIB report. It's not that techy.
And also pop over to the website of Flight International magazine, where you will read that the powers that be are already talking about the use of additives to stop this kind of thing happening (as per AAIB report, the military have been using additives for this purpose for decades).
Another option is operational changes so that fuel doesn't get so cold, and that fuel flow patterns do more to break down any ice which does build up. BA's 777s are already doing this (this isn't on Flight's website yet, but subscribers to ATI Breaking News can read about it).
The AAIB report also makes clear that there is roughly zero chance that spooks and RF jammers caused this crash - the cavitation marks on the pumps wouldn't have been expected as a result of an ECU failure.
Nobody here mentioned filters. Years ago I had an old Citroen that had a fuel filter you could put your foot in. I think it was some 3 or 4 litres. When I checked it I found it full of water but the engine -a diesel, worked fine.
Paraffin is somewhere between petrol and diesel so should filter even better. (IIRC petrol is 8 C atoms to paraffin's 20 and diesel's 30.) I imagine the military need to use additives as they keep their aircraft grounded most of the time?
Commercial aircraft have their tanks rinsed through every day -24/7. Catching water in the sumps might be a problem only because the engines are never switched off therefore keeping water suspended.
But draining the sumps every journey would cover any problems. I bet there was skimping there, especially with the weather here and in China over the past year.
I haven't looked at the report but this piccie makes it seem the wings broke:
May I take it the relevant tanks were undamaged?
Um...., no "broken wings", the Undercarriage sheared off on impact, but the wings themselves are "intact". Structurally, 2.3G's instant loading on a 777 wings is not a major deal (strong turbulence is likely to reach that level of load). The three tanks will likely have remained in tact, but as the report states (RTFR), the Fire and Rescues efforts to reduce the chances of fire, contaminated at least the central tank.
The report also states (RTFR) that the aircraft was Sumped on the 14th of January when it was in for maintainence, and was routinely sumped on the 15h prior to it's outbound flight to Beijing.
And I mentioned filters...
Aircraft was sumped on the previous day, hence the comment that there was not much water (5l in 100,000l of fuel).
Part of the wings broke, the main u/c legs are bolted to spars within the wing structure, and are designed to break off with minimal damage. In this case the soft earth applied stress in a way that prevented a clean break because the wheels gouged trenches rather than being able to rotate around their attachments.
Tanks were damaged on one side of the aircraft. About 6 or 7 tons of fuel escaped in total. The firemen were wading about in it just after the crash.
So steve Boeing learnt a lot by closing the hearings and restricting it to the investigators only no reporters and whenever a curious reporter turned up they would name and address an we will send a complete technical report in the mail now go away we are busy.
This allowed legal to completely rewrite out all the bad bits and self incriminating evidence period before final public release .
The Comet investigation was complete thorough and very much out in the open at all times and information was released regularly .
This closed shop investigation gave out the odd snippet or tidbit , since the pilots were proclaimed heroes on day one , oh curses we can't blame them any more can we !
But then again the most dangerous time for any twin engine aircraft not far off stalling speed and low altitude under 1500 feet is asymetric thrust as any twin engine prop pilot will say on take off on full power when one engine suddenly fails at end of runway "We just bought the farm oh crap " as they have no more room to move due low speed sudden spin right or left and no altitude to trade for speed either .
Now since modern jets have both smart and dumb computer chips with both feed forward and feedback loops at the same time thus if one engine began to speed up but the second one says after you and then they both get in that loop and say to each other no you first then me vice versa and suddenly you have a live logic bomb go off if you have no loop limit instruction that says crap emergency firewall all engines now not later when both of you can't make up your mind as both are waiting for each other to spool up in a situation that will never happen hence just above idle speed thrust limit . Since the master electric switches and relays were activated to cut all power to everything due to ten tonnes of flammable Jet A sloshing around on the ground this would wipe the logic bomb off all the computers as after ten minutes they forget all register instructions held in the stack as the temorary memory is flushed from lack of power .
The other aspect is that most people regarding major aircraft incidents tend to remember the first rushed headlines and thereafter do not follow up unless spoon fed hence the goldfish memory syndrome which of course plays into the hands of those that seek cover up first of which Boeing is well versed in for decades since 1932 !
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