Just a quick question, but maybe irrelevant, but BAW38, BAW39 is now done by a 747, is this due to its lack of problems during cold flights that it does, and or that BAW38 crashed in a 777 its a Public relations issue that its been changed to a 744?

Fewer problems flying cold? Public relations? Guess: both

What's Delta doing?

HeathrowAirport
 

Not a guess, an answer: Neither. Following the accident BA suddenly found itself a 777 short, so there was a change in Fleet utilisation and a 747 was slotted in.

BA continues to operate 777's on Shangai-London, an equally 'cold route' using Chinese fuel. It's also going to be using the 777 on one of it's HKG services this Summer ( which often routes home via overhead Beijing and then onwards via Siberia), and there is the possibility of BA using 777s on NRT this Winter......not exactly the warmest of routes either.

Ah thanks for that Information, but would also PR also be included, I wouldnt as a CEO even if it meant reducing pax vs fuel burn, a 777 operating a route that it crashed on.

HeathrowAirport
 

In all honesty most passengers are completely unaware and are utterly disinterested in what aircraft they are flying in, and don't know a 777 from a 747 from a 737.........

HeathrowAirport -

Don't discount the effects of #engines. I have seen plenty of pax count them on their fingers before boarding. I'd like to encourage you to continue to ask good questions, stay objective, and don't take casual commentary to the Bank. When ETOPS was proposed, a healthy percentage of pilots were questioning the format, some still do.

Don't allow your questions to be dismissed out of hand, certainly not on the Internet.

Having said that, there is no reason whatever to mistrust ETOPS. Make up your own mind.

Will

They are still flying their 777LRs between Atlanta and Shanghai, Seoul and Tokyo.

And I am here to verify that at least this one passenger does indeed know what type of aircraft I fly, and is keenly interested in a final fix to this problem, beyond operational work-arounds to unclog the ice from the heat exchanger tube sheet. The 777 is my most frequently flown airframe (I keep a log).

Edit: I meant 777ERs, not LRs. The LRs have different engines and are used on other routes.

Williams2353
 

I reckon you're probably the exception that proves the rule...:ok:

Actually, would anyone kindly be able to show me the loads for BAW38 pre the crash and after, even though this would be biased due aircraft size. Whats the loads?

And Will Thanks, I prefer the 777 to the 744, dont take offence, but since that crash Ive liked the 777.

BA 777 crash - second interim report out
 

This is essentially a refinement of interim report 1, tidying up some rough experiments. It's easy to criticize the slow progress but it's really difficult to simulate - think of the early wind tunnels.

At the end of the day, there needs to be a dedicated interagency fuel research centre to physically model these issues accurately, using a combination of actual engines and actual fuel systems in environmental test chambers (imagine!) and maybe even including extended duration high altitude flight testing. Irrespective of the current case, this kind of facility will anyway increasingly be needed when biomass derived fuels start to penetrate the market.

We need to get to the same level of sophistication with fuel testing as we are with blade containment. If you have never seen it its worth watching:

YouTube - Blade Containment

Pinkman

Some questions then. As a fuel guy, do you conclude that the (permitted) water was the culprit? Was it an accumulation of atmospheric moisture via venting? What about the conclusion that the ice was 'soft' and 'malleable'.

Also, Pinkman, what of Boeing's 60 years experience of turbo (fan) jet performance at levels up to 60k and above? It remains disconcerting to me, probably to others that the industry seems to be a bit coy with the purported 'mystery' of this event.

What about the 'slurry' theory from Airfoilmod? Some combination of waxy fuel and microcrystalline water-ice? Have you seen this before?

Tough questions. I don't have an answer for all of them. All I can tell you is what I think which is:

- I think that the dissolved water is a complete red herring. Free water, eg from fuel stratification, may not be. And if that came from the free water then maybe the free water is an issue after all.
- I don't think industry is being coy: they just dont know what is going on.
- I think airfoilmod is very close. I believe it was a unique situation related to the distillation properties of the fuel such that it met all the ASTM tests but didnt perform as conventional fuel under those unusual circumstances. Who knows, it might be related to biofuels. Yes, I have seen distillate fuels wax up and I have seen an ice-wax emulsion.

The thing about fuels testing is that you only test for the basic properties (freeze point, smoke point, distillation range, Calorific value, etc etc) and the qualities of the things you expect to be there. In the UK we had a gasoline contamination problem a few years ago that took thousands of vehicles off the road almost overnight. The fuel met all the BS/EN228 spec tests. It took nearly a fortnight for someone to trace the fact that the fuel had been adulterated with waste electrical solvent (mostly toluene). It got the Octane rating up (its aromatic) but had silicon in it which poisoned the oxygen sensor. But it was on spec!

Another example: Chinese baby milk scandal. It contained Melamine, which tests out as a protein, but is of no nutritional value and actually harmful. But it was on spec!

The point being that you dont test for the things you dont expect to be there. Fuels are heterogeneous things that dont always do what you expect. In the short term the only way to get on top of this is to test them in the environment in which they will be used and use the information to modify the testing regime.

Pinkman

Still not madly keen on the interim report.

They still used the "wrong" fuel condition (90 not 70 ppm water) in the tests (for the perfectly valid reason that that is the industry standard so it would give results against POSSIBLE future failures) and they still didn't get the results that occured on the day of the accident.

The point about the water content being very variable (possibly due to ice freezing and melting) and difficult to measure is a serious issue. One glaring question is what end conditions they would have expected (in real life the water sample taken was 40 ppm).

So the tests are still first steps NOT a "smoking gun".

I am still disurbed that they are only concentrating on the B777/Trent combination and not extending the research, although of course there are the other recommendations.

I am a little concerned that the reports are looking too narrowly at the problem.

.

Couldnt agree more, and actually while you wrote that I was editing my earlier post to reflect that.

The report refers earlier (p7) to the possibility of water accumulating during the flight rather than being ingested with the fuel burned .
and on page 8 to the effect of water injected into the fuel flow.

It seems to me that there is a serious possibility that at warmer levels, ice which has accumulated in the centre tank will melt, allowing the fuel scavenge pumps to feed it into the (still cold) main tanks, where on its way down to the boost pump inlets it will freeze. If the centre tank melt water is suddenly presented to the scavenge inlets, by a decelleration or a change of attitude, it will result in a significant temporary production of ice in the main tanks.

Cavitation on other Aircraft of this type?
 

That cavitation was present is interesting, but not dispositive, unless it is so unlikely to be found on other aircraft of this configuration that it almost certainly points to icing as a cause. Suppose the AAIB examined other RR 777s. What percent would be found to have cavitation of this pattern? If the answer is lots, the causal connection is less established. And as a factual matter, have they done this?

If this has been answered already, I apologize. Please refer me to the post # addressing my question.

Rightbase
 

Yes, thats what I mean when I, and many others, have referred to "fuel stratification". All you need is liquids of different densities and suitable environmental conditions. In the pub, you can get whisky to float on water if you are careful.

I thought this was interesting - on the web:

https://www.totalga.com/document/FAME%20Bulletin.pdf

and the attachment to it ( NE-09-25 ).

The industry has obviously recognized the issue and are taking steps to address it. If the AAIB hasnt yet positively discounted this by doing the GC-MS analysis to rule out FAME contamination then they need to. If they have, then they should say so.

Pinkman

Bear with me. Some questions. If the industry is lobbying for 100ppm that's more than dissolved water, and the problem there is patent (038)

Are the producers trying to keep their fuels "on test" by introducing and regulating a substance heretofore not allowed in any fuels test?

My concern is the fat itself. Organic fats have in the past been used as

1. Glue

2. Thickeners

3. Coatings (Varnish)

4. Resinous molded parts (phenolics, phthallates) etc.

The potential for disaster is apparent. Are they trying to put these substances in jet fuel, or defending their possible presence in jet because of an inability to keep separate the biodiesel from jet in mixed transport, and production processes? What is it?

Loaded Question
 

Will

I couldnt possibly comment except to say that its a contaminant, nothing more, and it arises from the tendency of the product to stick to the sides of the pipeline and contaminate other products. Its called tailing. You have to have multiproduct pipelines because you simply cannot have dedicated lines for every product... or that was the thinking until now.

I am seeing a lot of activity to devise safeguards against this, but that wasnt the point of my post, which was to look possible relevance to BA 038. The thing that has always puzzled me is that, while within the normal Jet A-1 spec (-47 C), the FP of the fuel when analysed was actually much less than typical RP-3 which I understood to be in the minus fifties. I was trying to work out whether this is consistent with FAME contamination. I havent reached a conclusion.

A long ago post by airfoilmod comes to mind. He took issue with the 'in spec' conclusion of AAIB testing, though the FP was markedly lower than standard Minimum. His position was something like "Where does 'meets and/or exceeds' come into play relative to 'in spec.' Does the authority accept the unusual characteristic (low FP) as long as the 'miminum' is met without questioning the mechanism for the drastic difference?

I don't think he ever got an answer.

He got an answer from me. I said he was talking rubbish. I may yet have to apologize - seems like he was way ahead of me. To be fair, I was thinking more along the lines that the aviation Kerosene produced in that region probably had more than one use (eg for military as well as commercial) so if it exceeded (bettered) the commercial spec by such a wide margin, so what, as long as it comfortably met Jet A-1 norms. Which, on the face of it, it did.

Meets or Exceeds
 

I would be cautious about the interchangeable use of the terms meets or exceeds in a complex substance or system. Whether its a hydro-carbon or a composite structure, its the balance that's important. The spec is based on the knowledge that in balance (meets) it works. Change something (an ingredient or structural stiffness) and you no longer can be sure that it will perform acceptly in the common situations like it did before.

The assumption is that the product has been analyized/tested with variations within the acceptable range of "meets"

That was exactly the point, it seemed that 'meets' and or 'exceeds' the spec. satisfied the authority. Should it have? In my opinion, NO. What is it about such a low FP that should be investigated?

E.G. What temperature is boiling water? Where on the Planet is one?

Made Jet-A1 for 14 years.
There were 66 samples of fuel drawn from this aircraft after the accident and the AAIB have reported that no contaminants were found other than traces of water. Chinese N03 Jet Fuel complies with the Spec for Jet-A1. In order for JetA1 to meet spec it has to pass 38 tests. If organic fats were present they would have been detected in at least three or four of the tests.
Some of the tests, e.g. density, are set with pass rates between upper and lower limits. If the results fall between the values then the spec for that test is met. Other results have to meet maximum or minimum values e.g. Flast point or Freeze point, if these minimum values are met or exceeded then the test is a pass.
When fuels exceed the values set then the quality of the fuel is not impaired.( The fuel producer just wastes money in the fuel production as they get the same price for it whether is meets or exceeds the spec. In my experience we played safe with Jet A-1 and never tried to be clever achieving a perfect blend, it was almost always better than spec.) In order to meet all the spec requirements some of the results will exceed the spec and this will vary from batch to batch. The Certificate of Quality is only issued if all tests have met or exceeded the minimum requirements.
Jet 1 is stored in tanks, pumped and transfered in it own dedicated pipework and was not in my days physically connected to any other pipework. Even drain valves had lead seals on them to demonstrate to an Inspector that the Jet A-1 containment system had not been disturbed. The seals were numbered with the refinery inspector's number on one side and a Government seal on the other. The small number of people who could fit these seals were registered and issued with their own seal compression tongs
The problem here is the management of water in an aircraft/ engine combination which was susceptable to any ice formation at low temperatures. There did not seem to be any fuel temperature control, the pilot got what the airframe produced in the climate in which he flew.The unlagged/non heat-traced pipe run from the fuel header out to the exposed FOHE and back to the engine being a cold section of the fuel system under discussion. The first time I saw the FOHE inlet tube
sheet I mistook it for a filter screen. I await the modifications to this system with interest. Like many of you I do feel it seems a long time coming. The final report? I am happy to wait for this.

I was also in the industry for a number of years (outside the UK). Where I worked, the Jet-A1 was kept totally separate from the other products within the refinery, but was transfered to the distribution centre via a multi-product pipeline.

Pinkman's concerns about possible contamination could certainly have applied there.

Good point Sooty655. If multi product pipeline was used then the Distributor has the responsibility to re-test on receipt and issue the appropriate Certificate of Quality before delivery to the end user. I am asuming that these products were separated by pigs. Having used these for years I do not have any confidence that there would be no leakage past them. My own opinion is that Jet A-1 is not really suitable for multi pipeline use. If the multi pipeline deliveries did not use pigs and relied on Operator intervention to separate the fluids on receipt then Pinkman is right to be concerned.
Another problem area is Jet A-1 delivered by ship. I have yet to receive liquids from a Super Tanker or Coaster which did not contain water. We obviously drained this water away on receipt but another source of water contamination if the onshore guys are not switched on. The quality control inspector, either way, is still responsible for delivery of non contaminated Jet A-1.
In the offshore business we still check each fuel delivery to a chopper for water. I have even had a RN pilot asking my Helideck Landing officer why he was holding a syringe up to the cockpit window. When the HLO told him he said they never bothered their Jet A-1 was always water free!!!

Hi Oil & Gas man... yes, I'm ex-refinery too. Multi-product pipelines are the norm nowadays in many countries, even for jet. I think that what the non-oilheads have to realize though is that the levels of FAME that can cause a problem are in the parts per million range. There is no field test yet (maybe next year) for FAME: at the moment specialized Gas Chromatography/mass spectrometry is the only way to be certain. There is no re-test done at the airport for FAME after transit, and none of the standard ASTM tests detect FAME (eg D-1655). The only way to be sure is to downgrade the interface slug and then some. There were some trials at CDG last year and it was astounding to me the amount of Jet that had to be downgraded before it was classed as "clean". I still think that AAIB should state whether they tested for FAME or not.

Its all very well saying "we didnt find any contaminants" but if there's a contaminant you were not expecting, you wouldnt test for it, would you, so how would you know?

See, thats the bit that really worries me because back last year there was only one test for FAME (GC/MS) so I know - bein' a kemmist an' all - that we are not looking at the same test. If the Chevron letter is correct and that even now there is only a handful of labs that can test for FAME at the moment, which of these "handful" were the 66 fuel samples sent to?

Question? Would Fatty acid methyl ester be a danger at any level? With its sticky propensity, wouldn't 1ppm be too much? Seems to me 038 fuel testing results entertained that 70ppm water was cumulative, and could be a problem regardless the presence or not of atmospheric moisture or lack of sumping over time? I recall they pointed out that even very small amounts of water was a problem, because so little was known of fuel performance at very low temps due to ETOPS, etc.?

Is the industry then actually trying to allow some amount of this contaminant in the test simply because it "is too expensive to maintain isolated piping and production storage"??

FAME
 

But...

My understanding is that FAME is a component used in automotive gas oil (diesel), in markets where there is, for whatever reason, a need to use renewables.

Pinkman and others are quite right about multi-product pipelines, and I know that there are all sorts of concerns about aviation fuels passing thus, particularly where there are fuels containing renewable components passing along the same line; even if it's pigged, as pointed out, the piggies are not fool- (or leak-), proof.

And the but is... does anyone know if there is any likelihood that the Chinese market is using renewable components in their diesel or other fuels? I'd have guessed not, but it's a while since I have been there, and the one thing that one can say about China is that change is rapid... or, was there a period when the fuel supplied at Beijing was from an 'unusual' source (perhaps cargoes brought in by sea), and there might have been contamination from such a component introduced, e.g., from a product tanker?

GemDeveloper

Thats the $64K question. China does use biodiesel but until recently it was primarily a bioethanol market. In 2006 it was the third largest producer of bioethanol in the world.

Will

I realize I wont convince you that the industry isnt trying to "get away" with leaving the maximum amount on FAME in Jet. But the fact is that every critical aviation activity is subject to a balance of risk and cost with an adequate safety margin thrown in. A main spar is designed as a trade off considering weight, design strength, manufacturing techniques etc. Fuels are no different. For airlines, fuel as an input cost has gone from 13% to 40% in seven years. The Jet demand has gone up by two and a half times since the 1970's. There is no way the latter can be sustained without using MPP's without also making the former even worse. Dedicated lines are not an option and MPPs are here to stay. However avoiding FAME contamination means that 50% extra buffer volumes of Jet have to be "thrown away" (transmix volumes sent for reprocessing) to ensure "FAME free Jet" (<5ppm). This extra cost is of course reflected in the cost of the fuel. Yet 5ppm is actually arbitrary, because its currently set at the level of detection. There is currently no agreement on at what level FAME becomes an issue in Jet although some say 400ppm. Changing the specification to a more practical limit gives two advantages: firstly it gives the airlines a break on costs. Secondly, it becomes possible to develop a field test that can be used at that lower level of sensitivity without having to have a PhD analytical Chemist at each airport. The trick is to establish the balance of cost and risk in the right place. And that hasn't happened yet.

AD Issued...
 

Airworthiness Directive for replacement of FOHE issued here: EASA Airworthiness Directives

Excellent solution. Now, remind me, what was the problem that was definitively replicated?

I have been reviewing this thread for several hours. I found this post amongst others, but it has a premonition I thought interesting.

15 May 2008 #1151 (page 58)

Will


Pinkman Not so 'excellent' Eh? If the new FOHE is a fuel heater as well as an oil cooler, (as the original part is not), not so bad, but.......

Will
 

My understanding is that the problem is yet to be replicated. If it is AFM's theory of accretion of solids at low temperature followed by blockage on demand then the mod will clearly help. But I find it extraordinary how someone can propose and start to implement a solution - especially one costing presumably a huge amount of money - in the absence of a clear problem definition.

How very British.

"Dammit man - don't just stand there! Do something! Anything!"

Not so much British, more "international politician". See:- Politician's syllogism :ok:

:suspect:

RTFM
 

Excellent! :}

Nearly eighteen months on, the "solution" appears to be "melting the ice"?

Bravo ? Arse about. Why not keep the ice out of the fuel, after FIRST addressing that as the problem itself. "Previously unknown characteristics of fuel at very low temperatures?" Using an oil cooler to melt ICE that is NOT supposed to be present in the first place? For a pilot, any one peeping the pictures of ice clogged fuel lines, reading the "AD" has to be perplexing.

Pinkman, taking note of the ice build up, do you conclude the ice derives from "in spec" fuel giving up its soluble water content in long duration cruise to block crucial lines at the engine? Because that's where I am. In your experience, isn't a simpler explanation poor fuel handling? As in, tanking, sumping, pumping, storing, etc.? Is it really the Trent or are other installs vulnerable?

As AFM said, "It's the Fuel".

Will,

See my post 2443. It is only the Trent based on a tiny sample of three engine rollbacks on two flights. No-one knows how many times other power plants have been hit with enough ice to almost (but not quite) cause problems.

Watch this space.

Sooty