Pinkman

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.

Will Fraser

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.

Pinkman

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.

lomapaseo

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"

Will Fraser

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?

Oilandgasman

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.

sooty655

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.

Oilandgasman

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!!!

Pinkman

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?

Will Fraser

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"??

GemDeveloper

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?

Pinkman

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.

RomeoTangoFoxtrotMike

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

Pinkman

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

Will Fraser

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.......

Pinkman

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!"

RomeoTangoFoxtrotMike

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

Pinkman

Excellent!

Will Fraser

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".

sooty655

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