HeathrowAirport

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?

Will Fraser

Fewer problems flying cold? Public relations? Guess: both

What's Delta doing?

wiggy

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.

HeathrowAirport

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.

wiggy

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.........

Will Fraser

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

Williams2353

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.

wiggy

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

HeathrowAirport

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.

gtf

Available at http://www.aaib.gov.uk/cms_resources...0%20G-YMMM.pdf

Pinkman

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

Will Fraser

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?

Pinkman

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

phil gollin

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.

.

Pinkman

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

Rightbase

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.

maynardGkeynes

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.

Pinkman

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.

Pinkman

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.

Will Fraser

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?