'Ice in fuel' caused BA jet crash

[Captain Nemo]

See http://news.bbc.co.uk/1/hi/england/london/7598267.stm

Doesn't sound right to me. Any views?

Nemo

[sharkbit]

Very possible.

I've been an aircraft mechanic in the US for the past 20 years.

I know that, at least in the US and probably in most places in the world, an additive called Prist is put in the fuel to help prevent the formation of ice in the fuel. If the fuel vendor wasn't putting this in the fuel or something like that, that may contribute to it.

"Water in the fuel is controlled by draining it regularly out of the fuel tanks - and on the Boeing 777 a so-called "scavenge system" pumps it out. "

I'm not sure about a "scavenge system" to pump the water out. I've never heard of a dedicated system to pump water out of fuel-I don't see how that would work. There are scavenge pumps in fuel tanks to pump the fuel to a collector tank or to the engines but nothing to pump water out of the fuel. However, I am not familiar with the 777 systems, so maybe there is something like that but it just doesn't make sense.

I suppose a combination of factors, which usually happens in accidents, could link together and cause the ice to form and cause a blockage-malfunctioning equipment, contaminated fuel, improper sumping of the tanks, etc. Coupled with the extreme cold that the aircraft encountered, all of these and more could do it. Cold can do really weird things to aircraft.

With the level of accident investigation nowadays, they'll do a bunch of tests and be able to determine if ice actualy caused this.

[sharkbit]

One more thing:
I don't know how it is in England, but usually "aviation" and "media" do not mix.
They usually have no clue what they are talking about and the stories are usually pretty full of inaccurate information.

[antikristuseke]

Originally Posted by sharkbit

One more thing:
I don't know how it is in England, but usually "aviation" and "media" do not mix.
They usually have no clue what they are talking about and the stories are usually pretty full of inaccurate information.

It's not just aviation that the media get wrong. Usualy mainstream media ****s up on every subject they try to get technical on. The more detailed their peice the more wrong it usualy is.

[sharkbit]

Originally Posted by antikristuseke

It's not just aviation that the media get wrong. Usualy mainstream media ****s up on every subject they try to get technical on. The more detailed their peice the more wrong it usualy is.

It is kind of scary. You see a subject in the media that you know a lot about and you see how badly they muck it up and you wonder how badly they're mucking up subjects you know nothing about.

[Tinfish]

I often think the same thing.
I'm training to be an aircraft mechanic and where I used to assume the media at least had some idea I now realise most of it is bollocks.

[Captain Nemo]

Thanks for your expert views Sharkbit.

What's interesting is that the report seems to contradict it's own theory by stating that "Water is naturally present in aviation fuel and the investigators believe there may have been as much as five litres within this aircraft's fuel load. But the report says levels of water found in fuel recovered after the 17 January crash were very low for a Boeing 777." This you would think, would lead investigators away from the ice theory.

Also in one of the first BBC reports to come out after the crash, it stated that the planes captain said that all the aircrafts electronics had failed. Would ice cause this?

If ice were the cause and at the high altitudes that jet planes fly, you would have thought there would have been more instances of this type of problem occurring in the past in other aircraft.

Nemo

[sharkbit]

Also in one of the first BBC reports to come out after the crash, it stated that the planes captain said that all the aircrafts electronics had failed. Would ice cause this?

No.

Even if the engines quit, causing the electrical generators on the engines to stop producing power, the aircraft is equipped with batteries which can power all of the essential electrical equipment for a fair amount of time-enough to get the aircraft to an airport and land it.
Aircraft are certified with that eventuality covered. Even if the airplane went totally "black"-no electrical power what so ever-the airplane's control systems should still be able to function and the aircraft should still be able to fly. Difficult-yes.(I wouldn't want to be in that situation!)

If ice were the cause and at the high altitudes that jet planes fly, you would have thought there would have been more instances of this type of problem occurring in the past in other aircraft.

Engines are equipped with fuel heaters that warm the fuel prior to it getting to the fuel control unit on the engine. The fuel is heated by the hot oil from the engine. They don't mix-oil and fuel lines pass close together in a oil-fuel heat exchanger, usually mounted somewhere on the engine.

...been as much as five litres within this aircraft's fuel load.

5 litres isn't much. I don't know how many thousands of gallons(Sorry, I'm an American ) of jet fuel a 777 carries, but 5 litres is a pretty small amount and spread out on both sides, it does seem likely that frozen fuel can cause it.

But, stranger things have happened and different factors may have linked to cause the problem.

[XabbaRus]

I thought with water being denser than fuel it sinks and I'd imagine a scavenge system would pull it out from the bottom, but then if you have 5 litres in a thousands of litres of fuel it would be so dispersed that draining it off would be very difficult.

[jumpy]

Fills me with confidence for my BA flight to canada next week

[sharkbit]

Originally Posted by XabbaRus

I thought with water being denser than fuel it sinks and I'd imagine a scavenge system would pull it out from the bottom, but then if you have 5 litres in a thousands of litres of fuel it would be so dispersed that draining it off would be very difficult.

It does sink to the bottom. But I can't think of a way a scavenge pump will take just the water and not the fuel or somehow seperate the 2 without adding one more complex system.
Again though, I'm not familiar with the 777, so maybe they do have something that can, but I'd be suprised though.

Normally, all aircraft have fuel sump drains in the lowest part of each tank for the purpose of draining water from the fuel. That might be part of the routine maintenance at BA. Who knows, if it is part of their checks, maybe they haven't been doing it.

I work for a charter company in Denver, CO. We maintain Lears, King Airs, Hawker 800's and a couple of Challenger 600 aircraft(biggest airplane we have) and we have a fuel sumping procedure to check for water that we do as part of our departure checks. Normally we'll find some globules of water floating around and those are not normally a problem. It is when the water becomes suspended in the fuel, that is when there can be a problem. There is a test that we then do and there is a limit on how much water can be suspended in the fuel sample. It is a fair amount though before it becomes out of limits.

I've taken a pint sample jar filled 3/4 of the way with jet fuel and filled it the rest of the way with water, mixed and did the test, and it still didn't show out of limits for suspended water. Normally, jet fuel is clear, maybe a slight straw tinge. If there is suspended water in it and you swirl a sample of fuel with suspended water, it is very cloudy. that is whe we normally do the test.