BA Crash Landing at Heathrow caused by ice in fuel?

shamwari

Have a read of this

http://news.bbc.co.uk/2/hi/uk_news/england/london/7598267.stm

They think that ice in the fuel "probably" caused the 777 to crash land at the threshold of the runaway at Heathrow back in January.

Foggy43

This has been suspected since very early in the investigation. Again the issue is raised that this 'problem' is happening with Rolls Royce Trent engined 777's only.

Rumour control in BA has heard nothing new.

Our man in Havana

How on earth would fuel freeze?

tracker-man

At high altitudes its cold. Fuel=Liquid. Freeze.

Thats my understanding of it anyway

Our man in Havana

That should not happen with a modern aircraft.

tracker-man

damn right it shouldn't

Foggy43

Fuel will freeze but turns to a gel. Jet A1 around most of the world will start freezing at -47C. In America, their Jet A1 will start freezing at -40C.

Aircraft in winter arriving LHR from the USA with -40 fuel in tanks must have all this fuel transfered to the Centre fuel tank (CWT). This is so it gets used first. This is only required when polar routes are the next sector. Some LHR NRT flights route over the North Pole.

If the fuel had frozen the engines would have died. There is the problem of water drops suspended in the fuel and this freezing thus causing a possible blockage. But both engines coming down with this at the same time? I suppose there is a remote possibility.

Our man in Havana

Do they not preheat the fuel?

Foggy43

Fuel is used to cool the engine oil but this takes place at the high pressure end, on the engine.

Foggy43

Anyway here is was the investigators are saying at the moment!

http://www.aaib.dft.gov.uk/cms_resources/G-YMMM%20Interim%20Report.pdf
The same link as on the BBC News report!

vulcan57

On Sky news there was an aviation "expert" that said that there is always some condensation / water droplets that build up in fuel tanks. The water, being heavier sinks to the bottom of the fuel tanks and is usually below the outlet pipe for the fuel. Because this particular flight flew over part Siberia, I think, where it was unusually cold, that caused the water to freeze. There are, apparently, heaters for the tanks but they cannot cope if there is a breakaway chunk of ice, that is probably what happened in this case. Not my version of this but just what was being said on sky news.

*Kol*

vulcan57 wrote: »

On Sky news there was an aviation "expert" that said that there is always some condensation / water droplets that build up in fuel tanks. The water, being heavier sinks to the bottom of the fuel tanks and is usually below the outlet pipe for the fuel. Because this particular flight flew over part Siberia, I think, where it was unusually cold, that caused the water to freeze. There are, apparently, heaters for the tanks but they cannot cope if there is a breakaway chunk of ice, that is probably what happened in this case. Not my version of this but just what was being said on sky news.

I dont know about heaters in the tanks. But normally there would be scavenge pumps at the lowest point of the tanks that feed any water to the pump inlet and into the engines to be "burned". The idea behind this is that the water doesn't get a chance to build up in any great quantity as its always being drained away from the lowest point of the tank.
The other thing that prevents a build up of ater is draining the fuel tank sumps during the daily check. There is a drain at the lowest point of the tank and the water is manually drained into a receptacle.

There is always entrained water in the fuel which may have frozen in this case. It's the amount of it that would be worrying if there were chunks of ice present. The refuellers are supposed to check the water content in the fuel.

barnicles

vulcan57 wrote: »

On Sky news there was an aviation "expert" that said that there is always some condensation / water droplets that build up in fuel tanks. The water, being heavier sinks to the bottom of the fuel tanks and is usually below the outlet pipe for the fuel. Because this particular flight flew over part Siberia, I think, where it was unusually cold, that caused the water to freeze. There are, apparently, heaters for the tanks but they cannot cope if there is a breakaway chunk of ice, that is probably what happened in this case. Not my version of this but just what was being said on sky news.

Was that eric moody?

vulcan57

barnicles wrote: »

Was that eric moody?

Could well have been.