[Yo-Yo]

The aircraft passed through a region of particularly cold air between the Russian Ural mountains and eastern Scandinavia, although the fuel temperature did not fall below -34°C (-29°F). The fuel on board had a measured freezing point of -57°C.

I wonder if the fuel temp probe only measured fuel temp at one point in the tank, but that a layer of frozen fuel formed against the wing skins (which are also the tank walls.)

Once frozen, the layer of frozen fuel remained frozen until the aircraft lowered into warmer air on final approach. At that point, the frozen fuel released from the tank walls and got sucked into the pump intakes.

Or maybe some water ice at the bottom of the tanks did the same thing.

In either case, by the time the AAIB inspected the tanks and fuel, said frozen fuel or water ice would have long since been melted away.

[DuncanWaring]

Your theory’s roughly the same as mine.

To the best of my recollection, they spent considerable time enroute at outside air temperatures well below -57C.

[RobinOfKingston]

Last winter arrived while my tractor still had some summer formula diesel in it. A nice, cold day began to cause jelling of the diesel and the filter in the sediment bowl clogged. Tractor idled fine, but no power to do any work ‘til I added ‘juice’ to the fuel tank.

[sam_paine]

My thinking exactly.

When they say:

"although the fuel temperature did not fall below -34°C "

...they've already oversimplified the situation beyond resolution.

There's no such thing as one fuel temperature. There's multiple tanks, then what's the temp in the lines? Through various valves? before and after the pumps?

Furthermore, like you said...water/junk in the fuel.....can you say..." Beijing->London flight????"

[Mr. Quarterpanel]

I somewhat agree, I was thinking the same thing. I am troubled by the fact that both engines had the same thing happen at the same time.

It is obvious that the AAIB is also thinking this, but unless both engines are sourced off the same tank, both inlets getting clogged by ice at the same time are pretty slim.

It is likely that ice will be ruled the cause, simply because nothing else was found that could have caused it.

It still is damn strange.