RBF: Good questions. I was an analytical chemist for about 20 years up to the 90's - all over the world, and have done many assays of Jet A-1. If you run through the last thread and look at the discussion between Tubby Linton, myself and Moggiee, (before the latest AAIB report) you pretty much have it. It was so crashingly obvious to all of us then and it is even more obvious now that the 8 seconds differential has been revealed. The incident was fuel and temperature related and if you look at Belgiques' post I think he's more or less got it right (can we call them wax crystals, not globules, because they have the behaviour of crystals).
If you live in the UK you will know that if you have water running through a pipe, it is unlikely to freeze. You also know that if your pipe to your sink goes outside before coming inside again, when you open the tap, you will get a small spurt of water...then nothing or a trickle. If that trickle is left for long enough, then the ice in the pipes melts and you get flow back again.
Wax crystals form easily but it takes an increase in temperature and also motion to resolubilize them. There was sufficient fuel flow during cruise to prevent blockage (ice,wax, or both). during the decent, there was not.
When the increase in thrust was commanded, there was initially enough fuel to cause a small increase in thrust, then there was not. There was insufficient time to resolubilize the crystals during the decent.
It doesn't necessarily mean - in fact its unlikely - that the fuel was off-spec by the way. If I am right, this may be a landmark event that forces a re-evaluation of Jet A/A1 specs. If I am wrong, I promise to kiss Dannys left buttock.
Pinkman
Last edited by Pinkman; 26th Jan 2008 at 19:18.