Chambudzi:
I was flying a 747 that morning across Russia and Germany, landing in LHR at 0500am from the Far East. I have never had to decend to a lower FL in order to increase my fuel temperatue in 25 years of jet flying. That particular morning I had to go down for the last hour of cruise to FL250 before my fuel temp began to warm up. Every other jet in my vicinity that day also decended for the same reasons and some were unable to decend as low as requested. IE Qantas, Malasian and Thai Air) There was an unusually cold air mass over S Russia and Germany that day so it could well have been the cause of the 777s problems.
Then I stand corrected and withdraw my refutation.
RRAAMJET:
A question for the kerosene expert above: does increased flow rate in cold-soaked fuel cause a greater propensity for any water particles in suspension to form ice crystals upon hitting the face of a filter or pump casing? ie: if the EEC's commanded more thrust and hence increased fuel flow, could this cause instantaneous increase in ice crystal formation?
I have had it explained to me once that a filter face can cause a multitude of microscopic points of decreased pressure perpendicular to the direction of flow, much as we all learned during fluid dynamics with a varying pipe diameter.
As I mentioned in my post, I am NOT an expert, I just happen to work with solvents, some of which are various types of kerosene. I certainly do not work with them at these extremely low temperatures, in fact I only mentioned it to explain my interest in this angle of speculation. Unfortunately my lack of expertise means I cannot answer your questions without resorting to speculation and guesswork.
