Hydroman
I have the schematics for both the Trent and GE somewhere in my computer, and I acknowledge your comment re: Boeing's note that RR has no upstream inflow of discharge from the Spill Valve. Another poster suggested that beyond the added heat issue of HP passage, the gears would additionally masticate any solid Ice in fuel that had passed through the tube matrix of the HE.
The salient question becomes, If this process ('Spill', 'Mixing') mitigates Fuel Ice in any way and remains unaddressed relative to upgrading the Trent, well, is the AD a "Palliative", mechanically and politically? Airfoilmod was on about re-engineering the architecture as well as the FOHE, and SmilinEd suggested Fuel Heat, a process Boeing has utilized in a/c that fly to 60k feet routinely. Severing the protruding tubes at the face sheet amounts to a "Subtraction", indicating that nothing new has been added to this system, and no substantial change has occurred.
In addition I would add that removing the extra length of the tubes eliminates an (inadvertent?) nesting area for some amount of ice accumulation of the type identified by Boeing as "Migratory". In this sense, I would suggest that the FOHE performance has been actually degraded relative to Fuel Icing caused rollback.
bear
Last edited by bearfoil; 21st Jan 2010 at 15:01.