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Old 1st Apr 2017, 23:49
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tdracer
 
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The 777 accident was not due to cold/freezing fuel as such - the fuel in the tanks, while quite cold, was still comfortably above the fuel freezing temperature.
The problem was WATER ice that formed on the heat exchanger. As noted earlier, the Rolls heat exchanger was redesigned to prevent water ice formation.
All Boeing aircraft have a passive 'sumping' system that draws fuel from the lowest point in the tanks (where water would accumulate) and sprays it in the vicinity of the fuel pump inlets. This is intended to prevent significant accumulation of water in the fuel tanks.
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