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Old 15th Sep 2007, 22:36
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Monom
 
Join Date: Jan 2006
Location: New Forest
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B757 Fuel problem

This is for the B757 unusual symptoms section (No16).
Just finished Centre Tank feeding. One wing then lost fuel rapidly (100kgs every 2 mins). Daylight, but no visual cues. Will the aircraft fly with one wing tank empty and the other with 6 tons? I was not really prepared to experiment. When 1 ton lost, decided to make an emergency landing at a major airfield just below us. On stand, one wing had lost 1.2 tons. Inspection and engine run produced no fault. Refuelled and prepared to continue, when a junior mech came to me and said he had seen this once before. Origin was Turkey. Fuel density is measured at only one point (so I am told) - unlike the quantity. He suggested that water had come to rest over the density measuring point and the auto refuel cut-out had operated when 6.5 tons was registered. Further - he said - fuel from Turkey often had a higher than normal water content. (I have operated from there for several years and had not noticed this.)
When the wing tank started to feed, the water rapidly movd from the measuring point and the correct density prevailed. Difference in water/fuel density = 20%. Difference in full wing tank contents (6.5t) and 'lost' fuel (1.2t) = 20%. When I suggested this to Quality Control, they flew into a rage - but my shoulders are broad.
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