SyEng,
Quote:
"This seems rather a lot of water. Are you sure?"
Yes, i am sure. G-YMMM is a B777-236 ER with a large center tank. The centertank carries a huge amount of fuel, approx. 176,400 lb (26,100 gallons).
The original B777-200 has small center tanks (near left and right wing root only, not in the fuselage/wing center section). Its capacity is approx. 83,800 lb (12,400 gallons). In the B777-200, the center tank message is shown at approximately 14.5 gallons.
Water detectors are ultrasonic devices. The FQPU sends signals to the water detectors. The water detectors send a puls to the bottom of the tank. If there is water at the bottom of the tank, the pulse reflects off the boundary layer between water and fuel. I think there is a minimum layer of water required before water can be detected. Since the large (ER) center tank has a large relatively flat surface area, it is not surprising there is a larger amount of water present before it can be detected.
Last edited by Green-dot; 21st Feb 2008 at 23:53.