Tsufang@ci From Taiwan, joined Feb 2002, 39 posts, RR: 0 Posted (13 years 6 months 3 weeks 5 days 15 hours ago) and read 2914 times:
as the 777 maintenance manual said that if u want to transfer fuel u must open the cross valve and make the pump on (the quantity greater one) ,then open the defueling valve and control the refuel valve(on the refueling panel) which in the tank that u want to transfer to and u can make it
but i have a question i've see the fuel system schematic
and in according with the schematic if u make the jettsion system operation u just need to control the refueling valve then u can do the fuel transfer too...(because the jettsion nozzle valve will not open during ground)
could anyone tell me it's possible to do that?
Cdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 25
Reply 1, posted (13 years 6 months 3 weeks 5 days 13 hours ago) and read 2874 times:
From what I know about the sys (or at least what I understand about it) is that when you push arm, the pumps in the L & R tanks operate along with the isol valves. The Ctr Jettison pumps wont operate with activation of the jettison arm sw...u must select them on.
So I suppose you could xfer fuel evenly from wing tanks to the center. But I don't see how you can xfer from left to right/right to left with both pumps with an output pressure on that same manifold.
And if you do turn a ctr pump on, then you've got 3 pump outputs on that manifold.
So I say it depends on the type of xfer you want to do.
If u wanna move 1000 lbs from each tank (L&R) to get 2000 lbs extra in the center (Don't know why you'd do that for any reason other than MX purposes), then you can use the jettison sys. But if you want to xfer from Left to right/rt to left or from Ctr to right or left - it doesn't look possible.