According to the diagram provided in an earlier post (sorry - can't find it at the moment) the centre tank fuel scavenge outlet is at the outboard (high) end of the main tank. To get to the engines any water scavenged from the centre tank at this stage has to find its way back down to the main tank water scavenge pump which moves it to near the boost pump inlet.
(see post 461 Page 24 )
Last edited by Rightbase; 5th March 2008 at 20:26.
Reason: Found it!