I noticed that the new A320's in our company got the same fuel system as the A321 so with the transfer valve for the center tank. What is the whole idea behind this system? I know we dont need the center tank pumps anymore and fuel is being fed to the inner tanks by suction but why? Saves a few bucks and weight but I cant imagine that it is the only reason. It is also not very clear if this fuel can be used i.c.o. gravity feeding. Maybe someone that knows this system can clarify these things. Thanks guys