That will depend on whether centre tanks are new type or old. In new design centre tank cannot feed engines directly. It will have to be through inner tanks only. Center tank fuel keeps emptying into inner tanks automatically when the inner tank fuel reaches the under full sensors. It can also be controlled manually with mode selector in MAN. In the old design the centre tank will not drain into inner tank but feed the engine directly itself first anyway. There is no question of overflow.
Last edited by vilas; 17th Jan 2020 at 07:14.