Method and arrangement for sealing a capless fuel tank filler tube

A flapper door (28) is spring biased closed against a valve seat on the underside of a filler tube bulkhead (14) having a refueling nozzle aperture (16). The valve seat has an annular tapered surface (20) and a resilient annular seal (34) on the flapper door (28) contacts the valve seat in wiping engagement. A pneumatic dampener (42) retards the speed of closure of the flapper door (28) onto the valve seat.