What was found
EN ROUTE AT FL250, RECEIVED A RT WING TANK OVER FILL EICAS MESSAGE. VISUALLY CONFIRMED VENTING FUEL. ACCOMPLISHED CHECKLIST & VENTING STOPPED. REMOVED FUEL BAY ACCESS PANELS TO O/B VENT FLOAT VALVE AND CLIMB VENT PLUMBING. FOUND O/B VENT FLOAT VALVE DAMAGED AND CHAFED. VISUALLY INSPECTED FLAPPER VALVE AND VENT PLUMBING. NO DEFECTS NOTED. REMOVED O/B VENT FLOAT VALVE. INSTALLED NEW O/B VENT FLOAT VALVE IAW MM 28-10-04. VERIFIED VENT IS CLEAR OF ANY OBSTRUCTIONS. INSTALLED ALL FUEL BAY ACCESS PANELS. LEAK CHECK AND OPS CHECKS GOOD. VERIFIED CHECK GOOD.