What was found
AFTER BEING ESTABLISHED IN LEVEL FLIGHT FOR 20+ MINUTES AT FL260 - AMBER "WING TANK O'FULL R" EICAS MSG DISPLAYED. FOLLOWED CHECKLIST. NOTICED FUEL VENTING FROM RT WING TIP. DEFUELED RT WING TANK, GAINED ACCESS TO AND INSPECTED VENT HOSE POSITION WITH NO DEFECTED NOTED. REPLACED RT WINGS VENT SYS VENT FLAPPER VALVE AND VENT TANK FLAPPER VALVE WITH NEW VALVES. REFUELED TANK; NO DEFECTS NOTED. LEAK CHECK RT WING FUEL PANELS GOOD IAW MM 28-10-01.