What was found
RT LOWER WING PLANK HAS FRETTING CORROSION AT FUEL TANK ACCESS CUTOUTS, (610AB NOT IN CRITICAL AREA), (640DB, 640EB, 640FB, 650AB, 650CB, 650DB, 650FB, 650HB IN CRITICAL AREA). REPAIRED LOWER WING PLANK FUEL TANK ACCESS CUTOUTS IAW BOMBARDIER REO 601R-57-21-030.