What was found
DURING SCHEDULED MAINTENANCE INSPECTION, TECHNICIANS FOUND SIGNIFICANT CORROSION ON THE INTERNAL SURFACE OF CERTAIN EXTERNAL FUEL ACCESS PANEL COVERS. IN MOST CASES, THE CORROSION WAS CORRECTABLE PER THE STRUCTURAL REPAIR MANUAL BUT FOUR PANELS HAD TO BE REPLACED DUE TO THE EXTENT OF THE CORROSION ON THEM. CESSNA SERVICE BULLETIN (SB) 750-57-12 WAS INTENDED TO REDUCE THE FORMATION ON CORROSION ON THESE PANELS AND WAS COMPLIED WITH IN OCTOBER 2006. TECHNICIANS CONFIRMED THAT THE NEW FASTENERS (CALLED OUT IN THE SB) WERE INSTALLED AND NO CORROSION WAS NOTED ON THE WING SKIN SURFACES AROUND THE PANELS.