What was found
OWNER NOTED SOME DETERIORATION ON THE WING FLAP TRACKS. UPON CLOSER INSPECTION, THE TRACKS WERE NOTED TO HAVE SIGNIFICANT CORROSION. REVIEW OF THE CESSNA 208 STRUCTURAL REPAIR MANUAL DETERMINED THAT CORRODED AREA WAS WITH IN LIMITS. CORROSION WAS REMOVED AND THE EXISTING MATERIAL WAS TREATED PER THE SRM. FLAP TRACK ASSEMBLIES ARE ALUMINUM AND DUE TO THE NATURE OF THE DESIGN HAVE UNPAINTED AREAS WHERE THE ROLLERS MOVE. IT IS SUSPECTED THAT CORROSION STARTED IN THE ROLLER AREA AND THEN EXPANDED. WE SUGGEST A CHANGE IN DESIGN OF THE TRACK OR USE OF DIFFERENT MATERIAL TO PREVENT OCCURRENCES IN THE FUTURE.AIRCRAFT SPENDS SIGNIFICANT TIME IN COASTAL AREAS WHICH CONTRIBUTED TO THIS CONDITION.