What was found
REAR SPAR SEVERELY CORRODED UNDER STEEL ATTACH PLATES, P/N 66762-00. DAMAGE WAS FOUND WITH A FLASHLIGHT AND MIRROR, LOOKING AT THE FORWARD SIDE OF THE SPAR THROUGH THE INBOARD RIB LIGHTENING HOLES AND WAS SO FAR PROGRESSED THAT THE EXFOLITATION PROCESS HAD BULDGED AND SPLIT THE SPAR MAKING IT VISIBLE FROM INSIDE THE WING. NO EXTERNAL CORROSION WAS NOTED DUE TO A SIX YEAR OLD PAINT JOB. STEEL PLATES ON FUSELAGE CARRY-THROUGH STRUCTURE ALSO REMOVED TO REVEAL SIMILAR CORROSION WHICH WAS LESS SERVERE.