As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND BACKSIDE OF LT WING SPAR CORRODED TO 20 PERCENT LOSS OF MATERIAL NEAR FS 70. CORROSION ALSO FOUND ON RT WING IN SAME LOCATION. CORROSION WAS BETWEEN LOWER SPAR CAP AND SPAR WEB. THE CORRODED AREA IS APPROXIMATELY 48" INBD OF THE AILERON BELLCRANK INSPECTION HOLE. LOWER AFT WING SKIN HAD TO BE UNRIVETED TO ALLOW ULTRASONIC TESTING.