As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A 2 YEAR INSPECTION, LEVEL 2 CORROSION WAS FOUND ON THE T-FITTINGS ATTACHING THE RIBS TO THE SPAR. THE FITTINGS AFFECTED ARE LOCATED AT THE I/B, O/B HINGE POINTS. THE PROBABLE CAUSE IS DISSIMILAR MATERIALS (STEEL BOLTS IN ALUMINUM ALLOYED FITTINGS (2024T351). THE FITTINGS WERE REPLACED AT RIBS 4, 11/12, AND 9. REFERENCE ATR42 SRM 57-61-10 FIG 101.