As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND LEFT AND RIGHT ENGINE SUPPORT STRUCTURE TO BE EXCESSIVELY CORRODED WHERE ENGINE BEAMS INTERSECT CANTED BULKHEAD. RIVET TAILS WHERE FLAKING OFF WITHIN BULKHEAD (THIS NORMALLY CAN NOT BE SEEN BY VISUAL INSPECTION THIS CONDITION WAS DISCOVERED DURING DISASSEMBLY. SB LED TO THIS DISCOVERY. LT AND RT ENGINE SUPPORT STRUCTURES HAD TO BE REPLACED.