As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE INSPECTION, LOOSE RIVETS WERE FOUND IN THE TOP PLATE CURBED AREA AFT OF THE ENGINE IN BOTH MOUNT BEAMS OF LEFT ENGINE. SOME RIVET HEADS HAD FRETTED INTO THE SURFACE OF THE PLATE. THE SUSPECTED CAUSE WOULD BE A VIBRATION IN THIS AREA. AN ENGINEERING APPROVED REPAIR WAS MADE AND AIRCRAFT RETURNED TO SERVICE. (X)