As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A SCHEDULED A-CHECK VISIT, DAMAGE WAS FOUND TO THE #4 ENGINE OUTBOARD THRUST REVERSER. FURTHER INSPECTION REVEALED THE #4 OUTER FAN EXIT LINER SEGMENT HAD DETACHED FROM THE FAN CASE RING AND DEPARTED THE AIRCRAFT. SUBSEQUENT C-DUCT DAMAGE WAS REPAIRED AND THE MISSING LINER SEGMENT WAS REPLACED PER THE MANUFACTURERS SRM & AMM INSTRUCTIONS.