As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED BAD VIBRATION ON FINAL APPROACH. UPON INSPECTION IT WAS DISCOVERED THAT THREE OF FOUR OF THE TOP CYLINDER HOLD DOWN STUDS ON THE NR 3 CYLINDER HAD BROKEN OFF AT THE ENGINE CASE. NO INTERNAL DAMAGE WAS FOUND. CAUSE UNKNOWN.