As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON LANDING, 6 MILES OUT APPROX. THE AC STARTED SHAKING VIOLENTLY. AFTER A COUPLE SECONDS THE RIGHT TORQUE GAUGE STARTED TO FLUCTUATED BETWEEN 60 PERCENT AND 20 PERCENT TORQUE. SHUT DOWN RIGHT ENGINE AND VIOLENT SHAKING STOPPED. LANDED WITHOUT INCIDENT. SHUTDOWN THE RIGHT HAND ENGINE FOR VIBRATION. FOUND THE FORWARD YOKE EAR HAD BROKEN OFF ON THE PROPELLER HUB. VISUAL INSPECTION INDICATES THAT A PREVIOUS MANUFACTURING DEFECT OR CRACK EXISTED IN THE HUB.