As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT COMPLAINED OF NOISE AND VIBRATION ON SHUT DOWN. INSPECTED MAIN ROTOR HUB, FOUND ROLL PINS ON DROOP STOP FOLLOWER ASSEMBLIES HAD BACKED OUT AND WERE CONTACTING THE LOWER SHOE. THE INTERFERENCE WAS CAUSING THE FOLLOWERS TO BE FROZEN IN PLACE. WHEN THE AIRCRAFT WAS SHUT DOWN AND THE ROTOR BLADES CONTACTED THE ROLLERS. THEY ONLY APPLIED A FORCE TO A FROZEN ITEM. THIS MADE A VERY LOUD NOISE, ALL FOLLOWERS AND BUSHINGS WERE REPLACED AND MFG WAS NOTIFIED.