As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ROTORCRAFT EXPERIENCED UNUSUAL VIBRATION. REMOVED MAIN ROTOR BLADES FOUND UPON VISUAL (BY FEEL) SPINDLE BEARINGS WERE ROUGH AND BRINELD. FACTORY STATES THIS IS CAUSED BY MAIN ROTOR OVERSPEEDS. IF AIRCRAFT/ROTORCAFT EXPERIENCES UNUSUAL VIBRATION TO CHECK SPINDLE BEARINGS FOR CONDITION.