As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT REPORTED AN AIRFRAME VIBRATION IN FLIGHT. AFTER TROUBLESHOOTING OF ALL AIRFRAME VIBRATION DAMPENING SYS AND MAIN ROTOR DYNAMIC BALANCING IT WAS DISCOVERED THAT THE REAR LT ARIS, TRANSMISSION MOUNT, WAS UNSERVICEABLE WITH NO INDICATION OF FAILURE. THE MOUNT WAS REPLACED AND VIBRATION LEVELS RETURNED TO NORMAL.