As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE FLIGHT THE AIRCREW FELT AN ABNORMAL VIBRATION COME ON ALL OF A SUDDEN. THEY REDUCED AIRSPEED AND LOWERED LANDING GEAR. LANDED BACK AT BASE. UPON INSPECTION AFTER THE ACFT HAD SHUTDOWN, ON OF THE MAIN ROTOR DAMPERS WAS FOUND HANGING FROM 1 END. THE BORE OF THE INBD END OF THE DAMPER WHICH RETAINS THE SPHERICAL BEARING HAD FAILED.