As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(OG5S) DURING 800 HR, 12 AND 24 MONTH INSP, THE MAIN ROTOR DRIVE SHAFT WAS FOUND TO BE WORN JUST ABOVE THE MAIN ROTOR THRUST BEARING. UPON FUTHER INSP, THE WEAR WAS DETERMINED TO BE CAUSED BY THE M/R THRUST BEARING TUBE NOT BEING CHAMFERED IN THE CONTACT AREA. THIS WAS CONFIRMED BY COMPARISON WITH A NEW THRUST BEARING TUBE. MFG HAS BEEN CONTACTED AND MAIN ROTOR DRIVE SHAFT HAS BEEN SENT TO THEM FOR EVALUATION.