As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING A SCHEDULED INSPECTION THE MAIN ROTOR DRIVESHAFT WAS REMOVED AND INSPECTED. THE DRIVE SPLINES SHOWED EVIDENCE OF CORROSION UNDER THE COATING ON THE SPLINES. ALL SPLINES SHOWED BLACK FLAKES OF THE COATING COMING OFF AND YOU COULD SEE CORROSION UNDER THE COATING.