As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHEN REASSEMBLED 1/2 OF THE SPLIT CONE ASSEMBLY HAD NOT SEATED PROPERLY IN THE GROVE IN THE MAST. MAIN ROTOR MAST NUT TORQUE CHECK WAS CARRIED OUT AFTER 1.3 HOURS OF OPERATION AND TORQUE LOSS WAS NOTED. WHEN DISASSEMBLED AGAIN DAMAGE TO THE SPLINE WAS FOUND. MAIN ROTOR MAST AND SPLIT CONES WERE REPLACED.