As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE A/C IN CRUSE FLIGHT LOW ROTOR HORN CAME ON. ROTOR RPM INDICATED (0). WHEN PILOT LOWERED COLLECTIVE, HE HAD NO HYDRAULIC PRESSURE. A/C LANDED AND MAIN ROTOR CONTACTED TAILBOOM. ON REMOVAL ROTOR TACH GEN DRIVE SHAFT INTERNAL SPLINES WERE FOUND TO BE WORN TO THE POINT OF DISENGAGEMENT.