As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON SHUTDOWN HEARD LOUD CLUNK FROM REAR OF CABIN AT APPROXIMATELY 100 RPM, PULLED ROTOR BRAKE. UPON INSPECTION NOTICED THAT THE PULLEY SYS TO HYDRAULIC PUMP WAS MISSING. LOCATED PULLEY AT REAR OF FIREWALL AS NOTED IN PICTURES. NO EFFECTS, ABNORMALITIES ON ANY FLIGHT CONTROLS THROUGHOUT FLIGHT. IT APPEARS THAT THE FITMENT OF THE PULLEY TO THE BEARING WAS LOST, TOO LOOSE AND THIS CAUSED THE RETAINING CLIP TO FAIL.