As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT REPORTED TO THE ENGINEER, HIGH FREQUENCY VIBRATION IN FLIGHT. A GRINDING NOISE WAS HEARD DURING SHUTDOWN WHILE THE BLADES WERE SLOWING. TAIL ROTOR DRIVE SHAFT WAS REMOVED FOR INSP AND FOUND THE C172-1 HANGER BRG HAD NO LUBRICATION. THERE WAS NO EVIDENCE OF EXCRETED LUBRICATION AROUND THE BRG SO PROBABLE CAUSE COULD HAVE BEEN A LACK OF LUBRICATION FROM THE FACTORY.