As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE INTERNAL TACHOMETER DRIVE SEIZED UP AND SHEARED THE TACH DRIVE PIN. REMOVAL OF THE TACH DRIVE COVER REVEALED METAL HAD PASSED THROUGH THE OIL PUMP. FURTHER INVESTIGATION REVEALED THE NR 5 CYLINDER VALVE LIFTER AND CAM LOBE WERE BREAKING UP AND SCOURED. THE ENGINE WAS REMOVED FOR SERVICE. SUBMITTER SUGGESTS POSSIBLE CAUSE AS DEFECTIVE PARTS INSTALLED IN THE ENGINE AT REMANUFACTURE.