As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) TURBOCHARGER WAS INSTALLED AS PART OF AN OVERHAULED ENGINE. TURBOCHARGER WAS PREOILED AND GROUND RUNS WERE SATISFACTORY. TWO TRAINING FLIGHTS WERE CARRIED OUT PRIOR TO THE FAILURE. PILOT REPORTED FLUCTUATING OIL PRESSURE AND SHUT THE ENGINE DOWN. POST FLIGHT INVESTIGATION FOUND THE TURBINE SHAFT HAD SHEARED ALLOWING THE COMPRESSOR TO DESTROY ITSELF.