As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TURBO CHARGER FAILED AT 450 HOURS. INVESTIGATION POINTS TO THE POSSIBILITY OF A RESTRICTED CHECK VALVE AT TURBO OIL PORT INLET, PREVENTING PROPER OIL FLOW TO THE TURBINE. VALVE HAS NOT BEEN DISTURBED, AWAITING FURTHER INVESTIGATION BY OUTSIDE AGENCY IF DESIRED.