As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, THE ENGINE LOW OIL PRESSURE WARNING ANNUNCIATED AND THE ENGINE WAS SHUT DOWN IN FLIGHT. SUBSEQUENT INVESTIGATION REVEALED THE THE ACCESSORY GEARBOX TOWERSHAFT LOCKWASHER TO BE FRACTURED AND THE TOWERSHAFT RETAINING NUT DISLODGED.