As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OIL PRESSURE & POWER LOSS DURING CLIMB, PASSING FL40, A MASTER WARNING OCCURRED WITH OIL PRESSURE LOSS AND TORQUE DROPPING TO ZERO. ENGINE WAS SHUT DOWN AND SECURED BEFORE THE ACFT RETURNED TO THE POINT OF DEPARTURE FOR AN UNEVENTFUL SINGLE ENGINE LANDING. POST FLIGHT INSP REVEALED A TOWERSHAFT FRACTURE. ENGINE WILL BE REPLACED.