As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT PILOT LOST HYDRAULIC POWER TO FLIGHT CONTROLS AND PERFORMED AN UNPLANNED LANDING AT AN AIRPORT. DURING MAINTENANCE INVESTIGATION IT WAS FOUND THAT THE SPLINES IN THE TACHOMETER GENERATOR DRIVE THAT DRIVE THE SHAFT FOR THE HYDRAULIC PUMP HAD FAILED.