As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT WAS ON HIS INTENDED ROUTE AND NOTIFIED OPERATIONS BASE THAT HE WAS TURNING AROUND AND THAT HAD LOST HYDRAULIC ASSIST TO FLIGHT CONTROLS. RETURNED TO BASE AND LANDED WITH NO INCIDENT. MAINT FOUND THAT THE HYDRAULIC PUMP SPLINES HAD FAILED AND REMOVED AND REPLACED WITH A SERVICEABLE PUMP. AC HAS BEEN RETURNED TO SERVICE. (K)