As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE, FLUID LOSS FROM THE #1 HYDRAULIC SYSTEM. AIRCRAFT RETURNED TO THE POINT OF DEPARTURE. MAINTENANCE INVESTIGATION DISCOVERED A DAMAGED O-RING ON THE #1 HYDRAULIC MANIFOLD. THE O-RING WAS REPLACED, RETURN TO SERVICE ACTIONS WERE CARRIED OUT AND THE AIRCRAFT WAS SUBSEQUENTLY RELEASED FOR SERVICE.