As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN)DURING FLIGHT, YELLOW HYDRAULIC SYSTEM LOW PRESSURE INDICATION. AIRCRAFT RETURNED TO BASE FOR MAINTENANCE. INVESTIGATION REVEALED PRESSURE RELIEF VALVE LEAKING DUE TO DETERIORATION OF SEALS. HYDRAULIC SEALS REPLACED AND LEAK CHECKED CARRIED OUT IN ACCORDANCE WITH MM 05-51-11.