As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 1808 -ATB- RETURN TO GRU DUE TO CTR HYD SYSTEM QUANTITY DECREASE AFTER TAKEOFF. CORRECTIVE ACTION: C/W OVERWEIGHT LANDING INSPECTION. FOUND BROKEN UNION ON CTR HYD SYSTEM PRESSURE RELIEF VALVE. REPLACED RELIEF VALVE UNION, LEAK CHECK GOOD. (5328876)