As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT CREW REPORTED THAT THE CENTER HYDRAULIC SYSTEM WAS LOOSING QUANTITY AND WOULD LIKELY BE EMPTY UPON ARRIVAL INTO ORD. CAPTAIN DELCARED EMERGENCY AND LANDED WITHOUT INCIDENT. TROUBLE SHOOTING FAULTY/LEAKING DELTA-P AT PRESSURE AND CASE DRAIN FILTER AC MOTOR PUMP C2. REPLACED DELTA P ASSEMBLY PER AMM 29-11-18. OPERATIONS AND LEAK CHECK GOOD. AC OK FOR SERVICE. AIRCRAFT WAS GROUNDED.