As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 4211 - GREEN SYSTEM HYD LOW LEVEL WARNING CAME ON AFTER TAKEOFF. AIRCRAFT RETURNED TO ORD AND DECLARED EMERGENCY AND LANDED SAFELY. MAINTENANCE FOUND THE HYD T-FITTING HAD FAILED. REPLACED T-FITTING AND SERVICED HYDRAYULIC SYSTEM. AIRCRAFT WAS RETURNED TO SERVICE. (M)