As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO ORD DUE TO THE FLIGHT CREW REPORTING A GREEN HYDRAULIC SYSTEM LOW PRESSURE ECAM ASSOCIATED WITH GEAR RETRACTION - THE FLIGHT CREW REPORTED THAT THE LANDING GEAR DID NOT RETRACT AND THAT THE GREEN HYDRAULIC SYSTEM PRESSURE WAS AT ZERO WHILE THE YELLOW AND BLUE HYDRAULIC SYSTEM PRESSURES WERE AT 3000 PSI - THE FLIGHT CREW ACCOMPLISHED THE QRH CHECK LIST AND LANDED SAFELY AT ORD WHERE THE AIRCRAFT WAS TOWED TO THE GATE. (OPEN)