As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD INFLIGHT T564/30MAY. AT FLIGHT LEVEL 310 PRESSURIZATION FLOW LIGHT ILLUMINATED AND THE CABIN ALTITUDE WAS CLIMBING AT 300 TO 500 FEET PER MINUTE. DECLARED AN EMERGENCY AND BEGAN A DESCENT. DURING DESCENT CREW TURNED ON ANTI ICE TO THE TAIL AND THE PRESSURIZATION RETURNED TO NORMAL. LANDED ORD WITHOUT INCIDENT. REPLACED BLOWN DUCT IN RIGHT AIR CONDITIONING PACK SYSTEM. SYSTEM GROUND CHECKED NORMAL OPERATION. (A)