What was found
FLIGHT CREW REPORTED A PRESSURIZATION AUTO FAIL MESSAGE WHILE CLIMBING THROUGH FL270. CREW ALSO REPORTED THAT THE CABIN ALTITUDE WAS ALSO CLIMBING. THE PASSENGER OXYGEN GENERATORS WERE DEPLOYED AND THE AIRCRAFT DESCENDED TO FL100. THE AIRCRAFT LANDED IN MKE WITHOUT INCIDENT. MAINTENANCE REPLACED THE DIGITAL PRESSURE CONTROLLER ALONG WITH BOTH OUTFLOW VALVES AND THE MANUAL PRESSURE CONTROLLER AS A PRECAUTION AND A TORN DUCT BOOT ON THE NR 2 PACK WAS ALSO REPLACED BUT WAS UNRELATED TO THE EVENT. THIRTEEN PASSENGER OXYGEN GENERATORS HAD BEEN ACTIVATED DURING THE FLIGHT AND REQUIRED REPLACEMENT.