As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AUS) DURING CRUISE, THE CABIN ALTITUDE CLIMBED SUDDENLY. MANUAL PRESSURIZATION WAS SELECTED AND AN ATTEMPT WAS MADE TO CLOSE THE OUTFLOW VALVE BUT THIS COULD NOT BE ACHIEVED. GROUND TEST FOUND THE OUTFLOW VALVE PN 9023-15703-81 BEHAVED ERRATICALLY.