As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE OPERATING ON RT PACK, A/C CABIN ALTITUDE REACHED 9800 FT AND CONTINUED TO CLIMB UNTIL DECENDED TO 10,000 FT. AT 10,000 FT CABIN STABILIZED AT 1.0 PSI/8000 FT, IN BOTH AUTO AND MAN MODE. DEFERRED PER MEL 21-16-1C. RT OUTFLOW VALVE REMOVED AND A/C FLEW UNPRESSURIZED DMI 2273. REINSTALLED OUTFLOW VALVE AND PRESSURIZED A/C. FOUND NORMAL AFTER LT ACM AND REPOSITIONED DISTRIBUTION LEVER. THIS CLEARS DMI 2273.