As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN ALTITUDE UNCONTROLLABLE IN STBY MODE. CABIN ALTITUDE 10,000 AT FL220. CABIN ALTITUDE CONTROLLABLE AFTER DESCENT INITIATED TO 10,000 FEET. REPLACED FWD OUTFLOW VALVE, ALSO FOUND CLAMP ON RH HEAT EXCHANGER BROKEN AND REPAIRED. OPS AND PRESSURE CHECK NORMAL.