As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL330, CABIN ALT WARNING HORN SOUNDED. PRESSURIZATION WAS IN AUTO AND OUTFLOW VALVE INDICATED FULL CLOSED. SWITCHED BOTH PACKS TO HIGH AND STARTED DESCENT. AT FL280, CABIN RATE SLOWED. DURING TROUBLESHOOTING OF CBN PRESSUR IZATION PROBLEM, FOUND RT PACK NOT OPERATING WHEN SWITCHED TO ON . SFOLM BRENDEL. REPLACED ACM AND RPL RT PACK VALVE PER MM 21-51-11..OPS CK GOOD..