As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND CABIN PRESSURE OK TO 12,000, THEN COULD NOT MAINTAIN CABIN PRESSURE IN AUTO OR MANUAL. TROUBLESHOT AND REMOVED AND REPLACED RIGHT PACK VALVE P/N P4271 IN ACCORDANCE WITH MAINTENANCE MANUAL 21-510. REMOVED AND REPLACED OUTFLOW VALVE P/N 127365 IAW MM 21-32-0 OPERATIONS CHECK NORMAL. (M)