As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED DUAL UNANNOUNCIATED PACKS/PRESSURIZATION FAILURE DURING CLIMB OUT. RESULTED IN EMERGENCY DESCENT AND AIR RETURN. MX FOUND A BLOWN DUCT ON PACK 1 AND RESECURED DUCT TO HEAT EXCHANGER WITH PACK 1 OPS CHECK SUCCESSFUL. PACK 2 OPS CHECKED SUCCESSFUL. ACFT PRESSURIZATION CHECK GOOD. ACFT APPROVED FOR RETURN TO SERVICE.