What was found
CREW REPORTED PACK 1 AND 2 FAILED IN FLIGHT AND A BAD ODOR AFTER SELECTING. RESET PACK 2 CREW CONTINUED TO DESTINATION WITH PACKS DEACTIVATED AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE ACFT AND FOUND THE "Y" DUCT BETWEEN THE PACK VALVE AND DUAL TEMP CONTROL VALVE TO BE CRACKED AND HAVE A BLOWN DUCT. MAINTENANCE R & R THE AFFECTED "Y" DUCT, RECONNECTING THE BLOWN DUCT IN THE PROCESS, OPERATIONALLY TESTED THE NR 1 AND 2 PACKS WITH NO DEFECTS NOTED, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.