What was found
FLIGHT 5541, LIT TO IAH. ON CLIMBOUT OF LIT THE CREW RECEIVED A CARGO BTL LO CAUTION MESSAGE. THE QRH WAS FOLLOWED AND IT WAS DECIDED TO RETURN TO LIT WHERE THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND A BROKEN DUCT COMING OFF THE LEFT PACK HEAT EXCHANGER THAT HAD CAUSED THE BOTTLE TO DISCHARGE. THE PACK WAS DEFERRED ALONG WITH THE CARGO FIRE SUPPRESSION SYSTEM. THE CARGO BOTTLE WAS REPLACED ON 3/25 IN IAH, AND THE BROKEN DUCT WAS REPLACED ON 3/26 IN SDF WITH NO FURTHER DEFECTS NOTED.