What was found
(CAN) FLIGHT CREW REPORTED, LEFT HAND BLEED DUCT WARNING, THEN CHANGED TO LT BLEED DUCT CAUTION MESSAGE, LEFT PACK OFF. QRH ACTIONED. LT BLEED SELECTED OFF, LT BLEED DUCT WARNING RETURNED AGAIN WHEN POWER APPLIED TO CLIMB, RT BLEED SHUTDOWN & STARTED LOSING PRESSURIZATION. A/C RETURNED TO AIRPORT. MAINTENANCE TROUBLESHOOTING IDENTIFIED A RUPTURED BLEED CROSSOVER DUCT AS THE CAUSE. BLEED DUCT TO BE REPLACED IN ACCORDANCE WITH THE APPLICABLE AMM REFERENCE.