What was found
CREW REPORTED A RIGHT HAND BLEED DUCT MASTER WARNING MESSAGE DURING CLIMBOUT. CREW ELECTED TO RETURN TO CLT AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND FOUND THE O-RING DAMAGED ON THE FLANGE FROM THE RIGHT HAND PACK HEAT EXCHANGER TO THE ACM CONNECTION. MAINTENANCE REMOVED AND REPLACED THE O-RING IN ACCORDANCE WITH THE AIRCRAFT MAINTENANCE MANUAL. OPS CHECKS GOOD AT THIS TIME. AIRCRAFT WAS RELEASED FOR SERVICE.