What was found
FLIGHT 1171, BWI-CLT - THE FLIGHT REPORTED A PRESSURIZATION PROBLEM AFTER TAKEOFF FROM BWI. THE CREW ADVISED, HAD A CABIN ALT HIGH LIGHT. MAINTENANCE PERFORMED A SATISFACTORY CHECK OF THE PRESSURE CONTROL SYSTEM AND THE AIRCRAFT RETURNED TO SERVICE. AFTER TAKEOFF A SECOND TIME BOTH PACKS WERE LOST MOMENTARILY AND RETURNED TO NORMAL OPERATION. THE CREW RETURNED TO BWI A SECOND TIME. MAINTENANCE FOUND BOLT MISSING FROM RIGHT RAM DUCT SUPPORT BRACKET. ALSO REPLACED THE AIR CONDITION CHECK VALVE AND RECIRCULATION FILTERS.