What was found
DURING CRUISE AT FL360, EN ROUTE FROM CLT TO DFW, THE CABIN ALTITUDE INDICATED A SLOW CLIMB (200 FPM) UP TO 10,000 FEET. THE CABIN ALTITUDE WARNING HORN SOUNDED. CREW DESCENDED AIRCRAFT TO FL300 WITH PACKS IN HIGH. CABIN DESCENDED TO 8,000 FEET AND STABILIZED. FLIGHT LANDED AT DFW WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE FORWARD OUTFLOW VALVE PER MM 21-43-11-004-001. PERFORMED OPERATIONAL TEST PER MM 21-43-11-705-001. TEST OK. PERFORMED PRESSURE LEAK TEST PER MM 05-51-91-702-01. TEST OK.