What was found
ON FLIGHT 4431 THE CREW REPORTED THAT WHILE LEVEL AT 31,000 FEET STARTED TO GET SMALL PRESSURIZATION BUMPS. BEGAN A PRECAUTIONARY DESCENT DURING WHICH CABIN RATE SWINGS BECAME MORE EXTREME. FOLLOWING AIRCRAFT OPERATING MANUAL PROCEDURES, SELECTED MANUAL MODE ON THE PRESSURIZATION CONTROL BUT THIS APPEARED TO HAVE NO EFFECT. THE CREW DESCENDED TO 10,000 FEET AND DUMPED CABIN PRESSURIZATION PER THE AIRCRAFT OPERATING MANUAL. THE AIRCRAFT LANDED WITH NO INCIDENT AT DESTINATION. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED PNEUMATIC OUTFLOW VALVE IAW EMB-140 AMM 21-31-04. THE OPERATIONAL CHECK WAS GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.