What was found
PDIS 921 21-30 8717 20NOV19 MEM FACT U LOGPAGES:3170064 SAME PROBLEM AS YESTERDAY WITH PRESSURIZATION EXCEPT AUTO 1, AUTO 2 AND MANUAL CONTROL WORKED. HOWEVER THE PRESSURIZATION OF THE AIRCRAFT COULD NOT KEEP UP ABOVE FL 250. CABIN PRESSURE CLIMBED BETWEEN 700'/MIN AND 1000FT/MIN ONCE 10,000' THE PRESSURE WAS ABLE TO MAINTAIN CABIN BETWEEN 0-2000' IN AUTO MODE. FOUND EQUIPMENT COOLING OVERBOARD EXHAUST VALVE FLAPPER BROKEN AND DAMPING FUNCTION OF FLAPPER INOPERATIVE. REMOVED AND REPLACED THE EQUIPMENT COOLING OVERBOARD EXHAUST VALVE REFERENCE BOEING AMM 21-58-05-4. CHECK OF THE OVERBOARD EXHAUST VALVE GOOD. PART NAME: AEROMATIC VALVE. MANUFACTURER: SUNDSTRAND PNEUMATIC SYSTEMS. PART NUMBER: 5669-18. SERIAL NUMBER: 4906.