What was found
CMH - FLT 2688 - CMH-EWR - AIR TURNBACK, LOSS OF CABIN PRESSURE. CREW DESCENDED TO 10,000 FEET. REMOVED AND REPLACED OUTFLOW VALVE, IAW 21-31-51. REMOVED AND REPLACED CABIN PRESSURE CONTROLLERS NR 1 AND NR 2 AS PRECAUTION IAW 21-31-34. RESTOWED CABIN MASKS. REMOVED AND REPLACED USED OXYGEN GENERATORS IAW 35-23-00. REFERENCE AWXA960337.