What was found
SHIP 0649-PRESS- CABIN ALTITUDE EXCEEDED 10K FEET WHILE AT FL400. AFTER DESCENT TO FL280 & USING MANUAL CONTROL, THE AUTO CONTROLLER MONITORED CABIN ALTITUDE AT 5K FEET. INITIAL CORRECTIVE ACTION: APPLIED MEL. FOLLOW UP CORRECTIVE ACTION (4/18 MSP): REPLACED CABIN PRESSURE CONTROL PANEL, RT PACK FLOW CONTROL VALVE, CABIN PRESSURE OUTFLOW VALVE, BOTH CABIN PRESSURE CONTROLLERS. FIXED RT PACK SUPPLY & LT PACK PRI HEAT EXCHANGER DUCT LEAKS. SINGLE PACK & HULL DECAY CHECKS OK.