What was found
RSW - FLT1052 - DURING CRUISE AT FL250, EN ROUTE FROM CLT TO RSW, A/C LOST PRESSURIZATION JUST SW OF JAX. CREW CAUGHT THE PROBLEM BEFORE THE CABIN PRESSURE DROPPED ENOUGH TO DEPLOY THE OXYGEN MASKS. CREW DESCENDED FLT TO 10,000 FT AND THEN LANDED AT RSW WITHOUT FURTHER INCIDENT. AN EMERGENCY WAS DECLARED. MX REMOVED AND REPLACED THE AFT OUTFLOW VALVE PER MM 21-31-111-4 AND THE FORWARD OUTFLOW VALVE PER MM 21-43-11-4. OPERATIONAL CHECK AND LEAK CHECK GOOD. ALSO, REMOVED AND REPLACED THE LEFT ENGINE PRECOOLER CONTROL VALVE SENSOR PER MM 36-12-45, DUE TO A MEL FOR A DUCT PRESSURE SPLIT. OPERATIONAL CHECK GOOD. REPAIRED MULTIPLE HULL LEAKS AND ACCOMPLISHED SATISFACTORY CABIN LEAK RATE CHECK.