What was found
DURING CRUISE, THE PRESSURIZATION SYSTEM ON AUTOMATIC AND STANDBY MODE WERE UNABLE TO HOLD THE A/C PRESSURE AND OUTFLOW VALVE INDICATIONS WERE ERRATIC. THE A/C RETURNED TO MIAMI STATION FOR MAINTENANCE. AFTER UNEVENTFUL LANDING AT MIA STATION MAINTENANCE TECHNICIANS PERFORMED AN INSPECTION OF THE WIRING IN THE PRESSURE CONTROL SYSTEM AS PER AMM 21-31 AND WDM 21-34. FOUND NO DISCREPANCIES. AN OPERATIONAL CHECK OF THE PRESSURIZATION SYSTEM WAS PERFORMED AS PER AMM 21-31-. FOUND THE AUTOMATIC, STANDBY, MANUAL AC AND MANUAL DC MODES WORKING NORMALLY. THE AIRCRAFT WAS PRESSURIZE TO 3.5 PSI AND NO LEAKS WERE FOUND AS PER AMM 21-31. THE AIRCRAFT RETURNED TO NORMAL OPERATION. (M)