What was found
COULD NOT MAINTAIN PRESSURIZATION IN STANDBY OR MANUAL MODE S AFTER TAKE OFF. UPON ARRIVAL CREW REPORTED PRESSURE COULD NOT BE CONTROLLED IN ANY MODE. THE OUTFLOW VALVE INDICATION WAS VERY ERRATIC. PERFORMED TEST ON PRESSURE CONTROLLER AND TEST FAILED SEVERAL STEPS IAW JRH. REMOVED AND REPLACED CONTROLLER IAW 21-31-010-4. ALL ADJUSTMENT TEST STEPS WERE NORMAL. BUT OUTFLOW VALVE STILL INDICATES CLOSED IN AUTO, STNBY AND MANUAL MODES, VALVE INDICATES NORMAL. OUTFLOW VALVE SEEMS TO BE OPERATING NORMAL. INSPECTED LANDING GEAR SWITCHES AND EVEN NASI DOOR SWITCHES. R AND R CABIN PRESSURE CONTROLLER REF MM 21-31-010-4. PERFORMED ADJUSTMENT TEST IAW MM 21-31-000-5 STEPS 1A THRU E. ALL TEST UP TO 1E SATISFACTORY.