What was found
MIA/UIO - AIR TURNBACK, AFTER TAKEOFF, PRESSURIZATION INOPERATIVE. EXCESSIVE RATE OF CLIMB. WENT TO MANUAL. NO INDICATION OF FAILURE. NO RATE LIMIT LIGHT. FOUND BOTH OUTFLOW VALVES OPEN. UNABLE TO CONTROL PRESSURE MANUAL 'L' OR 'R'. NO FUEL DUMPED. REMOVED AND REPLACED THE PRESSURE CONTROLLER. SYSTEM OPS CHECK NORMAL IAW MM 21-31-02. (M)