What was found
AIRCRAFT DEVELOPED HIGH OIL TEMPERATURE (120 DEGREES CELSIUS) AND LOW OIL PRESSURE (60 PSI) DURING A ROUTINE TRAINING MISSION. OUTSIDE AIR TEMPERATURE WAS ABOVE 80 DEGREES FAHRENHEIT. AIRCRAFT PILOT MADE ATTEMPT TO COOL ENGINE DURING RETURN FLIGHT TO THE AIRFIELD. MAINTENANCE TECHNICIANS CHECKED THE ENGINE OIL PRESSURE WITH A DIRECT READING GAUGE. OIL COOLER THERMAL BYPASS VALVE WAS TESTED BY PLACING THE UNIT IN OIL HEATED TO 120 DEGREES CELSIUS. THE BYPASS VALVE OPENED ABOVE 120 DEGREES CELSIUS. SEVERAL BYPASS VALVES HAVE MALFUNCTIONED IN THE T-3A FLEET. THE VALVES TESTED AT TEMPERATURES ABOVE 120 DEGREES CELSIUS.