What was found
12 MINUTES AFTER TAKEOFF, THE PILOT NOTICED TRANSMISSION OIL TEMP FLUCTUATING BETWEEN 60 DEGREES AND 75 DEGREES C, RETURNED TO AIRPORT. THE MECHANIC REMOVED TRANSMISSION TEMP BULB CONNECTOR PLUG AND FOUND IT DIRTY, CLEANED THE CONNECTOR PLUG, IT DID NOT CURE THE PROBLEM, THEN REMOVED AND REPLACED THE TRANSMISSION TEMP BULB, AIRCRAFT WAS LEAK CHECKED AND RETURNED TO SERVICE.