What was found
SHORTLY AFTER TAKEOFF DURING CLIMB. SCANNED THE AIRCRAFT INSTRUMENTS AND EVERYTHING WAS IN THE NORMAL OPERATING RANGE. NOTICED THE OIL TEMPERATURE HAD CLIMBED AROUND 7-8 DEGREES PAST THE INITIAL SCAN, STILL WITHIN NORMAL OPERATING LIMITATIONS. THE OIL TEMPERATURE WAS INCREASING A DEGREE CELSIUS EVERY 1-2 SECONDS. THE OIL TEMPERATURE WAS STILL WITHIN NORMAL OPERATING RANGE BUT STEADILY INCREASING. HEADED BACK TO DEPARTURE AND NO MORE THAN A QUARTER MILE AWAY FROM THE AIRPORT, THE OIL TEMPERATURE BEGAN TO CLIMB MORE STEADILY. THE OIL TEMPERATURE CLIMBED AND EXCEEDED THE 115 DEGREE CELSIUS LIMITATION. FOLLOWED THE EMERGENCY PROCEDURE AND THE OIL TEMPERATURE DID NOT PLATEAU OR DECREASE. DECLARED AN EMERGENCY. LANDED. ON SHUTDOWN THE LAST OIL TEMPERATURE READING WAS ABOVE 130 DEGREES CELSIUS. THERMOSTATIC SWITCH THAT CONTROLS OIL COOLER FAN WAS FOUND TO NOT RESPOND TO TESTS,