What was found
PILOT NOTED A SLIGHT INCREASE, WITHING LIMITS IN THE NR 1 ENGINE OIL TEMP DURING FLIGHT. DURING FINAL APPROACH, THE OIL TEMP STARTING INCREASING, THE PILOT ABORTED THE APPROACH, SECURED THE NR 1 ENGINE IAW THE RFM AND SUCCESSFULLY COMPLETED A RUN ON LANDING. DURING INSPECTION OF THE OIL COOLER DRIVE SPLINES, THERE WAS EXCESSIVE WEAR ALLOWING THE SPLINES TO SLIP. THE BEARING THAT SUPPORTS THE SHAFT WAS CORRODED AND WORN. THIS IS THE NEW STYLE OIL COOLER THAT DOES NOT REQUIRE A PERIODIC SPLINE INSPECTION.