What was found
WHILE INFLIGHT, THE PILOT OBSERVED THAT THE NO 1 ENGINE OIL PRESSURE DECREASED INTO THE YELLOW PRECAUTIONARY RANGE. THE NO 1 ENGINE WAS SHUT DOWN AS A PRECAUTION TO PREVENT POSSIBLE ENGINE DAMAGE. AIRCRAFT LANDED WITH NO FURTHER INCIDENT. NO DAMAGE OR INJURY. MAINTENANCE PERSONNEL PERFORMED MAINTENANCE ON THE AIRCRAFT OIL SYSTEM AND FOUND A DEFECTIVE OIL PRESSURE TRANSMITTER. REPLACED SAME. AIRCRAFT WAS OPERATIONAL CHECKED AND LEAK CHECKED AND FOUND TO BE ACCEPTABLE.