What was found
DURING FLIGHT THE LT NR 1 ENGINE STARTED TO LOSE OIL PRESSURE PILOT FEATHERED AND SHUTDOWN ENGINE PER AIRCRAFT POH. DECLARED AN EMERGENCY AND LANDED. ON THE GROUND IT WAS FOUND THAT THE L/H ENGINE OIL FILTER HOUSING ADAPTOR P/N 894117-2 HAD CRACKED OFF COMPLETELY FROM AT THE L/H UPPER AND LOWER MOUNT STUDS. NUTS WERE STILL IN PLACE BUT HAD LESS BREAK TORQUE THEN THE R/H ONES. IT WAS NOTED THAT TAE AREOSPACE HAD REPLACED THE SAME ADAPTOR 54.1 HOURS AGO WITH AN INSPECTED KNOW GOOD PART. TAE REPRESENTATIVE CAME AND REPLACED WITH AN UPGRADED OIL FILTER ADAPTOR P/N 896700-2 AND PLATE P/N 3102616-2. RUN UPS WERE PERFORMED AND NO LEAKS WERE PRESENT.