What was found
DURING FLIGHT, HAD A LOW TRANSMISSION OIL PRESSURE MASTER CAUTION AND CORRESPONDING GAUGE LOW INDICATION, CO-PILOT LOOKED IN THE BACK OF THE AIRCRAFT TO FIND A LARGE AMOUNT OF OIL COVERING THE FLOOR. IMMEDIATELY BEGAN A DECENT OUT OF 3800 FEET MSL TO LAND AT A FIELD AND DECLARED AN EMERGENCY. WHEN ACFT SETTLED TO THE GROUND THE AIRCRAFT MADE A LOUD HOWL AND SQUEAL. IMMEDIATELY SHUTDOWN BOTH ENGINES AND AIRCRAFT. A VISUAL INSPECTION OF THE MAIN GEARBOX REVEALED THE NR 2 OIL PUMP FILTER HOUSING MOUNTING STUD HAD SHEARED AND THE HOUSING WAS HANGING OFF THE FILTER DISCS.