What was found
PILOT REPORTED AT 22,000 MASTER WARNING WITH A RT LOW OIL PRESSURE ANNUNCIATOR, GOT THE LIGHT AND HAD 2300 LBS OF TORQUE DROPPED TO BELOW 2000 LBS, OIL WAS 45 TO 50, PRECAUTIONARY-SHUTDOWN THE RT ENG & DELCARED AN EMERGENCY. MX FOUND A LOOSE B-NUT ON THE RT ENGINE OIL LINE, TIGHTENED LINE AT THE RUDDER BOOST TRANSDUCER IAW BMM 20-06-00, LEAK CHECKS GOOD.