What was found
DURING LEVEL FLIGHT, THE RT ENGINE BEGAIN TO VIBRATE, THE ONLY ENGINE INDICATION WAS A 20 PERCENT LOSS OF TORQUE AND ALL OTHER INDICATIONS WERE NORMAL. AFTER ABOUT 15 SECONDS THE OIL PRESSURE GAUGE FLICKERED ONCE AND THE PILOTS SECURED THE ENGINE. THERE WAS NO RISE IN THE OIL TEMP INDICATION AND THE OIL PRESSURE LIGHT REMAINED EXTINGUISHED PRIOR TO SECURING THE ENGINE. MAINTENANCE REMOVED AND REPLACED THE ENGINE, PERFORMED ALL THE NECESSARY GROUND RUNUP CHECKS, PERFORMED A SATISFACTORY FLIGHT TEST AND RELEASED THE AIRCRAFT FOR SERVICE.