What was found
AFTER DEPARTING, EXPERIENCED ENG VIBRATION OF UP TO 1.9, QRH WAS FOLLOWED, POWER REDUCED, ENG VIB FEL TO .8, THEN WENT BACK TO 1.3, AND PERFORMED A PRECAUTIONARY SHUTDOWN. OIL QTY PRIOR TO START AND TAKEOFF .7500 - .5000. AFTER SHUTDOWN .2500. OIL PRESSURE 10 PSI IN FLIGHT. MAINTENANCE 1 CHECK NR 3 OIL BYPASS PIN AND CHIP DETECTORS. 1 FOUND BYPASS PIN POPPED. ALL CHIP DETECTORS FOUND TO BE CLEAN 2 CHECK NR 3 ENG OIL LEVEL 2 NR 3 ENG 3.5 QTS LOW. SERVICED ENG W/ OIL (NOTED INSIDE OF TAILPIPE AND AFT TURBINE TO BE SOAKED W/ OIL.) 3 REPLACE NR 3 ENG OIL FILTER 3 REPLACED NR 3 ENG OIL FILTER IAW AVRO AMM 79-20-01. 4 REPLACED NR 3 ENGINE 4 REPLACED NR 3 ENGINE REF WORK PACKAGE DATED 7/7/04.