What was found
(CAN) DURING CLIMB THROUGH 10,000 FEET NOTICEABLE VIBRATION FELT FOLLOWED BY NR1 ENGINE OIL PRESSURE/FILTER BYPASS LIGHT ILLUMINATION. THRUST LEVER WAS RETARDED TO 60 PERCENT N1, LIGHT EXTINGUISHED. OIL PRESSURE AND TEMPERATURE WERE WITHIN LIMITS. 10 SECONDS LIGHT RE-ILLUMINATED AND AIRCRAFT RETURNED TO ITS POINT OF DEPARTURE. POST FLIGHT INSPECTION FOUND METAL PARTICLES IN THE MAIN OIL FILTER. THE ENGINE WAS REPLACED