What was found
MODERATE VERY NOTICEABLE SMELL OF OIL PRIOR TO AND DURING TAKEOFF ROLL, AT POWER CHANGES IN CRUISE AND DESCENT, MOST CERTAINLY ENGINE OIL, EITHER NR 1 OR NR 3 DUE TO BLEED CONFIGURATION. SUPPLEMENTAL DATA UPDATE: FOUND N-1 ACCESSORY DRIVE CASE COVER LEAKING. REMOVED COVER, REPLACED O-RING, AND REASSEMBLED.