What was found
NR 1 ENGINE HAS VIBRATION AT IDLE ON GROUND AND IN FLIGHT, AIRCRAFT TAIL SWAP WITH 819NK. PERFORMED ENGINE VIBRATION TEST ON NR 1 ENGINE AND NO DEFECTS NOTED, WITHIN LIMITS. INSPECTED INLET AND EXHAUST AREAS, INSPECTED CSD, GEAR BOX MAG PLUGS AND OIL FILTER, NO DEFECTS NOTED. (K)