What was found
RT ENGINE FAN VIBRATION INDICATIONS WERE HIGH. BETWEEN 2.5 AND 3.5, FL 390, M .80. ACCOMPANIED BY AIRFRAME/ENGINE VIBRATION. SETTLED BACK TO 1.5 THEN BACK TO 3.0. THIS CONTINUED FOR APPROXIMATELY 30 MINUTES THEN WENT AWAY. PERFORMED FIM 71-05-00-60, NO DEFECTS NOTED. PERFORMED AMM 71-00-00-5, TEST NR 7, ENGINE VIBRATION WITHIN LIMITS. ENGINE WITHIN LIMITS IAW AMM 71-00-00-2, PARA. J.