What was found
A/C AT FL330 EXPERIENCED RIGHT ENGINE VIBRATION. THROTTLE RETARDED AND VIBRATION REMAINED 1.2 AND 3.1 AT EPR 1.71. CREW REPORTED LEFT ENGINE VIBRATION DURING DESCENT. A/C REQUESTED DIVERSION TO ORF. VIBRATION RETURNED TO NORMAL RANGE ON DESCENT AT FLIGHT LEVEL 170. CREW SUSPECTED ICING. ON GROUND FAULT ISOLATION MANUAL TASK 77-31-00 AVM BITE TEST PERFORMED. NO FAULTS. BOTH LEFT AND RIGHT ENGINE CHIP DETECTORS INSPECTED. NO METAL FOUND. ENGINE TEST 6 VIBRATION SURVEY PERFORMED. ALL ENGINE PARAMETERS WITHIN LIMITS. (M)