What was found
SHUTDOWN ENG NR 1 INFLIGHT FOR UNUSUAL VIBRATIONS. VIBES START AT 91 PERCENT - AND VERY NOTICABLE ABOVE 94 PERCENT - LIGHT TO MEDIUM "SHUDDER" RAPTED VIBRATION. REMOVED NR 1 ENGINE SPINNER ASSY & FIRST STAGE FAN ROTOR BLADES IAW MM 72-21-00-4. LUBED IAW AMM 72-21-00-4. INSPECTED MASTER CHIP DETECTOR. NO METAL FOUND ON DETECTOR. INSTALLED NR 1 ENG FAN BLADES & SPINNER. IAW MM 72-21-00-4. PERFORMED VSV RIG CHECK ON NR 1 ENGINE REF AMM 73-20-01-2-0; FOUND IN RIG. PERFORMED VIBRATION SURVEY ON NR 1 ENG REF AMM 72-00-00-5; WITHIN LIMITS. NO VIBRATION ON VIBE EQUIPMENT OR FELT DURING MULTIPLE RUNS AT TAKEOFF POWER.