What was found
ON WALK AROUND FOUND #1 ENGINE, #4 BLADE HAS DISTORTION. GROUNDED - YES. FAN BLADE DAMAGE APPROX .100 FROM BLADE TIP ON LEADING EDGE WAS FOUND TO BE OUT OF LIMITS. ACCOMPLISHED GVI AROUND #1 ENGINE INTAKE AND FAN BLADE IAW B737-900 AMM 72-21-02. NO OTHER DEFECT NOTED .REMOVED AND REPLACED FAN BLADE #4 AND #16 AS BLADE PAIR REF AMM 72-21-02-000-802-F00. REPLACED #4 SPACER AND PIN-AXIAL STOP ON REAR SPINNER CONE. REF AMM 72-21-02-000-802-F00. PERFORMED TEST-7 VIB SURVEY REF AMM 71-00-00-700-814. PARAMETER WITHIN LIMITS.