What was found
MFR - FLIGHT 2557 ON FLIGHT FROM PDX TO ONT AIRCRAFT DIVERTED TO MFR DUE TO NR 1 ENGINE VIBRATION. REPLACED FAN BLADES SERIAL NUMBERS, IHI3069N, IHI3130N, IHI3140N, IHI3144N, IHI3149N, IHI3150N, IHI3156N, IHI3158N, IHI3160N, IHI3178N, IHI3180N, IHI3182N, IHI3186N, IHI3188N, IHI3190N, IHI3191N, IHI3192N, IHI3193N, IHI3194N, IHI3195N, IHI3196N, IHI3198N, IHI3200N, IHI3202N, IHI3203N, IHI3204N, IHI3206N, AND IHI3208N. OPERATION CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.