What was found
BOS - FLT 548 - DURING TAKEOFF ROLL, FIRST OFFICER NOTICED A SMALL BIRD OFF THE LEFT SIDE OF THE AIRCRAFT. SHORTLY AFTER TAKEOFF, CREW EXPERIENCED A STRONG VIBRATION FROM NR 1 ENG. ENGINE VIBRATION SHOWED ABOVE FOUR. CREW RETURNED TO FIELD AT BOS WHERE THE FLIGHT LANDED WITHOUT INCIDENT. NO EMERG DECLARED. INSP CONFIRMED A BIRD STRIKE. MAINT REMOVED AND REPLACED DAMAGED 1ST STAGE FAN BLADES, 19, 20, AND 23, ON THE NR 1 ENGINE. ALSO, REPLACED OPPOSITE FAN BLADES 1, 4, AND 38. ACCOMPLISHED BORESCOPE OF NR 1 ENG HIGH PRESSURE COMPRESSOR 3RD, 5TH, AND 9TH STAGES. ALSO INSPECTED COMBUSTION CHAMBER AND TURBINE SECTION PER MM 71-00-47. PERFORMED ENG RUN AND AVM SIGNAL CONDITIONER CHECK. OPS CHK GOOD. (X)