What was found
PHL - FLT 1217 - ON TAKEOFF OUT OF MDT, THE NR 2 ENGINE INJESTED A SEA GULL. EVERYTHING WAS NORMAL UNTIL ABOUT 12,000 FEET, WHEN THE NR 2 ENGINE STARTED TO GET A VIBRATION. VIBRATION EXCEEDED 4.0 AND INCREASED TO 5.0 UNTIL POWER WAS REDUCED TO IDLE WHEREAS THE VIBRATION STABILIZED TO LESS THAN 1.0. FLIGHT DIVERTED TO PHL WHERE THE NR 2 ENGINE OPERATED AT IDLE THE REMAINDER OF FLIGHT. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED FOUR FIRST STAGE COMPRESSOR BLADES ON THE NR 2 ENGINE IN ASSOCIATION WITH MM 72-31-02, PAGE 401. ALSO, PERFORMED VIBRATION SURVEY. OPERATIONAL CHECK GOOD. VIBRATION WITHIN LIMITS. (X)