As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT ENGINE FAN VIBRATION SHOWED 2.7 MILS IN FLIGHT AND HAD TURNED YELLOW. COULD NOT FEEL PRONOUNCED VIBRATION IN THROTTLE. CREW RAN QRH AND DETERMINED THAT ENGINE SHUTDOWN WAS NOT REQUIRED DUE TO NO OTHER ABNORMAL ENGINE INDICATIONS PRESENT. CREW DECLARED AN EMERGENCY AND RETURNED TO PHL. ACCOMPLISHED FAN BALANCE ON RIGHT ENGINE, FAN VIBRATION AT 0.4 AT TAKEOFF POWER.