What was found
ON INITIAL CLIMB OUT HEARD VIBRATION FOLLOWED BY A LOUD BANG, SAW OBJECT FLY BY FO WINDOW EMERGENCY DECLARED WITH ATC, RETURNED TO LAND IN ATL, NO ABNORMAL INDICATIONS ON EICAS ON POST FLIGHT WALK AROUND, A PIECE OF HEAD SET JACK WAS DISCOVERED STILL CONNECTED IN SERVICE PANNEL. FOUND LARGE DENT ON RIGHT ENGINE COWL AND DAMAGE TO FAN BLADES. R/R RIGHT ENGINE ASSY IAW JOBCARD 900-72-430-902. ALL OP/C & LEAK CHECKS GOOD.