THE #2 ENG ON AN ACR MLG WAS LOST TO FOREIGN OBJECT DAMAGE.

Narrative

AFTER TKOF LEAVING 8000 FT; THE CABIN CALLED AND SECONDS LATER CALLED AGAIN. THE #3 SAID THERE WAS AN UNUSUAL NOISE/VIBRATION COMING FROM THE R SIDE OF THE ACFT BY THE ENG. WE CHKED THE ENG INSTS AND EVERYTHING WAS NORMAL. SINCE THE #3 WAS CONCERNED TO GET MY IMMEDIATE ATTN DURING THE STERILE PERIOD; I IMMEDIATELY WENT TO THE BACK OF THE ACFT AND THE VIBRATION INCREASED; I WENT BACK TO THE COCKPIT AND NOTICED THE R N1 NEEDLE VIBRATING. ATC WAS INFORMED THAT WE NEEDED TO LEVEL OFF AND I DISCONNECTED THE AUTOTHROTTLES AND REDUCED PWR TO 1.2 EPR. THE VIBRATION STOPPED IN THE COCKPIT. I CALLED BACK TO THE #3 AND SHE TOLD ME IT WAS BETTER. WE DECLARED AN EMER AND RETURNED TO DFW. NOT KNOWING SPECIFICALLY WHAT CAUSED THE VIBRATION AND THE POSSIBILITY IT WAS ICE INGESTION; THERE WAS A REMOTE CHANCE THE SAME COULD OCCUR TO THE L ENG. SINCE THE R ENG WAS PRODUCING PWR AND ALL ENG INDICATIONS WERE NORMAL AT THAT PWR SETTING; I ELECTED TO MAINTAIN USE OF THE ENG. WE REVIEWED THE QRH AND LANDED WITH 28 FLAPS. THE ACFT WAS DEICED AND INSPECTED BY A CERTIFIED DEICER. THE MAINT PERSONNEL SUSPECT ICE INGESTION. THE FAN BLADES WERE DESTROYED. I WAS INFORMED I WAS THE FIFTH ACFT WITH THIS PROB THAT NIGHT. WE WERE ON THE RAMP FOR 3 HRS BEFORE WE WERE DEICED. SUPPLEMENTAL INFO FROM ACN 257626: WE ELECTED NOT TO SHUT DOWN THE R ENG SINCE IT STOPPED SHOWING ERRATIC SIGNS ONCE PWR WAS REDUCED FOR DSCNT.