ACR ON INITIAL CLB HAS A POP; LOUD BUZZ AND AIRFRAME VIBRATION. EMER DECLARED. RETURN LAND.

Narrative

DURING TKOF CLB OUT FROM LGA PASSING 1000 FT MSL JUST PRIOR TO FLAP RETRACTION THERE WAS A POP AND LOUD BUZZ WITH AIRFRAME VIBRATION. INITIALLY THOUGHT IT MIGHT BE A NOSE GEAR PROBLEM BUT AFTER IMMEDIATELY CHKING THE ENGS IT WAS OBVIOUS THAT THE R ENG HAD ROLLED BACK TO APPROX 1.3 EPR. INITIAL INDICATIONS WERE OF A POSSIBLE COMPRESSOR STALL. I DIRECTED THE CAPT TO PULL THE R THROTTLE TO IDLE TO SEE IF WE COULD RECOVER THE ENG. VIBRATION PERSISTED AT ALMOST THE SAME LEVEL BUT THE BUZZ DECREASED. THE CAPT DECLARED AN EMER WITH LGA/NEW YORK DEP CTL AT ABOUT THE SAME TIME HE DECIDED TO SHUT THE ENG DOWN WHICH I AGREED WITH. I WAS BUSY FLYING AND HAD JUST CALLED FOR AND RAISED THE FLAPS TO UP BUT TOLD THE CAPT I WOULD LEAVE THE SLATS OUT. AT THE SAME TIME FOLLOWING HDG INSTRUCTIONS FROM DEP AND CLBING TO 2000 FT MSL. ONCE WE WERE LEVEL THE REST OF THE AFTER TKOF AND PRELIMINARY LNDG CHKS WERE COMPLETED. THE CAPT ALSO NOTIFIED COMPANY; THE PAX; AND THE FLT ATTENDANTS OF THE SITUATION. AFTER THE ENG WAS SHUTDOWN WITH THE FUEL SHUTOFF HANDLE THE VIBRATION STOPPED. THE CAPT AND I THEN EXCHANGED ACFT CTL AND I COMPLETED THE ENG FIRE/SEVERE DAMAGE/SEPARATION CHKLIST. WE HAD NOT PULLED THE FIRE HANDLE UNTIL NOW BECAUSE WE DIDN'T KNOW THE EXTENT OF DAMAGE; WE THOUGHT IT WAS JUST A COMPRESSOR STALL. WE COMPLETED THE EMER CHKLIST AND THE LNDG CHKLIST FOR A LNDG ON RWY 31 LGA; FINAL FLOWN AT FLAPS 25. ON ABOUT A 3 MI FINAL OR LESS WHILE ON TWR; TWR WAS CLRING ACFT FOR TKOF ON RWY 31 (LGA WAS SINGLE RWY OPS). A SERIOUS PROBLEM HERE IF THE ACFT ON THE RWY ABORTED OR HAD A PROBLEM WE WOULD HAVE BEEN PLACED IN A SE GAR SITUATION AT A FAIRLY HVY WT. WE LANDED UNEVENTFULLY WITH THE FIRE EQUIP STANDING BY. TAXIED BACK TO THE GATE WHERE WHEN WE INSPECTED THE ENG IT HAD THROWN THE #3 AND #4 COMPRESSOR SECTION BLADES AND DESTROYED THE ENG. MOST DAMAGE WAS CONTAINED BUT PIECES OF METAL HAD PUT HOLES IN THE RUDDER TRIM TAB AND SEVERAL DENTS ALONG THE R SIDE OF THE TAIL CONE AFT OF THE ENG EXHAUST.