C550B CITATION DURING CLB HEARS A LOUD BANG AND THEN A SERIES OF CONSECUTIVE BANGS. R HAND ENG VIBRATION LIGHT ACTIVATED. INSTS INDICATED THE R HAND ENG WAS ERRATIC. SHORTLY AFTER FLC DECLARED AN EMER; THE L ENG STOPPED RUNNING.

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I DEPARTED AT APPROX XX00 ON AN IFR FLT PLAN. ALL ENG INSTS WERE NORMAL DURING THE TAXI; TKOF; AND CLB. DURING THE CLB PHASE OF FLT AT APPROX 25500 FT; A LOUD BANG WAS HEARD FOLLOWED BY A SERIES OF CONSECUTIVE BANGS. I IMMEDIATELY SCANNED THE ENG INSTS AND ANNUNCIATOR PANEL AND THE ONLY ANNUNCIATOR LIGHT ILLUMINATED WAS THE R HAND ENG VIBRATION LIGHT. I THEN HEARD A LOUD CONTINUOUS ROAR. I RETARDED THE R HAND THROTTLE; BUT THE LOUD ROAR CONTINUED. A SECOND LOOK AT THE ENG INSTS THE N1 FOR THE L HAND ENG WAS ERRATIC. I ADVANCED THE R HAND THROTTLE AND RETARDED THE L HAND THROTTLE AND THE ROARING NOISE BECAME QUIETER. THE R HAND ENG VIBRATION ANNUNCIATOR LIGHT REMAINED ILLUMINATED. I DECLARED AN EMER AND REQUESTED PRIORITY HANDLING WITH A RETURN TO ZZZ. AFTER THE L HAND THROTTLE WAS IN THE IDLE POS FOR APPROX 2-3 MINS IT STOPPED PRODUCING THRUST/QUIT RUNNING. I THEN PLACED THE L HAND THROTTLE IN THE CUT-OFF POS. THERE WAS NO ATTEMPT TO RESTART THE ENG. THE R HAND ENG VIBRATION LIGHT EXTINGUISHED AND SINGLE ENG LNDG PROCS WERE ACCOMPLISHED. THE TOTAL LENGTH OF THE FLT WAS APPROX 31 MINS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THE CAUSE OF THE VIBRATION WAS AN INTERNAL COMPONENT WHICH HAD RUBBED AGAINST THE CASE AND ULTIMATELY BROKE APART INSIDE THE ENG. PRATT AND WHITNEY HAD PROBS WITH THIS TYPE ENG BEFORE AND REQUESTED THEY SEND THE ENG TO HAVE THE PART REMOVED AND REPLACE THE COMPONENT. THE COMPANY HAS SINCE REPLACED BOTH ENGS. THE SECOND PROB WAS THAT THE WIRING FOR THE ENG VIBRATION LIGHT HAD BEEN REVERSED AND INDICATED THE INCORRECT ENG HAD THE PROB. HAD THEY SHUT DOWN THE ENG INDICATED; IT WOULD HAVE BEEN THE GOOD ENG. WHOEVER BUILT OR INSTALLED THE WIRING HARNESS REVERSED THE CONNECTION.