DURING GAR; ACR FLC OVERBOOSTS ENGS.

Narrative

THE FO WAS FLYING A NIGHT VISUAL APCH INTO A MOUNTAINOUS ARPT. HE FLARED A LITTLE HIGH AND FLOATED FAR ENOUGH DOWN THE RWY THAT I WAS CONCERNED ABOUT BEING ABLE TO STOP ON THE RWY. I COMMANDED A GAR. THE FO IMMEDIATELY APPLIED PWR AND WE BEGAN OUR MISSED APCH PROCS. I NOTICED A FLASHING COMING FROM THE ENG INST PANEL; LOOKING CLOSER I NOTICED THE EPR WAS A LITTLE ABOVE THE TARGET EPR BUG. I POINTED TO THE EPR GAUGES. THE FO IMMEDIATELY PULLED THE THROTTLES BACK A LITTLE; ALL THE FLASHING STOPPED. AT THIS POINT; I THOUGHT WE HAD SIMPLY 'OVERBOOSTED' THE EPR BY A LITTLE FOR 3-5 SECONDS. WE COMPLETED THE MISSED APCH; CAME AROUND AND HAD A NORMAL LNDG. A FEW MINS LATER; RIDING THE HOTEL VAN TO THE LAYOVER HOTEL; I REALIZED THE 'EPR OVERBOOST' WASN'T THE ONLY PROB WE HAD. I COULD NOT REMEMBER WHICH GAUGE HAD BEEN FLASHING; BUT THE FLASHING HAD BEEN BELOW THE EPR GAUGES; MAKING IT EITHER N1; EGT; OR N2. AFTER ARRIVING AT THE LAYOVER HOTEL; I IMMEDIATELY CALLED THE DISPATCHER; AND WITH MAINT ONLINE; EXPLAINED THAT I HAD DIAGNOSED THE PROB INCORRECTLY. IN ADDITION TO WHAT I THOUGHT WAS A MINOR; SHORT DURATION EPR OVERBOOST; WE MUST HAVE EXCEEDED THE ENG LIMITS ON EITHER N1; EGT; OR N2. THE COMPANY TOOK THE PLANE OTS; WE LATER FERRIED THE EMPTY AIRPLANE TO A MAINT STATION. SUPPLEMENTAL INFO FROM ACN 440307: FLT DATA RECORDED WAS REMOVED. ENG CHKS WERE PERFORMED WITH MAINT ON BOARD. ENG RUN-UPS WERE OK AND ACFT WAS FERRIED BACK TO MAINT BASE FOR THOROUGH ENG CHKS AND FLT DATA RECORDER REVIEW. ENGS DID TURN OUT TO BE OVERBOOSTED AND WERE REPLACED.