SUDDEN PITCH RATE IN PROX OF GND CHANGES RATE OF DSCNT NECESSITATING A MISSED APCH GAR PROC. ENGS OVERBOOSTED IN PROCESS.

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THE ACFT REQUIRED A COUPLED APCH TO RETURN IT TO CATII STATUS. FO WAS FLYING. JUST BEFORE 100 FT THE ACFT PITCHED OVER. FO DISCONNECTED AUTOPLT. JUST PRIOR TO 100 FT I CALLED BUG PLUS 10 KTS ON LOC ON GS. THE FO BEGAN A GRADUAL PWR REDUCTION. EVERYTHING WAS FINE UNTIL 100 FT WHEN THE AUTOPLT PITCHED OVER. AT THAT POINT WE WERE ALL HEADS UP EYES OUTSIDE. I IMMEDIATELY CALLED 'SINK RATE' TWICE. I COULD SEE WE WERE CLOSING ON THE RWY TOO FAST. THE FO BEGAN A PULL BACK BUT MUCH MORE AGGRESSIVE ACTION WAS NEEDED. I PULLED BACK TO HELP HIM AND ANNOUNCED I'VE GOT IT. I PULLED BACK AND ADDED A HEALTHY AMOUNT OF PWR WHICH WAS MORE THAN THE NORMAL AMOUNT TO ARREST AN LGT'S SINK RATE. BUT THIS WAS AN EXAGGERATED SITUATION DUE TO THE PITCH OVER AT 100 FT. THE ACFT CONTINUED TO SINK. I SHOVED THE THROTTLES WAY FORWARD AND 2 HANDS WERE REQUIRED TO PULL WAY BACK ON THE YOKE. THE GND PROX STARTED WARNING 'SINK RATE.' AT ABOUT 10-20 FT ABOVE THE RWY I WAS ABLE TO ARREST THE SINK. THE ACFT WAS SLIGHTLY BEYOND THE TOUCHDOWN ZONE. THE RWY WAS 7000 FT LONG. THE PWR WAS HIGH. I ELECTED TO GAR. CLBING THROUGH 500-600 FT I NOTICED THAT THE EPRS WERE OVER 'GAR' EPR. I PULLED THE PWR BACK TO 'GAR' EPR. ON THE DOWNWIND LEG AT 3000 FT I TURNED THE ACFT BACK OVER TO THE FO. I FELT IT WOULD BE GOOD FOR HIS CONFIDENCE TO MAKE A MANUAL LNDG AND APCH. THAT WAS DONE UNEVENTFULLY. I KNOW THAT I USED MORE THAN GAR EPR. NONE OF US NOTICED OTHER ENG PARAMETERS PRIOR TO THE THRUST REDUCTION. WE WROTE UP THE PITCH OVER AND ASKED TO HAVE THE ENGS INSPECTED FOR POSSIBLE EXCEEDING ENG LIMITS. THE NTSB WAS NOTIFIED BY COMPANY ALONG WITH FAA. ALL ENGS WERE REPLACED AND ARE NOW BEING EVALUATED. THE COMPANY HAS PULLED THE FLT DATA AND VOICE RECORDERS. NOTE: LANDED BEHIND A LIGHT TWIN; NO OBSERVED WIND SHEAR. SUPPLEMENTAL INFO FROM ACN 205198. ESTIMATED PEAK SINK RTE ATTAINED WAS 1500 FPM. FIREWALL PWR (OR CLOSE TO) WAS NEEDED TO ARREST THE SINK. (ACTUAL N1; N2 AND EGT WERE NOT NOTED PRIOR TO RETARDING THRUST). ONE HUMAN FACTOR CONSIDERATION: ONCE THE GAR WAS INITIATED AND ANNOUNCED; TWR MADE SEVERAL INSISTENT INQUIRIES AS TO REASON. WE HAD OUR HANDS FULL EXECUTING A DIFFICULT AND UNUSUAL MISSED APCH AND DID NOT NEED TWR BUGGING US UNTIL WE WERE WELL CLR OF THE GND AND CLBING SAFELY. SUPPLEMENTAL INFO FROM ACN 205443. THIS INCIDENT HAS REMINDED ME THAT MY PRIMARY RESPONSIBILITY IS TO MONITOR THE ENG INSTS DURING A GAR SITUATION THEN BACK UP THE FOLKS AT THE CTLS. I WISH I COULD HAVE NOTED THE ENG READINGS.