AC80 WITH HISTORY OF A FAILURE OF THE RIGHT ENGINE TO COME COMPLETELY TO FLT IDLE EXITS LEFT SIDE OF RWY AFTER LNDG FOLLOWING INFLT TEST OF ASSOCIATED MAINT.

Narrative

THE R ENG HAD AN INTERMITTENT PROB THAT OCCASIONALLY CAUSED THE ENG NOT TO REDUCE PWR COMPLETELY TO FLT IDLE WITH THE PWR LEVER AT THE FLT IDLE STOP. THIS DID NOT INTERFERE WITH THE SAFETY OF FLT BUT MANIFESTED ITSELF MORE AS AN INCONVENIENCE. I DESCRIBED THIS PROB IN DETAIL TO MY MAINT SHOP AND OVER THE COURSE OF SEVERAL VISITS THEY MADE A SERIES OF INSPECTIONS AND ADJUSTMENTS TO THE ENG AND ITS RIGGING TO ADDRESS THIS PROB. AFTER EACH MAINT VISIT THE PROB KEPT RECURRING INTERMITTENTLY. FINALLY; THEY IDENTED A STICKY PROP PITCH CTL AND REBUILT IT. THEY TOLD ME THAT THIS WAS LIKELY THE ROOT CAUSE OF THE PROB. I FLEW THE AIRPLANE ON THE DAY OF THE INCIDENT AND PERFORMED AN INFLT FLT IDLE TEST AS RECOMMENDED BY THE MANUFACTURER. THE TEST WAS COMPLETED SATISFACTORILY AND I BELIEVED THAT THE PROB WAS INDEED FIXED. I WAS PARTICULARLY ATTUNED TO DETECTING AND MAKING ACCURATE AND DETAILED OBSERVATIONS OF ANY ABNORMALITIES DURING ALL PHASES OF THIS FLT; AND HAD OBSERVED NONE. WHILE ON SHORT FINAL; I NOTICED A SLIGHT L YAW WITH THE PWR LEVERS MATCHED AND SOMEWHAT AHEAD OF THE FLT IDLE STOP; BUT I CORRECTED THIS EASILY WITH A SMALL AMOUNT OF R RUDDER. I REDUCED PWR ON BOTH ENGS TO THE FLT IDLE STOP DURING THE FLARE FOR LNDG; AND AS THE MAIN WHEELS TOUCHED DOWN THE ACFT BEGAN TO DRIFT TO THE L. AS THE ACFT CONTINUED TO SLOW; AND WITH FULL R RUDDER APPLIED; I WAS UNABLE TO KEEP THE ACFT FROM DRIFTING OFF THE L EDGE OF THE RWY. AS I WAS BRINGING THE ACFT TO A STOP; THE TIP OF 1 BLADE OF THE R PROP CONTACTED A SIGN AT THE EDGE OF THE RWY; KNOCKING IT OVER. THE R ENG BEGAN TO VIBRATE; SO I SHUT IT DOWN IMMEDIATELY. THE OBSERVED DAMAGE WAS LIMITED TO THE R PROP; THE R ENG COWLING; AND SOME SMALL DENTS AND PUNCTURES IN THE SKIN OF THE FUSELAGE; IN ADDITION TO THE DAMAGE TO THE ARPT SIGN.