SF340B FLT CREW REPORTS TORQUE METER FAILURE ENROUTE WHICH CAUSES THE ENGINE TO AUTO-COURSEN ON SHORT FINAL AS POWER IS REDUCED.

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MAINT COULD HAVE CONTRIBUTED TO THE ISSUE; AS THERE WAS A PREVIOUS WRITE-UP FOR THE R-HAND TORQUE GAUGE. ENRTE THE R-HAND IGNITION LIGHT BRIEFLY ILLUMINATED AND THE R-HAND ENG TORQUE GAUGE WENT TO ZERO SHORTLY AFTER LEVELOFF IN CRUISE FLT. NO OTHER ABNORMAL ENG OR PROP INDICATIONS WERE NOTED NOR ANY ADVERSE FLT CHARACTERISTICS. NO QRH FOUND FOR THIS MALFUNCTION. CALLED DISPATCH WITH THE ISSUE AND WAS TOLD TO CONTINUE TO ZZZ. THE R-HAND ENG HAD A SIMILAR WRITE-UP PREVIOUSLY AND WAS NEW TO THIS AIRFRAME IN THE LAST 5 DAYS. A SHORT DISCUSSION WAS HELD BTWN MYSELF AND THE FO REGARDING THE REPERCUSSIONS OF THE FAILED TORQUE GAUGE AND WHETHER OR NOT IT WOULD EFFECT THE AUTO-COARSEN SYS. AFTER A NORMAL DSCNT AND CONFIGN FOR LNDG THE R-HAND ENG AUTO-COARSENED AT 200-300 FT AGL; PLUS OR MINUS. WE ELECTED TO DO A NORMAL LNDG AND DEAL WITH THE FAILURE AFTERWARDS. A NORMAL LNDG WAS MADE AND WE RAN THE ENG SHUTDOWN QRH AFTER CLRING THE RWY. THE ENG WAS RUNNING NORMALLY WITH NO FIRE INDICATIONS; JUST A COARSENED PROP. AFTER PARKING AT THE GATE THE APPROPRIATE WRITE-UPS AND PHONE CALLS WERE MADE. IT WAS OBVIOUS FROM THE FLT CHARACTERISTICS AND ENG/PROP GAUGE AND LIGHT INDICATIONS.