B190 CREW HAD GRADUAL #2 ENG FAILURE RESULTING IN AN AUTO FEATHER OF THE ENG. THE CREW DID NOT DECLARE AN EMER DURING THE DIVERSION TO THE NEAREST SUITABLE ARPT.

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THE ENG FAILURE BEGAN TO OCCUR AT 16000 FT OVER THE CITY OF OSHKOSH. WE NOTICED THE R TORQUE WAS SEVERAL HUNDRED LBS LOWER THAN THE L. AT FIRST WE THOUGHT THIS WAS DUE TO NORMAL PWR LEVER SPLIT; BUT SOON FOUND THAT MOVING THE PWR LEVER GAVE NO ADDITIONAL TORQUE WHEN PUSHED FORWARD AND LITTLE TO NO DECREASE IN TORQUE WHEN PULLED BACKWARD. THE PWR WAS SLOWLY BUT GRADUALLY DECREASING. WE DECIDED TO DIVERT TO APPLETON; AN ON-LINE CITY WE HAD JUST PASSED OVER. WE CONTINUED TO LOSE PWR ON THE R SIDE AS WE APCHED THE ARPT. AT THIS TIME; I CALLED DISPATCH ON THE RADIO AND ADVISED THEM OF OUR PLANS. WE ALSO ASKED FOR PRIORITY HANDLING INTO ATW. WE DID NOT DECLARE AN EMER; BECAUSE UNTIL WE GOT DOWN LOW WE HAD NO REASON TO BELIEVE THE ENG WOULDN'T STAY RUNNING. AT LOWER ALTS; THE TORQUE BEGAN TO DECREASE AT A SLIGHTLY INCREASED PACE. AT AROUND 1000 FT AGL ON THE GS FOR RWY 29 IN ATW; THE R PROP AUTO FEATHERED. WE THEN SECURED THE PROP LEVER IN THE FEATHER DETENT AND CONTINUED THE LNDG WITH THE ENG RUNNING AT MINIMUM FLOW PWR. AT NO TIME DID WE EVER SEE ANY ADVERSE INDICATIONS FROM THE ENG SUCH AS A FIRE WARNING; LOW OIL PRESSURE; HIGH OIL TEMP; OR WARNING/CAUTION LIGHTS OF ANY KIND. WE COMPLETED AN OTHERWISE UNEVENTFUL SINGLE ENG LNDG. AS SOON AS WE TURNED ONTO THE TXWY; WE SECURED THE R ENG. AT THAT TIME; N1 WAS SOMEWHERE BELOW 40%. DURING THE LOSS OF PWR; ALL GAUGE INDICATIONS WERE AS YOU WOULD EXPECT WITH A NORMAL PWR REDUCTION. TORQUE; ITT; FUEL FLOW; AND N1 ALL DECREASED TOGETHER AS WOULD BE EXPECTED. THE ENG IN FACT CONTINUED TO RUN NORMALLY UNTIL WE SHUT IT DOWN; EXCEPT FOR THE FACT THAT IT BASICALLY DID NOT MAKE ANY USABLE PWR. THE PAX WERE REMOVED FROM THE AIRPLANE AFTER SEVERAL MINS AND WERE ALL REBOOKED ON OTHER FLTS WITHIN AN HR. WE DID NOT EVAC ON THE RWY OR AT THE TERMINAL AS WE SAW NO EVIDENCE TO CAUSE THE PANIC OR DISORDER OF AN EVAC. A WALKAROUND BY THE FO IMMEDIATELY AFTER SHUTDOWN (WHILE THE ATW STATION PERSONNEL WERE TALKING TO THE PAX) DID NOT REVEAL ANYTHING WRONG WITH THE R ENG; SUCH AS FUEL LEAKS; FLUID ON THE GND; MISSING PARTS; ETC.