Narrative:

We departed the runway at the gcn. The aircraft was able to reach takeoff calculated torque without exceeding any temperature limitations or any redline limitations. On climb out, the right T5 (5TH stage turbine temperature) gauge was at the top of the yellow arc at 725 degrees C. As we climbed out the T5 lowered into the green arc as the first officer reduced power in order to reduce the percentage on the propellers. After calling for the after takeoff checklist the first officer and I noticed the gas generator speed higher than normal. As we reached cruise altitude the gas generator speed was at red line. I advised the first officer to reduce power in order to reduce propeller speed, as soon as possible. I checked the caution lights for any discrepancies followed by checking the other engine instruments. Everything was in the safe arc. I then checked the abnormal checklist and emergency checklist. T5 never went past the red line, it was at red line. The first officer reduced the power to 35 pounds of torque. T5 still remained in the red. At that time I made the decision to return to the field. I saw no need to shut down the engine because the other engine gauges were showing in the green, and the power plant showed no trend of exceeding limitations. I told the first officer to turn around and return to the suitable airport. I advised dispatch and got an amendment to the release. I advised ATC of the return and our condition. I also advised the passenger that we were returning and it was just a precautionary landing. I then called dispatch via satellite phone and gave them an update. The passenger remained calm throughout the flight. I advised the first officer to prepare for a possible engine shutdown and a single engine approach and a possible single engine go around. We executed a normal approach to the airport.

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Original NASA ASRS Text

Title: FLT CREW OF DHC6 ENCOUNTER EXCESSIVE ENG TEMP INDICATIONS AND RETURN TO LAND AT GCN.

Narrative: WE DEPARTED THE RWY AT THE GCN. THE ACFT WAS ABLE TO REACH TKOF CALCULATED TORQUE WITHOUT EXCEEDING ANY TEMP LIMITATIONS OR ANY REDLINE LIMITATIONS. ON CLBOUT, THE R T5 (5TH STAGE TURBINE TEMP) GAUGE WAS AT THE TOP OF THE YELLOW ARC AT 725 DEGS C. AS WE CLBED OUT THE T5 LOWERED INTO THE GREEN ARC AS THE FO REDUCED PWR IN ORDER TO REDUCE THE PERCENTAGE ON THE PROPS. AFTER CALLING FOR THE AFTER TKOF CHKLIST THE FO AND I NOTICED THE GAS GENERATOR SPD HIGHER THAN NORMAL. AS WE REACHED CRUISE ALT THE GAS GENERATOR SPD WAS AT RED LINE. I ADVISED THE FO TO REDUCE PWR IN ORDER TO REDUCE PROP SPD, AS SOON AS POSSIBLE. I CHKED THE CAUTION LIGHTS FOR ANY DISCREPANCIES FOLLOWED BY CHKING THE OTHER ENG INSTS. EVERYTHING WAS IN THE SAFE ARC. I THEN CHKED THE ABNORMAL CHKLIST AND EMER CHKLIST. T5 NEVER WENT PAST THE RED LINE, IT WAS AT RED LINE. THE FO REDUCED THE PWR TO 35 LBS OF TORQUE. T5 STILL REMAINED IN THE RED. AT THAT TIME I MADE THE DECISION TO RETURN TO THE FIELD. I SAW NO NEED TO SHUT DOWN THE ENG BECAUSE THE OTHER ENG GAUGES WERE SHOWING IN THE GREEN, AND THE PWR PLANT SHOWED NO TREND OF EXCEEDING LIMITATIONS. I TOLD THE FO TO TURN AROUND AND RETURN TO THE SUITABLE ARPT. I ADVISED DISPATCH AND GOT AN AMENDMENT TO THE RELEASE. I ADVISED ATC OF THE RETURN AND OUR CONDITION. I ALSO ADVISED THE PAX THAT WE WERE RETURNING AND IT WAS JUST A PRECAUTIONARY LNDG. I THEN CALLED DISPATCH VIA SATELLITE PHONE AND GAVE THEM AN UPDATE. THE PAX REMAINED CALM THROUGHOUT THE FLT. I ADVISED THE FO TO PREPARE FOR A POSSIBLE ENG SHUTDOWN AND A SINGLE ENG APCH AND A POSSIBLE SINGLE ENG GAR. WE EXECUTED A NORMAL APCH TO THE ARPT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.