Narrative:

After dropping passenger off in destin, fl, I returned home to lafayette, la. Initial cruise altitude was 14000 ft. Everything was within prescribed parameters until about 100 mi east of lft. Oil temperature on left engine began to creep up. I reduced power on left engine, opened cowl flap, enriched mixture. Although egt, cht, and oil pressure responded normally, oil temperature continued to rise. About 30 mi from airport, oil temperature red-lined, despite all efforts to control it. I felt it prudent to shut down the engine in a precautionary effort to prevent catastrophic loss of the left engine. Since all other indications were normal, I suspected a bad sending unit. Since the oil temperature rise was gradual, it did not seen to indicate a short. The shutdown was strictly precautionary. I was near the airport and there were no passenger on board. I did not require special handling and did not declare an emergency. Callback conversation with reporter revealed the following information: the reporter stated the high oil temperature was caused by a malfunctioning engine mounted oil temperature bulb. The reporter said the left engine oil temperature system was suspected to be a false reading but if it were proved to be correct the engine would have incurred severe damage by continuous operation.

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Original NASA ASRS Text

Title: A C414 IN CRUISE AT 11000 FT SHUT DOWN THE L ENG DUE TO HIGH OIL TEMP CAUSED BY A DEFECTIVE ENG OIL TEMP BULB.

Narrative: AFTER DROPPING PAX OFF IN DESTIN, FL, I RETURNED HOME TO LAFAYETTE, LA. INITIAL CRUISE ALT WAS 14000 FT. EVERYTHING WAS WITHIN PRESCRIBED PARAMETERS UNTIL ABOUT 100 MI E OF LFT. OIL TEMP ON L ENG BEGAN TO CREEP UP. I REDUCED PWR ON L ENG, OPENED COWL FLAP, ENRICHED MIXTURE. ALTHOUGH EGT, CHT, AND OIL PRESSURE RESPONDED NORMALLY, OIL TEMP CONTINUED TO RISE. ABOUT 30 MI FROM ARPT, OIL TEMP RED-LINED, DESPITE ALL EFFORTS TO CTL IT. I FELT IT PRUDENT TO SHUT DOWN THE ENG IN A PRECAUTIONARY EFFORT TO PREVENT CATASTROPHIC LOSS OF THE L ENG. SINCE ALL OTHER INDICATIONS WERE NORMAL, I SUSPECTED A BAD SENDING UNIT. SINCE THE OIL TEMP RISE WAS GRADUAL, IT DID NOT SEEN TO INDICATE A SHORT. THE SHUTDOWN WAS STRICTLY PRECAUTIONARY. I WAS NEAR THE ARPT AND THERE WERE NO PAX ON BOARD. I DID NOT REQUIRE SPECIAL HANDLING AND DID NOT DECLARE AN EMER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE HIGH OIL TEMP WAS CAUSED BY A MALFUNCTIONING ENG MOUNTED OIL TEMP BULB. THE RPTR SAID THE L ENG OIL TEMP SYSTEM WAS SUSPECTED TO BE A FALSE READING BUT IF IT WERE PROVED TO BE CORRECT THE ENG WOULD HAVE INCURRED SEVERE DAMAGE BY CONTINUOUS OP.

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.