Narrative:

During climb out in IMC, we received red warning lights, cas, triple chime warning, indicating right engine pylon overheat. I, as PF, retarded the right engine to flight idle, and called for the QRH and had the copilot run the appropriate procedure. While procedure in progress, I informed ATC of intent to return to departure airport (ZZZ1). The problem was cleared, and once again, we turned south to continue to original destination of fll. 2 or 3 mins later, problem recurred. Then I asked for WX at company maintenance facility located nearby at ZZZ, and was cleared direct. The right engine nacelle heat had to remain off, but the right engine worked normally, with the right pylon overheat warning again extinguished. We monitored the engine parameters, watched for signs of icing, and diverted to ZZZ without further incident. Callback conversation with reporter revealed the following information: the reporter stated the nacelle overheat warning is a recurring problem on the lear 45 and has happened 3 times to the reporter with 2 separate airplanes. The reporter said a piccolo tube distributes the hot pneumatic air into the pylon and it is believed a combination of overly sensitive heat sensors and inadequate insulation is causing the problem. The reporter stated this is just what maintenance suspects and is just theory.

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Original NASA ASRS Text

Title: LEAR 45 AT 15000 FT DIVERTED DUE TO REPEATED R ENG NACELLE OVERHEAT. RECURRING PROB CAUSED BY OVER SENSITIVE SENSORS AND INADEQUATE INSULATION.

Narrative: DURING CLBOUT IN IMC, WE RECEIVED RED WARNING LIGHTS, CAS, TRIPLE CHIME WARNING, INDICATING R ENG PYLON OVERHEAT. I, AS PF, RETARDED THE R ENG TO FLT IDLE, AND CALLED FOR THE QRH AND HAD THE COPLT RUN THE APPROPRIATE PROC. WHILE PROC IN PROGRESS, I INFORMED ATC OF INTENT TO RETURN TO DEP ARPT (ZZZ1). THE PROB WAS CLRED, AND ONCE AGAIN, WE TURNED S TO CONTINUE TO ORIGINAL DEST OF FLL. 2 OR 3 MINS LATER, PROB RECURRED. THEN I ASKED FOR WX AT COMPANY MAINT FACILITY LOCATED NEARBY AT ZZZ, AND WAS CLRED DIRECT. THE R ENG NACELLE HEAT HAD TO REMAIN OFF, BUT THE R ENG WORKED NORMALLY, WITH THE R PYLON OVERHEAT WARNING AGAIN EXTINGUISHED. WE MONITORED THE ENG PARAMETERS, WATCHED FOR SIGNS OF ICING, AND DIVERTED TO ZZZ WITHOUT FURTHER INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE NACELLE OVERHEAT WARNING IS A RECURRING PROB ON THE LEAR 45 AND HAS HAPPENED 3 TIMES TO THE RPTR WITH 2 SEPARATE AIRPLANES. THE RPTR SAID A PICCOLO TUBE DISTRIBUTES THE HOT PNEUMATIC AIR INTO THE PYLON AND IT IS BELIEVED A COMBINATION OF OVERLY SENSITIVE HEAT SENSORS AND INADEQUATE INSULATION IS CAUSING THE PROB. THE RPTR STATED THIS IS JUST WHAT MAINT SUSPECTS AND IS JUST THEORY.

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.