A SAAB 340B PILOT REPORTS AN ENG INTAKE HEATER MAT FIRE UNDETECTED BY THE CREW DURING POST FLT WAS DISCOVERED THE NEXT MORNING DURING PREFLT.

Narrative

I MUST HAVE WENT DIRECTLY FROM INSPECTING THE PROP BLADES TO INSIDE THE INTAKE WHILE GLANCING AT THE LIP. I BELIEVE THAT THE COMBINATION OF A BURNED AREA ON A BLACK AREA WITH THE RAIN AND DARKNESS CONTRIBUTED TO THIS OVERSIGHT. WHILE ENRTE TO PIB WE ENCOUNTERED ICING CONDITIONS THAT LASTED FOR APPROX 15 MINS. AFTER EXITING THE CONDITIONS; BUT NOT BEFORE 5 MINS HAD ELAPSED; WE RECEIVED AN INTAKE CAUTION LIGHT. THE LIGHT EXTINGUISHED BEFORE WE COULD GET THE QRH OUT. WE CONSIDERED THE LIGHT TO BE TRANSIENT AND THAT NO FURTHER ACTION BE REQUIRED. IT WAS ABOUT XA30 WHEN I DID MY POSTFLT INSPECTION. IT WAS DARK AND RAINING. I DID UTILIZE A FLASHLIGHT; HOWEVER; I OVERLOOKED THE BURNED AREA ON THE LIP ON THE L-HAND INTAKE. THE FO OBSERVED THE INTAKE CONDITION DURING HIS PREFLT INSPECTION. ONCE THE FO BROUGHT IT TO MY ATTN I WROTE UP THE INTAKE AND THEN CONTACTED DISPATCH FOLLOWED BY MAINT. I'M SURE EXPECTANCY PLAYED A PART IN MY OVERLOOKING OF THE INTAKE CONDITION. I WILL USE THIS EXPERIENCE TO BUILD UPON.