What was found
IN CRUISE HAD FIRE T HANDLE LIT UP. WAITED 15-20 SECONDS TO BE SURE HANDLE WAS ON. SECURED ITEMS THEN CHECKLIST. SECURED ENGINE, CONTINUES TO BUTTE (WAS OVER HIA). CALLED CENTER AND LANDED WITHOUT INCIDENT, TAXIED CLEAR OR ALL RUNWAYS, WAS TOWED INTO HANGAR. CALLED CP. FLIGHT LINE MECHANICS INSPECTED ENGINE, SIGNED OFF NO ISSUES. RETURNED TO BILLINGS WITHOUT INCIDENT. INSPECTED FOR ANY INDICATION OF FIRE NOTHING INDICATING INSIDE COWLING. OPS CHECKED ENGINE FIRE DETECTOR. NO DEFECTS NOTED.