As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN CRUISE FLIGHT THE CIRCUIT BREAKER PANEL STARTED SMOKING. PILOT REQUESTED APPROACH FOR PRIORITY IN HELENA, MT. PILOT SAID THE SMOKE SHORTLY STOPPED AFTER 5 SECONDS. PILOT HAD A NORMAL LANDING IN KHLN AND CONTACTED MAINTENANCE. MAINTENANCE SAID THAT DE-ICE FLUID HAD LEAKED INTO THE PANEL.