As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING NORMAL FLIGHT, PILOT NOTICED A BURNING SMELL. SHORTLY THEREAFTER, COCKPIT BEGAN TO FILL WITH SMOKE. AN EMERGENCY LANDING WAS MADE WITHOUT INCIDENT. MECHANIC FOUND ART HORIZ INOP AND BURNED INTERNALLY. (HEAVY SMOKE ON INSTRUMENT GLASS.) INSTRUMENT REPLACED AND AIRCRAFT RETURNED TO SERVICE. NOTE: NO SECONDARY DAMAGE WAS FOUND DUE TO INSTRUMENT FAILURE.