As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE STARTED WHEN PROP WAS ROTATED TO CHECK OIL LEVEL AS PER POH. IGNITION SWITCH WAS OFF AND KEY REMOVED. IGNITION SWITCH FOUND TO HAVE CARBON TRACKING BETWEEN CONTACTS. AIRCRAFT ARE SHUTDOWN USING IGNITION SWITCH, NO PROBLEMS WERE NOTED ON PREVIOUS SHUT DOWN.