As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON APPROACH WITH PROP HEAT ON, HAD SPARKS COMING OUT OF BOTH PROPS CLOSE TO THE SPINNER. PERFORMED GVI OF PROPS, SPINNERS, BRUSH BLOCK ASSY. FOUND NO EVIDENCE OF SPARKING. RAN BOTH ENGINES WITH PROP HEAT FOR 15 MINUTES AND NO SPARKING OCCURRED. RE-INSPECTED PROPS, NO DEFECTS NOTED. FUNCTIONAL OF PROP DEICE C/W IAW AMM 30-61-00-720-801. RETURNED TO SERVICE. NO PARTS REPLACED.