What was found
CABIN EMERGENCY LIGHTS STARTED TO FLICKER WHEN PROP HEAT SELECTED. CYCLED PROP HEAT OFF AND LIGHTS STOPED. TURNED HEAT BACK ON AND EMERGENCY LIGHTS DID NOT COME BACK ON INSPECTED AND CLEANED BOTH PROP BRUSH BLOCK ASSEMBLIES AS REQUIRED. NO DEFECTS FOUND AT THIS TIME. GROUND RAN 1 ENGINE AT A TIME, FOUND PROP HEAT OPS NORMAL IAW START RUN TAXI MANUAL. NO EMERGENCY LTS FLICKERERING NOTICED OK FOR SERVICE.