What was found
WHILE ENROUTE, THE PILOT NOTICED THE RT WING OVER HEAT ANNUNCIATOR LIGHT ILLUMINATED. THIS WAS FOLLOWED BY VISIBLE SMOKE OBSERVED IN THE COCKPIT. THE PILOT FOLLOWED THE EMERGENCY PROCEDURES, TURNED OFF THE RT BLEED AIR, LOWERED THE LANDING GEAR AND DONNED HIS OXYGEN MASK. ONCE THE LANDING GEAR WAS LOWERED AND THE RT BLEED AIR WAS TURNED OFF, THE SMOKE STARTED TO DISSIPATE AND THE WING OVERHEAT LIGHT EXTINGUISHED. THE PILOT LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOOTING REVEALED THE RT COOLING TURBINE FAILED CAUSING THE SMOKE IN THE COCKPIT AND THE WING OVER HEAT LIGHT TO ILLUMINATE. R & R THE RT COOLING TURBINE, PN: 204755-4-6, SN: 110-991. GROUND RUNS COMPLETED THE RT COOLING TURBINE FUNCTIONAL CHECKED NORMAL; NO DEFECTS WERE NOTED AT THIS TIME.