What was found
WHILE PICKING UP CLEARANCE AT NIGHT WITH INSTRUMENT EMERGENCY LIGHTS IN THE ON POSITION. CREW NOTICED SMOKE FROM THE COPILOTS SIDE EMERGENCY INSTRUMENT LIGHT BULBS. LIGHTS WENT OUT AND BATTERY MASTER SWITCH WAS TURNED OFF. MAINTENANCE NOTICED A BURNT INOPERATIVE BULB RUBBER PLASTIC MATERIAL WITH SMALL MINOR BURNT AREAS. REPLACED INOPERATIVE BULB. ALL EMERGENCY INSTRUMENT LIGHTS OPERATIONAL CHECKS GOOD. NO SMOKE NOTED. AIRCRAFT WAS RETURNED TO SERVICE.