What was found
AIRCRAFT WAS COMING FOR LANDING ON APPROACH, GEAR WAS EXTENDED BUT NLG DOWN & LOCK INDICATION WAS NOT INDICATING. PILOTS WENT THROUGH THEIR TROUBLESHOOTING CHKLIST, NLG STILL NOT INDICATING. PILOTS CONFIRMED NLG DOWN USING COWLING MIRROR & TOWER FLYBY, PILOT PERFORMED EMERGENCY LANDING WITHOUT INCIDENT. MX INSPECTED SYSTEM & FOUND LIGHT BULB HAD FAILED, OPS CHK OF LANDING GEAR SYS WAS GOOD. INCANDESCENT LIGHT BULBS USED IN MULTIPLE SYS AS INDICATOR LIGHTS & ARE PRONE TO FAILURE & HAVE EXPERIENCED MULTIPLE ISSUES WITH THEM. MOST OF OUR OTHER DA42NG ACFT CAME WITH LED BULBS WHICH WE HAVE NO ISSUES WITH, THEY ARE MUCH MORE RELIABLE. WE HAVE BEEN TOLD THE LED BULBS ARE NO LONGER IN PRODUCTION P/N 461K_02_2801_WS.