What was found
DURING FINAL APPROACH, THE FLIGHT CREW SELECTED GEAR DOWN AND NOTICED THAT THE RT MAIN GEAR LIGHT WAS NOT ILLUMINATING. THE GEAR WARNING HORN DID NOT SOUND, AND THE RED GEAR UNSAFE LIGHT WAS EXTINGUISHED. THE FLIGHT CREW ELECTED TO PROCEED WITH AN EMERGENCY GEAR EXTENSION PROCEDURE TO HELP ENSURE POSITIVE DOWN LOCK. THEY TOUCHED DOWN NORMALLY, EXITED THE RUNWAY AND TAXIED WITHOUT ANY FURTHER ISSUES. MAINTENANCE REMOVED AND REPLACED ALL FOUR LANDING GEAR DOWN LOCK INDICATOR LAMPS WITH NEW AND PERFORMED SATISFACTORY GEAR RETRACTION AND EXTENSION TEST.