What was found
FLT 4134 - ON APPROACH WHILE EXTENDING THE LANDING GEAR IN PREPARATION FOR LANDING, THE LT MAIN GEAR DID NOT INDICATE DOWN AND LOCKED. THE CREW FOLLOWED PROCEDURES AS SPECIFIED IN THE QUICK REFERENCE HANDBOOK, AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. PIT MX REPLACED DEFECTIVE BULBS IN THE LANDING GEAR POSITION INDICATOR. GROUND CHECKED GOOD, AIRCRAFT RETURNED TO SERVICE.