What was found
DURING APPROACH, THE LANDING GEAR WAS SELECTED TO THE DOWN AND LOCKED POSITION. THE #1 MAIN LANDING GEAR ASSEMBLY DOWN AND LOCK LIGHT DID NOT ILLUMINATE, AND THE FLIGHT CREW PERFORMED A MANUAL LANDING GEAR EXTENSION. MAINTENANCE TROUBLESHOT THE FAILURE TO A FAULTY LANDING GEAR DOWN LOCK SWITCH. THE SWITCH WAS REPLACED, LANDING GEAR EXTENSION AND RETRACTION CHECKS WERE SUCCESSFUL, AND THE AIRCRAFT HAS BEEN RETURNED TO SERVICE. NO REPEAT DISCREPANCIES HAVE BEEN REPORTED.