What was found
IAH - FLIGHT 2561, THE CREW REPORTED THAT THE NOSE LANDING GEAR DOOR OPENED IN FLIGHT. THE AIRCRAFT RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE NOSE LANDING GEAR DOOR SEQUENCE PROXIMITY SWITCH, OPERATIONALLY TESTED WITH NO DEFECTS, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.