In accordance with NAVSEA SW020-AF-HBK-010 only one horn is required for each motor vehicle. If the vehicle is equipped with two factory installed horns must both work?

Yes, if a motor vehicle is equipped with two factory-installed horns, both must work to ensure compliance with safety standards and regulatory requirements. While only one horn is required by NAVSEA SW020-AF-HBK-010, having both operational ensures the vehicle can effectively signal and communicate in various situations. Proper maintenance of all safety equipment, including horns, is essential for vehicle reliability and safety.