Why are locknuts or lock washers commonly used in assembly?

Locknuts and lock washers play a crucial role in ensuring the integrity and safety of an assembly, particularly in applications like aviation where vibration can be a significant concern. The primary purpose of these fasteners is to prevent loosening that can occur due to vibrations during operation.

When a fastener is subjected to vibrations, it can gradually work itself loose over time, which could lead to critical failures. Locknuts are designed with features such as nylon inserts or serrated surfaces that grip the threads of the bolt, creating friction that resists turning. Similarly, lock washers are placed under the nut or bolt head to create additional tension and maintain the clamping force. This prevents the fasteners from becoming loose and ensures that the assembly remains secure throughout the operational life of the component.

Other options like adding weight, improving speed, or enhancing visual appearance do not address the fundamental necessity for secure fastening in dynamic environments. Thus, using locknuts and lock washers is primarily aimed at maintaining safety and reliability in structures subjected to movements and vibrations.