What type of fastening method requires the use of a cotter pin?

Using a cotter pin is specifically associated with through-hole fastening methods. In this approach, a hole is drilled through two or more aligned components. A fastener, such as a bolt or a rod, is inserted into these holes, and the cotter pin is then used to secure the fastener in place by passing it through a hole in the fastener itself. This method is essential in applications where it is critical to prevent the fastener from loosening due to vibration or external forces.

Through-hole fastening offers significant advantages in terms of reliability and security, especially in aerospace applications where safety and structural integrity are paramount. The cotter pin can be easily inspected and replaced if needed, which enhances maintenance efficiency. While other fastening methods may involve different components and techniques, the use of a cotter pin is distinctive to the through-hole fastening method, making it the correct choice for this question.