What is the primary use of cotter pins in aviation?

Cotter pins are primarily used in aviation to secure castellated nuts, pins, and shafts. When used with castellated nuts, the cotter pin passes through a hole in the nut and then bends to lock it in place. This prevents the nut from loosening due to vibration or movement, which is especially important in aviation applications where safety and reliability are critical. By ensuring that these components remain secure, cotter pins play a crucial role in maintaining the integrity of various aircraft systems.

While securing bolts is a common function in many applications, the specific role of cotter pins is more associated with locking components like castellated nuts and shafts. They are not used for decorative purposes or specifically designed to reduce vibration, which further distinguishes their primary function in secure fastening.