The 654711 Cotter Pin is a small safety locking fastener used in Continental aircraft engine assemblies. It is designed to secure castellated nuts, clevis pins, and other fasteners by mechanically preventing them from loosening during vibration and engine operation.

It is inserted through a drilled hole in a fastener and then bent over to lock it in place, providing a simple but highly reliable retention method.

Its primary functions include:

Locking fasteners such as nuts and clevis pins in position
Preventing loosening due to vibration and thermal cycling
Providing a mechanical safety retention feature in engine assemblies

Cotter pins like the 654711 are critical low-cost safety components in aviation, ensuring that essential fasteners remain securely locked in high-vibration engine environments.