Why are locking wires used in fastener assemblies?

Why are locking wires used in fastener assemblies?

• A. To mark the fasteners for identification.
• B. To provide easy disassembly for maintenance.
• C. To prevent fasteners from loosening due to vibration by securing the nut or bolt in place.
• D. To indicate torque value.

Answer: (C)

Locking wires are used to prevent fasteners from loosening in vibration-heavy environments by securing the nut or bolt in place. The wire is threaded through holes in the fastener (or through a locking feature like a castellated nut and bolt head) and twisted tight to create tension. This tension keeps the nut and bolt from turning independently, so even under repeated vibration the joint stays at its designed preload. Maintaining that preload is crucial to preventing loosening and potential failures in aircraft assemblies. It’s not about marking, easy disassembly, or indicating torque—those are separate functions handled by other methods.

Locking wires are used to prevent fasteners from loosening in vibration-heavy environments by securing the nut or bolt in place. The wire is threaded through holes in the fastener (or through a locking feature like a castellated nut and bolt head) and twisted tight to create tension. This tension keeps the nut and bolt from turning independently, so even under repeated vibration the joint stays at its designed preload. Maintaining that preload is crucial to preventing loosening and potential failures in aircraft assemblies. It’s not about marking, easy disassembly, or indicating torque—those are separate functions handled by other methods.