Safety wire
A safety wire or locking-wire is a type of positive locking device that prevents fasteners from falling out due to vibration and other forces.
Briefly, safetying is defined as: "Securing by various means any nut, bolt, turnbuckle etc., on the aircraft so that vibration will not cause it to loosen during operation."
These practices are not a means of obtaining or maintaining torque, rather a safety device to prevent the disengagement of screws, nuts, bolts, snap rings, oil caps, drain cocks, valves, and parts.
This property allows it to remain locked around an object, such as when it is passed through a small hole on a fastener, looped back upon itself and then twisted.
Since it remains twisted instead of unraveling, it acts as a fixed loop and will not back out without considerable force (greater than the stresses which it is intended to counter) being applied.
This is done by passing a couple of turns of mousing wire through the reach-hole provided for this purpose in the unthreaded end of the clevis pin and around the body of the shackle's hoop.
A cotter pin or a couple of loops of mousing wire through this hole serves the same purpose and secures the shackle in a closed position.
Common applications include the security of safety equipment such as fire extinguishers, and safety equipment bags, but also as an assurance that critical system switch covers remain in place, such as those associated with the application of fire suppression, or ejection systems.
This application of witness wires is widely varied, and may cover a broad range of types of equipment and numerous situations.
Witness wires also serve the purpose of providing a rapid method for ensuring critical safety equipment or systems have not been used or tampered with since their last repair, reset, or inspection, and also that the container of such equipment has not been inadvertently opened, disturbed or tampered with, therefore providing confidence in their readiness for use.
In a similar manner, critical system switch covers are protected from inadvertent activation, through the application of witness wire.
[7] For consumer applications, it is typically sold in 1 lb (0.45 kg) spools enclosed in a small cardboard or plastic canister.
The advantage to this tool is its long and thin design, which can access hard-to-reach areas where one's hands or pliers do not fit.
Several companies manufacture safety cable, and it is becoming an industry standard due to easier control of critical inputs and reduced installation time.
In addition to installing 3 times quicker than safety wire, Safe-T-Cable also produces a stronger and safer result.
Unlike safety wire, Safe-T-Cable installations have no sharp edges, which greatly reduces the risk of injury.
Operation overview:[10] Although many systems purport to be more efficient than installing traditional safety wire, an advantageous by-product of the twisting method of installing safety wire is that it leaves a highly visible and easily inspectable indication that the fasteners in question are in fact properly secured.
The primary disadvantage of traditional safety wire is the time it requires to install properly when securing fasteners, although technicians who use it often can implement it fairly quickly.
It also leaves behind waste products when ends are clipped off or when it is cut off secured fasteners that need to be removed during maintenance, resulting in sharp metal bits that can easily damage soft materials or injure skin.
