How to Wire Tie Aircraft Nuts & Bolts

Many components that operate flight controls are secured with safety wired bolts.

Aircraft bolts can secure critical parts and components in locations that may be subject to extreme stress and high vibrations. This is why it is so important to follow the specified torque values for all aircraft bolts. A common precaution to ensure that even properly torqued bolts do not loosen is to secure them to other bolts or secure aircraft structures with metal wire (safety wire). Nuts are not commonly wire tied or safety wired, but they are often secured with cotter pins. When nuts are safety wired, follow the same procedures as you would for safety wiring bolts.

Things You'll Need

• Safety wire
• Safety wire pliers
• Bolts with safety wire holes in the bolt heads
• Torque wrench

Instructions

1. 

   Tightening bolts to their proper torques is the first step in installing saftey wire.

   Tighten the bolt to its proper torque. Safety wiring is a fail-safe measure to ensure that a bolt does not loosen if primary installation measures have become insecure. The primary installation measure is always to torque the bolt properly.

2. Insert safety wire through the bolt head and loop one end of the wire around the bolt head so that both ends of the wire are extending from the same side of the bolt.

3. Grab the wire with the safety wire pliers and slide the locking sleeve of the pliers into the locked position.

4. Loosen your grip on the pliers handles and pull the knob outward. The pliers will begin to spin with the two strands of wires locked in its jaws, twisting the safety wire. Repeat this process if needed until the twisted wire reaches the next attaching point. This may be another bolt or a whole drilled into the aircraft structure.

5. Insert one strand of the safety wire into the hole at the attaching point. If it is another bolt, loop one strand of wire around the bolt head to bring both strands together at the other end of the bolt.

6. Grip the strands of wire in the safety wire pliers and lock them. Pull the knob on the pliers again to twist the wire for about four to six turns. Make sure you are guiding the wire toward the next location that it will attach to and that if the wire were to pull, it would pull the bolt in a tightening direction.

7. Release the pliers and use their cutters to cut the wire strands, leaving the four to six twists extending from the second bolt or other attaching point.

8. Bend, or pigtail, the remaining twisted wire strand over, looping, bringing the free end as close to the bolt or other attaching point as possible. This will prevent snagging.

References

• Sport Aviation: Safety Wire and Other Failsafe Precautions
• Ultralight News: Safety Wire, Proper Safety Wire Technique for Using Safety Wire on Ultralights, and Ultralight Aircraft