Aircraft Safety Wire Standards: Mil-Specs, Features & Benefits

Safety wire, also known as lock wire or locking wire, is used on an aircraft to prevent vibrational loosening, enhance structural integrity and prevent tampering. Required in some applications by aircraft safety wire standards set by Federal Aviation Administration (FAA) standards, aircraft safety wire provides an additional level of security and protection if a fastener or locking mechanism fails. Military Standard aviation safety wire comes in various diameters and strengths, each offering different features and benefits that can be beneficial to a specific application. Whether you're learning how to safety wire for the first time or brushing up on safety wire how-to techniques, it's a key skill in maintenance.

Safety wire is lightweight and easy to use, making it the ideal choice for securing fasteners and ensuring the integrity of critical systems. Safety wire comes in a variety of sizes to match the type of fastener you are trying to secure. The wire is lightweight and flexible, yet strong enough to keep everything together.

Mil-Spec Aircraft Safety Wire

When shopping for aircraft safety wire, you'll notice that mil-spec standards are usually used to classify different types of safety wire. While there are many standards, a few stand out in aircraft safety wiring and safety wiring applications:

• M22759 (SAE AS22759) Safety Wire: M22759 mil-spec safety wire is engineered for extreme environments, making it ideal for aircraft engine controls, critical electronic systems, and aviation wiring exposed to severe weather. This safety wire offers excellent resistance to moisture, abrasion, and thermal stress, and is frequently used in military-grade and aerospace electrical applications.
• M16878 Safety Wire (Mil-Spec Wire for High Voltage & Temperature): M16878 mil-spec safety wire is the preferred choice for applications that demand high voltage ratings and extreme temperature resistance. Constructed from materials like PTFE, PVC, ETFE, and polyalkene-PVC, this wire is commonly used in power supplies, appliance wiring, and industrial electronic systems that operate in high-heat conditions.
• M25038 Safety Wire for Vibration & Flame Resistance: M25038 mil-spec safety wire is specifically designed to withstand intense vibration and direct flame exposure, making it ideal for aircraft systems, avionic circuitry, and other critical aerospace applications. Its rugged durability ensures long-term performance in demanding flight conditions.
• M13486 Safety Wire for Low-Tension & Moisture-Prone Environments: M13486 safety wire is optimized for low-voltage and low-tension applications where flexibility, moisture resistance, and abrasion protection are essential. Commonly used in military ground vehicles and automotive wiring systems, it maintains pliability even in sub-zero temperatures.
• M5086 Safety Wire - General Purpose Military Wire: M5086 mil-spec safety wire features a tin-plated copper conductor, PVC insulation, and a nylon jacket for enhanced durability. It is a trusted solution across military, aerospace, and industrial applications, especially where chemical exposure, abrasion, or impact may occur. Its rugged design makes it ideal for general-purpose electrical installations in harsh environments.

Aircraft Safety Wire Features

From 032 safety wire to ultra-flexible options, aircraft safety wiring offers plenty of unique features that make it a valuable tool in various applications that require a little extra stability and security. While not all safety wire is created the same, some primary features are fairly universal no matter which type or size of safety wire you choose. Here are the primary characteristics you’ll find across most types of safety wire:

• Strong Hold: No matter which type of safety wire you choose, you can expect it to have a strong hold. The primary function of safety wire is to secure components, preventing nuts, bolts, screws and other types of fasteners from coming loose due to vibration, temperature fluctuations or other hazards of flight. This feature is critical and universal.
• Locking Mechanism: Safety wire is designed to lock in place, keeping components secure flight after flight. How you install the safety wire can impact how well it locks. Pigtail twisting is a common method of installing safety wire and can be done using safety wire pliers.
• Flexible and Pliable: Safety wire is made to be flexible enough to wrap around components and fasteners. It is also pliable, allowing it to conform to the shape of the fastener it is securing. Flexibility and pliability are key features to look for when choosing safety wire.
• Corrosion Resistant: Most safety wire is corrosion resistant because it will come in contact with moisture at some point. Being resistant to environmental hazards is critical to maintaining strength and a solid hold.
• High Tensile Strength: A high tensile strength means the safety wire can withstand heavy loads before breaking. This is especially important in high-stress environments.
• Color-coded: Some safety wires are color-coded so it's easy to distinguish. The color coding may indicate the wire diameter or how the safety wire is being used.
• Versatile: All safety wire is versatile and can be used wherever you need extra strength and stability. Use safety wire in a variety of applications throughout your aircraft to make sure fasteners are secure, components are in place and nothing has been tampered with. Enjoy versatility across all aircraft safety wiring tasks.

Benefits of Aircraft Safety Wire

There are many benefits to using safety wire on your aircraft. When used correctly, safety wire can help reduce repairs and in-air emergencies, improving safety overall without adding a lot to your operational budget. The right safety wire is a key component in any toolbox, offering security and allowing for quick in-flight repairs.

Not all safety wire is the same, so benefits may vary from one type of wire to another. However, the basic benefits are similar no matter which type of safety wire you buy. Some of the benefits of safety wire include:

• Prevents Loosening: Safety wire is most often used to keep fasteners secure and prevent detachment. When used properly, safety wire can prevent fasteners from backing out or loosening, keeping all the connections on your aircraft tight and ready for flight.
• Fewer Repairs: A lost nut or screw can spell disaster in the sky, grounding your aircraft and throwing off your schedule. Fewer repairs mean less downtime and less revenue loss. A simple length of safety wire can prevent many small repairs and keep your aircraft in the sky - where it belongs.
• Inexpensive: Safety wire is one of the cheapest and easiest preventative measures you can take when it comes to keeping your aircraft flight-ready. Safety wire is typically sold by the roll and is relatively cheap compared to other maintenance tools and consumables. Even safety wire pliers and other tools are relatively cheap compared to other items.
• Streamlines Inspections: Properly installed safety wire can streamline the inspection process, saving time and improving safety. Properly installed safety wire provides a visual indicator that a component is secure and has been meticulously installed. Maintenance personnel can easily identify any components needing repair by simply checking to see if the wire has been disturbed.
• Detecting & Preventing Errors: Safety wire acts as an invaluable visual indicator. Its proper application provides an immediate visual cue if a component has been disturbed or if a fastening task was not completed correctly during maintenance.
• Adherence to Mandatory Aviation Requirements:For many critical applications on an aircraft, the use of safety wire is not optional. Implementing correct safety wiring techniques is crucial for passing inspections and maintaining the operational integrity demanded by regulatory bodies.

Conclusion

The importance of aircraft safety wire standards cannot be overstated, as Mil-spec safety wire offers a durable, reliable, and inexpensive solution to preventing vibrational forces, temperature changes, and other common flight hazards from grounding your aircraft. Whether you're performing routine maintenance or prepping for a long haul, safety wire is an essential part of your toolkit. Safety wire is used to keep fasteners in place, to secure components and, in some cases, to guard against tampering or accidental loosening caused by in-flight stress. Safety wire is a simple, yet effective way to enhance overall safety and ensure your aircraft always stays airworthy. Safety wire comes in various diameters and is typically sold by the roll for the best value possible. Make sure your aircraft is ready for flight by securing fasteners and other critical components with high-quality Military Standard safety wire from SkyGeek.