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What are AN Bolts and why are they used on Aircraft?

Within aerospace manufacturing applications, safety and reliability are of utmost importance. Every component used in or on an aircraft must meet stringent standards to ensure the integrity of the structure and its overall airworthiness. Among the many threaded fasteners utilized in aircraft assembly, AN bolts are arguably the most important. In this blog, we will delve into the world of AN bolts, discussing their characteristics and why they are so prevalent in aircraft design.

AN stands for "Army-Navy," as these bolts were initially standardized for use by the U.S. Army and Navy during World War II. Over time, the designation “AN” has become synonymous with high-quality, precision-engineered bolts in the aviation industry. In terms of design, AN bolts are typically threaded fasteners made from stainless steel, offering excellent strength, corrosion resistance, and durability. While AN bolts are not always a mandated part for design, they can provide various advantages over more conventional options. These advantages include:

  • High Strength: AN bolts are engineered to withstand high levels of stress and vibration encountered during standard aircraft operations. Their strength is achieved through the use of high-quality materials, precise manufacturing techniques, and stringent quality-control measures.
  • Corrosion Resistance: Stainless steel is the primary material used for AN bolts, providing resistance to corrosion and rust. This is crucial in an aviation environment where exposure to moisture, chemicals, and extreme temperatures can occur normally.
  • Precision Engineering: AN bolts are manufactured with strict tolerances to ensure uniformity and precise fits. The standardized dimensions and thread pitches allow for easy replacement and maintenance, reducing operational downtime and costs.

Different Types of AN Bolts

AN bolts come in various types to suit different needs, each being designed for specific applications. These include popular options such as:

  • AN3 to AN20: These are the most commonly used AN bolts, ranging in size from 3/16 inches to 1-1/4 inches in diameter. They have a hexagonal head and are typically used for general-purpose fastening, including attaching components, structures, and panels.
  • AN21 to AN26: These bolts have a drilled head, which allows for safety wiring to be added. Safety wiring is a method of mechanically securing bolts to prevent them from loosening due to vibration or other forces.
  • AN173 to AN186: These bolts feature a double hex head design, allowing for increased torque capacity. They are often used in critical areas where a higher clamping force is required.

Why AN Bolts are Used in Aircraft

  • Safety and Reliability: AN bolts undergo rigorous testing during the manufacturing process and adhere to strict industry standards. Their strength, corrosion resistance, and precision engineering ensure the structural integrity of an aircraft, enhancing its overall safety and reliability.
  • Interchangeability and Standardization: AN bolts are designed to be interchangeable, meaning they can be easily replaced without requiring modifications. This method of standardization simplifies maintenance, repairs, and component replacement, saving time and money.
  • Compatibility with Aerospace Materials: Stainless steel AN bolts are compatible with various aerospace materials, such as aluminum, titanium, and composites. Their corrosion-resistant properties help prevent galvanic corrosion when in contact with dissimilar metals, maintaining the structural integrity of the aircraft assembaly.


AN bolts have become a staple in aerospace manufacturing due to their exceptional strength, corrosion resistance, and precision engineering. They provide a reliable and standardized solution for fastening critical components in aircraft, guarenteeing the safety and integrity of the structure. If you find yourself interested in top-quality AN bolts that can be steadily relied on, we at Aerospace 3sxity have you covered with an expansive set of offerings that are ready for purchase at any time.

Aerospace 3sxity is a website owned and operated by ASAP Semiconductor, and we present customers access to over 6 billion new, used, obsolete, and hard-to-find products that are readily available for procurement today. Take the time to explore our expansive offerings as you see fit, and once you narrow down items of interest, fill out and submit an RFQ form at your earliest convenience as provided on our website. Once we receive and review your request, a member of our staff will contact you in 15 minutes or less to present a tailored solution for your comparisons. Get started today and see why so many customers steadily depend on Aerospace 3sxity for their sourcing needs. 


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