What Types of Fasteners Are Used in Aviation?

Fasteners are implemented throughout aircraft to bind structural areas and other accessory components. Of the millions of parts in a jet aircraft, fasteners tend to account for close to 50% of the total. These elements must be durable and resistant to the harsh operating conditions present in aviation. In this blog, we will discuss several types of aircraft fasteners and how they find use in modern aircraft.

Bolts, nuts, screws, and rivets account for a vast majority of the fasteners in the aviation industry. Provided below is a brief description of each:

Aircraft Nuts: Made from stainless steel, 2024T aluminum alloy, or cadmium-plated carbon steel, aircraft nuts are found in different sections of the aircraft with varying tension requirements. They may either be non-self-locking or self-locking depending on the application, with the latter being preferred in places prone to excessive and constant vibration.

Aircraft Bolts: Aircraft bolts are generally more specialized to fit a particular application, manufactured to accommodate the exact dimensions and strength wherever needed. In contrast, general-purpose bolts, such as the hex head design, may be used on structural elements as long as the tolerances are decently high.

Aircraft Screws: Aircraft screws may be further classified as structural, machine, and self-tapping. Structural screws are explicitly designed to be durable and corrosion resistant. Made from heat-treated alloy steel, aircraft screws may be used in place of structural bolts and commonly are due to narrower tolerances. Meanwhile, mechanical screws are considered general-purpose and may be made from various materials, including low-carbon steel, brass, or aluminum alloy. Finally, self-tapping screws are used to secure removable parts in place.

Aircraft Rivets: Rivets are the most used fastener to join skin, spar, and other structural sections of aircraft together. A large commercial aircraft may require hundreds of thousands of these components during manufacturing.

There are also several specialty fasteners used primarily in light-sport aircraft (LSA), but also in traditional models:

Turn lock Fasteners: These fasteners are handy for frequently inspected parts of the aircraft, such as panels, inspection plates, and doors. Unlike other elements which are significantly tightened and may require specialized tools to remove, turn lock fasteners are designed to be extracted with little effort.

Taper-Lok: Taper-Lok fasteners are widely considered to be the strongest in aviation. With their tapered shape, these components apply a continuous force to the walls of the hole without deforming it.

Hi-Tigue: This fastener type resembles a standard bolt and may be used in place thereof for several applications. In addition to the shank, Hi-Tigue fasteners also feature an attachable bead which increases the strength of the overall joint.

In addition to understanding the various types of fasteners used in aviation, it is equally important to appreciate the different materials used in their manufacturing. While ubiquitous in aircraft structure manufacturing, aluminum is generally limited to rivets in the context of fasteners. Although stainless steel is heavier than aluminum, it is much stronger and features a similar degree of corrosion resistance. Fasteners used in high-stress areas, such as the landing gear, are typically made from this metal alloy. Most recently, titanium has been considered as an alternative material to aluminum since it has a favorable strength profile while also being lightweight and temperature resistant.

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