Some Important Nuts and Fasteners in the Aviation Industry

Though they are some of the smallest components on aircraft, the nuts and fasteners serve the major function of holding together all of the components that make up the whole. To meet all these various demands, there are a large number of hardware types employed in airplane construction, including nuts, washers, cotter pins, and more. While many of these items can be found in a hardware store, it is imperative and required that those used on aircraft are aviation grade to ensure that they can withstand the vibrations, pressure changes, temperature shifts, and other harsh conditions that they may be exposed to during each flight. Here, we will be discussing a few of the important nuts and fasteners used in aircraft construction to create a reliable hold.


As a highly versatile form of hardware, washers are used all over aircraft to add space between components, protect mounting surfaces from damage, and work in conjunction with other fasteners for a stronger attachment. The most simple of these fasteners will consist of a flat metal disc with a round hole through the center, but for more particular applications there are washers with specialized designs. One such example is the lock washer which often has internal or external teeth that add more friction and strength to the fastener. Still other types of washer include those with nylon inserts, a spring-like design, and a convex shape. Washers are very commonly made of metal but they may also be made from plastic, ceramic, or other materials to offer different properties.

Nuts and Cotter Pins

Aside from washers, aviation-grade nuts are also used on aircraft in the thousands to add strength and create a desired head shape for a fastener. Nuts are often used in conjunction with bolts and pins to better distribute their load over a mounting surface, or add a second head onto a rod to hold multiple components in between the two heads. This function is commonly used for securing the metal sheets that are common in plane design. Similar to aircraft washers, aviation-grade nuts also come in a variety of shapes, materials, and sizes that can suit an array of operations. Here are some of the most commonly used:

Plain Nuts

It may not come as a surprise that plain nuts are one of the most commonly used types in aircraft. These fasteners are typically hexagonal with a threaded interior that can be effectively fastened onto a bolt. To install, they must be twisted on a bolt either by hand or by a wrench or similar tool. Often plain nuts are used alongside shake-proof or lock washers so that they have a better resistance to vibration and other mechanical forces occurring on the plane.

Castellated Nuts

As a nut with raised notches cut radially into its face, these nuts are called “castellated or castle nuts” because their overall shape resembles that of a castle’s tower. This particular shape of nut is designed to be used in conjunction with a cotter pin to add security to a bolt. After tightening a castellated nut onto the end of a bolt, a pin is inserted through the center of both the nut and bolt where it will essentially hold the castle nut in place. For this to work, the bolt used must feature a radial hole into which the cotter pin can be inserted.

Self-locking Fiber Nuts

Finally, self-locking fiber nuts are used throughout an aircraft because of their locking ability that guarantees a durable hold. Removing the need for a lock washer, these nuts include a fiber insert which adds much greater friction than metal alone. It should be noted however, that you should not use the same fiber nut over and over as the nylon wears with each tightening and does not give the same locking strength.


Each time that an aircraft flies, the entirety of its components are subjected to extensive vibration and other strain. As such, high quality hardware is essential for keeping aircraft working at their best. On ASAP NSN Hub, we make it easy for you to find the hardware you need at a competitive price and uncompromising aircraft grade quality. Browse our inventory of over 2 billion new and obsolete parts with ease, including aircraft hardware from top manufacturers. Send us an instant Request for Quote (RFQ) form today and receive a competitive quote in 15 minutes or less!


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