AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

Design and Benefits of Spring Pins

Of the millions of components that make up a commercial aircraft, nearly 50% are fasteners. These critical devices help bind structural areas of the plane and secure other elements in their required place. Due to the varying architecture of different aircraft regions, it is important to note that there is a diverse range of fastening devices found in aviation. Regardless of the design, the fasteners should be durable and resistant to the various stressors encountered by the plane. In this blog, we will discuss the spring pin, which is a mechanical fastener used to join pieces together securely.

Like most fasteners, spring pins are designed to be placed in a pre-drilled hole. Unique to spring fasteners is the requirement for the diameter of the hole to be smaller than that of the pin. In their installation, the user will compress the walls of the pin, causing it to fit in the hole. Once in place, the diameter will then attempt to re-expand, thereby creating a strong retaining force. Commonly manufactured from sheet metal, spring pins are produced in accordance with the regulations set forth by several professional societies, including the National Aerospace Standards (NAS).

We will now explore the two most common commercially available variants of spring fasteners.

Slotted Pins

These devices are designed with a longitudinal slot down the length of the material, allowing the user to compress them easily. Although typically fabricated in alloy steel, carbon steel, or beryllium copper, some manufacturers offer clear zinc, cadmium, and black oxide options. When choosing a slotted pin, it is critical to ensure that the unit is round and can tolerate shear forces. Particularly, the roundness contributes to increased compliance during installation, and enhanced shear strength helps ensure a longer operational lifespan. Although it is often hard to predict, users should consider orienting the longitudinal slot perpendicular to the direction of the load since this simple intervention is proven to reduce forces by up to 5%. In applications where there is an exceptionally high expectation of shear forces, a concentric smaller pin may be installed with its slot facing the opposite direction of the parent fastener.

Coiled Spring Pin

Unlike slotted pins, the coiled spring variant features a single piece of sheet metal rolled upon itself to create a spiral cross-section. They are beneficial in that their resistance to loading is not affected by installation orientation, permitting protection in every direction. Coiled spring pins are also designed to remain somewhat flexible, contributing to their superior vibratory-dampening capabilities. This is particularly useful in aviation applications, where vibrations often lead to a shorter operational lifespan.

Depending on the loading demands of the application, coiled spring fasteners may be manufactured in a variety of materials and coil wraps. When choosing a particular model, it is critical to determine the flexibility and strength needed since a device with more coils is less flexible. They are also the easiest to install, only requiring the aid of a standard hammer or widely available pressing devices. Additionally, coiled spring pins may be reused if removed correctly.


When you are in need of high-quality spring pin components, look no further than Aviation Parts Distributor. Owned and operated by ASAP Semiconductor, we give customers direct access to an inventory of over 2 billion ready-to-purchase items for the civil and defense aviation industries. Using our helpful part catalogs or our advanced search engine, customers may find the exact component they require with ease. Get started on the purchasing process today with the submission of an Instant RFQ form, and one of our account managers will provide you with a quotation for your comparisons within 15 minutes or less.


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