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5 Types of Bolts Used in Aircraft

5 Types of Bolts Used in Aircraft

Aircraft are complex machines that require precision, durability, and reliability. Every component of an aeroplane contributes to its overall safety and efficiency. Among these, bolts are one of the most critical components as they hold the aircraft together and ensure it stays intact during flight. Different bolts are used in an aeroplane, each with a unique purpose and characteristics. In this blog post, we will explore aircraft’s most commonly used bolts and their functions in detail.

Structural Bolts

Structural bolts are the most crucial bolts in an aircraft. They maintain the plane’s structural integrity, holding the fuselage and wings together. These bolts are high-strength steel and require critical torque for proper installation.

Machine Screws

Machine screws are used in aircraft for securing lightweight metal parts, such as aluminium panels and fairings. They are primarily found in the cockpit and other areas where access is easy. Machine screws can be of different sizes and shapes, including flathead, pan head, and round head.

AN Bolts

AN, or Air Force-Navy bolts, are military-grade bolts designed for aircraft use. They come in different sizes, and their length is indicated by a numbering system, which helps ensure accurate bolts replacement. Bolts have a hexhead design and are fitted with a washer and a nut.

Clevis Bolts

Clevis bolts are used to connect parts with a load-bearing component. These bolts are shaped like a horseshoe and secured by a cotter pin. Clevis bolts are commonly used in aircraft’s landing gear and engine mounts.

Hi-Lok Bolts

Hi-Lok bolts are threaded fasteners with a compression-fit design to hold the components together. They are used to attach sheet metal or composite parts. They are quick and easy to install and require a unique hi-lok tool for proper installation. Hi-Lok bolts also come in a variety of sizes and lengths.


Choosing the correct type of bolts is crucial in the aviation industry as it ensures the safety and reliability of an aeroplane. The different types of bolts used in aircraft have unique features, functions, and installation requirements. Proper installation and maintenance of these bolts are essential to prevent any safety issues and ensure the long-term performance of an aircraft. Knowing the properties of each type of bolt will help aviation maintenance technicians to make the right decision when selecting and installing bolts in an aeroplane.

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