Every single aircraft that takes flight each day is held together by an ensemble of tiny fasteners such as nuts, bolts, and screws. In an industry like aviation, where only the highest quality workmanship is tolerated, fasteners play a critical role in the performance of a machine. The average passenger jet has tens of thousands of fasteners among its parts. While not one of the more technologically marvelous components, fasteners are integral in the safe flight of an aircraft.
and commercial grade fasteners are both used in high-performance machinery, however it is important they not be confused. For instance, aircraft bolts are made from corrosion resistant steel and can exceed a tensile strength of 125,000 psi. On the other hand, commercial grade fasteners are made from carbon steel, have very little corrosion protection, and their strength is about half of aircraft bolts - between 50,000 and 60,000 psi.
There are four main types of fasteners used in aircraft: bolts, nuts, washers, and fastener covers. Bolts are used in areas where extra strength is needed. Aircraft standard bolts
are made with alloy steel, stainless/corrosion resistant steel, aluminum alloys, or titanium. These materials allow the bolt to be stronger and lighter than a commercial grade bolt. Aircraft nuts are distinct in two ways. First, they are made from the same material as bolts. Second, they require a locking device to stay in place because of the vibration and pressure they must withstand during flight. These locking devices may be referred to as castle nuts, lock washers, safety wire, and fibre inserts.
A washer's function in aerospace is the same as in everyday life - to support fastening systems by distributing the load they bear. However, aerospace washers
are constructed of stronger, more lightweight materials. Fastener covers, as their name suggests, are used to provide a cover for nuts, bolts, and washers alike. They are machined in a variety of specialty materials and must be resistant to the fickle environmental factors within the atmosphere. Cadmium, zinc, nickel, silver, phosphate, and black oxide are just some of the materials aerospace fastener covers are made from.