Aircraft bolts are fabricated from cadmium or zinc plated corrosion resistant steel, unplated corrosion resistant steel, and anodized aluminum alloys.

Most bolts used in aircraft structures are general purpose. In certain cases, aircraft manufacturers make bolts of different dimensions or greater strength than the standard types. Such bolts are made for a particular application, and it is of extreme importance to use like bolts in replacement. Special bolts are usually identified by the letter "S" stamped on the head.

The hex head aircraft bolt (AN-3 through AN-20) is an all purpose structural bolt used for general applications involving tension or shear loads where a light drive fit is permissible (0.006 inch clearance for a 5/8 inch hole, and other sizes in proportion).

• Hex head
• Alloy steel; NASM6812
• Cadmium plated; QQ-P-416 type I
• Heat treated