AN Series AN3 Airframe Bolts
AN Bolts are manufactured to the “Army-Navy” military standard, predecessor to “Mil-Spec” (MS) and “National Aerospace Standard” (NAS) which followed. AN Bolts are typically cadmium plated for superior corrosion resistance when compared to commercial grade zinc plated bolts. Threads are pressed into the steel, not cut, thus maintaining strength throughout the entire shank. The surface under the head of AN bolts is designed to be a bearing surface to reduce non-uniform stress as the bolt is torqued thus reducing premature fatigue.