AN3 through AN20 Airframe Bolts
AN series bolts are a commonly used hardware throughout the aviation and mil-spec industry. Mostly know as airframe bolts or machine bolts, they are utilized for it's high strength metals.
What each letter, or number represents in the string of part numbers:
The first number after AN designates the diameter of the
bolt. The next symbol designates the material and head drill if applicable.
The use - after the diameter for steel, Cad II plated. (NO
hole in the head)
Use C In place of - for corrosion resistant steel.
An H in place of - or after C is for a hole in the head.
The use of the A at the end of all the part numbers means
that there will be NO hole in the shank.
The last number, either single or double digit denotes
length. If it is a single digit this is the nominal length in 1/8ths of an
inch. If it is a two digit number, the first is whole inches, the second is
additional 1/8ths, and this is a nominal sizing.
Hex head aircraft bolts are made of high-strength type
4037 or 8740 alloy steel (type 8740 is most commonly used). The bolts are
centerless ground and threaded after heat treatment. Minimum tensile strength
125,000 PSI. Cadmium plated per specification QQ-P-416A, Type II, Class 3.
Available with shank drilled for cotter pin or undrilled for stop nut
application, and with or without drilled head for safety wire. Specify bolts to
have undrilled shank by adding letter A after the dash number. For bolts with
drilled head add letter H after the AN number. C represents Type 431 Stainless
Steel (contains iron which is magnetic). The length of AN aircraft bolts is
measured from under the head to the end of the shank. The grip is the
unthreaded portion of the shank.
