DD—Aluminum alloy, 2024-T composition

B—Aluminum alloy, 5056 composition

C—Copper

M—Monel

The absence of a letter following the AN standard number indicates a rivet manufactured from mild steel.

The first number following the material composition letters expresses the diameter of the rivet shank in 32nds of an inch. For example, 3 indicates 3⁄32, 5 indicates 5⁄32, and so forth. [Figure 7-38]

The last number(s), separated by a dash from the preceding number, expresses the length of the rivet shank in 16ths of an inch. For example, 3 indicates 3⁄16, 7 indicates 7⁄16, 11 indicates 11⁄16, and so forth. [Figure 7-38]

An example of identification marking of a rivet is:

AN470AD3-5—complete part number

AN—Air Force-Navy standard number

470—universal head rivet

AD—2117-T aluminum alloy

3—3⁄32 in diameter

5—5⁄16 in length

There are many places on an aircraft where access to both sides of a riveted structure or structural part is impossible, or where limited space does not permit the use of a bucking bar. Also, in the attachment of many non-structural parts, such as aircraft interior furnishings, flooring, deicing boots, and the like, the full strength of solid shank rivets is not necessary.

For use in such places, special rivets have been designed that can be bucked from the front. Special rivets are sometimes lighter than solid shank rivets, yet amply strong for intended use. These rivets are produced by several manufacturers and have unique characteristics that require special installation tools, special installation procedures, and special removal procedures. That is why they are called special rivets. Because these rivets are often inserted in locations where one head (usually the shop head) cannot be seen, they are also called blind rivets.