What does the rivet code AD indicate in an MS20 455 AD 4-8 rivet?

The rivet code "AD" in the designation MS20 455 AD 4-8 indicates that the rivet is made of alloy 2117. The letters in the code generally denote the alloy type and composition of the rivet material, which directly affects the rivet's strength, durability, and suitability for specific applications in aircraft construction and maintenance. Alloy 2117 is particularly known for its good strength-to-weight ratio and is commonly used in applications where weight savings are critical.

Understanding the alloy designations is crucial for selecting the appropriate rivet for various structural components of an aircraft, as it ensures that the materials used can withstand the specific stresses and environmental conditions to which they will be exposed.