What unique feature identifies a DD solid rivet?

The feature that distinctly identifies a DD solid rivet is the presence of two raised dashes on the head. This marking indicates that the rivet is a part of a specific series used in aerospace applications, particularly as it relates to the strength and material properties of the rivet. The two dashes help distinguish it from other types of rivets and ensure that it is appropriately selected for applications that require particular performance characteristics, like fatigue resistance and strength.

The unique head marking of two raised dashes serves both a practical purpose in identification and a safety function by reducing the likelihood of using an incorrect rivet, which could compromise the integrity of a structure. Understanding these details is crucial for anyone working in aerospace manufacturing, as the correct hardware is essential to maintaining safety and performance standards in aircraft design and maintenance.