The (National Aerospace Standard 523) is a vital fastener coding system used throughout the aviation industry to standardize the identification and installation of permanent fasteners, particularly solid rivets. This system simplifies complex engineering drawings by consolidating critical data—such as part numbers, diameters, material alloys, and hole preparation methods—into a single four-quadrant "crosshair" symbol. What is the NAS523 Fastener Code?
The system uses a symbolic "cross" located on blueprints to give technicians immediate instructions for a specific location: Part number and material alloy code.
Fastener diameter and manufacturer head location. nas523 pdf
Often identifies an MS20426AD rivet (countersunk 2117 alloy). ↗️ Northeast (NE): Diameter & Head Placement
This quadrant indicates the shank diameter, typically in increments of . The (National Aerospace Standard 523) is a vital
Often identifies an MS20470AD rivet (2117 aluminum alloy).
The NAS523 code is a standardized practice that includes all types of fasteners that undergo permanent deformation during installation. Removing these fasteners typically requires their destruction, making precise initial installation essential for structural integrity. The system uses a symbolic "cross" located on
Indicated by "N" (Near side) or "F" (Far side) to show where the manufactured head should rest. AIA/NAS - NAS523 - FASTENER CODE | GlobalSpec
This quadrant specifies the fastener's basic part number (often or MS standards) and the material it is made from.
Required hole preparation (e.g., dimpling or countersinking). SE (Southeast): Fastener length. Breakdown of the NAS523 Symbol Quadrants