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?
If you need an insulating washer to prevent galvanic corrosion between a steel bolt and an aluminum airframe, you need NAS523 . If you need a load-spreading metallic washer, you need NAS412 or AN960 . nas523 pdf
In aircraft construction, where a single plane like a Boeing 747 can have over a million fasteners, standardizing how information is presented is vital for safety . The (National Aerospace Standard 523) is a vital
The code organizes information into four quadrants, typically referred to by compass directions (NW, NE, SW, SE), though these labels are not explicitly drawn on the symbol. Upper Left (Northwest): Contains the rivet part number If you need an insulating washer to prevent
: The full official standard document is maintained by the Aerospace Industries Association and is available for purchase on platforms like GlobalSpec .
: Represents the MS20470AD (Universal Head, 2117 aluminum alloy).