Using a standardized symbolic code like NAS523 prevents errors that could compromise aircraft structural integrity. It ensures that every technician, regardless of the company, can look at a blueprint and know exactly which fastener, material, and installation method is required for a safe and airworthy repair.
Note: The official NAS523 standard excludes some diameters like -2 or -12. Always refer to the PDF for exact availability. nas523 rivet code pdf
The head is on the side of the metal closest to the person reading the drawing. F (Far Side): The head is on the opposite side. 3. Southwest (SW): Hole Preparation Using a standardized symbolic code like NAS523 prevents