Because NAS523 is a National Aerospace Standard, it is managed by AIA (Aerospace Industries Association). You can find the document, often referred to as "NAS523 PDF top" or "NAS 523 Rev.31," at several technical standard distributors, with pricing often around $41 USD.
The code specifically applies to fasteners that are permanently deformed during installation, meaning they must be destroyed to be removed. Locating Points:
: The manufacturer's head is installed on the side of the metal closest to the technician viewing the layout sheet.
Here are the key historical revisions you need to know about: nas523 pdf top
Provides instructions for hole preparation, such as D for dimpling, C for countersinking, or D2C (dimple two sheets and countersink the third).
: Specifies the shank diameter, calculated uniformly in 1/32-inch increments . A value of 4 indicates a 4/32” (1/8”) diameter. This quadrant also houses the letters N (Near Side) or F (Far Side) to inform the technician which side of the sheet metal receives the manufactured head.
This is where the "top" decision-making happens. For aerospace, the standard calls for for major defects and AQL of 4.0% for minor defects. However, critical defects (e.g., missing thread, crack through head) mandate Zero AQL – meaning 100% sorting if one is found. Because NAS523 is a National Aerospace Standard, it
The identifies the governing specification of the fastener (such as an AN or MS standard number) and the specific alloy composition.
The NE quadrant states the body diameter of the rivet shank, usually measured in increments of 1/32 of an inch. Right next to the size, it lists a letter denoting the position of the manufactured head:
You have downloaded the "top" PDF. Now what? Here is the standard operating procedure for a receiving inspector. Locating Points: : The manufacturer's head is installed
Standards change. Using an old revision is a major audit finding (NCR - Non-Conformance Report). Historically, NAS523 has gone through several revisions. As of the current decade, the industry typically references the latest revision, often denoted as NAS523-1 or similar numeric suffixes.
The is the structural backbone of aerospace engineering blueprints, establishing a universal four-quadrant crosshair symbol to specify permanent-deformation fasteners without cluttering technical drawings. For Aircraft Maintenance Engineers (AMEs), structural repair technicians, and aerospace draftsmen, finding a comprehensive NAS523 PDF guide is critical to accurately identifying rivet materials, head placements, hole preparations, and exact lengths.
NAS 523, officially titled "Fastener Code," is not merely a document but a complete symbolic system defined by the Aerospace Industries Association (AIA). It provides a uniform method for engineers and draftsmen to specify fasteners on technical drawings without lengthy written notes. This standard is the most recognized method for indicating rivets and other fasteners in engineering, especially within the United States.