What does AN, NAS, MS and others mean?

In the aerospace and aviation sectors, complete clarity in part specifications, usage, and other such parameters is mandatory. One of the ways this manifests is through universally accepted classification systems that validate that certain components meet the highest safety and compatibility standards for their applicable industry.

Standards like AN, NAS, MS, and AS define precise dimensions, tolerances, materials, and testing procedures across different aerospace platforms. Beyond ensuring quality, these classifications serve as standardized references for aerospace parts, easing the process of sourcing and validating compatibility. This blog will break down the creation and uses of various standards, helping you understand how to use them for product management.

Key Aerospace Part Standards

1. Aerospace Standards (AS)

AS standards were created to unify part classifications and gradually replace many government-issued specifications, especially after the 1994 Perry Memorandum, a U.S. Department of Defense (DoD) directive encouraging adoption of non-government standards (NGS). It is actively maintained and updated by the Society of Automotive Engineers (SAE) to reflect current engineering practices and safety requirements. AS documents encompass a wide range of aerospace equipment and components, including avionics, hydraulics, wiring systems, and mechanical hardware.

2. Army-Navy Specifications (AN)

Originally created in the early 1940s to standardize components for the U.S. Army and Navy, AN specifications standardized bolts, nuts, washers, fittings, and other critical hardware for mass production and interoperability across military platforms. Although officially discontinued in the 1950s, many parts continue to carry AN classification due to legacy aircraft systems and military surplus suppliers.

3. Military Standards (MS)

Introduced in the 1950s by the DoD and coordinated through the Defense Standardization Program Office (DSPO), Defense Logistics Agency (DLA), and other relevant military departments, MS standards were designed to replace many AN specifications, establishing uniform engineering and technical requirements for U.S. military equipment. Although widely adopted, the aforementioned 1994 memorandum resulted in many MS standards being canceled. Still, thousands remain active or partially retained due to military-unique requirements, and MS-designated parts are still frequently specified in defense procurement and maintenance.

4. NAS Military Converted Specs (NASM)

In response to the DoD’s cancellation of MS specs, roughly 500 military standards were converted into NASM specifications with the aid of SAE International. These retained the same part number format as the MS version and were mapped to commercially managed technical data, minimizing disruption in sourcing, logistics, and maintenance. For example, MS20426 became NASM20426.

5. National Aerospace Standards (NAS)

Established in 1941 by the Aerospace Industries Association (AIA) in coordination with major aerospace manufacturers and U.S. military authorities, NAS items are distinguished by tighter tolerances, durability requirements, and traceability controls than general commercial standards. Covering components such as fasteners, clamps, fittings, and structural parts used in mission-critical assemblies, NAS documents are actively maintained by AIA and are recognized by the FAA, DoD, and international aerospace authorities.

Standard Use Reference Chart

ASAP Aviation Hub: A One-Stop Shop for Industry-Standard Parts

In all, aerospace standards are not simply technical jargon, instead helping professionals guarantee safe, compliant parts while aiding them in navigating through a myriad of items in the federal supply chain. For those looking to shop for desired products by standards like AN, NAS, and MS, ASAP Aviation is your go-to resource.

Here, we feature a variety of catalogs to browse items by various standards, manufacturers, part types, and more, as well as a search engine to quickly narrow down options. As an ASAP Semiconductor website, you can trust that everything is exclusively from reputable entities and meets all applicable performance standards. Moreover, we regularly present our customers with competitive pricing and rapid lead times, so connect with our experts to see how we can serve you with leading procurement options.

1. james wolf
2. Posted on November 28, 2019
aviation

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