Posted on September 15, 2026 Kyle Salem
A National Aerospace Standard (NAS) is an aerospace industry standard used to define requirements for specific hardware, components, materials, and practices. NAS numbers are commonly found on aerospace fasteners and other standardized parts used in aviation, space, and defense.
Depending on its scope, a document may control dimensions, materials, finishes, threads, strength, testing, marking, or quality requirements. The complete designation and correct revision are essential when identifying a part. This guide explains NAS coverage, part numbers, and verification.
National Aerospace Standards are voluntary industry standards developed and maintained through the Aerospace Industries Association (AIA). According to the AIA National Aerospace Standards program, subject-matter experts from member companies participate in committees and working groups that develop and maintain the NAS library. AIA is also an ANSI-accredited standards developer.
A National Aerospace Standard may establish requirements for:
Requirements vary by document, so a general description cannot replace the applicable standard sheet.
Aircraft and spacecraft contain large numbers of repeated hardware items. A recognized aerospace standard gives designers, manufacturers, inspectors, maintenance teams, and procurement specialists a common technical reference for those items.
It helps engineers specify recognized configurations, manufacturers control production, inspectors evaluate conformity, maintenance teams identify required hardware, and buyers communicate exact requirements. However, size, material, finish, configuration, revision, and effectivity must still match the application.
NAS parts are strongly associated with aerospace fasteners, although the standards library covers more than fastening hardware. Depending on the series, NAS standard parts may include:
These items may appear in airframes, controls, landing gear, engines, interiors, and support equipment. Aircraft data establishes where each item is used.
Within the NAS standard series, part-number records may be associated with item names, manufacturers, and National Stock Numbers. Those references can assist identification, while the governing document remains the technical authority.
A NAS part number begins with NAS, followed by a basic number and, when required, letters, dashes, or suffixes. These characters may represent features such as thread size, diameter, grip, length, material, finish, drilling, or locking configuration.
There is no single decoding formula for every NAS series. The positions and symbols are defined by the individual standard. For example, a number used as a grip code in one bolt series may not have the same meaning in a screw or washer series.
Record the complete prefix, basic number, dashes, letters, suffixes, and leading zeroes. Also note the required revision, drawing-specific restrictions, and current status. Copy the designation exactly without shortening or reformatting it.
Consider NAS387-440-8P, an example that can be decoded directly from the NAS387 standard. That document covers a 100-degree oval recessed-head machine screw and defines the designation as follows:
Accordingly, NAS387-440-8P identifies a No. 4-40, 1/2-inch-long, chromium-plated screw covered by NAS387. The related NAS387-440-8, without the P suffix, identifies the cadmium-plated version.
NAS387 defines these characters, but another standard may organize its codes differently. Always decode a designation with the applicable revision of its own governing document.
A NAS number identifies requirements established by a standard; a manufacturer part number belongs to a producer’s own numbering system. An NSN supports government supply identification. Although records may associate these identifiers, they serve different purposes. Compare the manufacturer, CAGE Code, configuration, and supporting documentation when confirming an item.
NAS standards can be revised as materials, manufacturing methods, testing practices, or industry needs change. A document may also be marked inactive, cancelled, or superseded.
Before using an older reference, verify the document title and status, the revision cited by the controlling drawing, any cancellation or supersession notice, stated replacements, and installation effectivity. The latest published revision is not automatically the one required by controlled aircraft data. A superseding document may also require review before substitution.
Aerospace hardware may carry several familiar prefixes. They identify different standards systems and should be kept distinct.
NAS refers to AIA’s National Aerospace Standards. An AS standard commonly refers to an Aerospace Standard published by SAE International. Confirm the complete designation and issuer.
An MS standard belongs to the Military Standard series. The Defense Logistics Agency’s ASSIST database identifies approved defense and federal standardization documents. Use the applicable document and an approved cross-reference when evaluating an MS-to-NAS relationship.
A BAC standard is a Boeing-controlled company standard. Any claimed relationship to an industry-standard item requires supporting technical data.
NAS hardware may use alloy steel, corrosion-resistant steel, aluminum, titanium, or another specified material. Heat treatment and finish can influence strength, temperature capability, corrosion behavior, compatibility, and installation friction. Since finishes can look alike, confirm the required treatment through the part number, specification, packaging, and trace records.
Correctly identified hardware still requires proper installation. Relevant factors may include:
Use the NAS document with the applicable aircraft manual, drawing, and authorized procedure. A catalog description is not an installation instruction.
Begin with the designation shown in the approved source, then compare the physical item and its records. Review the revision, dimensions, material, finish, manufacturer, CAGE Code, NSN or NIIN, condition, and traceability. If a marking is incomplete, use packaging, certificates, purchase history, drawings, and dimensional inspection as supporting evidence; final acceptance should follow the approved process.
When requesting NAS parts from ASAP Aerospace, provide the complete designation, quantity, condition, delivery date, and traceability needs. Include the manufacturer, NSN, or CAGE Code when known so closely related configurations can be distinguished.
NAS generally identifies the National Aerospace Standards series. The rest of the designation must be interpreted through the applicable standard.
No. NAS fasteners are prominent, but the NAS library also addresses other aerospace parts, components, materials, and practices.
Locate the governing standard for that bolt series and use its part-number table or code notes. Do not apply a decoding pattern taken from another NAS family.
Only when an approved drawing, cross-reference, or engineering source authorizes the substitution for the intended application.
No. An NSN is a government supply identifier, while a NAS number identifies requirements under a National Aerospace Standard. Both can help confirm an item.
A revision may change dimensions, materials, testing, marking, or other requirements. Use the revision specified by the controlling technical data.
A National Aerospace Standard gives the aerospace industry a controlled way to define recurring parts and technical requirements. Reading NAS part numbers accurately requires the correct series document, every character in the designation, and the applicable revision.
Whether the item is a bolt, screw, nut, washer, rivet, or another component, verify its configuration and records against approved data. This supports accurate identification, inspection, and sourcing without overlooking details that affect fit or performance.
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