Aerospace Sourcing
Buying by NSN

How Do You Buy Aerospace Parts by NSN?

A national stock number (NSN) is the 13-digit identifier the federal catalog assigns to an item of supply: a 4-digit Federal Supply Class followed by a 9-digit NIIN. To buy by NSN, look up the manufacturer CAGE codes and part numbers cataloged behind it, then order one of those exact references with traceable paperwork.

Request a quote

Updated

What is an NSN, and what does it actually identify?

An NSN identifies an item of supply, not a manufacturer's part. It is the government's label for a thing that does one job, and one NSN can have several manufacturer part numbers cataloged behind it. That difference is where most NSN buying mistakes start.

Federal property regulations define the national stock number as the identifying number assigned to each item of supply, made up of the Federal Supply Classification (FSC) code and the national item identification number (NIIN). The FSC groups similar items into classes. The NIIN is the part that actually identifies the item. Two NSNs with the same FSC are only related by category; nothing else about them is shared.

Because the NSN points at a cataloged item rather than a specific maker, a quote that says only "NSN-compliant" tells you very little. What matters is which cataloged reference the supplier intends to ship, who made it, and whether that reference is one your contract or drawing will accept.

How is the 13-digit NSN structured?

An NSN is written in a 4-2-3-4 pattern, such as 0000-00-000-0000. The first four digits are the FSC. The last nine are the NIIN, and the first two digits of the NIIN are the National Codification Bureau (NCB) code for the country that cataloged the item.

DigitsElementWhat it tells a buyer
1 to 4Federal Supply Class (FSC)The class of item, grouping similar items together. Useful for sorting, useless for proving what you are buying.
5 to 6NCB code (first two digits of the NIIN)Which national codification bureau cataloged the item. Read the code in the federal catalog record rather than assuming a country from memory.
7 to 13Remainder of the NIINA serial with no built-in meaning. Do not try to decode it.
5 to 13NIIN (all nine digits)The unique item identifier. Catalog lookups and cross references key on the NIIN, so a mistyped FSC still often finds the right record.

The regulation describes the seven digits after the NCB code as nonsignificant. In practice that means two NSNs with similar trailing digits can be completely unrelated items.

Have a part like this?Send it in under a minute. A person replies within 1 business day.

Where can you look up an NSN and the parts behind it?

Start with DLA's Federal Logistics Information System (FLIS) data, which is public. DLA publishes it in two forms that a commercial buyer can use without a government login.

  • WebFLIS public query. DLA has offered a public version of WebFLIS that anyone with internet access can use. A search on an NSN returns the part numbers, also called reference numbers, and the CAGE codes associated with that item.
  • PUB LOG. DLA describes PUB LOG as a product for public users who need NSN and cataloging information, including FSC data and CAGE codes. It is offered as a free download, updated monthly, from DLA's FLIS Data Electronic Reading Room, with no subscription or Common Access Card required.
  • CAGE search. To see who a CAGE code belongs to and where that facility is, use the CAGE search at cage.dla.mil, which is also the tool FAR 4.1803 points contracting officers to.

Tool names, access rules and download formats change from time to time. Confirm the current versions on dla.mil before you build a process around any one of them.

What is a CAGE code, and why does it matter on an NSN?

A CAGE code tells you which company, at which location, owns a cataloged part number. Under FAR 52.204-16, the CAGE code is an identifier the DLA CAGE Branch assigns to entities in the United States or its outlying areas to identify an entity by its unique location. Entities outside the United States get an NCAGE code, assigned by a NATO member or the NATO Support and Procurement Agency and recorded in the same CAGE master file.

Two things follow for a buyer. First, the CAGE paired with a reference number on an NSN record usually names the design owner or manufacturer of that part number, so it is the anchor for traceability. Second, CAGE codes are location specific. A distributor's CAGE on a certificate is not the manufacturer's CAGE, and a part number that appears under a reseller's CAGE has not become a different part. When paperwork arrives, match the manufacturer named on the certs to the CAGE you accepted on the PO.

Our glossary has short definitions of CAGE, NCAGE and related catalog terms if you are briefing someone new to defense buying.

Which part numbers behind an NSN are acceptable?

Only the references your contract, drawing or engineering authority accepts. An NSN record lists what has been cataloged, not what is approved for your application. On DoD spares, the acquisition method codes tell you how restricted the item is.

DFARS PGI 217.7506 defines acquisition method codes (AMC) and suffix codes (AMSC) that DoD assigns to spare parts. A few that buyers meet most often:

  • AMC 1 and 2: suitable for competitive acquisition, for the second or subsequent time and for the first time.
  • AMC 3 and 4: acquire directly from the actual manufacturer.
  • AMC 5: acquire from a sole source contractor that is not the actual manufacturer.
  • AMSC C: the part requires engineering source approval by the design control activity to maintain the quality of the part.
  • AMSC P and R: the government does not own the rights to the data needed to buy the part from other sources.

If you are a prime or a sub buying to a customer's parts list, the same logic applies even without the codes: the parts list or drawing names the acceptable references, and anything else is a substitution that needs approval. The mil-spec versus commercial parts page covers who can approve a swap.

Source-controlled items versus specification items: what changes for the buyer?

A source-controlled item can only come from the sources the design owner has approved. A specification item can come from anyone who builds and proves it to the spec. That one distinction decides how wide your supplier search can be.

For a source-controlled reference, such as one carrying AMSC C, the question is never "can this shop make it" but "is this the approved source." A perfectly good part from an unapproved maker is still nonconforming. Your search is limited to the named manufacturer, its authorized distribution, and stock that traces back to them.

For a specification item, the governing document controls. If the spec requires qualification, the product must be listed on the applicable qualified products list before award; our QPL and QPD guide explains how to check that. If the spec has no qualification requirement, a supplier that can meet every requirement and show the evidence can be acceptable, subject to your own supplier approval rules.

What should the purchase order say when you buy by NSN?

Put the NSN on the PO, but buy the part number. The NSN tells everyone which item you mean; the CAGE and part number tell the supplier exactly what to ship and give receiving something to check against.

  • The NSN and the exact accepted reference: manufacturer CAGE and part number, and whether any listed alternates are acceptable.
  • The governing specification or drawing and its revision, if the reference is a specification part number.
  • QPL requirement, where the specification calls for one, and the listed plant if it matters to you.
  • Quantity and unit of issue, since catalog units do not always match how a manufacturer packages the part.
  • Certificate of conformance plus the manufacturer's certification or traceability back to the original manufacturer. See what a CoC must show.
  • Applicable clauses to flow down, such as DFARS 252.246-7008 for electronic parts and DFARS 252.225-7009 where specialty metals apply.
  • Date code, lot and shelf life limits for parts that age, plus packaging and marking requirements from your contract.
  • Where inspection and acceptance happen, so the supplier knows what evidence has to travel with the shipment.

What goes wrong when parts are ordered by NSN alone?

The supplier gets to choose the reference, and you find out what you bought at receiving. That is the common failure, and it gets worse on older items.

Typical problems: a reference that is cataloged but not approved for your program; surplus stock with an NSN label and no trail back to the manufacturer; mixed lots in one shipment; a manufacturer that no longer makes the part, so the quote is really for aftermarket or open market stock; and certificates that name a distributor but never the maker. For electronic parts on DoD work, buying outside the original manufacturer and its authorized suppliers triggers added duties under DFARS 252.246-7008. Our counterfeit parts avoidance page covers those controls, and buying from AS9120 distributors covers how to read distributor paperwork.

If the NSN points to a part that is out of production, treat it as an obsolete part search from the start. The obsolete aerospace parts page walks through the sourcing paths from lowest to highest risk.

How do we source parts by NSN?

We work from the NSN and the references you accept, not from a catalog of our own. We do not hold inventory, publish prices or show stock, and we are not an authorized or franchised distributor for any manufacturer.

For an NSN request we confirm the cataloged references and CAGE codes, buy from the manufacturer or its authorized and franchised distributors where the part is available, and flow your clauses and paperwork requirements down to that source. Before shipment we check the manufacturer, part number, lot and date codes on the certs against your PO. NSN items can ride on the same PO as machined or fabricated parts, or be built into kits, across categories such as fasteners, seals and fluid parts, electrical parts and electronic components. When the part is out of production, we run the search under counterfeit avoidance controls and tell you plainly what tier of source the part would come from before you commit.

Send us the NSN and the references you accept

Send the NSN, the CAGE and part numbers you will accept, quantity, need date and any contract clauses through the parts search request form. Listing the accepted references up front is what keeps the search to parts you can actually use. A person replies within 1 business day, and every order ships with a certificate of conformance plus the traceability documents your request calls for. If the item or its data is export controlled, read controlled programs before sending drawings, and see confidentiality for how files are handled.

Quote this

Send the job. A person replies within 1 business day.

Part, quantity and date are enough to start. Drawings and the mutual NDA follow by reply, and controlled programs never send technical data through this site.

Export classification *

Need to attach drawings or sign the NDA first? Use the full request form.

Questions

Is an NSN the same as a part number?

No. An NSN identifies an item of supply in the federal catalog, and one NSN can have several manufacturer part numbers cataloged behind it. The part number, paired with the manufacturer's CAGE code, identifies one maker's specific design. Buy the part number your drawing or contract accepts and put the NSN on the order as a cross reference, so the supplier cannot pick a different cataloged reference without telling you.

Why does one NSN list several part numbers?

Because the catalog groups every reference that has been accepted as the same item of supply. That can include the original design owner's number, a specification part number and other manufacturers' numbers for the same item. Not every listed reference is approved for every program. Check your drawing, parts list or acquisition method code to see which references you can accept, and name them on the purchase order.

How do I find who makes the part behind an NSN?

Look the NSN up in DLA's public FLIS data. DLA has offered a public WebFLIS query that returns the reference numbers and CAGE codes tied to an NSN, and PUB LOG is a free monthly download with NSN, FSC and CAGE data. Then look up each CAGE code at cage.dla.mil to see the company and location. Confirm current tool names and access rules on dla.mil, since they change.

What is the difference between a CAGE code and an NSN?

An NSN identifies an item. A CAGE code identifies a company at a specific location. Under FAR 52.204-16, the DLA CAGE Branch assigns CAGE codes to entities in the United States and its outlying areas, and foreign entities receive NCAGE codes. On an NSN record, each reference number is paired with a CAGE code, which is how you tell whose part number it is.

What does AMSC C mean on a spare part?

DFARS PGI 217.7506 defines acquisition method suffix code C as a part that requires engineering source approval by the design control activity to maintain the quality of the part. In practice it means the part is source controlled. Only approved sources qualify, and a new source has to go through the design control activity's approval before its parts can be accepted, however good they are.

Can a distributor substitute another part number under the same NSN?

Only if your purchase order allows it. Sharing an NSN does not make two references interchangeable for your program, because approval depends on your drawing, parts list or contract. State on the PO whether alternates are acceptable and which ones. If a supplier offers a different reference, get written approval from whoever owns the design before accepting it, and keep that approval with the receiving records.

Related

Sources

Ready to
source it?

A person replies within 1 business day. NDA first.

Request a quote