What Is a Certificate of Conformance in Aerospace?
A certificate of conformance (CoC) is the supplier's signed statement that a specific shipment meets every requirement of the purchase order, drawing and specifications. It names the PO, part number and revision, quantity, lot and the person who released it. It is a declaration, not evidence, so material certs, FAI reports and test reports travel with it.
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What is a certificate of conformance, and what does it prove?
A CoC is the supplier's formal promise that a specific shipment conforms. It proves who is accountable for the parts and which requirements they claim to meet. It does not, by itself, prove chemistry, dimensions or test results.
In standards language a CoC is a first-party attestation: the supplier attesting to its own product. ISO/IEC 17050-1, the general standard for a supplier's declaration of conformity, puts the purpose plainly: give assurance that an identified object conforms to specified requirements and make clear who is responsible for that conformity and the declaration. It also says a declaration can refer to results from other parties without reducing the supplier's responsibility: the shop that signs owns the result, even when it lists a heat treater's cert.
What must an aerospace certificate of conformance contain?
At minimum: supplier identity, the PO number and line, the part number with revision, quantity, lot or serial identification, a statement of conformance to the PO, drawing and specifications, the date, and the signature of someone authorized to release product. Your PO quality clauses decide the full list.
Prime contractor flow-downs show what is typical. Lockheed Martin Missiles and Fire Control quality PO note 2000 requires the manufacturer or supplier name, date of certification, Lockheed Martin PO number, part number and revision level, and a statement that the items meet the drawings, specifications and PO with inspection and test evidence available for examination, signed or authenticated by a person responsible for quality assurance of the item. The L3Harris (Aerojet Rocketdyne) distributor requirements in AR2 go further and list the items below.
| Field | Why receiving needs it |
|---|---|
| PO number and line item | Ties the statement to one order, so it cannot be recycled for another shipment |
| Part number with revision, plus any industry standard part number (AN, MS, NAS, AS) | Proves the configuration shipped matches the configuration ordered |
| Quantity | Lets receiving reconcile the cert to the packing slip and the count in the box |
| Lot, batch, manufacturing order or serial numbers | Links the parts to production records, and to the original manufacturer's lot when a distributor ships |
| Supplier name and contact, and manufacturer name if different | Shows who made the parts, not just who sold them |
| Special process specs with revision and processor name | Lets you confirm an approved processor did the plating, heat treat or NDT |
| Conformance statement | The actual declaration, ideally naming the drawing, specs and PO requirements |
| Exceptions, deviations or waivers | Anything that does not conform must be disclosed with its approval reference, not left off |
| Date, printed name, title and signature | Traces the release decision to a person with authority |
AR2 also requires that the CoC link, through the supplier's records, to all documentation for the product, and that it include the manufacturer's certification or complete traceability to the original authorized manufacturer. If your contract carries a DFARS specialty metals clause, add a statement of compliance or the exception relied on. Our DFARS specialty metals guide covers what that statement needs behind it.
Have a part like this?Send it in under a minute. A person replies within 1 business day.How is a CoC different from a material cert, FAI report or test report?
The CoC is the supplier's declaration about the shipment. The other documents are evidence for specific requirements: material certs prove what the metal is, the FAI proves the process can make the part, and test reports prove performance. You usually need the CoC plus whichever evidence your PO calls for.
| Document | Who issues it | What it proves | What it does not prove |
|---|---|---|---|
| Certificate of conformance | The supplier shipping the item | The supplier declares this shipment meets the PO, drawing and specs, and names who is responsible | Any measured value, chemistry or test result |
| Mill test report or material cert | The mill or producer, carried forward by distributors | Chemistry and mechanical properties for one heat or lot, and often country of melt | That the finished part was made from that heat, unless traceability is kept |
| AS9102 FAI report | The manufacturer, for a new or changed part | The production process can make a part meeting every characteristic | That a later production lot conforms |
| Test report | A test lab or the manufacturer | Results of a specific test, such as proof load, pressure, vibration or chemical analysis | Conformance to requirements the test did not cover |
| Special process cert | The plater, heat treater, NDT house or cleaner | The process was done to the named spec on identified parts | Dimensions or anything outside that process |
The most common receiving mistake is treating a CoC as a substitute for the evidence. If the PO asks for a mill cert, a CoC that says "material per AMS 4911" does not satisfy it. See material certs and traceability for reading a mill report, and our AS9102 first article inspection guide for the FAI side.
Is FAR 52.246-15 still in the FAR?
Yes. As of October 2026, acquisition.gov still carries FAR 52.246-15, Certificate of Conformance (Apr 1984), prescribed at FAR 46.315, and the current FAR text shows FAC 2026-01. The Revolutionary FAR Overhaul class deviations for Part 46, which agencies began applying in November 2025, retained the Part 52 clauses with no changes to the text.
The clause is narrower than many people think. Under FAR 46.504, a contracting officer may accept supplies on the contractor's certificate instead of source inspection when that is in the government's interest and either small losses would result from a defect, or the contractor's reputation or past performance makes acceptable supplies likely. The clause lets the contractor ship on a CoC only after the contract administration office authorizes it in writing, and the government keeps its right to inspect and to reject defective supplies within a reasonable time after delivery.
In practice, CoC content requirements reach shops and distributors through prime quality clauses and PO notes, not through the FAR.What do AS9100 and ISO/IEC 17050-1 require?
AS9100 requires documented information on the release of product, including evidence of conformity with the acceptance criteria and traceability to the person who authorized the release. In aerospace, that record is usually the CoC, even though the standard does not use the term.
That is AS9100 clause 8.6, release of products and services. It also says product is not released until the planned checks are complete, unless a relevant authority and, where applicable, the customer approve otherwise. Two consequences matter to buyers. First, a CoC from an AS9100 shop should sit on top of real inspection records, which you can ask to see. Second, a part shipped before planned inspection was complete needs a documented approval, and that should show up as an exception, not a silent omission.
ISO/IEC 17050-1 applies to any sector. Part 2, ISO/IEC 17050-2, covers the supporting documentation behind a declaration. The standard also deprecates the term "self-certification" to avoid confusion with certification by an accredited body. That distinction is useful at receiving: a CoC is a supplier's own claim, while an AS9100 certificate or Nadcap accreditation comes from a third party.
Who is allowed to sign a certificate of conformance?
A person the supplier has authorized to release product, and whoever your PO names. Prime clauses commonly require a quality assurance representative or a responsible company official.
AS9100 leaves it to the organization to decide who may authorize release, based on competence. Customer clauses usually narrow that. Lockheed Martin MFC note 2000 calls for a person responsible for the quality assurance of the item, and L3Harris AR2 calls for a company quality assurance representative or responsible company official. If your quality clauses name the signer, a CoC signed by someone else is a valid reason to reject it.
Electronic signatures and stamps can be acceptable when the supplier's system controls them and your clauses allow them. L3Harris AR2, for example, has its own section on electronic signatures. A blank signature block or a typed name with no release authority behind it is not acceptable.
How should a CoC trace to the PO and the lot?
One CoC should match one shipment against one PO, and every lot or serial number in the box should appear on it or be linked to it. If a shipment mixes lots, the CoC should list each lot and its quantity.
Check the arithmetic. The quantity on the CoC, the packing slip, the part labels and the physical count should agree. Partial shipments need their own CoC for the quantity shipped, not a copy of the first one. Our receiving inspection guide covers the full order of checks at the dock.
What is the difference between a distributor CoC and a manufacturer CoC?
A manufacturer CoC certifies the parts it made. A distributor CoC certifies what the distributor did: that it bought from an identified source, kept the parts identified and handled them under its quality system. For aerospace work you normally want both, with the distributor CoC tracing to the original manufacturer's lot.
L3Harris AR2 is a good model. It requires distributors to be registered to AS9120, the aerospace quality standard for stocking distributors, and requires the distributor CoC to carry traceability to the original manufacturer's lot, manufacturing order or batch number, and to include the manufacturer's certification or complete traceability to the original authorized manufacturer.
For electronic parts on DoD work, DFARS 252.246-7008 (Jan 2023) adds weight. Contractors are expected to buy from the original manufacturer, its authorized suppliers, or suppliers that buy only from those sources. When a contractor that is not the original manufacturer or an authorized supplier cannot establish traceability, the part has to be inspected, tested and authenticated, with the records kept. A distributor CoC with no upstream trace is exactly the gap that clause targets. The counterfeit parts avoidance guide covers AS5553 and AS6081 in more depth.
Why does receiving reject a certificate of conformance?
Receiving rejects a CoC when it cannot be checked against the order or the parts. The usual causes are missing or wrong identifiers, a missing revision, no lot trace, an unauthorized signer, or required evidence that never arrived.
| Accept when | Reject or hold when |
|---|---|
| PO number and line match your order | No PO number, or a PO from another customer |
| Part number and revision match the PO and the part marking | Revision missing, or a revision your PO did not call out |
| Quantity matches the slip and the count | Quantity differs, or one cert covers several partial shipments |
| Lot or serial numbers listed and on the parts | No lot, or lots on the parts that are not on the cert |
| Special processes listed with spec, revision and processor | "Finished per print" with no spec or processor named |
| Signed and dated by an authorized person | Unsigned, undated, or signed by someone your clauses do not allow |
| Deviations disclosed with approval references | Known nonconformance not mentioned |
| Required mill certs, FAI and test reports attached | CoC offered in place of evidence the PO requires |
Red flags worth escalating, not just correcting:
- A CoC dated before the parts could have finished processing
- Identical CoCs, down to the date, across different shipments
- Edited fields, correction fluid, or overwritten values. AR2, for example, requires errors to be lined through once, corrected in ink, initialed and dated, and prohibits correction tape or fluid
- A distributor CoC that names no manufacturer, or a manufacturer that does not make that part
- A conformance statement that says "to the best of our knowledge" or limits itself to visual inspection
- Supporting certs whose heat, lot or dates do not line up with the CoC
What should a buyer put on the PO about the CoC?
Spell out the content and the evidence. A PO that just says "C of C required" gets the minimum.
- Require a CoC with each shipment, listing PO and line, part number and revision, quantity, and lot or serial numbers
- Name the signer: quality representative or another authorized official
- Require special processes to be listed with spec, revision and processor
- For distributors, require the original manufacturer's CoC and lot trace, and AS9120 if your program needs it
- List the evidence that must ship with the CoC: mill certs, FAI, test reports, process certs
- Require disclosure of any deviation or waiver on the CoC
- Add the DFARS clauses that apply, such as 252.225-7009 or 252.246-7008, and ask for a compliance statement
- Cite your quality clauses by number and revision
The aerospace RFQ checklist puts these alongside drawings, export classification and need dates, and the certified aerospace material page covers the mill cert side for raw stock.
Get parts with a CoC that passes receiving
If your receiving team keeps holding shipments over paperwork, send the job through the inspection and quality request form and attach your quality clauses. A person replies within 1 business day. We flow your CoC content, signer and evidence requirements down to the supplier, check the certificate and supporting certs against your PO before the order ships, and every order ships with a certificate of conformance plus the other certs your request requires. If your drawings are export controlled, read how we handle confidential files and controlled programs before you send anything.
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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.
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Questions
Is a certificate of conformance the same as a certificate of compliance?
In aerospace purchasing the two terms are used almost interchangeably. Lockheed Martin MFC's PO note 2000, for example, is titled certificate of compliance but reads like any CoC requirement. What matters is the content your PO requires, not the title. Some quality teams reserve compliance for statements about regulations and conformance for statements about drawings and specs, so if your clauses make that distinction, follow them.
Does a certificate of conformance replace a mill test report?
No. A CoC is the supplier's declaration that the shipment meets the order. A mill test report is evidence of chemistry and mechanical properties for a specific heat or lot. If your PO requires material certs, the CoC should reference them and they should be in the package. A CoC that only says the material is per a named spec does not satisfy a requirement for the actual mill report.
Who should sign a certificate of conformance?
Someone the supplier has authorized to release product, and whoever your PO names. AS9100 requires traceability to the person who authorized release but lets the organization decide who that is. Prime clauses often require a quality assurance representative or responsible company official. If your clause names a role, reject a CoC signed by anyone else and ask for a reissue.
Can a distributor issue its own certificate of conformance?
Yes, but for aerospace parts it should not be the only document. The distributor certifies its own handling and source, and should pass along the original manufacturer's certification or complete traceability to the manufacturer's lot. L3Harris distributor requirements AR2 spell this out and require AS9120 registration. For DoD electronic parts, DFARS 252.246-7008 adds traceability or authentication requirements when the seller is not an authorized source.
Is FAR 52.246-15 still used?
Yes. The clause, Certificate of Conformance (Apr 1984), is still in the FAR on acquisition.gov and is prescribed at FAR 46.315. It lets a contractor ship on a certificate instead of government source inspection, but only when the contract administration office authorizes it in writing, and the government keeps its right to inspect and reject. The 2025 FAR overhaul deviations for Part 46 kept the Part 52 clauses unchanged.
What makes a certificate of conformance invalid?
It cannot be checked or it does not cover the shipment. Common problems are a missing PO number, part number without revision, no lot or serial identification, quantity that does not match the delivery, no signature or an unauthorized signer, special processes listed without spec or processor, and undisclosed deviations. A CoC dated before processing could have finished, or one that looks copied from another shipment, should be escalated.
Should a certificate of conformance list special processes?
Yes, when the part went through them. List each special process, such as heat treatment, plating, anodizing, passivation or nondestructive testing, with the specification, its revision and the processor's name. That lets receiving confirm an approved source did the work and match the processor's own cert. Many prime clauses require it, including L3Harris AR2, which also asks for processor names where applicable.
Related
Sources
- Acquisition.gov, FAR 52.246-15 Certificate of Conformance (Apr 1984)
- Acquisition.gov, FAR 46.504 Certificate of conformance
- U.S. Department of Energy, PF 2025-63 class deviation adopting RFO FAR Part 46
- Lockheed Martin Missiles and Fire Control, Quality PO Notes (Procedure QC 524 Rev AG)
- L3Harris (Aerojet Rocketdyne), AR2 Quality Management Systems Aerospace Requirements for Distributors (11/5/2025)
- Acquisition.gov, DFARS 252.246-7008 Sources of Electronic Parts
- ISO/IEC 17050-1:2004 Supplier's declaration of conformity, Part 1 (IEC preview)
- Advisera, Who can sign a CofC in AS9100 (clause 8.6)
- Acquisition.gov, DFARS 252.225-7009 Restriction on Acquisition of Certain Articles Containing Specialty Metals
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