First Article Inspection for CNC Machined Parts: FAI Report Guide

A CNC machined part can look correct and still contain a missed drawing requirement, an incorrect material condition, or a feature measured with an unsuitable method. First article inspection helps identify those problems before a production order progresses too far.

For buyers, however, the phrase “first article” can be confusing. It may describe a simple first-off dimensional check, a customer-specific approval package, or a formal first article inspection report prepared to an aerospace standard. These services do not have the same scope, cost, or lead time.

This guide explains what CNC first article inspection is, when it may be required, what an FAI report normally contains, how balloon drawings connect design requirements to results, and what to include in a request for quotation.

What Is First Article Inspection in CNC Machining?

First article inspection, commonly abbreviated as FAI, is a planned verification process performed on a representative item produced by the intended manufacturing process. Its purpose is to provide objective evidence that the process has correctly interpreted and incorporated the applicable design requirements.

For a CNC machined component, the review may cover more than finished dimensions. Depending on the contract, it can include:

• Part number, drawing revision, and configuration

• Raw material grade, specification, and condition

• Dimensions, tolerances, and geometric requirements

• Drawing notes and model-based requirements

• Threads, inserts, markings, and identification

• Surface roughness and cosmetic requirements

• Heat treatment, plating, anodizing, passivation, or other special processes

• Material and process certificates

• Functional or acceptance test results

• Nonconformance references and disposition, when applicable

The International Aerospace Quality Group explains that the 9102 standard creates consistent FAI process and documentation requirements for aviation, space, and defense products. It also notes that the approach can be used in other sectors that need a standardized FAI process.

FAI does not guarantee that every future part will conform. It verifies the planned production realization process at a defined configuration. Ongoing production control, sampling, final inspection, calibration, and change management are still necessary.

FAI, First-Off Inspection, and Sample Approval Are Not the Same

The word “first” causes many purchasing misunderstandings. Before quoting, the buyer and supplier should agree on the required deliverable.

First-off inspection

A first-off inspection is usually an internal check of the first part, or first few parts, from a setup. The machinist or inspector uses the results to adjust offsets, confirm tooling, and release the batch. The scope may focus on selected dimensions rather than every design characteristic.

Dimensional inspection report

A dimensional report records measured results for an agreed list of features. It may cover critical dimensions only or all ballooned dimensions. Unless specifically requested, it may not include complete material, process, configuration, and traceability documentation.

Customer sample approval

Some buyers request one or more samples before authorizing the remaining quantity. The approval may consider fit, appearance, assembly, or performance as well as dimensions. The buyer should define whether production must stop until written approval is received.

Formal first article inspection report

A formal FAIR is a controlled documentation package with a defined scope and format. When AS9102 or another customer standard is contractually required, the supplier must follow that requirement rather than treating the task as an ordinary dimensional check.

Never use “FAI report,” “full dimensional report,” and “sample approval” as interchangeable terms in an RFQ. State exactly what the supplier must inspect, document, submit, and wait for before continuing production.

When Is a CNC First Article Inspection Needed?

FAI requirements come from the purchase order, drawing, quality clauses, industry rules, or the buyer’s internal risk controls. Not every prototype or machined order needs a formal FAI package.

A buyer may request first article inspection when:

• A part number is entering production for the first time

• A new supplier or manufacturing source is being qualified

• A design revision changes fit, function, material, or production requirements

• Tooling, fixtures, programs, machines, or manufacturing methods change

• Production moves to another site or process route

• A long interruption creates concern that the original process is no longer representative

• A previous nonconformance requires renewed verification

• The component is safety-critical or used in a controlled industry

• The buyer needs documented approval before releasing the balance of an order

Whether these events require a full FAI, partial FAI, or another verification method depends on the invoked standard and customer requirements. The supplier should not guess. The purchase order should identify the governing document, revision, forms, submission method, and approval process.

What Is AS9102?

AS9102 is an aerospace first article inspection standard published by SAE International. The SAE standard record states that it establishes documentation requirements for FAI and identifies AS9102C, issued in 2023, as the current verified revision on its page.

AS9102 is not automatically mandatory for every CNC machined part. It becomes a contractual requirement when it is invoked by the customer, purchase order, drawing, or applicable quality clause. A buyer who needs AS9102 should specify the exact revision and any customer-specific supplements during quotation.

Do not ask for “AS9102-style” paperwork if a simpler report will meet the real need. A formal aerospace FAIR requires additional planning, characteristic accountability, documentation review, and quality labor. Conversely, do not accept an ordinary dimensional table when the contract requires a compliant AS9102 package.

Full FAI vs Partial FAI

A full FAI addresses the complete applicable product definition for the part or assembly. It is commonly associated with a new product or a situation in which previous results cannot establish that the current process and configuration remain valid.

A partial FAI addresses the characteristics affected by a change. For example, a revised hole location may require renewed verification of that feature, related datum relationships, and any other requirements influenced by the change. Unaffected characteristics may reference an accepted previous FAIR when permitted by the governing requirements.

The decision should be documented. Before work begins, clarify:

1. What changed?

2. Which design characteristics can the change affect?

3. Are previous results still valid for unaffected requirements?

4. Does the customer require approval of the proposed FAI scope?

5. Must manufacturing pause while the FAIR is reviewed?

Treating every change as a full resubmission can add unnecessary cost. Treating a major process change as a minor update can leave risk unexamined.

What Does an FAI Report for a Machined Part Contain?

The exact package depends on the contract, but a complete CNC machining FAI report commonly brings together several types of objective evidence.

The package should be internally consistent. Part numbers, revisions, material descriptions, certificate references, and result units must agree across the purchase order, drawing, report, and supporting records.

Understanding the Three AS9102 Forms

When AS9102 forms are required, the information is organized into three broad accountability areas. Always use the forms and instructions required by the applicable revision and customer; the summary below is only an orientation.

Form 1: Part number accountability

This area identifies the part or assembly, revision level, organization, manufacturing reference, and FAI status. For assemblies, it also helps account for lower-level parts included in the configuration.

Form 2: Product accountability

This area records materials, special processes, functional testing, and related certificate or report references. It connects the finished part to evidence that specified material and process requirements were satisfied.

Form 3: Characteristic accountability

This area lists the design characteristics, requirements, results, and supporting references. Each numbered characteristic on the balloon drawing should connect clearly to a report entry.

The forms are not a substitute for the underlying evidence. Material certificates, process certificates, test reports, and approved nonconformance records may still need to accompany the submission.

How Balloon Drawings Work

A balloon drawing is a controlled copy of the drawing in which each applicable design characteristic receives a unique identifier. The identifier links that requirement to a corresponding row in the inspection report.

Ballooning usually covers more than numerical dimensions. Depending on the product definition, accountable characteristics can include:

• Linear and angular dimensions

• Geometric tolerances and datum references

• Hole, thread, and insert requirements

• Surface-roughness callouts

• Material and heat-treatment notes

• Coating, plating, anodizing, or passivation notes

• Marking, cleaning, and workmanship requirements

• Drawing notes and specification references

• Model-based characteristics not fully shown on the 2D drawing

Good ballooning prevents omissions. Poor ballooning creates duplicated numbers, skipped notes, unclear multi-element callouts, or report rows that do not match the drawing.

The drawing revision used for ballooning must match the item being manufactured. If a revision changes after inspection planning begins, both the inspection scope and previously collected results need review.

Planning Inspection Methods Before Machining

The inspection plan should be developed before the first production run, not after the component is complete. Some characteristics are difficult or impossible to verify after later operations hide or alter them.

Examples include:

• Internal features that become enclosed during assembly

• Dimensions that change during heat treatment or coating

• Features removed by a subsequent machining operation

• Deep bores or intersecting passages with limited access

• Profile or position requirements that depend on a defined datum setup

• Surface condition before plating, polishing, or blasting

Boeing’s supplier guidance emphasizes planning inspection methods and sequencing, accounting for all design characteristics, identifying in-process evidence, reviewing model-based requirements, and evaluating changes that may invalidate previous results.

The chosen equipment must suit the characteristic and tolerance. Calipers may be appropriate for some general dimensions, while close bores, geometric relationships, surface roughness, threads, or complex profiles may require micrometers, bore gauges, thread gauges, a height gauge, an optical system, a profilometer, or a coordinate measuring machine.

For more detail on matching instruments to requirements, see the guide to CNC machining quality control. Tight limits and datum relationships should also be reviewed with the CNC machining tolerances guide.

Step-by-Step CNC FAI Process

1. Review the contract and product definition

Confirm the purchase order, part number, drawing revision, 3D model revision, specifications, quality clauses, and customer-specific requirements. Resolve conflicts before material is ordered or machining begins.

2. Define the FAI scope

Decide whether the submission is full or partial, which forms or templates apply, how many pieces are involved, and whether customer approval is required before the remaining quantity can proceed.

3. Build the characteristic list

Balloon the drawing and extract applicable model-based requirements. Include notes, specifications, material, processes, tests, and workmanship requirements rather than recording dimensions alone.

4. Plan manufacturing and inspection

Determine when each characteristic will be created and verified. Identify in-process checks, special gauges, CMM programming, outsourced processes, certificate needs, and features that require independent verification.

5. Manufacture the representative item

Use the intended production location, process route, CNC program, tooling, fixtures, material, and operators as required by the applicable plan. A hand-finished development sample made by a different route may not represent the production process.

6. Collect objective evidence

Record actual results where required, verify notes, and gather material certificates, special-process certificates, test reports, and traceability records. Record measurement units and equipment references consistently.

7. Review nonconformances

Do not hide an out-of-tolerance result by selecting another sample or changing a report value. Identify the nonconformance, determine the affected scope, obtain any required customer disposition, and document corrective action or reinspection.

8. Perform an independent package review

Check for missing balloons, transposed values, incorrect revisions, expired or unsuitable calibration, incomplete certificates, and inconsistent part identification. The paperwork should be reviewed as carefully as the physical component.

9. Submit and control production release

Send the package through the agreed channel. If the order requires customer approval before continuing, hold the remaining production or shipment until authorization is received.

Common FAI Mistakes

Quoting before the documentation scope is known

“FAI required” is not enough information for accurate pricing. The supplier needs to know the standard, revision, forms, characteristic count, certificate requirements, submission portal, and approval hold points.

Inspecting only dimensions

A part can meet every listed dimension but use the wrong material condition, miss a finish note, or lack a required test. Review the entire product definition.

Using the wrong drawing revision

This makes otherwise accurate results unreliable. Revision control should be confirmed at contract review, manufacturing release, inspection, and final package review.

Leaving drawing notes unaccounted for

Notes such as “remove all burrs,” “passivate,” “mark part number,” or “clean before packaging” are product requirements when applicable. They need an acceptance method and evidence. Edge requirements can be clarified using the CNC deburring guide.

Reporting “pass” instead of an actual result

For variable characteristics, the customer may require recorded measured values rather than a general acceptance statement. Attribute and process requirements may use certificate or verification references when permitted.

Measuring with an unsuitable method

Instrument resolution alone does not prove that a method is capable. Fixturing, datum simulation, access, repeatability, environment, surface condition, and operator technique can all affect the result.

Continuing production before approval

If the purchase order includes an approval hold point, producing the entire batch before acceptance can create avoidable rework and schedule risk.

Treating FAI as a one-time paperwork exercise

An accepted FAIR relates to a defined configuration and process. Later changes should be reviewed to determine whether previous results remain valid.

How FAI Affects Cost and Lead Time

The cost of first article inspection is driven by the work needed to plan, measure, document, review, and submit the package—not only by the number of parts.

Major cost drivers include:

• Number and complexity of design characteristics

• Tight geometric tolerances and datum setups

• CMM or optical inspection programming

• Custom gauges or fixtures

• In-process inspection points

• Material, process, and test certificates

• Outsourced laboratory or special-process reports

• Customer forms, portals, or source-inspection requirements

• Package revisions after engineering changes

• Production hold time while approval is pending

Send quality requirements with the initial RFQ. Adding a full FAIR after machining is underway may require new planning, repeated measurements, certificate recovery, or even remanufacture if the original process did not preserve the required evidence.

FAI vs PPAP vs Routine Inspection

These quality deliverables serve different purposes.

One document does not automatically replace another. A certificate of conformity is not a complete FAIR, and an FAI package is not automatically a PPAP submission.

What Buyers Should Include in an FAI RFQ

Provide the following information before the supplier quotes:

1. Part number, part name, and current revision

2. Controlled 2D drawing and matching 3D model

3. Order quantity and number of first article pieces

4. Required FAI standard and exact revision

5. Full or partial FAI status and reason for the submission

6. Customer-specific forms, quality clauses, and portal requirements

7. Characteristics requiring actual measured values

8. Material, special-process, functional-test, and traceability documents

9. Source-inspection or witness requirements

10. Required language, units, and file format

11. Approval authority and expected review time

12. Whether production or shipment must stop pending approval

13. Previous FAIR reference for a partial submission

14. Required delivery date for samples and documentation

The CNC machining RFQ checklist provides a broader list of CAD, drawing, material, quantity, finish, and delivery information needed for an accurate quotation.

FAI RFQ Template

Copy and adapt the following text:

Please quote CNC machining and first article inspection for part [part number], revision [revision]. Quantity: [total quantity], including [number] first article unit(s). The required submission is [full/partial] FAI to [standard and revision/customer requirement]. Provide [forms or template], a balloon drawing, recorded results for [all/identified] characteristics, material certificates, special-process certificates, and [test reports/other records]. Production [may proceed/must stop] after the first article until written approval from [approver] is received. Submit the sample and report by [date] in [file format/portal]. The previous FAIR reference for this partial FAI is [reference], and the change reason is [reason].

Clear instructions allow the supplier to separate machining cost, inspection cost, documentation lead time, and approval risk in the quotation.

Choosing a CNC Supplier for FAI Work

A suitable supplier should ask detailed questions before promising a report. Look for evidence of controlled document review, material traceability, calibrated inspection equipment, suitable measurement capability, qualified special-process sources, and a disciplined final review process.

Useful questions include:

• Who reviews the drawing and creates the characteristic list?

• How are 3D model requirements accounted for?

• Which features require in-process inspection?

• What measurement equipment will be used?

• How are material and external-process certificates linked to the work order?

• How are nonconforming results controlled and reported?

• Can the supplier use the required customer forms or portal?

• How are engineering changes reviewed after an accepted FAIR?

A low machining price can be misleading if the supplier has not included the documentation effort. Compare quotations on the same technical and quality scope.

Frequently Asked Questions

Is FAI required for every CNC prototype?

No. Development prototypes often use a simpler dimensional or functional inspection unless the contract specifically requires formal FAI. The appropriate level depends on risk, industry, product maturity, and customer requirements.

Does “first article” mean only the first physical part?

Not necessarily. The term describes a verification process and representative production item, not merely the first piece removed from a machine. The contract should define sample selection and process conditions.

Is a CMM report the same as an FAI report?

No. A CMM report may provide dimensional evidence, but an FAI package can also require configuration, material, process, test, traceability, and characteristic-accountability records.

Must every drawing dimension be measured?

For a formal FAI, applicable design characteristics must be accounted for as required by the invoked standard and customer. Some requirements are verified by measurement, while others may be supported by certificates, test reports, or approved records.

Can a supplier use “pass” for every result?

Not always. Buyers or standards may require actual variable measurement results. The acceptable recording method should be defined before inspection begins.

What happens if the first article fails?

The supplier should document the nonconformance, control the affected product, determine the cause, take appropriate action, and repeat affected verification. Any concession or deviation requiring customer authorization must be approved through the agreed process.

Can production continue while the customer reviews the FAIR?

Only if the contract allows it. When approval is a hold point, continuing production transfers significant rework risk to the supplier or buyer. State the release rule in the purchase order.

When is a partial FAI appropriate?

A partial FAI may be suitable when a documented change affects only part of the product definition and previous results remain valid for unaffected characteristics. The governing requirement and customer determine the acceptable scope.

Does an accepted FAI approve all future lots?

No. It provides evidence for a defined configuration and production process. Routine inspection, process control, change review, and lot acceptance remain necessary.

Should FAI requirements be included before requesting a quote?

Yes. Early disclosure gives the supplier time to plan inspection access, collect traceability, price documentation, and schedule any customer approval hold.

Request a CNC Machining Quote with the Right Inspection Scope

A useful first article inspection starts with an unambiguous product definition and a clearly defined deliverable. State whether you need a first-off check, dimensional report, customer sample approval, full FAIR, or partial FAIR. Include the applicable standard, forms, certificates, recorded-result requirements, and approval hold points with the RFQ.

Send your CAD files, controlled drawing, quantity, material, finish, tolerance, and inspection requirements through the Aluprototype request-a-quote page. The team can review manufacturability and confirm the inspection scope needed for your CNC machined parts.