A CNC process may run without alarms, hold cycle time, and still ship parts that fail at receiving. A small tool offset, a datum taken from the wrong surface, or an unaddressed drawing note can trigger a lot rejection. FAI is the checkpoint that exposes those issues on part one, not after hundreds have been cut. This article explains what an FAI covers, when customers require it, what belongs in the report, and how to complete it without derailing production.
An FAI is a formal record proving that a component made with the actual production tooling, materials, and process conforms to the engineering drawing and purchase order. Inspectors verify and record each dimension, tolerance, note, material requirement, and special process using actual measured values.
The “first” in first article means the first part produced under normal manufacturing conditions—not a prototype built on another machine with temporary workholding. This matters because the goal is to validate the process, not to celebrate one favorable sample.
In aerospace and defense work, AS9102 Revision C is the controlling standard. Automotive suppliers typically satisfy a comparable requirement through PPAP. Medical device and industrial buyers often use a custom template. The paperwork differs by sector; the verification logic stays the same.
CNC machining is highly repeatable, which is why a setup mistake can be so costly. Once a CAM program, fixture, and tool library are proven, the machine will reproduce the same geometry—and the same error—for as long as it runs. Frequent trouble spots include incorrect tool offsets, wrong datum selections, and drawing notes that never made it into the inspection plan.
Finding such a problem on the first article costs a few hours of inspection. Finding it after delivery can bring scrap, rework, expedited freight, a corrective action request, and a missed program milestone. For buyers of precision components, the FAI report is the strongest manufacturing quality control evidence that a supplier’s CNC process is ready for volume.
Most customers state the FAI requirement in the purchase order. AS9102 defines when aerospace suppliers must perform one; other industries apply similar triggers. A full FAI checks every drawing characteristic. A partial FAI—sometimes called a delta FAI—checks only the features affected by a change and points to an approved baseline report for the rest. Partial reports can save time when the baseline is complete and traceable. If the original report has gaps, the customer will usually demand full re-verification instead of accepting a reference to incomplete data.
Under AS9102, the first article inspection report consists of three forms, each serving a distinct purpose.
Form 1 identifies the inspected part. It includes part number, part name, revision, drawing number, serial or lot number, inspection reason, and any sub-assemblies included in the build. Each sub-component receives its own line with its own part number and revision.
Form 2 documents raw material, specifications, special processes, and functional tests. For a machined part, entries might include alloy and temper, heat treat condition, anodizing or plating specification, and any proof or leak test required by the drawing. Every line should identify where the requirement appears on the drawing or purchase order so an auditor can trace it to its source.
Form 3 is the core of the report. Each drawing characteristic gets a unique balloon number, and every balloon number gets a row listing the requirement, measured result, and conformance status. This is where dimensional inspection data sits, along with notes, surface finish callouts, and general tolerances that apply to the part. The balloon numbers on the drawing must match the characteristic numbers on Form 3 exactly; that linkage is what makes the report auditable.
A complete submission normally also includes the ballooned drawing or annotated 3D model, material certifications, special process certifications, CMM output, and functional test records.
The FAI process follows a predictable sequence, and most schedule delays begin when steps are skipped. Inspection method must match the tolerance being verified. A caliper may be acceptable for a 0.5 mm general tolerance but is ineffective for a 0.01 mm position callout.
Two measurement details deserve control. Work at a stable temperature near 68°F, because aluminum expands and contracts noticeably in a warm shop. Align to the drawing datums in the specified order; a technically correct measurement taken from the wrong datum structure is still wrong. Suppliers who perform this work in a climate-controlled metrology room with calibrated equipment can support their results when a customer re-measures.
Many rejections have little to do with the part itself. They originate in the paperwork. Setting expectations before the first chip is cut is the least expensive way to avoid them. A brief conversation during quoting prevents most FAI delays.
Suppliers that treat first article work as a routine production step—with documented procedures and a defined quality assurance process—tend to submit cleaner reports and move through customer review faster. This is especially important in regulated markets, where aerospace and medical programs will not release production until the report is approved. Teams sourcing machined components for these programs can discuss inspection support and capabilities with XC Machining before placing a first article order.
Q: How long does an FAI take?
A straightforward machined part with 20 to 40 characteristics generally takes one to two days, including measurement and documentation. Complex aerospace components with hundreds of ballooned features may require a week or more, depending on fixturing and review time.
Q: Who pays for the FAI report?
The buyer usually covers the cost, either as a separate line item or included in the first article part price. Suppliers should quote it transparently, because a full report on a complex part consumes real engineering and metrology hours.
Q: Is an FAI required for non-aerospace CNC parts?
It is not a regulatory requirement, but many industrial, medical, and energy buyers request one. Automotive programs use PPAP instead. Even without a customer requirement, running the FAI process internally is a practical manufacturing quality control step before committing to a volume run.
Q: What happens if a dimension fails during dimensional inspection?
The nonconformance is recorded on Form 3 with the actual value and submitted for disposition. The customer may accept it as is, request rework, or require a process correction and re-inspection before approving the report.
Q: Does a new revision always require a full FAI?
No. If the change affects only specific characteristics, a partial or delta report covering those features is usually acceptable, provided it references an approved baseline report. Changes to manufacturing source or a production lapse beyond two years typically require a full FAI.
