What Is First Article Inspection (FAI)? A Plain-English Guide for Engineers and Buyers

If you've sourced parts from a new CNC machining supplier and been asked whether you require a First Article Inspection report, you may have wondered: what exactly is FAI, do I need it, and what should it actually contain?

This guide explains FAI clearly — what it is, why it exists, what a proper FAI report includes, and when it's worth requiring one.

What Is First Article Inspection?

First Article Inspection (FAI) is a formal verification process that confirms the first production part — or a small sample of the first production run — fully conforms to all drawing requirements before the full order proceeds. It's the checkpoint between "we think we can make this" and "we have proven we can make this."

FAI is not a prototype review. It's not an informal check that the part looks right. It's a documented, measurement-based confirmation that every dimension, tolerance, material specification, and special requirement on the engineering drawing has been verified and recorded.

Why FAI Exists

The problem FAI solves is this: a CNC machining setup that looks correct can still produce out-of-tolerance parts. Tool runout, fixture positioning, thermal expansion, and program errors can all introduce dimensional variation that isn't visible to the naked eye. Without formal first article inspection, these errors often aren't discovered until parts fail in assembly — or worse, in service.

FAI catches problems at the earliest possible point — before the full production run is complete. A single setup error discovered at FAI costs one part and a setup correction. The same error discovered after 500 parts are shipped costs far more.

The FAI Process Step by Step

What a Proper FAI Report Contains

A complete FAI report should document the following:

• Part identification — drawing number, revision level, part description, material specification
• Dimensional inspection results — every dimension on the drawing with nominal, tolerance, actual measured value, and pass/fail status
• Material certification — mill certificate reference confirming material grade and traceability
• Surface finish measurements — Ra values at specified locations
• Special process records — heat treatment, surface treatment, or other specified processes
• Inspector sign-off — name, date, and measurement equipment used (with calibration status)

For aerospace applications under AS9102, the FAI report format and required content are standardized. For other industries, format varies by customer requirement, but the content above represents the minimum for a meaningful FAI.

FAI vs PPAP: What's the Difference?

Engineers from automotive backgrounds will be familiar with PPAP (Production Part Approval Process), which serves a similar purpose to FAI but with more extensive documentation requirements — including process flow diagrams, control plans, and capability studies (Cpk data).

FAI, as defined by AS9102 for aerospace, focuses on dimensional and material verification of the first article. PPAP, used in automotive supply chains, adds process documentation to ensure the manufacturing process itself is capable and controlled. Both serve the same fundamental purpose: proving that a supplier can make the part correctly before full production begins.

For most CNC machined parts outside of high-volume automotive production, FAI provides the right level of verification without the full overhead of PPAP.

When Should You Require FAI?

FAI is worth requiring for any new part from a new supplier or new setup, any part where dimensional failure would cause a safety, functional, or regulatory issue, any part with tight tolerances (±0.025mm or tighter on critical features), production runs where the cost of discovering errors late is high, and re-orders where the drawing has been revised since the last production run.

For low-risk, low-complexity parts from established suppliers with a proven track record, FAI may be overkill — a standard inspection report may be sufficient. The decision should be driven by the consequences of a non-conforming part reaching your assembly line or end customer.

Our Standard Practice

We provide dimensional inspection reports with every order as standard. For customers who require formal FAI documentation — whether for aerospace, medical, defense, or quality system compliance — we produce complete FAI packages including all the elements described above. FAI requests should be noted at the time of order so we can allocate inspection time accordingly.

→ Need FAI documentation on your next order? Let us know in your quote request and we'll confirm our FAI process.