First Article Inspection: What It Is and How to Run One

A First Article Inspection (FAI) verifies that the first part off a new process matches the drawing. It is the single cheapest way to catch a bad supplier setup before it becomes a bad production lot. Skip it and you ship defects you already paid to detect.

This guide covers what an FAI actually proves, when to trigger one, and how to document it so the report stands up months later when a part drifts out of spec.

What a First Article Inspection proves

An FAI confirms three things. The supplier read the drawing correctly. The process produces parts inside every called-out tolerance. The material and finish match the specification. It does not prove the process is stable over time. That comes from process capability studies and ongoing inspection.

When to trigger an FAI

• First part from a new supplier or new contract manufacturer
• Any drawing revision that changes a dimension, material, or finish
• Tooling repair, refurbishment, or replacement
• Process change such as a new machine, fixture, or heat treat vendor
• Production move to a new line, shift, or facility
• Resumption after a production pause longer than 12 months

The three-form structure

Aerospace teams use AS9102. Commercial hardware teams use the same three-form pattern without the aerospace fields. Build your template around these three sections.

Form 1: Part identification

Capture part number, revision, supplier, drawing number, and the serial or lot number of the inspected part. If the report cannot be traced back to a specific physical part, the report is worthless.

Form 2: Material and process certifications

Attach the mill cert for raw material, plating or coating certs, heat treat records, and any required process certifications. Each cert references the drawing callout it satisfies.

Form 3: Characteristic results

List every dimension, tolerance, and note on the drawing. Number each characteristic. For each one, record the nominal, the tolerance, the measured value, the measurement method, and pass or fail.

How to ballooning the drawing

Ballooning means numbering every characteristic on the drawing so the FAI report and the drawing share one index. Number sequentially across every view. Include dimensions, geometric tolerances, surface finishes, material callouts, and notes. A typical machined part has 40 to 120 balloons. Skip nothing.

Choose the right measurement method

The measurement method has to resolve at least 10 times finer than the tolerance. A 0.001 inch tolerance needs an instrument that reads to 0.0001 inch. Match the tool to the feature.

• Linear dimensions: calipers, micrometers, or CMM
• Geometric tolerances such as flatness, position, true profile: CMM
• Surface finish: profilometer with the correct cutoff length
• Threads: go and no-go gauges, not calipers
• Bores and ID features: bore gauges or CMM, not calipers

What to do when a characteristic fails

Quarantine the part and any lot it represents. Open a nonconformance record. Decide between three outcomes. Rework the part if the deviation is recoverable. Scrap if it is not. Approve a formal deviation if the out-of-spec value is functionally acceptable, signed by engineering, and bounded to a specific lot quantity. Never approve a deviation by email or verbally. The deviation record protects you when the same feature fails six months later in the field.

Storage and retrieval

Store FAI reports next to the drawing revision they verify. When a field failure traces back to a specific lot, you should be able to pull the exact FAI report tied to that lot in under five minutes. If your FAI reports live in someone's email, you do not have an FAI program.

TL;DR

Run an FAI on every new supplier, every design change, and every tooling event. Balloon every characteristic. Measure with the right tool. Document deviations on paper. Store the report against the revision. Do this and bad lots stop at the supplier instead of at your customer.

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