What a first article inspection proves
A first article inspection, or FAI, is a complete, documented check of one or more parts from the first production run against every requirement on the drawing and purchase order. Its purpose is to prove that the supplier's process, from raw material through machining, finishing and marking, can produce a conforming part. It is not a sample spot check; it is a full verification that the production method works.
FAI is standard in aerospace and common in automotive, medical and industrial programs. Even when not required by contract, many buyers request it for new parts with tight tolerances.
The AS9102 format
The aerospace standard AS9102 defines a widely used FAI report format with three forms. Many non-aerospace buyers adopt the same structure because it is clear and complete.
Form 1: part number accountability
Identifies the part, revision, drawing, and any sub-assemblies or detail parts included.
Form 2: product accountability
Lists raw materials, special processes such as heat treatment, anodizing or passivation, and functional tests, with the certificates and approved sources used for each.
Form 3: characteristic accountability
Lists every design characteristic on the drawing, its requirement and the actual measured result, with pass or fail. Automotive programs often use a production part approval process, PPAP, which includes dimensional results along with other documents. The dimensional part follows a similar logic.
Ballooning the drawing
Before measurement, every characteristic on the drawing gets a numbered balloon: each dimension, tolerance, note, GD&T frame, thread callout, surface finish and material or finish note. Each balloon becomes a line on Form 3. Ballooning makes sure nothing is overlooked and gives the buyer and supplier a shared reference when discussing any result.
Notes count too. A note such as "break all sharp edges 0.2–0.5" or "passivate per ASTM A967" is a characteristic and needs evidence, either a measurement or a certificate.
How the inspection is done
Planning
The inspector reviews the ballooned drawing and decides the method for each characteristic: CMM, calipers, micrometers, height gauge, thread gauges, surface roughness tester, optical comparator or visual check.
Measurement
The part is measured characteristic by characteristic. Results are recorded as actual values, not just "OK", wherever a measurement is possible.
Documentation
Material certificates, special process certificates and test results are collected and referenced in Form 2.
Review
Any nonconforming result is flagged. The supplier corrects the process and repeats the affected inspection, or the buyer formally accepts a deviation.
What a good report looks like
- Every balloon number appears in the report with its requirement and result
- Measured values are given with suitable resolution
- Measurement methods or equipment are identified
- Certificates are referenced for material and each special process
- The report states the part number, revision, serial or lot number and date
- Nonconformances are clearly marked, never hidden
When a new FAI is required
FAI is not a one-time event forever. Common triggers for a full or partial repeat:
- Drawing revision that affects form, fit or function
- Change of manufacturing location or major equipment
- Change in manufacturing process or method, such as moving from milling to casting
- Change of special process supplier, such as a new anodizer
- Long production gap, often around two years in aerospace practice
- Tooling replacement for tooled processes
- Corrective action after a significant quality problem
A partial FAI covers only the characteristics affected by the change. Agree the rules in the purchase order or quality agreement.
FAI versus routine inspection
| Topic | First article inspection | Routine production inspection |
|---|---|---|
| Scope | Every characteristic and requirement | Key characteristics, sampling plan |
| When | First production run and after significant changes | Every lot |
| Documentation | Full formal report | Inspection record, certificate of conformance |
| Purpose | Prove the process | Monitor the process |
Routine inspection relies on the FAI having proven the process. That is why FAI must be done on a part made with production methods, not on a specially crafted sample.
How buyers can make FAI smoother
- State the FAI requirement and format on the purchase order
- Provide the current drawing revision and any 3D model that defines geometry
- Identify key characteristics so inspection focuses on what matters
- Clarify the scope: one part or several, which features need actual values
- Agree on what certificates are needed and in what form
- Allow time in the schedule for FAI review before releasing production
Unclear drawings slow FAI more than anything else. A characteristic that cannot be measured because a datum is missing will stall the report.
Common FAI problems
Missing characteristics
A note or a hidden dimension was not ballooned. Use a systematic method to balloon every item.
Results without values
"OK" or check marks where measurements were possible. Ask for actual values.
Certificates missing or mismatched
Material or finish certificates are not linked to the right lot. Traceability needs consistent lot numbers.
Parts not from production
A carefully hand-finished sample can pass but does not prove the process. Ensure FAI parts come from the real production route.
A sample Form 3 extract
The table shows how a few lines might look in a characteristic accountability form. Values here are illustrative only.
| Balloon | Requirement | Result | Method |
|---|---|---|---|
| 1 | 40.00 ±0.05 | 40.02 | CMM |
| 2 | Ø6.00 +0.02/0 | 6.01 | Pin gauge |
| 3 | Position Ø0.10 Ⓜ A B C | 0.04 | CMM |
| 4 | M5x0.8-6H | Conforms | Go/no-go gauge |
| 5 | Ra 1.6 max | 0.9 | Roughness tester |
| 6 | Anodize per MIL-A-8625 Type II | Certificate ref. | Supplier certificate |
Each line is traceable to a balloon on the drawing, and anything that cannot be measured directly is backed by a referenced document.
Digital inspection and FAI software
Many shops now use software that reads the CAD model or PDF drawing, places balloons automatically and links CMM results straight into the report. This reduces transcription errors and speeds up repeat FAIs. Buyers do not need to require a particular tool, but they can ask for reports in a structured format, such as a spreadsheet, that is easy to review and archive.
Costs and timing
FAI takes measurable inspection time, especially on complex parts with many characteristics. CMM programming, ballooning and documentation all add work. It is normally quoted as a separate line item. For a simple bracket, the effort is modest; for a complex aerospace housing, it can be significant. Ask for FAI in the quote request so it is planned and priced from the start.
Sampling for multi-cavity and multi-fixture production
When parts are made on several fixtures, machines or mold cavities, each route can introduce its own variation. Many programs require an FAI part from each cavity or each fixture, or at least from each machine that will be used in production. Otherwise, a problem in one route can stay hidden behind a passing report from another. Clarify this point early, because it changes how many parts must be measured.
The same thinking applies to parts that are finished by different special process lines. If a supplier uses two anodizing lines, the report should identify which line the FAI part went through.
Storing and reusing FAI records
Keep FAI reports with the drawing revision they cover. When a revision changes, the old report shows exactly what was proven, which makes deciding the scope of a partial FAI easier. Good records also help when moving work between suppliers.
Summary
First article inspection proves that a production process makes conforming parts. A ballooned drawing, complete measurements, linked certificates and clear rules for repeat FAI turn it from paperwork into real risk reduction. Asking for it clearly at quote stage is the easiest way to get a useful report.