When is a FAI required?
The question is rarely whether a FAI is needed. It is almost always whether the whole thing has to be done again, or only part of it. That distinction decides whether the work is an afternoon or a week.
The principle behind the triggers
A FAI is evidence that a specific manufacturing process can produce a conforming part. So the question that decides whether a new FAI is needed is not “did the drawing change” but “does the existing FAI still describe the process actually being used”.
If it does not, the old FAI no longer proves anything about the current process.
Full FAI: commonly published trigger events
| Trigger | Why it invalidates the baseline |
|---|---|
| New part number, or first build to a customer design | There is no baseline at all. |
| Design change affecting fit, form, function, safety or performance | The requirements the old FAI verified have changed. |
| Production lapse — commonly 24 months or more | The process has not been demonstrated to be under control since it last ran. Customers may specify a shorter or longer interval. |
| New manufacturing site | Different facility, different process realisation. |
| New primary equipment or new process route | The capability being relied on is not the capability that was validated. |
| Change of material, source, or a key special process | Heat treat, plating, bonding and welding changes can affect a part in ways a dimensional re-check will not capture. |
| Customer-directed FAI | A purchase order, quality clause or corrective action can require it regardless of the above. |
Widely published as triggers for a full FAI. Your customer’s flowdown can be stricter than this list.
Partial (delta) FAI: when less is enough
A partial FAI covers only the characteristics affected by the change, and references the original baseline report by number and date. It is typically acceptable where the change is tightly scoped and the unchanged process is still demonstrably in control.
| Change | Commonly treated as |
|---|---|
| Drawing typo or spelling correction, no requirement change | Partial FAI |
| Clarified inspection method, same requirement | Partial FAI |
| Removal of an unused reference dimension | Partial FAI |
| Cosmetic or deburr note clarification with no critical impact | Partial FAI, with customer agreement where required |
| New machining centre and fixture for the same part | Usually full FAI — the manufacturing environment changed |
Illustrative only. The decision is yours, or your customer’s, based on the actual risk and the applicable flowdown.
Boundary cases are where the arguments happen
Two changes that look similar on paper can land differently:
- A note clarified, no functional effect — usually supports a partial FAI.
- A new fixture locating a critical feature — usually needs a full FAI, even though the drawing did not change, because the setup that produces the feature is different.
A widely used tie-breaker: if the risk is unclear, default to the fuller FAI. It is cheaper than a rejected submission or a late containment.
What this means for the paperwork
- A full FAI produces a complete report — all three forms, with Form 3 covering every characteristic on the drawing.
- A partial FAI produces a delta — Form 3 covering only the affected characteristics, plus a reference to the baseline report it builds on.
For the people assembling the package that is the practical consequence: much less Form 3 data, but it still has to be structured, and the reference back to the baseline still has to be correct. Getting Form 3 data into Excel.
Frequently asked questions
How long a production gap requires a full FAI?
A common aerospace rule is 24 months or more, unless the customer specifies a different interval. The underlying question is whether the existing FAI still describes the process actually in use, so a customer can specify shorter or longer.
Can a drawing typo correction be handled with a partial FAI?
Edits that change no requirement, such as spelling, unit symbols, unused reference dimensions or clarified inspection methods, are commonly handled as a partial or delta FAI. Where a change touches fit, form, function, safety or performance, a full FAI is the usual expectation.
Does moving production to a new machine require a full FAI?
Typically yes when the change affects the capability being relied on, such as a new machining centre, a new fixture locating a critical feature, or a move from manual to automated production. The drawing may be unchanged while the validated process is not.
What is a delta FAI?
Another name for a partial FAI: a submission covering only the characteristics affected by a change, referencing the original baseline report by number and date rather than restating the full inspection.
Sources
- Connect981 — When first article inspection is required
- IAQG — AS9102 forms and supporting form instructions
- Published aerospace supplier FAI requirements (example flowdown)
Standards are revised. Always work from the current published edition of AS9102 from SAE International. This page is orientation only and is not a substitute for the standard.