Inspection
First article inspection, done properly
A first article inspection is a simple promise with a formal wrapper: we made the first part off the real process, we measured everything the drawing asks for, and here is the evidence. Not a sample dimension here and there - everything. Every dimension, every note, every material call-out, verified on a part made the way production parts will be made.
The aerospace standard AS9102 gives the promise its best-known shape, but the need is universal. If you machine, mould, fabricate or assemble drawing-controlled parts for anyone, a first article - under that name or another - is how a new part, a new tool or a moved process earns the right to run. In the AIAG world it slots into PPAP as the dimensional-results element; the discipline is identical.
Three forms, three questions
AS9102 splits the evidence into three forms, and the split survives because each answers a different question:
- Form 1 - what part is this? Part number, drawing and revision, the engineering changes embodied, whether this is a full or partial FAI and why, and the sign-off block. This is the accountability page: when a customer pulls the FAI in three years, Form 1 tells them exactly which definition of the part it certifies.
- Form 2 - what is it made of and how? Raw material with its specification and certificate reference, special processes - welding, heat treatment, plating, NDT - each with the spec it was performed to and who performed it, and any functional tests. The form that catches the uncertified weld before the customer's receiving inspector does.
- Form 3 - does it measure right? The characteristic accounting: every dimension and note from the drawing, numbered, with its requirement, the measured result, the instrument that measured it, and a pass/fail verdict per characteristic.
Number the characteristics on a copy of the drawing itself - ballooning, in the jargon - so anyone can trace row 14 of Form 3 to the exact dimension it reports. An FAI without a ballooned drawing is a list of numbers with no address.
The asymmetric tolerance trap
Here is where home-grown FAI sheets quietly fail. Real drawings do not deal only in ±. They say 8.0 +0.1/-0, because the hole may be a shade big but never small. They say 25.4 +0/-0.2. A measurement grid with a single "tolerance" column cannot represent these - so someone converts 8.0 +0.1/-0 into "8.05 ± 0.05" (and everyone downstream misreads the nominal), or worse, types ±0.1 and accepts parts at 7.95 that the drawing forbids.
A first article sheet needs three tolerance inputs - nominal, plus, minus - and a pass/fail that evaluates them separately. 8.0 measured at 7.98 with a +0.1/-0 tolerance is a FAIL, and the spreadsheet has to know it.
And the verdict logic must roll up without mercy: one failed characteristic makes the whole FAI a fail, and that overall disposition should flow to the cover form by formula, not by hope. A FAIL is not a disaster - it is a finding. Raise the NCR, reference it on the failed row, fix the process, and re-verify the failed characteristics. An FAI file that shows a caught failure, properly dispositioned, is more convincing to an auditor than a suspiciously perfect one.
When you have to do it again
An FAI certifies a snapshot: this part, this drawing revision, this process, this location. Change any of them and the certificate ages accordingly. A drawing revision, a new or reworked tool, a process moved to a different machine or site, a new special-process supplier, or a long production gap (AS9102 uses two years) all trigger a new FAI - but usually a partial one, covering only the characteristics the change could affect. Form 1 asks whether the FAI is full or partial and why; a well-reasoned partial FAI is standard practice, not a shortcut. What matters is that the reasoning is written down: which characteristics, why those, why not the rest.
One last habit: record the gauge ID against every measured row. It costs seconds during the inspection, and it is the difference between a shrug and an answer when a calibration failure later asks what that instrument touched.
The FAI that understands 8.0 +0.1/-0
The AS9102-style three-form structure in plain Excel: separate plus and minus tolerances, automatic per-characteristic pass/fail, an overall verdict that flows to the cover form, and a worked welded-bracket example with one deliberate FAIL dispositioned to an NCR.