First article inspection is the moment three parties agree on a part: the design, the process and the acceptance criteria. Done early, it is the cheapest quality control there is.
First article inspection is a full measurement of a new or revised part against its drawing before series production is released. It typically runs for a new part, a revised drawing, a change of process or machine, or when a customer's quality plan requires it.
The report is submitted as a formal record. If a dimension is outside tolerance or a requirement cannot be met as drawn, it is raised and resolved before series release — not discovered later. Once accepted, the part is released and series production repeats the agreed process and inspection plan.
Without FAI, a design or process issue surfaces at volume, where it costs a batch, a rework loop and a schedule. With FAI, the same issue surfaces on one part. The inspection is not overhead — it is the cheapest possible place to be wrong.