FAI requirement in AS9100 Rev D

Answer:
Clause 8.5.1.3, Production process verification, contains the requirements which are commonly referred to as First Article Inspection (FAI). The requirements are basically that you take a representative item from the first production run of a new or modified product and use it to prove that everything works (processes, documentation, tooling, etc).
While this is not identified as an optional process (where the standard says “as required”, you do have the ability to claim exclusion from this clause as you do with all clauses. So if the exclusion is that this is only applicable when required by customer, this is acceptable in AS9100.
For more on how FAI works, see the article: How does First Article Inspection fit into AS9100 Rev D?, https://advisera.com/9100academy/blog/2017/11/07/how-does-first-article-inspection-fit-into-as9100-rev-d/