Understanding that machines and people cannot guarantee consistency of their performance and output is the point of in-process quality control. First Article Inspection (FAI) is conducted after the manufacturing system reaches ‘optimum stability’, not ‘perfect stability’ so further checks need to be made in order to ensure that any changes are both recognized and recorded.

It is important that standards are clearly specified from the beginning so that those conducting IPQC can know when production has reached a critical point and needs to be stopped and corrected.

If a problem is detected, all parts produced in the same batch must be quarantined and re checked 100%.