Material certificate

That the material is what was specified, traceable to a heat

Batch record

Which run, on which machine, with which tool changes

First and last piece

Measured, because they bracket the run

Thread gauging record

Which class, which gauge, and when it was calibrated

Coating certificate

That the finish is what was specified, and how thick

Inspection record

That a defined sample was measured against a written method

Revision statement

Which drawing revision the batch was made to

Retained sample

A piece kept from the batch, for as long as agreed

An illustrative list for a fictional range. A real programme agrees which documents are required, in what form, and how long they are retained.

The one that is most often missing.

The first and last piece measurements. A report that samples the middle of a run describes the run at its most stable, which is the least useful moment to measure.

Retention is part of the specification.

A retained sample discarded after a year is a sample that will not exist when the question is asked, and for a part in service the question is usually asked years later.