Factory acceptance testing is a key checkpoint. Its value comes from testing against an agreed baseline and retaining enough evidence to explain the result.
Before FAT: agree what a pass means.
Review the test plan, equipment readiness, sampling or coverage, instrument calibration and the status of earlier findings. Identify the agreed requirements and acceptance criteria that will be used for evaluation.
If the methods, conditions or data requirements are still unclear, resolve them before testing. Otherwise, the test day can become a negotiation over what should have been agreed earlier.
During FAT: connect observations to original data.
Witness the agreed tests and independently record observations. Examine the original records, the equipment identifiers and the actual test conditions. Review discrepancies against the project requirements and technical and quality annex.
A headline result is easier to evaluate when the underlying record shows what was tested, under which conditions, with which instruments and against which criteria.
Before release: make the exceptions visible.
Track clarification, correction and retesting. The report should identify the verified configuration, test scope, deviations, outstanding actions and the evidence supporting the recommendation.
- Release: evidence supports the agreed release conditions.
- Conditional release: only where the project contract and buyer permit it, with explicit actions and responsibilities.
- Hold: required conformity or evidence remains unresolved.
FAT complements production control.
Final testing cannot recreate every manufacturing step. Critical process checks should take place while the relevant materials and assemblies are still accessible, with the records retained for later review.
The useful output
A FAT witnessing and release recommendation report connecting the test process, original data, results, deviations, open issues and retest requirements. The buyer retains the final decision under the agreed project terms.