AUDIT EVIDENCE

What makes objective evidence effective in an AS9100D audit?

Connect requirements, actual work and results so that an audit conclusion can be checked and traced.

Evidence must support a specific conclusion

A procedure, a completed record, an observation or a verifiable interview statement can contribute to an audit trail. The question is what each item demonstrates about the requirement and the activity being sampled. A large collection of files does not automatically establish conformity or process effectiveness.

A procedure describes the intended control. A completed record can show that an activity occurred. Observation and comparison with results help establish whether the control was applied as intended. Check agreement between these sources instead of treating one document as proof of an entire process.

Five practical tests for useful evidence

Traceability

Connect the evidence to the relevant order, lot, process, equipment, person and date. An inspection result without a link to the sampled product may not support its release decision.

Completeness

Follow the activity through its outcome. For corrective action, look beyond the problem description to containment, cause analysis, implementation and effectiveness review, as applicable.

Consistency

Compare the procedure, system entry, retained record, interview and physical condition. Investigate contradictions rather than selecting the most convenient record.

Time relevance

Check the revision, authorization and status applicable when the sampled work occurred. A current certificate alone may not establish the equipment's status at an earlier inspection date.

Decision relevance

Explain how the evidence supports the applicable criterion and the result being evaluated. Distinguish evidence of implementation from evidence of effectiveness.

Follow one order across the process

Start with the customer requirement and its review. Trace the applicable drawing and specification into planning, purchasing, production and inspection. Check how any nonconforming output was controlled, how release was authorized and how the records remain retrievable.

At each handoff, identify the input, responsible role, control, output and evidence reference. This reveals gaps between departments that a folder-by-folder review can miss. State the sample and its limitations; one satisfactory order does not prove every order is satisfactory.

A synthetic example: supplier performance review

Imagine an organization whose own procedure calls for an annual supplier review. The procedure establishes the planned frequency, but the audit also needs to examine the actual review, underlying quality and delivery data, decisions and follow-up actions. If performance deteriorated, check what changed in the controls or approval status.

The annual interval belongs to this example's internal procedure. It is not presented here as a universal AS9100D review interval.

Recognize evidence gaps

Blank forms: show a recording format, not completion of the activity.
Uncorroborated statements: identify leads to investigate; verify them against relevant observations or records.
Incomplete records: may leave the date, result, authority or closure basis unclear.
Conflicting information: requires investigation of the actual control and applicable revision.
Unrelated files: do not answer the sampled audit question, however extensive the file collection.

Build the evidence chain into daily work

Map each control to its record or system entry, preserve product and process traceability, and periodically check agreement across functions. Use the resulting evidence to understand trends and improve controls, rather than assembling a separate set of documents only when an audit approaches.

Requirement → Process → Control → Evidence → Result

Use this working model to write a testable audit question, choose a relevant sample and record the basis of the conclusion.

About this guide

An English editorial adaptation of our Chinese article, with independently written practical guidance and synthetic examples. It is not a clause-by-clause translation, an official interpretation or a substitute for the applicable standard, customer requirements and organizational procedures.

FROM KNOWLEDGE TO PRACTICE

Build a traceable audit trail

Start with the free Audit Evidence Starter Sheet to connect an audit question with its sample, evidence and conclusion. For a broader internal-audit workflow, explore the AS9100D Internal Audit & Objective Evidence Master Toolkit.

Use the free evidence sheet Explore the AS9100D Audit Toolkit

Independent professional toolkit · Editable Excel · English + Traditional Chinese

Prefer to study AS9100D first? AS9100D in Practice is a practical guide from requirements to objective evidence, published in Traditional Chinese.