Wire harness supplier audit checklist

Before the visit

• Verify the credentials first. Check quality certificates, registrations and exclusions in their independent records. See how to verify supplier certifications.
• Ask for the quality manual or a summary of procedures, and the organization chart for quality.
• Send a representative part or drawing, so the audit can follow something like your work through the shop.
• Agree the scope. Which site, which processes, and whether controlled technical data will be discussed. If it will, confirm who is allowed to see it.

Document and configuration control

• How does a customer drawing arrive, get reviewed and get released to the floor?
• Can the auditor pick a traveler on the floor and see that it references the current drawing revision?
• How are superseded drawings removed from use?
• How are customer-approved deviations and alternates recorded?
• Are export-controlled drawings marked, stored and accessed according to a written procedure?

Purchasing and receiving

• Are connectors, contacts and wire bought from the manufacturer or its authorized distributors? What is the process when a part is only available elsewhere?
• Is there a counterfeit parts avoidance procedure, for defense and aerospace work?
• Are certificates of conformance checked at receiving and kept?
• Are lot or date codes recorded so they can be traced to finished assemblies?
• Is moisture-sensitive or shelf-life-limited material (some adhesives, potting compounds, heat shrink) controlled?
• How is nonconforming material identified and segregated?

Wire processing and termination

• Are cut lengths and strip lengths set from the drawing and verified at set-up?
• Is there a written crimp set-up approval with height checks and pull tests? See crimp pull testing.
• Are applicators and hand tools identified, verified and matched to approved terminals?
• Are soldering stations controlled for temperature, and are solderers trained to the relevant standard?
• Is stripping checked for nicked or cut strands?

Assembly

• Are formboards built to the current drawing, and checked after a revision?
• Are work instructions visual and at the point of use?
• Are insertion tools and extraction tools the ones specified by the connector maker?
• How is contact retention confirmed after insertion?
• Is there control over foreign object debris, especially for aerospace work?
• Is ESD protection used where the assembly contains sensitive components?

People

• How many operators and inspectors hold current IPC/WHMA-A-620 certificates, and at what level? Ask to see the list with expiry dates.
• Is there a training matrix showing who is qualified for which process?
• How are new operators supervised until qualified?

Test and inspection

• What electrical tester is used, and is its calibration current? See cable assembly testing.
• How are test programs created and checked against the drawing?
• Is there a daily check that the tester and fixtures detect a known fault?
• Are visual inspections done by someone other than the builder?
• Are inspection records kept per serial number or lot?
• Are measuring tools, including crimp micrometers and pull testers, in a calibration system?

Corrective action and improvement

• Ask for a recent corrective action, and follow it: root cause, containment, fix, and check that it worked.
• Are process indicators and rework rates tracked?
• How are customer complaints logged and answered, and in what time?
• When did the supplier last audit its own processes, and what did it find?

Shipping and records

• Is packaging defined per part, including ESD bags, coiling and labeling?
• What goes with each shipment: certificate of conformance, test records, first article report?
• How long are quality records kept, and can they be retrieved by serial number?

Scoring the audit

A simple scale works: in place and working, in place but not consistently followed, or not in place. Weight the items that protect your part most: crimp control, test coverage, configuration control and traceability. A written procedure that the floor does not follow counts as a finding, not a pass.

Red flags on a visit

• Drawings on the floor with no revision letter, or with a different revision from the traveler.
• Unlabeled applicators, or hand tools shared between contact types with no settings recorded.
• Test fixtures with no identification, or a tester whose calibration has lapsed.
• Nonconforming parts mixed with good parts.
• Records that exist only as "we can get that for you later".

Remote audits

When a visit is not practical, a video walk-through with the camera on the floor, plus sample records shared in advance, can cover much of this list. Ask to see live screens rather than screenshots, and ask for a traveler to be picked at random during the call.

Common questions

Do I need to audit a supplier that is AS9100 certified?

Certification means a third party audited the quality system. It does not check your part's specific requirements, so many aerospace buyers still perform their own audit or a first article review before approving a supplier.

How long does a harness supplier audit take?

For a small or mid-size shop, a focused audit often fits in a single day on site. Allow time to follow a real job through the process.

What is the most common finding?

Practices vary, but gaps between written procedures and what happens on the floor, such as crimp set-up checks that are skipped or not recorded, are frequent findings in harness shops.

Next steps: choosing a manufacturer and the RFQ checklist.