Engineering change impact checklist

Why changes go wrong

Most engineering changes that cause trouble were approved correctly. The drawing was updated and signed. What went wrong was something nobody connected to the change: the control plan still checked the old tolerance, the machine still ran the old program, the gauge could not resolve the new limit, 800 old-revision parts sat in finished goods, or the customer was never told. The change was right; the implementation was incomplete.

This checklist is for that second part. It lists every document, plan, program, record and stock location the change could touch, and asks for a yes or a no on each, an owner, the date it was updated and the date someone else checked it.

Configuration management

Configuration management is the discipline of knowing, at any time, exactly what a product is made to: which drawing revision, which specification, which software version, which bill of materials. It has four parts:

• Identification: each configuration item (drawing, specification, program, part) has a unique number and revision.
• Change control: a change is proposed, its impact assessed, and it is approved before it is made. This tool covers the impact assessment and the follow-through.
• Status accounting: a record of which revision is current and which units were built to which.
• Audit: a check that the product as built matches its documents.

Document control keeps the right revision at the point of use. Configuration management goes further: it keeps the whole set of documents, programs and parts consistent with each other.

Effectivity and interchangeability

Effectivity is the point from which the change applies: a date, a serial number or a lot. Date effectivity is simple but blurs when stock is built ahead. Serial or lot effectivity is precise, and is what makes a later recall or field action small. Either way, the new revision must be identifiable on the part or its paperwork.

Interchangeability decides what can happen to old stock. If old and new parts are fully interchangeable, old stock can usually be used up. If the change is one-way, new parts can replace old in service but not the reverse. If they are not interchangeable at all, old and new must never be mixed in an assembly or a shipment, and old stock is reworked, scrapped or kept only for older products.

Reading the checks

• Not assessed is the dangerous status. "No" with a reason is a decision; a blank is an oversight waiting to happen.
• Updated, not verified means a new revision exists but nobody has confirmed it is correct and in use on the floor.
• Items due after the effective date mean production will start on the new revision before everything is ready.
• A major change (form, fit, function, safety or regulation) usually needs the FMEA and control plan reviewed, and often customer approval before it is made.

For a change that also needs people to change how they work, pair this with the change management plan. For the control plan itself, use the control plan tool.

On the exam

CQPA I.B.6 asks you to identify the elements of document control systems, including configuration management. CQE II.B.2 asks you to evaluate configuration management, maintenance and document control, and CQE IV.B.1 covers material identification, status and traceability, which is what effectivity and stock disposition depend on. CSQP IV.C.2 includes updating the FMEA and control plan and product or process design change with a supplier, and CSQP V.A.3 covers change requests and notifications. CMDA III.D.2 covers design changes, and III.D.3 the document and change control system.

Other tools and templates