Engineering change request process flowchart (ECR to ECN)
An engineering change request process flowchart: ECR justification, form, fit and function assessment, change board approval, ECN, effectivity and old stock.
How it works
Rename the lanes to your real roles
Replace Requester, Engineering, Change control board, Manufacturing and Supply chain with the functions you actually have. In a smaller organisation the change control board may be two people meeting weekly, and manufacturing engineering and production planning may be one lane. Merge lanes rather than inventing roles, and keep the total at or below five so the chart stays readable.
Define what makes an ECR complete
The screening decision only works if "complete and justified" means something written down. A workable minimum: affected part numbers and their current revisions, the reason (defect, cost reduction, customer request, supplier or component obsolescence, safety or regulatory), the evidence behind it, the urgency, and whether the change touches anything safety-related or a customer-approved characteristic.
Write down your form, fit and function test
The assessment step decides whether the changed part is still interchangeable with the old one. Record your rule for what that means and what follows from it, since a non-interchangeable change normally needs a new part number rather than a new revision of the existing one. Configuration management practice keys this to interchangeability, not to how large the change looks.
Make the cost assessment cover every location of old stock
Give the supply chain step a checklist: on-hand stock, work in progress, goods in transit, open purchase orders and supplier commitments, finished goods, consignment stock and service spares. Obsolescence is the cost most change requests underestimate, and it is usually what turns an obviously good change into a deferred one.
Set the effectivity and disposition rules
Decide whether effectivity is expressed as a date, a serial or lot number, or the point old stock runs out, and put the choice on the ECN rather than leaving it to whoever schedules the works order. Then agree who authorises use up, rework and scrap, and where the cost of each is booked.
Define what first article verification means and publish the chart
Say who builds the first article, who inspects it, which characteristics are checked and who signs it off; in aerospace this is governed by AS9102, where a design change normally triggers at least a partial first article inspection. Then share the diagram next to the ECR form, and keep earlier versions so you can show when the procedure changed and why.
Frequently asked questions
What is the difference between an ECR, an ECN and an ECO?
An engineering change request is the proposal: what is wrong or could be better, why it matters, and which parts it touches. It is a question put to the change control board. An engineering change notice is the answer, issued only after approval: it authorises the new revision, lists the drawings, part numbers and BOMs affected, sets the effectivity point and states the disposition of existing stock. Engineering change order (ECO) is used interchangeably with ECN in many organisations, and some use ECO for the internal work instruction and ECN for the notification sent to customers and suppliers. Pick one convention and define it in your procedure, because mixed usage in the same company causes real confusion about what has actually been authorised.
How is this different from IT change management or a general change control process?
The shape is similar (request, assess, approve, implement, verify) but the content is not. IT change management moves a change into a live service, so the assessment is about affected services, downtime windows, rollback plans and blast radius, and it is normally run by a change manager and a CAB. An engineering change moves a revision into a physical product, so the assessment is about interchangeability, tooling, cost, supplier lead time and what to do with stock built to the old revision, and it is normally run by a change control board that includes engineering, manufacturing and supply chain. If you are documenting how code or infrastructure reaches production, use the IT change management or change control templates instead.
When does a change need a new part number rather than a new revision?
The usual test is interchangeability. If a part built to the new definition can replace an old one in every application without any other change, and the old one can replace the new one, it is a revision. If it cannot, because form, fit or function has moved, it normally needs a new part number so that both versions can coexist in stock, in BOMs and in service. Configuration management practice and drawing revision standards build this rule on interchangeability rather than on how large the change appears, which is why the form, fit and function assessment sits before the board decision in this chart rather than after it.
What happens to stock already built to the old revision?
That is the "Disposition of existing stock?" decision, and it needs an explicit answer on the ECN rather than an assumption. Use up means old stock is consumed first and effectivity is set at the run-out point, which is the cheapest option and the wrong one if the change fixes a defect or a safety issue. Rework means existing stock is brought up to the new revision, with the cost and the labour booked against the change. Scrap means the stock is written off. The same question applies to work in progress, goods in transit, stock held at suppliers and, for a safety-related change, units already with customers, which may pull the change into a field action rather than a routine ECN.
Who should sit on the change control board, and does every change need one?
The board needs whoever can commit the money and the capacity: engineering, manufacturing or industrialisation, supply chain or purchasing, and quality, with sales or programme management involved when a change is visible to a customer. It does not need everybody. Most organisations set a threshold so that low-risk changes (a drawing note, a tolerance clarification, a change with no cost or interchangeability impact) are approved by a named engineering authority, and only changes above that threshold go to the full board. Write the threshold next to the approval decision, and record the deferred decisions as carefully as the approvals, because a deferred change usually returns once the blocking stock or contract clears.