Engineering Change Management: ECR, ECO and ECN

Short answer

Engineering change management is the controlled process for proposing, evaluating, approving and implementing changes to released product data. It typically runs in three steps: an engineering change request (ECR) raises the issue, an engineering change order (ECO) authorises and executes the change, and an engineering change notice (ECN) informs affected teams, plants and suppliers.

Key takeaways

An ECR describes a problem or proposal, an ECO authorises specific changes to specific objects, and an ECN communicates the result.
Impact analysis across BOMs, documents, stock and suppliers is the step that most often fails without PLM.
Effectivity, by date, serial number or lot, defines when a change becomes active in production.
Track cycle time, backlog and post-release rework to see whether the process works.

Why is change control necessary?

Once a design is released, other teams act on it. Purchasing orders parts, plants build, suppliers tool up and service stocks spares. An uncontrolled change leaves some of them working from old data, which produces scrap, wrong orders and field issues. Regulated sectors make control mandatory. The FDA Quality Management System Regulation, effective 2 February 2026, incorporates ISO 13485:2016 by reference, including design change control. Aerospace suppliers work to AS9100, and automotive suppliers to IATF 16949, both of which require documented change control.

ECR, ECO and ECN explained

Object	Purpose	Typical content	Who acts
ECR (request)	Raise a problem or improvement	Description, reason, affected items, urgency, attachments	Anyone: engineering, quality, service, supplier
ECO (order)	Authorise and execute the change	Affected items with old and new revisions, redlines, effectivity, disposition	Engineering, change board
ECN (notice)	Communicate the released change	Summary, effective date, actions per recipient	Plants, purchasing, suppliers, service

Terminology varies. Some companies use ECR and ECO only, others add a problem report (PR) before the ECR or a deviation for temporary changes. Several ECRs can be combined into one ECO. The concept follows configuration management principles described in ISO 10007.

The change process step by step

Raise. A quality engineer reports cracked housings from a supplier lot and creates an ECR.
Triage. The change analyst checks for duplicates, assigns priority and links affected items.
Impact analysis. PLM shows where-used results across products, MBOMs per plant, open purchase orders, stock in hand, documents and service kits.
Decide. The change control board (CCB) approves, rejects or defers. Fast-track routes handle low-risk changes, such as documentation corrections.
Execute. Engineers revise CAD, drawings and BOMs under the ECO.
Release. The ECO is approved and new revisions become released, with effectivity.
Notify and implement. The ECN goes to plants and suppliers, and ERP receives the new revision.
Verify. First articles or audits confirm the change was implemented as intended.

What is effectivity?

Effectivity defines when a change takes effect:

Date effectivity: the new revision is used from a set date.
Serial effectivity: from a specific unit serial number, common in aerospace and machinery.
Lot effectivity: from a specific production lot, common in process industries.

Disposition instructions tell each team what to do with existing stock: use as is, rework, return to supplier or scrap. Effectivity and disposition are the main data that move from PLM to ERP, as described in PLM vs ERP.

How PLM systems support change

Most PLM platforms provide configurable change workflows, redlining, where-used analysis and electronic signatures. Examples include PTC Windchill, Arena and Propel. Smaller teams often prefer simple preconfigured workflows. Complex multi-site companies need parallel approvals, conditional routing and plant-specific tasks. Test these with your own scenarios in scripted vendor demos.

AI features are appearing in this area. Examples include suggesting affected items from similar past changes or drafting change summaries. Treat them as decision support and keep human approval, as discussed in AI in PLM. Supplier participation matters too. Portals that let suppliers acknowledge an ECN and confirm their implementation date close the loop that email leaves open.

Metrics that show whether change control works

Change cycle time: median days from ECR to release, split by priority. Simple changes often take more than 30 days in paper-based processes (estimate).
Backlog: open ECRs and ECOs by age.
First-pass yield: share of ECOs released without rework or rejection.
Post-release corrections: changes needed to fix a previous change.
Notification lag: days between release and ERP or supplier confirmation.

Publish these monthly to the change board, together with the five oldest open changes and their blocking reason. Long cycle times usually point to unclear ownership or overloaded boards. Fix the process design first, then automate it. Common fixes include clear criteria for fast-track changes, a single change analyst role per product line, and weekly board meetings with a fixed agenda instead of ad hoc approvals by email. Change management is also the backbone of the digital thread, since every link between data objects needs a controlled history.

Frequently asked questions

What is the difference between an ECR and an ECO?

An ECR (engineering change request) describes a problem or proposed improvement and asks for evaluation. It does not authorise any change. An ECO (engineering change order) is the approved instruction to change specific items, documents and BOMs, with new revisions, effectivity and disposition. One ECO can address several ECRs, and an ECR can be rejected without an ECO ever being created.

Who sits on a change control board?

A change control board usually includes representatives from engineering, manufacturing, quality, purchasing and often service or regulatory affairs. Larger companies may have separate boards per product line, with an escalation board for high-cost or safety-related changes. The board decides on approval, priority and effectivity. Low-risk changes can follow a fast-track route with fewer approvers.

What is a deviation or waiver?

A deviation is a temporary, approved departure from the released definition for a limited quantity, lot or period, for example using an alternative material during a shortage. It does not change the released design. A waiver typically accepts product already made outside specification. Both are recorded in PLM or QMS with approvals, so the history of each delivered unit stays traceable.

Sources

Reviewed 16 October 2026 by the PLM Vendors editorial team. Regulatory dates and vendor details change; check the sources for the latest position.