Short answer: An engineering change order (ECO) is the approved, formal instruction to change a product: it names the parts, drawings and documents affected, the new revisions, and from when the change applies. It usually follows an engineering change request (ECR), which proposes the change, and is announced by an engineering change notice (ECN), which tells everyone affected that the change is approved. Terminology varies, and many companies use ECO and ECN for the same record.
ECR, ECO and ECN: three steps of one change
| Record | The question it answers | What it holds |
|---|---|---|
| Engineering change request (ECR) | Should we change this? | The problem, the proposed change, the reason and its urgency. Anyone can raise one: engineering, production, quality, service, a supplier or a customer. |
| Engineering change order (ECO) | What exactly changes, and from when? | The affected items, their old and new revisions, the effectivity, the disposition of existing stock and the approvals of the change board. |
| Engineering change notice (ECN) | Who needs to know? | The announcement of the approved change to manufacturing, purchasing, service, documentation and suppliers. |
Defense programs often call the proposal an engineering change proposal (ECP), and some plants use a manufacturing change order (MCO) for changes to the process rather than the design.
What an ECO contains
- A change number, a title and a description.
- The reason: a defect, a cost reduction, a supplier change, a regulation or a customer request.
- The affected items: parts, assemblies, drawings, bill-of-materials lines and software.
- The revision of each item before and after the change.
- The effectivity: the serial number, date, lot or configuration from which the change applies.
- The disposition of existing parts and work in progress: use as is, rework or scrap.
- The approvals, usually from a change control board.
- Attachments: marked-up drawings, analyses and test results.
The engineering change process, step by step
- Request. Someone raises an ECR with the problem and a proposed change.
- Assess. Engineering weighs the cost, the risk and the impact on parts, tooling, stock, suppliers, certification and documentation.
- Approve. A change control board accepts the change, rejects it or sends it back.
- Release. The ECO is issued with its effectivity, and the ECN goes out to everyone affected.
- Implement. PLM, ERP, production, purchasing and suppliers move to the new revision.
- Update the documentation. Manuals, work instructions, parts catalogs, training and translations follow the change.
- Verify and close. The change is checked in production and the ECO is closed.
Where engineering changes get lost
Step 6 is where most changes leak. An ECO lists the drawings and bill-of-materials lines it touches, but rarely the maintenance manual section, the work instruction, the parts catalog page or the training module that show the same part. Those documents live in other systems, owned by other teams.
Example: Engineering replaces the yellow coupling guard of a pump with a stainless-steel one. The drawing and the bill of materials are updated on the ECO. The maintenance manual, the parts list and the technician training also show the guard. Update only the manual, and a technician can still order the old guard.
This is the footprint of a change: every page that one engineering decision touches. See how TwinWorks maps the documentation an engineering change reaches, or read the guide to keeping technical documentation aligned with engineering changes.
FAQ
What is the difference between an ECO and an ECN?
An ECO defines and authorizes the change; an ECN tells the affected teams that the change is approved and when it takes effect. Some companies use the two terms for the same document.
What is the difference between an ECR and an ECO?
An ECR proposes a change and asks for it to be evaluated. An ECO is issued once the change is approved, and defines exactly what changes, in which items and from when.
What is effectivity in an engineering change?
Effectivity is the point from which a change applies: a serial number, a production date, a lot or a configuration. It tells manufacturing, service and documentation which units get the new design.
Who approves an engineering change order?
Usually a change control board (CCB) with engineering, manufacturing and quality, joined by purchasing, service or the customer where the change affects them. The board weighs cost, risk and impact before the ECO is released.
Does TwinWorks replace our ECO process?
No. Your engineering change process decides what changes in the product. TwinWorks starts from the changed part, tool or source and shows which documentation it reaches, so the documentation work follows the same change.
Related terms and pages
See every page one change touches
Name a changed part, tool or source, and TwinWorks shows the manual sections, reusable blocks and work instructions that reference it, for your experts to review.