Engineering Change Order (ECO): Template and Process

ECR vs ECO vs ECN

Terms vary: some companies call the whole process an ECN. The Wikipedia summary describes an ECO as something that "is an artifact used to implement changes to components or end products" (Wikipedia). It also quotes a configuration-management definition: a "document approved by the design activity that describes and authorizes the implementation of an engineering change to the product and its approved configuration documentation". In federal contracting, the design activity is "an organization, Government or contractor, that has responsibility for the design and configuration of an item" (FAR 46.101). The most common split is below.

ECO template: the fields to include

Download the engineering change order template (CSV); it opens in Excel or Google Sheets and includes one filled-in row. The fields:

Filled-in ECO example: a dimension change that ripples (illustrative)

An illustrative example, not a real company record. NCRs show the hole on a bracket is hard to hold in tolerance and the mating panel has slack, so engineering widens the tolerance.

See the matching NCR in the NCR template examples.

The engineering change process: routing and the change board

Route each ECO by its class. A minor change that touches one drawing can go to engineering and quality. A change to form, fit or function, to a safety-related part, or to anything a customer has approved goes to a change control board (CCB): engineering, quality, manufacturing, purchasing and service, with the customer where the contract requires.

Aviation has a defined split. A type-design change is "minor" if it "has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product", and every other change is a major change (14 CFR 21.93). FAA production approval holders also need procedures "for controlling design data and subsequent changes to ensure that only current, correct, and approved data is used" (14 CFR 21.137).

Revision control: keeping drawings traceable

Each released ECO should produce new revisions of every affected document, and each revision block should name the ECO. In the US the common reference is ASME Y14.35, now titled "Revision of Engineering Product Definition Datasets and Associated Documents". ASME describes it this way: "This Standard defines the practices for revising drawings and associated documents and establishes methods for identification and recording revisions." Buy the standard for the rules on revision letters and records.

The same discipline applies to documents beyond drawings. FAA production approval holders must control "quality system documents and data and subsequent changes to ensure that only current, correct, and approved documents and data are used" (14 CFR 21.137). In a PDM or PLM system (SolidWorks PDM, Vault, Windchill, Teamcenter), run the ECO as a workflow so the release of new revisions and the ECO approval happen together.

Linking ECOs to NCRs and test results

Many ECOs exist because of quality problems: a tolerance nobody can hold, a material that cracks, a part that fails a test. Record the NCR, CAPA or 8D number on the ECO, and the ECO number back on the corrective action. Attach the verification test results to the ECO itself.

That two-way link is what lets an engineer, years later, see why a dimension is what it is, and stops the next person from tightening it back.

Common ECO mistakes

Most ECO problems are missing information, not wrong engineering.

• Affected documents incomplete: the drawing changes but the inspection plan, BOM or work instruction does not.
• No effectivity, so production builds a mix of old and new.
• Existing stock and open purchase orders forgotten.
• Reason field left as "update" with no link to the NCR, customer request or cost study.
• Revision letters raised without naming the ECO, so the history cannot be reconstructed.
• Changes made in the CAD model without an ECO, then discovered at the next release.
• Customer approval skipped on a change the contract classes as major.

Where the change history sits in common PDM and PLM systems

When an ECO process runs inside a PDM or PLM system, the change records and their reasons can be kept next to the revised files, so exporting them is part of exporting the design. The system guides cover each one in detail:

If ECOs were kept in spreadsheets or email instead, export them with their numbers so each change can still be matched to the drawing revision it produced.

Your change history is also a data asset

A long ECO history, with each revision of the model and drawing tied to the reason, the NCRs behind it and the test that verified it, shows how a design actually evolved. That is the part of engineering knowledge that never appears in a finished drawing.

AI developers building tools for quality and engineering work ask for this kind of linked, outcome-bearing history; where a license is agreed, it is de-identified and under written terms. Customer-owned drawings, export-controlled technical data and personal details stay out (see the export-control checklist and how to de-identify records). The guide for engineered-product manufacturers covers what is in scope and who signs; licensing CAD and engineering data covers the design side.

If your company keeps years of quality and engineering change records, the guide for engineered-product manufacturers explains what AI developers ask for and who signs. To see what yours could be worth, describe them in six questions; no files or system access needed.