Engineering Change Notice (ECN) / Change Request (CR)
An engineering change notice (ECN), or change notice, is a document which records or authorizes a change to a specific design. The reasons for the change should also be recorded.
Following sound engineering principles, control and documentation are necessary to ensure that changes are built upon a known foundation and approved by relevant authorities.
"[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".
An ECN must contain at least this information:
- Identification of what needs to be changed. This should include the part number and name of the component and reference to the drawings that show the component in detail or assembly.
- Reason(s) for the change.
- Description of the change. This includes a drawing of the component before and after the change. Generally, these drawings are only of the detail affected by the change.
- List of documents and departments affected by the change. The most important part of making a change is to see that all pertinent groups are notified and all documents updated.
- Approval of the change. As with the detail and assembly drawings, the changes must be approved by management.
- Instruction about when to introduce the change—immediately (scrapping current inventory), during the next production run, or at some other milestone.
A change request is declarative, i.e. it states what needs to be accomplished, but leaves out how the change should be carried out. Important elements of a change request are an ID, the customer (ID), the deadline (if applicable), an indication whether the change is required or optional, the change type (often chosen from a domain-specific ontology) and a change abstract, which is a piece of narrative (Keller, 2005). An example of a change request can be found in Figure 1 on the right.
Change requests typically originate from one of five sources:
- problem reports that identify bugs that must be fixed, which forms the most common source
- system enhancement requests from users
- events in the development of other systems
- changes in underlying structure and or standards (e.g. in software development this could be a new operating system)
- demands from senior management (Dennis, Wixom & Tegarden, 2002).
Additionally, in Project Management, change requests may also originate from an unclear understanding of the goals and the objectives of the project.