An Engineering Change Proposal (ECP) is a formal request to modify a contract deliverable's design, configuration, or technical requirements after the baseline has been established. ECPs are most common on hardware development, weapons systems, and other configuration-managed acquisitions where a controlled baseline must be maintained throughout the program lifecycle.
Each ECP follows a structured review and approval process involving the contractor, the contracting officer, and technical stakeholders such as the program manager and configuration control board. The ECP package documents the proposed change, its justification, cost and schedule impact, and implementation plan. Class I ECPs affect form, fit, function, or interface and require government approval; Class II ECPs are minor and may be approved at the contractor level depending on the contract terms.
For service contracts, the equivalent mechanism is typically a contract modification under FAR Part 43 — a more flexible instrument that doesn't carry the configuration management overhead of an ECP. Contractors should understand the change-control mechanism specified in their contract before the work begins, because the wrong path — submitting a contract modification when an ECP is required, or vice versa — can delay approval and create cost recovery risk if work proceeds before authorization.