The concept of Decision Theatre (DT) is of great interest to leverage knowledge sharing in early stage design decision events. Yet, few contributions show how to configure a DT to support design space exploration and concept selection in cross-functional teams. This paper describes the development of a model-driven decision arena (MDDA) for aero-engine sub-system design. After presenting the descriptive study findings, it illustrates the overall logic of the MDDA environment and exemplifies its use in a case study related to the design of a turbine real structure (TRS) for commercial use.