This manuscript presents a novel framework, the Multidimensional Design Assessment Model, which encompasses a multi-criteria approach to efficiency, eco-efficiency and costs assessment for a given design system in aeronautical industry production. The framework is established by adopting Design-for-X and Multi-Layer Stream Mapping approaches, based on Lean Thinking, for efficiency assessment and adopting modules of ecoPROSYS to eco-efficiency assessment. A real case study from aeronautical sector is given to demonstrate the approach, for the assembly of aircraft structure Horizontal Tale Plane, where different results are presented and discussed for each dimension of analysis and how improvement strategies can be designed.