Mechanical Systems, Externals, & Nacelles (MSEN) : The Mechanical Systems, Externals, and Nacelles Engineering organization is responsible for the design, development, and in-service support of power transmission systems, bearing compartment and rotor support design and analysis, oil and thermal management systems, engine externals packaging and architecture, as well as nacelles for commercial and military engine models. Technical disciplines include Project Engineering, Mechanical Design, Structural Analysis, Product Definition, System Modeling, Mechanical Design analysis for bearings, gears, and seals, and fluid-thermal modeling of associated components and systems.