An innovative structural Boundary Element Method (BEM) Solver is developed for interfacing the Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD) grids. Formulated as a solid mechanics problem with a minimum strain energy requirement, the BEM Solver generates a truly three dimensional (3-D) Universal Spline Matrix. The Universal Spline Matrix is a vector operator which includes the coupling of displacements and forces along all axes. Based on a similar formulation, an Exterior BEM solver is also developed to account for the flow grid deformation. Thus the BEM solver allows a unified treatment of the displacement and force transformation for CFD/CSD interfacing as well as the computation of the flow field grid deformation. The solution procedure is fully automated and requires no further user interaction, therefore it is ideally suitable for Computational Aeroelasticity (CAE) and Multidisciplinary Optimization (MDO) applications.