In recent years, our group has accumulated a wealth of experience in the development of surfaces for polyatomic systems based on valence bond functions augmented with molecular mechanic terms, VB-MM. This type of surfaces presents some advantages with respect to other strategies: a) capability to describe the reaction based on physically intuitive terms associated with familiar nuclear motions (stretching, bending, torsion, etc.); b) transferability of the adjustable parameters from a previous surface to a new one; c) easy refit to fine-tune the PES using new ab initio data at selected points; d) capability to reproduce zones of the reaction that were not included in the fit, due to the flexibility of the functional forms to represent the nuclear motions and e) lower computational demand. For the title reaction, the full-dimensional PES was developed based on recent research on the CN + CH4 reaction and the OH + C2H6 reaction. From the former, we reused the parameters describing CN stretching for the reactant and the stretching and bending modes in the HCN product. From the latter, we reused the parameters describing the ethane molecule in reactants and the ethyl radical in products.