The developed thesis work derives from an internship with TPS S.p.a company, in Turin. TPS S.p.a is a leader company in aeronautical field providing support for design and certification of aeronautical products and parts. Through this work, I have been able to familiarize with DOA concept and aspects related to certification process and demonstrability of capability for design. The thesis consists of two parts. The first part aims to complete and refine the model about main rotor blade, developed by previous students theses, on which the new tip is supposed to be assembled. Specially, the MATLAB ^® codes are added related to obtain the natural frequencies and the shape mode about edgewise and torsional axes.