The objective of this document is to present the methodology used to verify the structural integrity of a redesigned composite part. While shifting the manufacturing process of a composite part from pre-impregnated to a liquid resin injection process, the Composites Development team at Bombardier Aerospace had to redesign the component to a new set of design allowables. The Integrated Product Development Team (IPDT) was able to quickly provide a turnkey solution that assessed three aspects of airframe engineering: Design, Materials & Processes (M&P) and Stress. The focus of this paper will be the stress substantiation process led by the Stress Engineers. It will also bring up the synergies with M&P that are unique to the IPDT approach.The stress substantiation process required three distinct checks be confirmed. These were that the global behavior of the surrounding structure remained unaffected, that all local failure modes still exhibited positive margins of safety, and finally to organize detail level testing to provide complete substantiation for the certification authorities.The paper also exposes how this method was used successfully on components of programs currently under development at Bombardier Aerospace. The IPDT approach as well as the novel mean of substantiation allowed for a quick turnaround. This resulted in the rapid preparation of a positive business case for both weight and cost.