Main Rotor Weight Reduction and Performance Enhancement via the use of Carburized, High-Strength, Secondary Hardening Steel

Main rotor shafts, specifically those used on the CH-47, are among the largest, heaviest, and highly loaded single components on rotorcraft. As the materials technology used in these shafts are decades old, (carburized 9310) there exists an opportunity to redesign the component with state-of-the-art materials technology and reduce component weight 20-25%. Carburizing alloys available today may also provide benefits in thermal resistance, ballistic performance, and stress-corrosion cracking resistance; meaning a technology upgrade holds promise for both weight reduction and performance enhancement. QuesTek’s Materials by Design® technology has been used to design Ferrium® C61, which has a high-strength / high-toughness core to allow for weight reduction or increased power density of components compared to that of 9310. C61 is currently used to make V091 ring and pinions in transmissions for SCORE® 1600 class off-road racing cars. This alloy may represent a substantial weight-savings opportunity for the main rotor shaft on the CH-47 without requiring significant changes in the production process of the component. Other materials technologies using high strength steels may require weld zones, and titanium-based solutions would necessarily increase the design envelope and would likely not be backwards compatible with previous designs. A carburizing steel with high strength, load bearing capability offers the best solution for enhanced performance and lower weight at reasonable cost.