Low Maintenance Helicopter Tail Driveshaft Hanger Bearing

A high-performance, stainless bearing steel is needed to reduce maintenance inspection intervals and increase life of MH-60S hanger bearings operating in a corrosive environment. Available bearing alloys such as 440C, Pyrowear 675, etc. provide some level of corrosion resistance, but ultimately, corrosion resistance is compromised due to suboptimal case carburized microstructure, low matrix chromium content, low pitting resistance, and use of large Cr-rich primary carbides as strengthening mechanisms. QuesTek Innovations LLC proposes to evaluate alternate bearing materials to 440C for use in corrosive environments. Using a systems design approach, the materials will be selected based on anticipated corrosion and wear resistance. In addition to potential alloys available, QuesTek is currently working on a developmental alloy that meets the materials substitution requirements. Upon material down selection of candidate alloys with the TPOC, laboratory corrosion (via salt fog chamber) and wear testing (via pin-on-disc) will be completed to determine the most suitable replacement material for 440C. In addition to a material replacement, QuesTek will work to evaluate the need for potential redesign of the hanger bearing assembly due to debris entry. If required, a component redesign will be completed in the Phase II when demonstration components will be manufactured and bench tested.