Helical Face Gear Development under the Enhanced Rotorcraft Drive System Program

U.S. Army goals for the Enhanced Rotorcraft Drive System Program are to achieve a 40% increase in horsepower to weight ratio, a 15dB reduction in drive system generated noise, 30% reduction in drive system operating, support, and acquisition cost, and 75% automatic detection of critical mechanical component failures. Boeing's technology transition goals are that the operational endurance level of the helical face gearing and related split-torque designs be validated to a TRL 6, and that analytical and manufacturing tools be validated. Helical face gear technology is being developed in this project to augment, and transition into, a Boeing AH-64 Block III split torque face gear main transmission stage, to yield increased power density and reduce noise. To date, helical face gear manufacturing grinding development on Northstar's new face gear grinding machine and pattern-development tests at the NASA Glenn / U.S Army Research Laboratory have been completed and are described.