Advanced Gearbox Technology in Small Turbo Propeller Engines

This paper discusses some of the difficulties encountered in designing lightweight durable gearboxes. The increasing demand for higher power versus lightweight and high durability has shown the necessity for optimization in all components. This could not be achieved without recourse to advanced Finite Element methods to correctly calculate contact loads between components and a proper understanding of the load paths through individual components. Also important is the need for very thorough calibration and subsequent testing of some of the complex empirical models needed to understand mechanisms that can cause fretting, bolt loads or creep between bearing races and shafts. Misalignments between shafts, particularly in causing moments through gear couplings must be accounted for not only in tooth sizing but also in assessing bearing lives.