The key objective of this topic is to provide innovative design criteria for designing power gearboxes planet bearings in terms of base material, geometry and heat treatment, including residual stress profile. Minimal crack(s) may appear and/or develop beneath the raceway of the roller (cracks so small that are impossible to detect via Health Monitoring techniques in the driveline). Considering the presence of these defects, guidelines and best practices on optimal enhancement of the strength of the component as well as on the maximization of its reliability in service, shall be developed, to be applied in the early stage of the design and allowing for a robust design optimization. The applicant(s) shall build a comprehensive methodology for component sizing and required compressive stress field (produced by the hardening), confirming the results via a crack growth numerical analyses and by base material / rotating component tests with induced defects. Please refer to the full topic descriptions document published in this call.