US Patent 11840965 Aircraft engine

A gas turbine engine for an aircraft configured with an engine core that has a turbine, a compressor, and a core shaft connecting the turbine to the compressor. A fan located upstream of the engine core, that has a plurality of fan blades. A gearbox arranged to receive an input from the core shaft and to output to the fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox being an epicyclic gearbox having a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The gearbox having an overall gear mesh stiffness, and wherein the overall gear mesh stiffness of the gearbox is greater than or equal to 1.05×10