US Patent 10961918 Reliable gearbox for gas turbine engine

An engine for an aircraft has an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox. The gearbox for an aircraft is arranged to receive an input from a core shaft and to output drive to a fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, a plurality of planet gears, a ring gear, and a planet carrier having a plurality of pins, each pin being arranged to have a planet gear of the plurality of planet gears mounted thereon. A ratio of planet carrier torsional stiffness to pin stiffness is within a specified range.