Gearbox and a geared gas turbine engine

A gas turbine engine for an aircraft comprising:

• an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor;
• a fan located upstream of the engine core, the fan comprising a plurality of fan blades;
• and
• a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, wherein:
• the gearbox comprising a sun gear, a plurality of planet gears, an annulus gear and a planet carrier, the sun gear meshing with the planet gears and the planet gears meshing with the annulus gear, the planet carrier comprising a first ring, a second ring spaced axially from the first ring, a plurality of circumferentially spaced axles extending axially between the first ring and the second ring and a plurality of circumferentially spaced support structures extending axially between the first ring and the second ring, each planet gear being rotatably mounted on a respective one of the axles, each support structure being arranged circumferentially between two planet gears, the first ring has a plurality of circumferentially spaced recesses in a surface facing the second ring, the second ring has a plurality of circumferentially spaced recesses in a surface facing the first ring, each recess in the second ring being aligned circumferentially and radially with a corresponding one of the recesses in the first ring, a first axial end of each support structure locating in a respective one of the recesses in the first ring, a second axial end of each support structure locating in a respective one of the recesses in the second ring, each support structure being secured to the first ring and the second ring, each support structure is secured to the first ring and the second ring by at least one fastener extending axially through the support structure, each support structure has one or more internal passages for the supply of lubricant to the planet gears and/or the sun gear of the gearbox and one or more internal passages for the collection of lubricant from the planet gears and/or the sun gear of the gearbox, each support structure comprising fused/sintered powdered material and the support structures are manufactured by additive layer manufacturing.