Fan

A fan for a gas turbine engine, the fan comprising a hub and an annular array of fan blades mounted to the hub and extending radially outwardly from the hub, each of the fan blades comprises a blade root,

• the hub comprises a plurality of hub grooves having a shape complimentary to the shape of the blade root and each hub groove receives and radially retains one blade root;
• a slot is provided on each of the suction side and the pressure side of each blade root,
• a plurality of keys are provided, each key engages with the slots in one blade root and with the corresponding hub groove so as to axially retain the fan blade,
• wherein the key comprises two arms and a joining member, the two arms are received in the slots provided on the blade root and the joining member extends between the two arms,
• and wherein an interface is defined between the key arms and the slots in the blade root, and a greater or equal percentage of the interface is curved than is planar.