Hollow fan blade tuning using distinct filler materials and method of designing such a fan blade

A fan blade (20) comprises a main body extending between a leading edge (21) and a trailing edge (22). Channels (30) are formed into the main body, with a plurality of ribs (26) extending intermediate the channels (30). The fan blade (20) has a dovetail (24), and an airfoil (18) extending radially outwardly from the dovetail (24). Material is deposited within the channels (30), with a first type of material (102) being selected to provide additional stiffness to the fan blade (20), and a second type of material (104) being selected for having good damping characteristics. A method and gas turbine engine (210) are also disclosed.