A fan blade (20) has a main body (28) extending between a leading edge (21) and a trailing edge (22). Channels (30) are formed into the main body (28) from at least one open side. A plurality of ribs (26) extend across the main body (28) intermediate the channels (30). The fan blade (20) has a dovetail (24) and an airfoil (18) extending radially outwardly from the dovetail (24). The channels (30) have a termination end (100) adjacent a radially inner end (42) of the ribs (26). The termination end (100) is formed along a complex fillet with a first radius of curvature (r 4 ) formed at the termination end (100), and a second radius of curvature (r 5 ) merging into sides (102) of the ribs (26). The second radius of curvature (r 5 ) is greater than the first radius of curvature (r 4 ).
