An airfoil assembly (160; 260) for a gas turbine engine comprising: an airfoil (164; 264) including an airfoil section (168; 268) extending from a root section (170; 270), the airfoil section (168; 268) extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip portion and the root section (170; 270) in a radial direction, and the airfoil section (168; 268) defining a pressure side and a suction side separated in a circumferential direction; a root mount (178; 278) including first and second mount members (180, 182; 280, 282) secured to circumferentially opposed sides of the root section, wherein arcuate circumferential faces (180C, 182C; 280C, 282C) of the first and second mount members (180, 182) are dimensioned to pivotably mount the root section in respective slots defined about an outer periphery of a hub in an installed position, each of the fan blades includes a neck portion (171; 271) joining the airfoil section (168; 268) and the root section (170; 270), the airfoil (164; 264) is configured to be pivotable about a hinge line established along a mount axis, the mount axis established by the root mount (178; 278) in the installed position, the neck portion (171; 271) is configured to be situated between opposed circumferential walls (180R, 182R; 280R, 282R) of the respective slot that are dimensioned to limit rotation of the neck portion (171; 271) about the mount axis, and a projection of the mount axis extends between opposed ends of the respective slot in the installed position; and characterised in that at least one platform including a first portion and a second portion, the first portion extending circumferentially from the second portion, and the second portion trapped between the root section (170; 270) and a respective one of the first and second mount members (180, 182; 280, 282). an airfoil (164; 264) including an airfoil section (168; 268) extending from a root section (170; 270), the airfoil section (168; 268) extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip portion and the root section (170; 270) in a radial direction, and the airfoil section (168; 268) defining a pressure side and a suction side separated in a circumferential direction; a root mount (178; 278) including first and second mount members (180, 182; 280, 282) secured to circumferentially opposed sides of the root section, wherein arcuate circumferential faces (180C, 182C; 280C, 282C) of the first and second mount members (180, 182) are dimensioned to pivotably mount the root section in respective slots defined about an outer periphery of a hub in an installed position, each of the fan blades includes a neck portion (171; 271) joining the airfoil section (168; 268) and the root section (170; 270), the airfoil (164; 264) is configured to be pivotable about a hinge line established along a mount axis, the mount axis established by the root mount (178; 278) in the installed position, the neck portion (171; 271) is configured to be situated between opposed circumferential walls (180R, 182R; 280R, 282R) of the respective slot that are dimensioned to limit rotation of the neck portion (171; 271) about the mount axis, and a projection of the mount axis extends between opposed ends of the respective slot in the installed position; and characterised in that at least one platform including a first portion and a second portion, the first portion extending circumferentially from the second portion, and the second portion trapped between the root section (170; 270) and a respective one of the first and second mount members (180, 182; 280, 282).