A rotor assembly (60, 360, 460, 560, 860, 960) for a gas turbine engine comprising: a rotatable hub (62, 362, 462, 562, 662, 762, 862, 962) including a main body (62A, 362A, 562A, 762A, 862A) extending along a longitudinal axis, and including an array of annular flanges (62B, 362B, 462B, 562B, 762B, 862B, 962B) extending about an outer periphery (62C, 362C 462C, 562C, 762C) of the main body (62A...862A) to define an array of annular channels (62D, 362D, 462D, 562D, 762D, 862D) along the longitudinal axis; an array of airfoils (66, 166, 266, 366, 466, 566) circumferentially distributed about the outer periphery (62C... 762C), each one of the airfoils (66...566) including an airfoil section (66A, 166A, 266A, 366A, 566A) defining a pressure side and a suction side separated in a thickness direction, the airfoil section (66A...566A) extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip portion (66C, 266C, 366C) and a root section (66B, 266B, 366B, 466B, 566B) in a radial direction, the root section (66B...566B) received in the annular channels (62D...862D) and mechanically attached to the hub (62...962); a plurality of retention pins (68, 168, 368, 468, 568, 868, 968), each one of the retention pins (68...968) extending through the root section (66B...566B) of a respective one of the airfoils (66...566) and through the array of annular flanges (62B...962B) to mechanically attach the root section (66B...566B) to the hub (62... 962); an array of platforms (70, 270, 370, 470) mechanically attached to the hub (62...962) and that abut against respective pairs of the airfoils (66...566); and characterised by an array of retention members (590, 690), each of the retention members (590, 690) extending outwardly from one of the annular flanges (62B... 962B) and having a contact surface (590D, 690D) dimensioned to abut against the pressure side or the suction side of a respective one of the airfoils (66... 566); and the array of platforms (70... 470) is positioned radially inward of the contact surface (590D, 690D) of each of the retention members (590, 690). a rotatable hub (62, 362, 462, 562, 662, 762, 862, 962) including a main body (62A, 362A, 562A, 762A, 862A) extending along a longitudinal axis, and including an array of annular flanges (62B, 362B, 462B, 562B, 762B, 862B, 962B) extending about an outer periphery (62C, 362C 462C, 562C, 762C) of the main body (62A...862A) to define an array of annular channels (62D, 362D, 462D, 562D, 762D, 862D) along the longitudinal axis; an array of airfoils (66, 166, 266, 366, 466, 566) circumferentially distributed about the outer periphery (62C... 762C), each one of the airfoils (66...566) including an airfoil section (66A, 166A, 266A, 366A, 566A) defining a pressure side and a suction side separated in a thickness direction, the airfoil section (66A...566A) extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip portion (66C, 266C, 366C) and a root section (66B, 266B, 366B, 466B, 566B) in a radial direction, the root section (66B...566B) received in the annular channels (62D...862D) and mechanically attached to the hub (62...962); a plurality of retention pins (68, 168, 368, 468, 568, 868, 968), each one of the retention pins (68...968) extending through the root section (66B...566B) of a respective one of the airfoils (66...566) and through the array of annular flanges (62B...962B) to mechanically attach the root section (66B...566B) to the hub (62... 962); an array of platforms (70, 270, 370, 470) mechanically attached to the hub (62...962) and that abut against respective pairs of the airfoils (66...566); and characterised by an array of retention members (590, 690), each of the retention members (590, 690) extending outwardly from one of the annular flanges (62B... 962B) and having a contact surface (590D, 690D) dimensioned to abut against the pressure side or the suction side of a respective one of the airfoils (66... 566); and the array of platforms (70... 470) is positioned radially inward of the contact surface (590D, 690D) of each of the retention members (590, 690).