A gas turbine engine system includes a disk and an airfoil. The disk includes a first rail, a second rail, a retention slot located between the first and second rails, and a ridge extending radially outward from the second rail. The airfoil is engaged with the retention slot, and includes a platform with an upstream angled portion, a downstream angled portion, and a notch defined in the platform. The ridge of the disk extends at least partially into the notch of the platform.