A rotor assembly for a gas turbine engine includes a rotor configured for rotation about an engine axis, the rotor including an aft surface including a rotor slot and a cover plate attached to the aft surface of the rotor, the cover plate including a tab received within the rotor slot and a cover plate slot aligned with the rotor slot. A lock assembly disposed within the rotor slot holds a position of the cover plate relative to the rotor. The lock assembly includes a key portion conforming to the rotor slot, a lock portion engageable with a surface of the rotor slot and a threaded member for holding the lock assembly within the rotor slot.