Abstract: An actuation system which includes apparatus for transferring control signals for varying the blade pitch from a non-rotating member to a rotating member of a gas turbine engine is described. In one embodiment, the engine includes a main disk containing a row of blades, and the disk is coupled to a main shaft which rotates about the engine axis. An actuating disk, or cone, rotates with the main disk, and the torque required to rotate the actuating cone is transmitted through ball splines attached to the main shaft. The ball splines allow transmission of torque between the disk and the cone and at the same time enable the disk and the cone to move axially relative to each other without binding. The actuating cone is supported at one end by the ball splines and at its other end by ball thrust bearings. The ball thrust bearings are pre-loaded to enable the bearings to withstand axial loads in opposite directions.

Abstract: A blade retention system which allows a blade to be rotated about a blade stack axis by utilizing a cover, an anti-rotational key, and strap is described. The substantially cylindrical cover rotatably couples to a rotor disk opening using a thrust bearing. The cover includes a dovetail-load slot for receiving a rotor blade dovetail key. The anti-rotation key is positioned between the dovetail key and the dovetail-load slot to secured the blade to the cover. The strap holds the key in place and is clamped between the cover and the control mechanism.