Abstract: A rotor blade actuation system is disclosed for controlling extension and retraction of an outboard blade section of a rotor blade by varying the speed and direction of rotation between a main rotor shaft and a blade actuation shaft. The rotor blade actuation system includes a drive gear on the main rotor shaft and a blade actuation drive gear on the blade actuation drive shaft. A primary drive unit is engaged with and transmits rotary motion from the main rotor shaft to the blade actuation shaft. The primary drive unit includes an input gear engaged with the drive gear. A primary drive is engaged with the drive gear through an input gear and a master clutch. An output drive is engaged with the blade actuation drive gear. A forward clutch controls engagement of a forward planetary gearset with the primary drive and the output drive. The engagement of the forward planetary gearset causes the blade actuation shaft to rotate in the same direction as the rotation of the main rotor shaft.