The present invention relates to the provision of an actuator assembly for moving an aircraft wing tip device. The wing tip device is rotatable about a hinge axis relative to a fixed wing of the aircraft. The hinge axis is orientated non-parallel to a line-of-flight direction of the aircraft. The actuator assembly comprises a primary shaft having an axis of rotation orientated substantially parallel to the line-of-flight direction, a motor to cause rotation of the primary shaft, and a secondary shaft orientated substantially parallel to the hinge axis. The secondary shaft is couplable to the primary shaft and is arranged to rotate the wing tip device in response to the rotation of the primary shaft.