Flight control surface actuation system

A flight control surface actuation system comprising:

• a rotary actuator having an output part configured to rotate about an axis;
• a connecting rod for connecting a flight control surface to the rotary actuator;
• a connection mechanism connecting a first end of the connecting rod to the output part such that rotation of the output part about the axis causes at least part of the connection rod to rotate about the axis, the connection mechanism comprising:
• a connection structure fixed to the output part;
• and
• an engagement part mounted for rotation about a longitudinal axis thereof relative to the connection structure,
• wherein the engagement part extends through the connecting rod and is fixed thereto;
• and
• a position sensor arranged to measure the angular displacement of the first end of the connecting rod about the axis,
• wherein a first part of the position sensor is secured to the connection structure in a fixed position;
• wherein a second part of the position sensor is rotatably mounted to the first part and is configured to rotate with the engagement part and the connecting rod;
• wherein the position sensor is configured to measure the relative rotation between the first and second parts of the position sensor;
• wherein the engagement part comprises a first conical portion which tapers in a first axial direction;
• the first conical portion forms a first friction surface engaged with a corresponding first connecting rod friction surface.