The left aileron of an ATR 72 aircraft. Aerodynamic balance, trim tab, balance tab, and outer flap can all be seen clearly.
<a href="//commons.wikimedia.org/wiki/User:Ariadacapo" title="User:Ariadacapo">Olivier Cleynen</a>
2013-02
<span class="int-own-work" lang="en">Own work</span>