Static discharger

The movement of the aircraft and the friction of its fuselage with the air layers cause static electricity to be generated on the outer surface of the fuselage. 
this electric charge gradually increases and can potentially cause danger condition for aircraft systems , disturbing radio waves and Performance of navigation systems. 
Therefore, this electric charge must be discharged and  static dischargers are used for this purpose.
Due to the tendency of static electricity to accumulate at sharp points and corners and edges of surfaces, aircraft manufacturers have installed electrical dischargers in places such as wing tips , wing and control surfaces trailing edges and the end of empenage. So that static electricity is easily discharged into the surrounding air.