Although may be you are not very much common with Kopp-Etchells effect but this effect is an example of the Triboelectric effect.

Kopp-Etchells effect

The result of static electricity created by friction as materials of dissimilar material rapidly strike against each other. In the case of helicopter rotors at night, it is the titanium/nickel blades moving through the air and dust. It also occurs on the ground, but is not usually seen unless aircraft are landing or taking off, as the aircraft are generally earthed by contact with the ground.