I would strongly warn against using WD-40 on rotor blades. For two reasons:
1) The WD-40 film will attract sand and dust which will result in an enhanced environment for corrosion and possibly effect the blade aerodynamics.
2) The petroleum distillates in the WD-40 can enter faying surfaces and effect the bonding agent causing the bond to break down.
WD-40 is and was developed as a means of displacing water or moisture but in certain applications it is counter productive and can cause problems.
