All of the items in your average "Bush" Plane need coating! You spend good money for your Super Light Metal, do not let it turn to salt! In the case of Aluminum you also have to worry about Hydrogen Enbrittlement. You do not want to add coatings that will turn your aluminum into a battery or cause it to have interelectrode capacitance. Then it can go to hell in real short order! When Aluminum is going bad it looks like someone put salt on it and it is growing there! If thats what it looks like you are shit outa aluminum.
