NEVER use Simple Green for aircraft. It is corrosive to aluminum.
For that matter, if you use it on a vehicle engine, expect things to get ugly if you have a newer car, good chance there is aluminum in the engine it too.
Whenever considering using a cleaner on aircraft, you absolutely must research to see if it is corrosive to aluminum. If you don't, you take a very good chance on destroying an aircraft. Liquids get into lap seams, etc and will corrode where you can't see it. Once you do see it, the metal is too far gone.
Safest bet, and best way to go with aircraft, use a product designed for aircraft cleaning.
Luminox is excellent for aluminum, especially unpainted or untreated aluminum. Luminox is a low foaming, neutral pH detergent for use in manual, ultrasonic, and machine cleaning. Safe-handling detergent used for non-corrosive cleaning without chelation or alkalinity waste treatment problems. Recommended for aluminum and soft metal, medical devices, pharmaceutical equipment, alkaline sensitive labware, and medical instruments in aluminum trays. Free rinsing, eliminating interfering residues. Dilute 3:100. pH 7
We use it to clean freshly machined aluminum manifolds used in the F-35. After thorough rinsing with fresh water, the surface is clean, degreased, residue free and ready for anti-corrosion treatment and paint.
The only down side is that it isn't inexpensive. About $77 per gallon. However, one gallon will make 25 gallons of cleaning solution.
