DO NOT use Simple Green 409 or anything else with any chlorine or chloride fluorine or fluoride in it on any aluminum surface. It forms HCL/HFL and causes hydrogen embrittlement. This has brought down Chinooks, see the US Army's memo on simple green. or the FAA memo on hydrogen embrittlement.
409 says right on the bottle not to use on aluminium for this reason. Simple Green makes an "Aircraft Safe" cleaner with different ingrdients for this puropse.