Seems logical to me, unless I am mis-pronouncing "Achaeans" and it should be "ay KAY uns."
That's how its supposed to be, so you're mispronouncing it, at least according to my professor when I was taking "Classical Mythology." Sort of how Zeus is pronounced more like "zoos." An Odysseus is not "Oh dis e us," but "Oh dee sues."
Those who can, don't. Those who should not, do.