Hmm... It didn't rattle till after I changed props... Mabey I lost the washer? I don't think so though, because I never pulled the spinner backplate off. Its more like a buzz or clack than a rattle. I checked everything on it, it's all tight. Also, when I first got the plane, I loc-tited all of the engine and mount hardware, so if i missed checking something, its loc-tited anyway. So it's normal for these?