I have the same falling problem. I usually fly in my shop at work, but I flew at home a couple times last weekend and it did not have the problem. I am wondering if there is some kind of RF interference at work. I think that what's happening is, the pitch changes on the blades to negative but only for a fraction of a second and then comes back. I can see the blades flash differently when it happens. I cannot see the servo arms when it happens because the heli drops so suddenly it makes it hard to see. I have tried to reproduce the problem while holding the heli in my hand, and spinning up the blades for a while so I can see what's going on, but it will not fail while I am holding it for some reason. Maybe it is vibration causing the glitch, and holding it reduces the vibration. I don't know...