Now this is just talking and I am not claiming fact but I have seen 1 JR PCM go down but it was a strange crash.. The plane never went to failsafe settings it just held its last inputs and glided in at idle into the dirt. This was a single conversion PCM JR reciever on Ch14 or 16. The guy was flying a 40% Carden Cap... The failsafe was set to cut the engine and snap the plane into the ground or something, of which it did none. It just held its course at a low throttle setting and flew in a straight line right into the dirt at about a 30 degree angle.

At that time we discussed and I remember some talk about JR single conversion PCM receivers being more vulnerable than a Dual Conversion PCM. I wonder if that plays into your situation and if there is any truth to their being a difference between single and dual conversion PCM. So with that I will recant and say that I can truthfully say that I have never seen a Dual Conversion PCM receiver lockout or fail in any way. I cant even remember reading about a Futaba PCM locking out at all, I really cant.