Collective friction seizing in an S61 has occurred more than once, and lead Bristow to install a pip pin in a modified friction strut, so it could be pulled rapidly in the event of seizure. The incident leading to this change had supposedly been resolved using the saw blade on a Swiss army knife in true Macgyver fashion to sever the strut. Of course there is always the instances of the S61 flying off with the tail rotor gust lock still installed as well. And one of my friends experienced an alarming incident when the cyclic on his jetranger snapped off at the socket as he was starting it up one day, which probably would be classified as a total loss of control!