Bearing seizure obviously caused the accident, but what caused bearing failure, remains to be explained. Hovewer, I feel a bit uneasy that such failure dooms the helicopter.
I am trying to figure out if a feature, allowing rotation and thus integrity of flight controls, could (should?) be designed into the system, like alternative way of rotation between slider and control rod if bearing seizes-up and providing tell-tale sign (vibration) that would give time to pilot to recognize the problem and act before everything goes South. And I have a very personal interest in that.
As a helicopter pilot and instructor previously teaching others how to deal with tail rotor malfunctions, and knowing the irrecoverable situation this pilot and his passengers was put into, I'm horrified, rather than just a bit uneasy!
If the pin carrier had been designed to contain a simple bearing allowing free shaft rotation of the control end of the shaft, instead of clamping it, the nut would not have come undone.