ShyTorque, thanks for your explanation and that's how I initially read the report as well. However if you pick up a bolt and a couple of nuts it would seem that in order to loosen the bolt which came off the torque you need to apply via the inside race of a bearing would tend to loosen the nut holding that bearing on also. I am lost as to how this can happen the other way around. Do the actual directions make sense to you? If so I must be misunderstanding the way it is assembled.
M25,
The tail rotor hub and blades on a 169 are on the right hand side of the tail boom and rotate from nose to tail at the top (i.e
anti-clockwise as you look at them from the right hand side of the aircraft). The control shaft sits inside the outer drive shaft and hub. When the duplex bearing began to seize, the control shaft would have also tended to rotate in the same direction as the hub, i.e. anti-clockwise.
*Any drag on the nut on that end would tend to tighten it because it has a right hand thread; it would be the same as tightening any normal right hand threaded nut and bolt.
Edit: *
As the hub rotates in its entirety, this cannot actually have been the case, my error!
If you now move to the left side of the aircraft, the tail rotor and "errant" control shaft shaft appear to be moving in a relatively
clockwise direction. The castellated nut on that side also has a right hand thread. With the shaft rotating clockwise, any drag on the nut (i.e. from contact with the stationary pin carrier to which it was bolted) would tend to cause the two to be unscrewed.
If instead the control shaft and its nut on that end had a left handed thread, the relative motion would have tended to tighten them up, as is the case on the right hand side of the assembly. Whether that would have helped prevent the catastrophic failure, I really don't know. If the design of the pin carrier had allowed the control shaft and nut to spin freely together, they would have presumably stayed together, even in rotation.