Originally Posted by boandrv7a
Your reference to galling on the surface of the bolt in your video is no different than what you would likely see if you kept repeatedly hitting the bolt with a hammer over and over while rotating it (basically what has been happening with your bolt since the airplane first flew).
Because the tool you are measuring the bolt diameter with is tampered, it is impossible to measure as you did with any accuracy. If you use a tool that can measure accurately (a caliper or micrometer) you will probably find a diameter difference of only a few thousandths of an inch, but that is more than enough to cause a problem.
The view in your video isn't very clear but it looks like the failed ends are classic of a progressive failure through about 1/2 of the cross section and then evidence of a single event shear failure of the remaining un-failed portion.
Point being is that the bolt had probably been partially cracked for quite a while and then one single high load event (possible a hard pivot turn with one brake locked?) caused it to fail the rest of the way.
It is unfortunate that no one had detected it previously or caught it in the pre-buy inspection. (good evidence for using one of the shops that specialize in working on / inspecting RV's... even if it costs more to get it to them)
BTW, for anyone that finds their way to this thread in the future, the Service Bulletin related to this construction error describes a procedure for check for proper installation of the steering stop without removing the nose wheel fairing so this check can easily be done by anyone that is able to move the airplane with a tow bar. If you own a tri-gear 2 place RV (other than the RV-12) and you don't know whether this check/inspection has even been done, it would be a good idea to do it your self.