The NTSB report indicates there was evidence the upper left attachment bolt had previously been attached but that this bolt wasn't found with the wreckage. I could imagine that the bolt head end (that must have been lying inside the tailboom?) could have been flung out as the boom fell to the ground, and so it would be hard to now find. But would the nut end of the apparently failed bolt not have fallen down within the fuselage? Or could that likewise have been ejected once the fuselage started to spin on loss of the tailboom?