The boarding step on the plane I just bought was cracked. The previous owner left it off. I had it fixed and am ready to mount it. There were only two screws mounted to the plane, and the other 4 holes filled with some sort of putty. Question - the 2 screws that were in place threaded into the plane. In other words, it was a threaded hole and they did not need a backing nut. Does anybody know if the other 4 bolts will be the same? I have not removed the putty yet. If they are threaded holes I'll just use a tap to clean them out. I removed the access panel in the luggage area to see what was in there. It looks like most of the holes are not visible because of a truss-like piece of the fuselage.