Just saw the article about the horse thrown from the trailer when the back removable center post came out during an accident.  This was on an Exiss with removable tack, but my Sundowner has the same set up as I'm sure many other brands do.  Besides welding the post in place, would there be any other way this could have been kept from happening?

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Do you have a link to the story? Did the post truly fail or did the attaching hardware fail? Sure the removeable post was installed properly?

http://eventingnation.com/home/more-details-released-on-fatal-i-75-trailer-accident/ 

Here it is. 

Appears that it was the hardware, but still seems a shame that it would happen.  I would be willing to weld mine in and screw the removable tack if it would keep the thing from flying out.  I think my Sundowner had a little better way that it was attached. 

Doors and removable frames are not designed nor should they, IMO, be designed to be wreck proof. That is what the butt bar should do---keep the horses in the trailer. Doors have to be light weight to work properly as does the removable framing. I would be suspect that the butt bar was not installed or latched properly. Most bars, on this design, that I have seen, hooks to the side wall and than to the rear tack wall-not the removable post. If the tack room is folded up, as it appears in the pics, the butt bar is useless. If bar is attached to the rear tack room wall and side wall, it should be fairly resilient to most challenges. IF you can't attach to the wall (as if tack room is folded up) a properly installed high strength 3/8" or so chain from side wall to side wall works great..... We had a trailer years ago that we had to leave the butt bar out to get in 5 horses. After about 3 trips, the doors where getting bowed out. A high strength, light weight chain mounted side wall to side wall, solved the problem... IMO, welding or screwing the center post in will not solve any concerns.

I am offering a guess that the manufacturer will say the same. Good luck!

When the consideration of the forces acting against a fairly small extruded aluminum structure during an accident is made, it's remarkable that more injuries aren't common. A 1000 pound animal being slammed against the vertical post, can generate forces well in excess of his own body weight. Because it is made to be removable, the attaching hardware becomes its weakest parts. Even if it doesn't fail, the pressure exerted by a horses' butt can bend the post, which effectively shortens its overall length, and pulls the fittings from the trailers' framing structure.

I've seen a trailer door, closed and locked into place with its camlock bar and fixtures, bent open and broken by an errant horse. It happened just after loading, while the trailer was stationary. An accident can develop many G forces, that would make the placement of a large animal almost impossible to maintain.

We have two trailers equipped with removable rear center posts. One has a fitting for a butt chain, the other a butt bar. Neither structure could hold a horse in an accident, that would put any significant pressure rearward.

Aren't TONS of trailers designed like this? (like all stock trailers)???? Should I really get a super long butt chain? My trailer is XXW. Here's a pic.

This is the rear stall....no rear tack, no center post...just opens up.