A tractor operator was injured in the groin area when the machine’s seat clamps failed, releasing the seat. The seat was improperly installed using single bolted electrical straps (image below). The tractor was operated for a significant amount of time with this hazard, long enough for the electrical straps to rust. New electrical straps were obtained and tested for the forces required to initiate a failure that could result in the release of the seat. Normal use of the seat would not have caused the failure. Unusual shock forces, corresponding to a reported interaction with a tree limb at the time of the failure, were required.
