I believe no matter what guidelines or regulations that are set by osha and no matter how good the training is, there will be operators that will break the rules and cause accidents, even competent operators. There always will be great liability in training operators and statistic's show that the majority of the accidents were due to operator error, not following the rules set by their employer, failing to sound their horn, overlifting and etc. Not to say it can't happen, though I have not heard of a case where a trainer was faulted and charged for an accident that happened by an operator that he or she has trained. I believe if you follow the guidelines set by osha, keep good records, only certify competent operators and give the best and most detailed training you can, you most likely will not have something come back to haunt you and your employer and if it does you hopefully will have records to prove your innocence.