I don't know the details, my understanding is the Gander DC-8 investigation pretty much served to eviscerate the Canadian accident investigation communities credibility. I don't know if there was anything else in its history before this.
CASB was dissolved as a result of the Arrow 1285 investigation, and the conclusions that were adopted from it, with 4 board members dissenting due to complete lack of evidence. Eventually, both major theories on the accident were found to lack enough evidence.