Further reflection on the drogue shackle bolt issue leads me to ask this of the airworthiness and safety experts here. Was it sufficient for MB to deal with the known potential for shackle pinching by issuing maintenance guidance alone, and not doing anything more fundamental (such as introducing a shouldered bolt, reshaping the components, or even issuing a torque setting) to mitigate the issue? If it could be shown that a comparatively simple physical modification would have removed the accident mechanism, then would MB be open to a charge of negligence for not having taken such action in the 20-odd years between the risk becoming known and Sean's death?