Greybeard.... Your query is certainly worth further study. There is likely to be an intitiating event followed by further contributing factors that caused this accident. I used to research airborne lighting suseptability for a major avionics company and the TCAS antennas appear to be in areas that are prime for lightning attach points. Couple that with the photos showing rudder static dissipator tufts missing and it points to a possible event that needs to be eliminated or studied further. The root cause of the initiating event (beyond flying into a highly convective area) is not known, so all possible causes have to be fully explored and analyzed.