the Cessna Caravan is certified for known icing?
that is a tough certification---If these aforementioned icing incidents are ---continued flights into known icing--- then accidents are inevitable weight increases, drag increases, lift decreases, more power required ---welcome to test pilot school!
if it IS certified then hopefully airworthiness directives have been written and applied or the deicing certification will be downgraded or totally decertified---this seem like an interesting topics I have interest in part 23 icing certification.