EE had plywood getting hoisted up preheater. It was windy & piece of siding started to bend. It snapped off & hit ee in forehead. EE was running winch. Plywood blew away from building. EE lost grip as he regained control guy on 5th floor saw siding loosen, snap & fall. Witness noted ee was unconscious when he got down to him. Paramedics said cuts on both front & back of head.