By Dan Lyons The United States hadn’t won gold in aerials since 1998 in Nagano. ZHANGJIAKOU, China (AP) — A trio of Americans won gold in the Olympics’ first mixed team aerials event Thursday, giving the United States its first medals in the freestyle skiing discipline in a dozen years. Ashley Caldwell, Christopher Lillis and Justin Schoenefeld all earned their first Winter Games medals. Lillis’ back double full-full-double full was given the highest score of any trick in the finals, and the U.S. gold was assured when Schoenefeld followed with a clean back double full-full-full. The 28-year-ol…