Three Zhi-20 (Z-20) helicopters participate in a demo flight during the 5th China Helicopter Exposition in north China's Tianjin, Oct. 10, 2019. (Xinhua/Li Ran)

Photo taken on Oct. 10, 2019 shows a Zhi-20 (Z-20) helicopter during the 5th China Helicopter Exposition in north China's Tianjin. (Xinhua/Li Ran)

Photo taken on Oct. 10, 2019 shows a Zhi-20 (Z-20) helicopter during the 5th China Helicopter Exposition in north China's Tianjin. (Xinhua/Li Ran)

People look at a Zhi-20 (Z-20) helicopter during the 5th China Helicopter Exposition in north China's Tianjin, Oct. 10, 2019. A fleet of China's new self-developed Z-20 helicopters has made a demonstration flight at the ongoing helicopter expo in the city of Tianjin. (Xinhua/Li Ran)