A member of staff works at Bombardier Tianjin Aviation Services Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Sept. 17, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)

A member of staff works at Goodrich Aerostructures Service (China) Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Aug. 20, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)

A member of staff works at Bombardier Tianjin Aviation Services Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Sept. 17, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)

A member of staff works at Tianjin Haite Aircraft Engineering Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Sept. 17, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)

Members of staff work at Tianjin Haite Aircraft Engineering Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Sept. 17, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)

Members of staff work at Tianjin Haite Aircraft Engineering Co., Ltd. in Tianjin Pilot Free Trade Zone (FTZ), north China's Tianjin, Sept. 17, 2020. With a number of high-end aviation maintenance enterprises gathering in the FTZ in Tianjin, the area has become an advanced aviation maintenance and testing base in the Asia-Pacific region. (Photo by Zhao Zishuo/Xinhua)