1　引言快捷、灵活的特点决定了近年来轻型、中型民用直升机在发达国家和部分发展中国家的迅速普及。以美国为例 ,目前超过 12 4 0 0 0名个人、35 0 0 0个企业和几乎所有中心城市的警察局、大医院和电视台都配备了直升机 ,仅纽约市的民用直升机保有量就超过 2 0 0 0架 ,并有越? 1 Introduction The fast and flexible characteristics have determined the rapid popularization of light and medium-sized civilian helicopters in developed countries and some developing countries in recent years. In the United States, for example, at present there are more than 12 40 000 individuals, 35 000 companies and almost all central police stations, major hospitals and television stations equipped with helicopters, and only New York City’s civilian helicopter holdings exceed 2 0 0 0 frame, and more?