"Air fan maintenance mode" or the use of the environment is often crowded outdoor space, which requires the purchase of gas-turbine must have a waterproof and drop impact resistance. Because the outdoor environment often appear inevitable rain and other weather, if the fan does not have the waterproof function is prone to security issues. And for a crowded space, such as a street, shop doorway and so on, the fan must have anti-fall impact resistance, "Air fan maintenance mode" to avoid damage to the fan kicked pedestrians fan casing is formed using the security issue. Consumers to buy gas-turbine, the environment is often outdoors or in a crowded space, which requires the purchase of gas-turbine must have a waterproof and drop impact resistance. "Air fan maintenance mode" for outdoor use because the environment is often inevitable that there will be rain and other weather, if the fan does not have the waterproof function is prone to security issues. And for a crowded space, such as a street, shop doorway and so on, the fan must have anti-fall impact resistance, to avoid damage to the fan kicked pedestrians fan casing is formed using the security issue.