Abstract: A multicopter includes an airframe, multiple propellers mounted rotatably on the airframe, and a propeller guard installed to surround at least a part of the propellers. The propeller guard is deformed or displaced to contact the propellers and stops rotation of the propellers when the multicopter collides with a collision object. The propeller guard includes a fixed frame and a movable frame positioned near the rotation plane of each propeller. The movable frame is located on one side of the corresponding propeller opposite the airframe, and has a pivot point as a rotation center, supported by the fixed frame, and an engagement portion in which a part of the movable frame is detachably engaged with the fixed frame. When an external force is applied to the movable frame, the engagement portion is disengaged from the fixed frame and the movable frame turns toward the propeller about the pivot point.

Abstract: A blow-by gas returning (BGV) apparatus includes a blow-by gas storage unit, a throttle device placed in an intake passage, a BGV passage for allowing blow-by gas to flow to the intake passage downstream of the throttle device for recirculation, and a PCV valve for regulating a flow rate of blow-by gas. An abnormality diagnosis device includes an air flow meter to detect an intake amount in the intake passage upstream of the throttle device and an electronic control unit (ECU) for diagnosis. The ECU controls the PCV valve to a first opening degree and a second opening degree when an engine is during deceleration fuel cut, and diagnoses abnormality of the BGV apparatus based on a first intake amount detected under control with the first opening degree and a second intake amount detected under control with the second opening degree.