CS 22.173  Static longitudinal stability

CAA ORS9 Decision No. 1

(a) Under the conditions and throughout the speed range specified in CS 22.175: 

(1) The slope of the curve, stick force versus speed, must be positive and have a value such that any significant speed change will cause a variation in stick force plainly perceptible to the pilot. 

(2) The slope of the curve, stick displacement versus speed, must not be negative, except that a negative slope may be acceptable provided that it can be demonstrated that there is no difficulty in control. (See AMC 22.173(a)) 

(b) The air speed must return to within ±15% or ±15 km/h of the original trimmed speed, whichever is the greater when the control force is slowly released at any trimmable speed up to V_NE and where applicable V_NE and down to the appropriate minimum speed for steady unstalled flight. In addition, for a powered sailplane with the engine running, this requirement must be met at all allowable power settings. (See AMC 22.173(b))