CS 22.161  Trim

CAA ORS9 Decision No. 1

(a) General. Each sailplane must meet the trim requirements of this paragraph after being trimmed and without further pressure upon, or movement of, the primary controls or their corresponding trim controls by the pilot.

(b) Lateral and directional trim

(1) Lateral trim. The sailplane must be capable of being so trimmed that there is no tendency for the sailplane when in straight flight at 1.4 V_S1 with wing-flaps in all en-route positions, air brakes, and where applicable, landing gear retracted, to turn or bank, when the aileron control is released and the rudder control held fixed in the neutral position.

(2) Directional trim. The sailplane must be capable of being so trimmed that there is no tendency for the sailplane, when in straight flight at 1.4 V_S1 with wing-flaps in all en-route positions, air brakes, and where applicable, landing gear retracted, to yaw when the rudder control is released and the aileron control held fixed in the neutral position.

(c) Longitudinal trim

(1) If the sailplane has no in-flight adjustable trimming device, the trim speed must be between 1.2 V_S1 and 2.0 V_S1 for all c.g. positions.

(2) If the sailplane has an in-flight adjustable trimming device, the following requirements must be met without further pressure upon or movement of the primary control or the corresponding trim control: 

(i) the sailplane must maintain trim with wing-flaps in the landing position, the air brakes retracted and landing gear extended within the speed range between 1.2 V_S1 and 2.0 V_S1; 

(ii) in towed flight the sailplane must maintain trim within the speed range between 1.4 V_S1 and V_T; 

(iii) In the most adverse out-of-trim condition, the control force must be less than 20 daN between 1.1 V_S1 and 1.5 V_S1.

(3) For powered sailplanes, retraction and extension of the power-plant or propeller must not produce excessive trim changes.

(4) The powered sailplane, with the engine operating, must maintain longitudinal trim

during:

(i) a climb with maximum continuous power at a speed V_Y with landing gear retracted and wing-flaps in the take-off position; 

(ii) level flight at all speeds between V_Y and 0.9 V_H, with the landing gear retracted and wing-flaps in positions appropriate to each speed.