CS 25.147 Directional and lateral control

• ED Decision 2017/015/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.147 Directional and lateral control ED Decision 2017/015/R (See AMC 25.147) (a) *Directional control; general.* (See [AMC 25.147(a)](#_DxCrossRefBm1709820827).) It must be possible, with the wings level, to yaw into the operative engine and to safely make a reasonably sudden change in heading of up to 15° in the direction of the critical inoperative engine. This must be shown at 1·3 VSR1, for heading changes up to 15° (except that the heading change at which the rudder pedal force is 667 N (150 lbf) need not be exceeded), and with – (1) The critical engine inoperative and its propeller (if applicable) in the minimum drag position; (2) The power required for level flight at 1.3 VSR1, but not more than maximum continuous power; (3) The most unfavourable centre of gravity; (4) Landing gear retracted; (5) Wing-flaps in the approach position; and (6) Maximum landing weight. (b) *Directional control; aeroplanes with four or more engines.* Aeroplanes with four or more engines must meet the requirements of sub-paragraph (a) of this paragraph except that – (1) The two critical engines must be inoperative with their propellers (if applicable) in the minimum drag position; (2) Reserved; and (3) The wing-flaps must be in the most favourable climb position. (c) *Lateral control; general.* It must be possible to make 20° banked turns, with and against the inoperative engine, from steady flight at a speed equal to 1·3 VSR1, with – (1) The critical engine inoperative and its propeller (if applicable) in the minimum drag position; (2) The remaining engines at maximum continuous power; (3) The most unfavourable centre of gravity; (4) Landing gear both retracted and extended; (5) Wing-flaps in the most favourable climb position; and (6) Maximum take-off weight; (d) Lateral control; roll capability. With the critical engine inoperative, roll response must allow normal manoeuvres. Lateral control must be sufficient, at the speeds likely to be used with one engine inoperative, to provide a roll rate necessary for safety without excessive control forces or travel. (See [AMC 25.147(d)](#_DxCrossRefBm1709820826).) (e) *Lateral control; aeroplanes with four or more engines.* Aeroplanes with four or more engines must be able to make 20° banked turns, with and against the inoperative engines, from steady flight at a speed equal to 1·3 VSR1, with maximum continuous power, and with the aeroplane in the configuration prescribed by sub-paragraph (b) of this paragraph. (f) *Lateral control; all engines operating.* With the engines operating, roll response must allow normal manoeuvres (such as recovery from upsets produced by gusts and the initiation of evasive manoeuvres). There must be enough excess lateral control in sideslips (up to sideslip angles that might be required in normal operation), to allow a limited amount of manoeuvring and to correct for gusts. Lateral control must be enough at any speed up to VFC/MFC to provide a peak roll rate necessary for safety, without excessive control forces or travel. (See [AMC 25.147(f)](#_DxCrossRefBm1709820825).) [Amdt 25/18] [Amdt 25/19]