§23.147 Directional and lateral control.

[(a) For each multiengine airplane, it must be possible, while holding the wings level within 5 degrees, to make sudden changes in heading safely in both directions. This ability must be shown at 1.4 with heading changes up to 15 degrees (except that the heading change at which the rudder force corresponds to the limits specified in Sec. 23.143 need not be exceeded), with the-- (1) Critical engine inoperative and its propeller in the minimum drag position; (2) Remaining engines at maximum continuous power; (3) Landing gear-- (i) Retracted, and (ii) Extended; (4) Flaps retracted. (b) For each multiengine airplane, it must be possible to regain full control of the airplane without exceeding a bank angle of 45 degrees, reaching a dangerous attitude or encountering dangerous characteristics, in the event of a sudden and complete failure of the critical engine, making allowance for a delay of two seconds in the initiation of recovery action appropriate to the situation, with the airplane initially in trim, in the following conditions: (1) Maximum continuous power on each engine; (2) The wing flaps retracted; (3) The landing gear retracted; (4) A speed equal to that at which compliance with Sec. 23.69(a) has been shown; and (5) All propeller controls in the position at which compliance with Sec. 23.69(a) has been shown. (c) For all airplanes, it must be shown that the airplane is safely controllable without the use of the primary lateral control system in any all-engine configuration(s) and at any speed or altitude within the approved operating envelope. It must also be shown that the airplane's flight characteristics are not impaired below a level needed to permit continued safe flight and the ability to maintain attitudes suitable for a controlled landing without exceeding the operational and structural limitations of the airplane. If a single failure of any one connecting or transmitting link in the lateral control system would also cause the loss of additional control system(s), compliance with the above requirement must be shown with those additional systems also assumed to be inoperative.]