23.161—Trim.
(a) General.
Each airplane must meet the trim requirements of this section after being trimmed and without further pressure upon, or movement of, the primary controls or their corresponding trim controls by the pilot or the automatic pilot. In addition, it must be possible, in other conditions of loading, configuration, speed and power to ensure that the pilot will not be unduly fatigued or distracted by the need to apply residual control forces exceeding those for prolonged application of § 23.143(c). This applies in normal operation of the airplane and, if applicable, to those conditions associated with the failure of one engine for which performance characteristics are established.
(b) Lateral and directional trim.
The airplane must maintain lateral and directional trim in level flight with the landing gear and wing flaps retracted as follows:
(1)
For normal, utility, and acrobatic category airplanes, at a speed of 0.9 VH, VC, or VMO /MO, whichever is lowest; and
(c) Longitudinal trim.
The airplane must maintain longitudinal trim under each of the following conditions:
(i)
Takeoff power, landing gear retracted, wing flaps in the takeoff position(s), at the speeds used in determining the climb performance required by § 23.65; and
(ii)
Maximum continuous power at the speeds and in the configuration used in determining the climb performance required by § 23.69(a).
(2)
Level flight at all speeds from the lesser of VH and either VNO or VMO /MMO (as appropriate), to 1.4 VS1, with the landing gear and flaps retracted.
(3)
A descent at VNO or VMO /MMO, whichever is applicable, with power off and with the landing gear and flaps retracted.
(iii)
An approach gradient equal to the steepest used in the landing distance demonstrations of § 23.75, flaps in the landing position(s) at VREF.
(d)
In addition, each multiple airplane must maintain longitudinal and directional trim, and the lateral control force must not exceed 5 pounds at the speed used in complying with § 23.67(a), (b)(2), or (c)(3), as appropriate, with—
(e)
In addition, each commuter category airplane for which, in the determination of the takeoff path in accordance with § 23.57, the climb in the takeoff configuration at V2 extends beyond 400 feet above the takeoff surface, it must be possible to reduce the longitudinal and lateral control forces to 10 pounds and 5 pounds, respectively, and the directional control force must not exceed 50 pounds at V2 with—