Sec. 23.397 - Limit control forces and torques.

(a) In the control surface flight loading condition, the airloads on movable surfaces and the corresponding deflections need not exceed those that would result in flight from the application of any pilot force within the ranges specified in paragraph (b) of this section. In applying this criterion, the effects of control system boost and servo-mechanisms, and the effects of tabs must be considered. The automatic pilot effort must be used for design if it alone can produce higher control surface loads than the human pilot.

(b) The limit pilot forces and torques are as follows: 

------------------------------------------------------------------------
                                   Maximum forces or
                                  torques for design
                                    weight, weight     Minimum forces or
             Control               equal to or less       torques \2\
                                   than 5,000 pounds
                                          \1\
------------------------------------------------------------------------
Aileron:
  Stick.........................  67 lbs............  40 lbs.
  Wheel \3\.....................  50 D in.-lbs \4\..  40 D in.-lbs.\4\
Elevator:
  Stick.........................  167 lbs...........  100 lbs.
  Wheel (symmetrical)...........  200 lbs...........  100 lbs.
  Wheel (unsymmetrical) \5\.....  ..................  100 lbs.
Rudder..........................  200 lbs...........  150 lbs.
------------------------------------------------------------------------
\1\ For design weight (W) more than 5,000 pounds, the specified maximum
  values must be increased linearly with weight to 1.18 times the
  specified values at a design weight of 12,500 pounds and for commuter
  category airplanes, the specified values must be increased linearly
  with weight to 1.35 times the specified values at a design weight of
  19,000 pounds.
\2\ If the design of any individual set of control systems or surfaces
  makes these specified minimum forces or torques inapplicable, values
  corresponding to the present hinge moments obtained under §
  23.415, but not less than 0.6 of the specified minimum forces or
  torques, may be used.
\3\ The critical parts of the aileron control system must also be
  designed for a single tangential force with a limit value of 1.25
  times the couple force determined from the above criteria.
\4\ D=wheel diameter (inches).
\5\ The unsymmetrical force must be applied at one of the normal
  handgrip points on the control wheel.

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23-7, 34 FR 13089, Aug. 13, 1969; Amdt. 23-17, 41 FR 55464, Dec. 20, 1976; Amdt. 23-34, 52 FR 1829, Jan. 15, 1987; Amdt. 23-45, 58 FR 42160, Aug. 6, 1993]