IRImplementing rule
CS 25.397Control system loads
(a)General. The maximum and minimum pilot forces, specified in sub-paragraph (c) of this paragraph, are assumed to act at the appropriate control grips or pads (in a manner simulating flight conditions) and to be reacted at the attachment of the control system to the control surface horn.
(b)Pilot effort effects. In the control surface flight loading condition, the air loads 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 sub-paragraph (c) of this paragraph. Two-thirds of the maximum values specified for the aileron and elevator may be used if control surface hinge moments are based on reliable data. In applying this criterion, the effects of servo mechanisms, tabs, and automatic pilot systems, must be considered.
(c)Limit pilot forces and torques. The limit pilot forces and torques are as follows:
| Control | Maximum forces or torques | Minimum forces or torques |
|---|---|---|
| Aileron: Stick Wheel* | 445 N (100 lbf) 356 DNm (80 D in.lb)** | 178 N (40 lbf) 178 DNm (40 D in.lbf) |
| Elevator: Stick Wheel (symmetrical) Wheel (unsymmetrical)† | 1112 N (250 lbf) 1335N(300 lbf) | 445 N (100 lbf) 445 N(100 lbf) 445 N (100 lbf) |
| Rudder | 1335 N (300 lbf) | 578 N 130 lbf |
*The critical parts of the aileron control system must be designed for a single tangential force with a limit value equal to 1·25 times the couple force determined from these criteria. **D = wheel diameter in m (inches) †The unsymmetrical forces must be applied at one of the normal handgrip points on the periphery of the control wheel.
(d)For aeroplanes equipped with side stick controls, designed for forces to be applied by one wrist and not by the arms, the limit pilot forces are as follows:
(1)For all components between and including the handle and its control stops:
| PITCH | ROLL | ||
|---|---|---|---|
| Nose Up | 890 N (200 lbf) | Roll Left | 445 N (100lbf) |
| Nose Down | 890 N (200 lbf) | Roll Right | 445 N (100 lbf) |
(2)For all other components of the side stick control assembly, but excluding the internal components of the electrical sensor assemblies, to avoid damage as a result of an in-flight jam:
| PITCH | ROLL | ||
|---|---|---|---|
| Nose Up | 556 N (125 lbf) | Roll Left | 222 N (50 lbf) |
| Nose Down | 556 N (125 lbf) | Roll Right | 222 N (50 lbf) |
[Amdt 25/13]
[Amdt 25/18]
IR · CS 25.397 — CS-25 · ED Decision 2016/010/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023