25.399—Dual control system.
(a)
Each dual control system must be designed for the pilots operating in opposition, using individual pilot forces not less than—
(1)
0.75 times those obtained under § 25.395; or
(2)
The minimum forces specified in § 25.397(c).
(b)
The control system must be designed for pilot forces applied in the same direction, using individual pilot forces not less than 0.75 times those obtained under § 25.395.