IRImplementing rule
CS 25.181Dynamic stability
(See AMC 25.181)
(a)Any short period oscillation, not including combined lateral-directional oscillations, occurring between 1·13 VSR and maximum allowable speed appropriate to the configuration of the aeroplane must be heavily damped with the primary controls –
(1)Free; and
(2)In a fixed position.
(b)Any combined lateral-directional oscillations (‘Dutch roll’) occurring between 1·13 VSR and maximum allowable speed appropriate to the configuration of the aeroplane must be positively damped with controls free, and must be controllable with normal use of the primary controls without requiring exceptional pilot skill.
IR · CS 25.181 — CS-25 · ED Decision 2003/2/RM · CS-25 Easy Access Rules · EAR revision 26 Jan 2023