Abstract: This paper, presents a calculation Method of Powell optimization under certain constraints, which is specifically made and designed by authors. Then authors suggest a practical .. method which .. optimizes two parameters, a gain K and a time constant of washout. networkm In the damped （stability augmented） system （containing nonlinear links） of aircrafts by means of Powell optimization method according to level quality requirement . for MIL-F-8785C specifications under stick shift at sinusoidal signal input and aircraft fuselage . being instantly subjected to impulse wind.