Airworthiness Directives; Boeing Model 737 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737 series airplanes, that requires modification of the aileron centering spring and trim mechanism. This amendment is prompted by a review of the design of the flight control systems on Model 737 series airplanes. The actions specified by this AD are intended to prevent jamming of the aileron control system during flight due to fracturing of the springs in the aileron centering units; this condition, if not corrected, could result in reduced lateral control of the airplane.