Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737 series airplanes. This proposal would require modification of the aileron center spring and trim mechanism. This proposal is prompted by a review of the design of the flight control systems on Model 737 series airplanes. The actions specified by the proposed 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.