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 replacement of the flow restrictors of the aileron and elevator power control units (PCU's) with new flow restrictors. 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 reduced roll and/or pitch rate control of the airplane and consequent increased pilot workload as a result of fragments from a deteriorated flow restrictor filter screen becoming lodged in the PCU.