Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB 2000 series airplanes. This proposal would require replacing the dual shuttle valve in the number 2 hydraulic system with a new improved valve; and, for certain airplanes, modifying the hydraulic system. This action is necessary to prevent failure of the dual shuttle valve in the number 2 hydraulic system, with reduced maximum elevator rate on the left side, which could result in pilot induced pitch oscillation, and consequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition.