Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Dornier Model 328-100 series airplanes. This proposal would require repetitive tests to detect internal leakage of hydraulic fluid within the hydraulic components of the ground spoiler system and to detect a buildup of pressure in the return line of the bypass valve, and corrective action, if necessary; installation of additional hydraulic lines and an additional hydraulic shutoff valve in the ground spoiler system; and replacement of the valve block of the ground spoiler system with a new part. This proposal also would require eventual replacement of the relief restrictor valves of the ground spoiler system with redesigned parts, which would constitute terminating action for the repetitive tests. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent the ground spoilers from unlocking and deploying during takeoff or in flight, and consequent reduced controllability of the airplane.