Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB 340B and SAAB 2000 series airplanes. This proposal would require modification of the check valves of the airfoil de-icing system, or replacement of the check valves with improved valves. 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 failure of the check valves, which could result in loss of airfoil de-icing capability during single engine operation, and consequent reduced controllability of the airplane.