Airworthiness Directives; Saab Model SAAB 340B and SAAB 2000 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB 340B and SAAB 2000 series airplanes, that requires modification of the check valves of the airfoil de-icing system, or replacement of the check valves with improved valves. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this 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.