Airworthiness Directives; Saab AB, Saab Aeronautics (Type Certificate Previously Held by Saab AB, Saab Aerosystems) Airplanes

We are adopting a new airworthiness directive (AD) for certain Saab AB, Saab Aeronautics Model 340A (SAAB/SF340A) and SAAB 340B airplanes. This AD was prompted by reports of ruptured horizontal stabilizer de-icing boots. This AD requires a revision of the applicable airplane flight manual (AFM), repetitive inspections of the horizontal stabilizer de-icing boots, and applicable corrective actions. We are issuing this AD to detect and correct damage of the de- icing boot; such damage could lead to a ruptured boot, severe vibrations, and possible reduced control of the airplane.