Airworthiness Directives; Learjet, Inc., Airplanes

We are adopting a new airworthiness directive (AD) for certain Learjet, Inc., Model 60 airplanes. This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the upper fuselage skin under the aft oxygen line fairing is subject to multi-site damage (MSD). This AD requires a one-time inspection of the fuselage skin for corrosion, and related investigative and corrective actions if necessary. We are issuing this AD to address the unsafe condition on these products.