AD FAA-2018-0506

We are adopting a new airworthiness directive (AD) for certain Airbus SAS Model A350-941 airplanes. This AD was prompted by the discovery of inadequate corrosion protection in certain areas of the horizontal stabilizer and the rear fuselage cone structure. This AD requires application of sealant and protective treatment on the affected areas of the horizontal stabilizer and the rear fuselage cone structure and, for certain airplanes, modification of the trimmable horizontal stabilizer (THS) torsion box and re-identification of the elevator. We are issuing this AD to address the unsafe condition on these products.