AD 2021-26-25 Requires Replacing Certain Air Brake End Stop Bushings

The FAA is adopting a new airworthiness directive (AD) for certain Schempp-Hirth Flugzeugbau GmbH Model Duo Discus and Duo Discus T gliders. This AD was prompted by mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as jerky extension of the air brakes at very high air speeds, including cases where the air brake blades interlock. This AD requires replacing certain air brake end stop bushings, inspecting certain other air brake end stops, and repairing if necessary. The FAA is issuing this AD to address the unsafe con