Airworthiness Directive · Amendment 39-21884 · Drag control system
Schempp-Hirth Flugzeugbau GmbH Gliders
This AD applies to the Schempp-Hirth Flugzeugbau GmbH gliders identified in paragraphs (c)(1) and (2) of this AD, certificated in any category.
(1) Model Duo Discus gliders, serial number (S/N) 1 through 541 inclusive, except S/N 534.
(2) Model Duo Discus T gliders, S/N 1 through 174 inclusive.
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 condition on these products.
(1) For gliders with air brake end stop plastic bushings (22 mm) installed: Within 3 months after the effective date of this AD, replace each air brake end stop plastic bushing (22 mm) with an air brake end stop plastic bushing (32 mm) in accordance with Schempp-Hirth Flugzeugbau GmbH Working Instructions for Technical Note 890-16 rev1 and Technical Note 396-20 rev1 action 1, dated September 18, 2020.
(2) For gliders with single air brake metal end stops installed: Within 3 months after the effective date of this AD, inspect each single air brake metal end stop for overlap in accordance with Schempp-Hirth Flugzeugbau GmbH Working Instructions for Technical Note 396-20 rev1 action 2, dated September 18, 2020. If there is insufficient overlap, before further flight, repair using a method approved by the FAA or the European Union Aviation Safety Agency (EASA).
As of the effective date of this AD, do not install an air brake end stop plastic bushing (22 mm) on any glider.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
