AD 2023-03-10 Airworthiness Directives; Schempp-Hirth Flugzeugbau GmbH Gliders

This AD applies to Schempp-Hirth Flugzeugbau GmbH Model Duo Discus and Duo Discus T gliders, all serial numbers, certificated in any category.

Comply with this AD within the compliance times specified, unless already done.

(1) Before further flight after the effective date of this AD and thereafter at intervals not to exceed 12 months, inspect the elevator U-bracket for indications of cracking by following paragraphs 1.a) and 1.b) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). For the purposes of this AD, indications of cracking include elastic and permanent twisting. Note 1 to paragraph (g)(1): Technical Note Schempp-Hirth Flugzeugbau GmbH Technical Note 396-22; and Schempp-Hirth Flugzeugbau GmbH Technical Note 890-18; both Revision 1; both dated October 13, 2022, contain information related to this AD. Note 2 to paragraph (g)(1): This service information contains German to English translation. The European Union Aviation Safety Agency (EASA) used the English translation in referencing the document from Schempp-Hirth Flugzeugbau GmbH. For enforceability purposes, the FAA will refer to the Schempp-Hirth Flugzeugbau GmbH service information in English as it appears on the document. (i) If indications of cracking are present, remove the elevator U-bracket and inspect it for any crack and broken weld seam by following paragraph 1.c) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). (ii) If no indications of cracking are present and you do not have suitable tools such as a mirror, flashlight, borescope, or equivalent to do the inspection required in paragraph (g)(1)(i) of this AD, remove the elevator U-bracket and inspect for any crack and broken weld seam by following paragraph 1.c) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). (iii) If no indications of cracking are present and you have suitable tools such as a mirror, flashlight, borescope, or equivalent to do the inspection required in paragraph (g)(1)(i) of this AD, inspect the elevator U-bracket for any crack and broken weld seam by following paragraph 1.c) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). This inspection may be done without removing the elevator U-bracket. (2) If during any inspection as required by paragraph (g)(1) of this AD, there is any crack or broken weld seam in the elevator U-bracket, before further flight, replace the elevator U-bracket by following paragraph 1.d) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). (3) Before further flight after completing the actions in paragraph (g)(1) and (2) of this AD, as applicable, and thereafter at intervals not to exceed 12 months, rig the horizontal tail on the fin by following paragraph 1.d) of the Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). (4) Before further flight after completing the action in paragraph (g)(3) of this AD, and thereafter at intervals not to exceed 12 months, inspect for softness and play in the rear connection between the horizontal tail and the rear attachment on the fuselage by following paragraph 1.d) of Schempp-Hirth Flugzeugbau GmbH Working Instructions. Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). If there is softness or play, before further flight, do the applicable corrective actions by following paragraph 1.d) of the Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). Where the service information specifies contacting Schempp-Hirth Flugzeugbau GmbH for a repair, instead use a method approved by the Manager, International Validation Branch, FAA; EASA; or Schempp-Hirth Flugzeugbau GmbH's EASA Design Organization Approval (DOA). If approved by the DOA, the approval must include the DOA-authorized signature. (5) Before further flight after completing the action in paragraph (g)(4) of this AD, and thereafter at intervals not to exceed 12 months, inspect the foam support for compression between the vertical and horizontal tail by following paragraph 1.d) of Schempp-Hirth Flugzeugbau GmbH Working Instructions Technical Note 396-22, 380-3, 868-24, 890-18, A532-10, Revision 0, dated February 28, 2022 (issued as one document). If the foam support has settled to the point that it cannot be further compressed, it must be replaced before further flight.

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 identifies the unsafe condition as cracks in the connecting tube of the elevator U-bracket of the horizontal tail, which could compromise the stiffness of the elevator control system and of the attachment of the horizontal tail. The FAA is issuing this AD to address this condition. The unsafe condition, if not addressed, could result in failure of the elevator control system, loss of the horizontal tail attachment, and consequent loss of glider control.

None.