2025-20-07: Rudder Control System

1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2025-20-07 Fiberglas-Technik Rudolf Lindner GmbH & Co. KG (type certificate previously held by GROB Aircraft AG, Grob Aerospace GmbH i.l., Grob Aerospace GmbH, Burkhart Grob Luft- und Raumfahrt GmbH & Co. KG): Amendment 39-23160; Docket No. FAA-2025-3421; Project Identifier MCAI-2025-01202-G. (a) Effective Date This airworthiness directive (AD) is effective October 17, 2025. (b) Affected ADs None. (c) Applicability This AD applies to Fiberglas-Technik Rudolf Lindner GmbH & Co. KG (type certificate previously held by GROB Aircraft AG, Grob Aerospace GmbH i.l., Grob Aerospace GmbH, Burkhart Grob Luft- und Raumfahrt GmbH & Co. KG) Model G103 TWIN II, G103A TWIN II ACRO, G103C TWIN III ACRO, and G 103 C TWIN III SL gliders, certificated in any category. (d) Subject Joint Aircraft System Component (JASC) Code 2720, Rudder Control System. (e) Unsafe Condition This AD was prompted by a report of corrosion on the inner sides of the welded steel rudder drive plate. The FAA is issuing this AD to detect and address corrosion and water entry in the rudder drive plate. The unsafe condition, if not detected and corrected, could affect the structural integrity of the rudder drive plate, which could lead to reduced control or loss of control of the glider. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Definition For the purpose of this AD, a "serviceable rudder" is a rudder which has accumulated zero hours time-in-service (TIS), or a rudder that has been inspected and modified, as necessary, in accordance with paragraphs (h)(1) and (2) of this AD and is found to be crack and corrosion free. (h) Required Actions (1) Within 50 hours TIS or 3 months, whichever occurs first after the effective date of this AD, and, thereafter, at intervals not to exceed every 12 months, inspect the rudder drive plate for evidence of corrosion or water entry in accordance with the Actions and Instructions, section A, of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (2) Perform a one-time detailed inspection of the rudder drive plate in accordance with the Actions and Instructions, section B, steps 1 and 2 of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025, at whichever compliance time in paragraphs (h)(2)(i) or (ii) of this AD occurs first. (i) Before further flight if during any inspection as required by paragraph (h)(1) of this AD, evidence of corrosion or water ingress is found; or (ii) At the next service life extension inspection that occurs after the effective date of this AD. (3) If, as a result of the inspection required by paragraph (h)(2) of this AD, corrosion of the rudder drive plate is detected that exceeds light surface rust and cannot be removed using steel wool, before further flight, replace the rudder with a serviceable rudder, or contact the Manager, International Validation Branch, FAA; or EASA; or Fiberglas-Technik Rudolf Lindner GmbH & Co. KG EASA Design Organization Approval (DOA) for approved instructions. If approved by the DOA, the approval must include the DOA-authorized signature. (4) If the rudder is replaced with a serviceable rudder, before further flight, apply additional sealing to the rudder drive plate in accordance with the Actions and Instructions, Section C, of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (5) If, as a result of the inspection required by paragraph (h)(2) of this AD, light surface rust is detected, before further flight, modify the rudder drive plate in accordance with the Actions and Instructions, section B, steps 4 through 7 of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (6) If, as a result of the inspection required by paragraph (h)(2) of this AD, no evidence of corrosion or water ingress is detected, before further flight, modify the rudder drive plate in accordance with the Actions and Instructions, section B, steps 5 through 7 of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (7) Following completion of the modification of the rudder drive plate required by paragraph (h)(5) or (h)(6) of this AD, before further flight, apply additional sealing to the rudder drive plate in accordance with the Actions and Instructions, Section C, of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (8) Following completion of the sealing application required by paragraph (h)(7) of this AD, re-install the rudder in accordance with the Actions and Instructions, Section D, of Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. (9) Application of additional sealing to the rudder drive plate, as required by paragraphs (h)(4) and (h)(7) of this AD, constitutes terminating action for the repetitive inspections required by paragraph (h)(1) of this AD for that glider. (i) Alternative Methods of Compliance (AMOCs) The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the International Validation Branch, send it to the attention of the person identified in paragraph (j) of this AD and email to [email protected]. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (j) Additional Information For more information about this AD, contact Adam Hein, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (316) 946-4116; email: [email protected]. (k) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference (IBR) of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Fiberglas-Technik Rudolf Lindner Service Bulletin SB-G10, Revision 1, dated February 27, 2025. Note 1 to paragraph (k)(2)(i): This material contains German to English translation. The European Union Aviation Safety Agency (EASA) used the English translation in referencing the document. For enforceability purposes, the FAA will refer to the Fiberglas-Technik Rudolf Lindner service material in English as it appears on the document. (ii) [Reserved] (3) For Fiberglas-Technik Rudolf Lindner material identified in this AD, contact Fiberglas-Technik Rudolf Lindner GmbH & Co. KG, Steige 3 Walpertshofen, Germany; phone: +49 (0) 7353 22 43; email: [email protected]; website: ltb-lindner.com. (4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected] . Issued on September 30, 2025. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2025-19355 Filed 9-30-25; 4:15 pm]BILLING CODE 4910-13-P