2026-15-08: Aircraft Fuel System

1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2026-15-08 Stemme GmbH: Amendment 39-23420; Docket No. FAA-2026-4637; Project Identifier MCAI-2025-01226-G. (a) Effective Date This airworthiness directive (AD) is effective September 3, 2026. (b) Affected ADs None. (c) Applicability This AD applies to all Stemme GmbH Model Stemme S 12 gliders, certificated in any category. Note 1 to paragraph (c): All of the affected airplanes were produced and delivered with the affected copper sealing rings installed. (d) Subject Joint Aircraft System Component (JASC) Code 2800, Aircraft Fuel System. (e) Unsafe Condition This AD was prompted by reports of fuel leaking around certain copper sealing rings within the fuel system. The FAA is issuing this AD to prevent fuel leakage in the fuel system. The unsafe condition, if not addressed, could result in an in-flight fire. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Definitions For the purpose of this AD, the definitions in paragraphs (g)(1) through (4) of this AD apply. (1) An "affected location" is any of the following: (i) The copper sealing ring within the fuel pump set assembly having part number (P/N) 128201, between the screw-in adapter having P/N 831099 and the fuel distributor having P/N 128229, and between the screw-in adapter having P/N 831099 and the fuel distributor having P/N 128228. The fuel pump set assembly P/N 128201 is located at the front left area of the middle fuselage and may be accessed from below when the main landing gear is extended. (Location defined in Stemme Service Bulletin (SB) P062-980082, Revision 01, dated July 15, 2025, Page 1 of 3, Action 2 and Figure 1). (ii) The copper sealing ring within the drainer complete having P/N 128207, between the screw-in adapter having P/N 831099 and the drainer attachment having P/N 128271. The drainer complete P/N 128207 is located at the main landing gear bay and may be accessed from below when the main landing gear is extended. (Location defined in Stemme SB P062-980082, Revision 01, dated July 15, 2025, Page 2 of 3, Action 3 and Page 3 of 3 Figure 2). (2) An "affected part" is a copper sealing ring having P/N D7603-12016-CU. (3) "Group 1 gliders" are gliders that have an affected part installed. (4) "Group 2 gliders" are gliders that do not have an affected part installed. (h) Required Actions (1) For Group 1 gliders, before further flight after the effective date of this AD and thereafter before each flight until the replacement required by paragraph (h)(2) is accomplished, perform a visual check using a light source of the affected locations for indications of fuel leakage (staining, wetness, dripping, etc.). The owner/operator (pilot) holding at least a private pilot certificate may perform the visual check and must enter compliance with the applicable paragraph of this AD into the glider maintenance records in accordance with 14 CFR 43.9(a) and 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417. (2) For Group 1 gliders, at whichever compliance time in paragraph (h)(2)(i) or (ii) that occurs first, replace the affected part at each affected location with a sealing ring having P/N 831984 in accordance with the instructions of Action 2 or Action 3 of Stemme SB P062-980082, Revision 01, dated July 15, 2025, as applicable. (i) Before further flight if any leakage is detected during any preflight check required by paragraph (h)(1) of this AD. (ii) Within 100 hours time-in-service after the effective date of this AD. (i) Installation Prohibition For Group 1 and Group 2 gliders: As of the effective date of this AD, do not install an affected part as defined in paragraph (g)(2) of this AD on any glider. (j) 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 (k) 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. (k) Additional Information For more information about this AD, contact George Weir, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 222-4045; email: [email protected]. (l) 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) Stemme Service Bulletin P062-980082, Revision 01, dated July 15, 2025. (ii) [Reserved] (3) For Stemme material identified in this AD, contact Stemme GmbH, Flugplatzstrasse F2 Nr. 6-7, Strausberg, Germany 15344; phone: +49 (0) 3341 3612; email: [email protected]; website: stemme.com . (4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 1100 Main, Kansas City, MO 64105. 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 July 24, 2026. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2026-15466 Filed 7-29-26; 8:45 am]BILLING CODE 4910-13-P