# Proposed AD FAA-2026-4637: Stemme GmbH Gliders

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2026-15-08
- Products: Stemme
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: May 15, 2026, 91 FR 27876
- Comments due: June 29, 2026
- Became: [AD 2026-15-08](https://openairdocs.org/ad/2026-15-08)
- Docket: FAA-2026-4637 (https://www.regulations.gov/docket/FAA-2026-4637, where comments are filed)
- Project: MCAI-2025-01226-G
- FR document: 2026-09801
- Official PDF: https://openairdocs.org/files/sha256/6d/18/6d18fedf6f603ff5794a470ebf1a98071e78fe0f91356f820f9f99defe4d25af (from https://www.govinfo.gov/content/pkg/FR-2026-05-15/pdf/2026-09801.pdf)
- Federal Register: https://www.federalregister.gov/documents/2026/05/15/2026-09801/airworthiness-directives-stemme-gmbh-gliders
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/FR-ADNPRM-2026-09801-00000000000.0001
- Page: https://openairdocs.org/proposed/FAA-2026-4637

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for all Stemme GmbH (Stemme) Model Stemme S 12 gliders. This proposed AD was prompted by reports of fuel leaking around certain copper sealing rings within the fuel system. This proposed AD would require repetitive visual checks of the fuel system for fuel leakage, and replacement of the affected copper sealing ring. This proposed AD would also prohibit the installation of affected parts. The FAA is proposing this AD to address the unsafe condition on these products.

## Notices in this docket

- May 15, 2026: Notice of proposed rulemaking (NPRM). (first notice), FR document 2026-09801, comments due Jun 29, 2026 (https://www.federalregister.gov/documents/2026/05/15/2026-09801/airworthiness-directives-stemme-gmbh-gliders)

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