Aircraft Certification Service (AIR) Draft Advisory Circulars (ACs) Open for Comment
| Document Title: | AC 20-194, Airworthiness Approval of Air Traffic Control Radar Beacon System (ATCRBS)/Mode S Transponders |
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| Summary: | The Federal Aviation Administration (FAA) is issuing this advisory circular (AC) to guide applicants seeking airworthiness approval for installations of Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) transponders certified to Technical Standard Order (TSO)-C112c or later, Air Traffic Control Radar Beacon System/Mode Select (ATCRBS/Mode S) Airborne Equipment. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | July 6, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov |
| Document Title: | AC 25-17A CHG2, Transport Airplane Cabin Interiors Crashworthiness Handbook |
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| Summary: | Change 2 provides guidance for several new or amended cabin interiors regulations adopted by amendment 25-XXX. That amendment enables private use and low occupancy cabin interior arrangements, adds a definition of low occupancy, addresses passenger seat size and spacing, allows carriage of persons authorized by § 121.583 on cargo airplanes, and allows installation of medical stretchers with relief from the dynamic emergency landing conditions. In addition, Change 2 also provides guidance for other cabin interiors regulations adopted by amendments 25-114, 25-116, 25-123, 25-128, and 25-142. Regulatory text is available digitally in many places on the internet. In many cases the regulatory text is not included in an effort to minimize the changed pages of this document. In these cases, a link to the specific regulation section and amendment level is provided to the FAA’s online Dynamic Regulatory System (DRS). |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 25.981-2B, Fuel Tank Flammability Reduction Means |
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| Summary: | This AC provides information and guidance on compliance with the airworthiness standards for transport category airplanes about limiting the time a fuel tank may be flammable or mitigation of hazards from flammable fuel air mixtures within fuel tanks. This guidance is applicable to transport category airplanes for which a new, amended, or supplemental type certificate is requested, and for which amendment 25-XXX applies. It is also applicable to certain existing design approval holders and certain pending applications for new type certificates, supplemental type certificates and amended type certificates where required by §§ 26.33, 26.35, 26.37, and 26.39, contained in subpart D to title 14, Code of Federal Regulations (CFR) part 26, Fuel Tank Flammability. Guidance on compliance with the associated requirements for operators of affected airplanes that must comply with requirements in 14 CFR parts 121, 125, and 129, to incorporate flammability reduction or ignition mitigation means by specified dates, will be contained in a separate document. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 25.841-X, Regulatory Guidance on Compliance with § 25.841(a) |
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| Summary: | This AC provides information and guidance on compliance with the airworthiness standards for transport category airplanes about limiting the time a fuel tank may be flammable or mitigation of hazards from flammable fuel air mixtures within fuel tanks. This guidance is applicable to transport category airplanes for which a new, amended, or supplemental type certificate is requested, and for which amendment 25-XXX applies. It is also applicable to certain existing design approval holders and certain pending applications for new type certificates, supplemental type certificates and amended type certificates where required by §§ 26.33, 26.35, 26.37, and 26.39, contained in subpart D to title 14, Code of Federal Regulations (CFR) part 26, Fuel Tank Flammability. Guidance on compliance with the associated requirements for operators of affected airplanes that must comply with requirements in 14 CFR parts 121, 125, and 129, to incorporate flammability reduction or ignition mitigation means by specified dates, will be contained in a separate document. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 20-175A, Controls for Flightdeck Systems |
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| Summary: | This advisory circular (AC) provides guidance for the installation and airworthiness approval of flightdeck system controls, primarily from a human factors (HF) perspective. This AC addresses cursor control devices, software generated controls (soft controls), touch screens and speech recognition systems, as well as dedicated controls such as physical switches and knobs. It does not address primary flight controls, secondary flight controls, or controls that are located outside the flightdeck. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 25.1155-X, Reverse Thrust and Propeller Pitch Settings Below the Flight Regime |
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| Summary: | This advisory circular (AC) describes acceptable means for showing compliance with the requirements of title 14, Code of Federal Regulations (14 CFR) 25.1155, Reverse thrust and propeller pitch settings below the flight regime. The rule requires a means to prevent the flightcrew on propeller-powered airplanes from inadvertently or intentionally placing the power lever below flight idle while in-flight, unless the airplane has been certified for that type of operation. The rule also requires a similar provision for turbojet-powered airplanes with thrust reverser systems that are designed for use only on the ground. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 25.1193-X, Cowling and Nacelle Skin – Fire Protection |
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| Summary: | This advisory circular (AC) provides guidance for the prevention of hazards caused by a fire, within an engine or auxiliary power unit (APU) fire zone, burning through the fire zone external skin or exiting through a skin opening. Title 14 of the Code of Federal Regulations (14 CFR) 25.1193 requires accessory section cowls subject to flame in the event of a fire in the engine power section and other portions of the cowling subject to exhaust system heat or exhaust gases to be fireproof. It requires engine nacelle skin areas subject to flame in the engine power or accessory sections to be fireproof. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
| Document Title: | AC 25-7D CHG 2, Flight Test Guide for Certification of Transport Category Airplanes |
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| Summary: | This AC provides updated guidance for the flight test evaluation of transport category airplanes. These guidelines provide an acceptable means of demonstrating compliance with the pertinent regulations of Title 14, Code of Federal Regulations (14 CFR) part 25. The methods and procedures described herein have evolved through many years of flight-testing transport category airplanes and, as such, represent current certification practice. |
| Documents for Download: | Draft Document Comment Matrix |
| Comments Due: | August 26, 2026 |
| How to Comment: | Email Comments to: 9-AVS-TechWriters@faa.gov Physical Address: |
Related Information
- Final Aircraft Certification advisory circulars, other policy documents, and technical standard orders (TSOs) are available on FAA's Dynamic Regulatory System (DRS)
- Advisory Circulars (ACs)
- FAA Regulations
- Orders & Notices
- Policy & Guidance
- To comment on rulemaking documents, please visit the DOT Docket Management System.
Last updated: Monday, June 29, 2026