| Number | Title | Status | Office | Date |
|---|---|---|---|---|
| 20-135A |
Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and Criteria
This advisory circular (AC) provides guidance for powerplant fire testing and recognizes the Society of Automotive Engineers (SAE) Aerospace Standard (AS) 6826, Powerplant Fire Test Standards, as an acceptable Means of Compliance (MoC) for demonstrating compliance to the applicable regulations specified in Appendix A. |
Active | AIR-625 | 2025-09-29 |
| 33.67-1 |
Engine Fuel Systems
This advisory circular (AC) provides guidance for demonstrating compliance with the |
Active | AIR-625 | 2024-05-20 |
| 33.70-4 |
Fatigue Life of Nickel Powder Rotating Life-Limited Parts
This advisory circular (AC) provides guidance that may be used to demonstrate compliance with Title 14, Code of Federal Regulations (14 CFR) 33.70 for rotating life-limited engine parts made of nickel powder. |
Active | AIR-625 | 2023-08-15 |
| 20-29C |
Approval and Use of Fuel System Icing Inhibitors (FSII)
This advisory circular (AC) describes an acceptable method to demonstrate compliance with Title 14, Code of Federal Regulations (14 CFR) §§ 23.2620(a)(1), 25.1583(b)(1), 27.1583(b)(1), 29.1583(b)(1), 33.7(b)(2), and 33.7(c)(2) regarding the requirements for the approval and use of Fuel System Icing Inhibitors (FSII) in engines and aircraft. |
Active | AIR-625 | 2024-03-27 |
| 33-12 |
Geometry and Dimensional Considerations for Comparative Test and Analysis for Turbine Engine and Auxiliary Power Unit (APU) Replacement, and Repaired Parts
This advisory circular (AC) provides guidance to support the development of technical data needed to show that an engine or APU replacement part complies with the airworthiness requirements under test and computation, per Title 14, Code of Federal Regulations (14 CFR) 21.303, using the comparative test and analysis approach. |
Active | AIR-625 | 2025-09-08 |
| 20-197 |
Turbine Engine and Airframe Sensor Icing Compliance
This advisory circular (AC) describes an acceptable method for demonstrating compliance with title 14, Code of Federal Regulations (14 CFR) 33.28, 33.68, 33.75,33.89, a nd 33.91, concerning mixed phase, ice crystal icing (ICI), and other icingconditions for engine inlet sensors. |
Active | AIR-625 | 2025-06-18 |
| 33.15-1A | Manufacturing Process of Premium Quality Titanium Alloy Rotating Engine Components | Active | AIR-625 | 2025-09-08 |
| 33.17-1B |
Engine Fire Protection § 33.17
This advisory circular (AC) provides definitions, guidance, and acceptable methods, but not the only methods, to demonstrate compliance with the engine fire protection requirements of title 14 Code of Federal Regulations (14 CFR 33.17). |
Active | AIR-625 | 2025-05-20 |