Advisory Circulars

This advisory circular (AC) provides information on electrically caused faults, overheat, smoke, and fire in transport category airplanes. Acceptable means are provided to minimize the potential for these conditions to occur, and to minimize or contain their effects when they do occur.  These means are not mandatory.  An applicant may elect to use any other means found to be acceptable by the Federal Aviation Administration for compliance with the Federal Aviation Regulations (FAR).

This advisory circular (AC) provides guidance material for the airworthiness approval of flight management systems (FMS) in transport category airplanes. Like all AC material, this AC is not mandatory and does not constitute a regulation. It is issued for guidance purposes and to outline a method of compliance with the rules. In lieu of following this method without deviation, the applicant may elect to follow an alternate method, provided the alternate method is also found by the Federal Aviation Administration (FAA) to be an acceptable means of complying with the requirements of Part 25. Because the method of compliance presented in this AC is not mandatory, the terms "shall" and "must" used herein apply only to an applicant who chooses to follow this particular method without deviation.

Provides guidance on the use of SAE Class H11 bolts in primary structure on all aircraft, including gliders and manned free balloons, and on aircraft engines and propellers.

Sets forth an equivalent means of complying with the provisions of Part 25 of the Federal Aviation Regulations (FAR) pertaining to the certification requirements of active flight controls. The procedures set forth herein apply to load alleviation systems (SAS), and flutter suppression systems (FSS). These procedures provide compliance with Part 25 under the equivalent safety provisions of Section 21.21(b)(1) in addition to compliance with the applicable sections of Part 25.

Sets forth an acceptable means, but not the only means, by which compliance may be shown with FAR 25.253 during certification flight tests.

Sets forth one acceptable means of compliance with provisions of FAR 25.1457 (b), (e), and (f) pertaining to area microphones, cockpit voice recorder location, and erasure features.

Sets forth acceptable means of compliance with the “readily accessible” revisions in the Federal Aviation Regulations dealing with excess emergency exits.

Sets forth an acceptable means, but not the only means, of demonstrating compliance with the provisions of Title 14, Code of Federal Regulations (14 CFR) part 25 pertaining to the certification requirements for windshields, windows, and mounting structure. Guidance information is provided for showing compliance with § 25.775(d), relating to structural design of windshields and windows for airplanes with pressurized cabins. Terms used in this AC, such as “shall” or “must,” are used only in the sense of ensuring applicability of this particular method of compliance when the acceptable method of compliance described herein is used. Other methods of compliance with the requirements may be acceptable. While these guidelines are not mandatory, they are derived from extensive Federal Aviation Administration (FAA) and industry experience in determining compliance with 14 CFR. This AC does not change, create any additional, authorize changes in, or permit deviations from, regulatory requirements.

This advisory circular (AC) describes an acceptable means for showing compliance with the requirements of Title 14 of the Code of Federal Regulations (14 CFR) 25.729 regarding the landing gear retracting mechanism requirements. It will be incorporated into AC 25-21, “Certification of Transport Airplane Structure” and 25-22, “Certification of Transport Airplane Mechanical Systems” at a later date.

Sets forth acceptable methods of compliance with provisions of Part 25 of the FAR dealing with the certification requirements for taxi, takeoff, and landing roll design loads. Guidance information is provided for showing compliance with section 25.491 of the FAR relating to structural design for airplane operation on paved runways and taxiways normally used in commercial operations.

This advisory circular provides guidance material for acceptable means, but not the only means, of demonstrating compliance with the requirements of Part 25 of the Federal Aviation Regulations which includes probabilistic terms, as introduced by Amendment 25-23, for airplane equipment, systems, and installations.

This advisory circular (AC) sets forth an acceptable means, but not the only means, of demonstrating compliance with the provisions of part 25 of the Federal Aviation Regulations (FAR) related to the use of landing gear shock absorption tests and analyses to determine landing loads for transport category airplanes.

This advisory circular (AC) describes an acceptable means for showing compliance with the airplane certification requirements related to performance and handling characteristics of transport category airplanes for flight in the icing conditions defined in appendix C of Title 14, Code of Federal Regulations (14 CFR) part 25. Part 25 contains the airworthiness standards applicable to transport category airplanes. The means of compliance described in this document provide guidance to find compliance relative to airplane performance and handling characteristics in appendix C icing conditions.

Describes an acceptable means for showing compliance with the requirements of Section 25.905, “Propellers,” of Title 14, Code of Federal Regulations (CFR) Part 25. It provides guidance on design precautions to take to minimize the hazards that could occur to an airplane if a propeller blade fails or is released by a hub failure. The AC addresses the hazards associated with impact damage.

This advisory circular (AC) provides guidance material for use as an acceptable means, but not the only means, of demonstrating compliance with the airworthiness standards for transport category airplanes that contain hydraulic system requirements. It is not mandatory and does not constitute a regulation.

Provides revised guidelines on the marking of aircraft powerplant instruments and electronic displays (cathode ray tubes, etc.). These guidelines offer acceptable, but not exclusive, methods of compliance with the powerplant instrument color marking requirements.

This advisory circular (AC) provides guidance for the flight test evaluation of transport category airplanes. This AC includes flight test methods and procedures to show compliance with the regulations contained in subpart B of Title 14, Code of Federal Regulations (14 CFR) part 25, which address airplane performance and handling characteristics. This revision, AC 25-7C, is a complete revision to reduce the number of differences from the European Aviation Safety Agency’s Flight Test Guide, provide acceptable means of compliance for the regulatory changes associated with amendments 107, 109, 113, 115, 119, and 123 to part 25, respond to National Transportation Safety Board recommendations, and to provide a general update to reflect current FAA and industry practices and policies.

This AC provides an acceptable means of showing compliance with the underwater locating device (ULD) requirements of the Federal Aviation Regulations for recorder ULD’s.

Provides guidance material for demonstrating compliance with the Federal Aviation Regulations (FAR) pertaining to flammability of aircraft seat cushions.

Provides information and guidance regarding compliance with the provisions of Part 25 of the Federal Aviation Regulations applicable to dynamic testing of seats intended for use in transport category airplanes.

Sets forth an acceptable means , but not the only means, of demonstrating compliance with the provisions of part 25 of the Federal Aviation Regulations (FAR) related to the minimum speed margin between design cruise speed and design dive speed for transport category airplanes.

Presents guidelines and methods for complying with the requirements of section 25.994 of the Federal Aviation Regulations (FAR). These guidelines pertain to protecting fuel system components located in the engine nacelles and the fuselage from damage which could result in spillage of enough fuel to constitute a fire hazard as a consequence of a wheels-up landing on a paved runway. This material is not mandatory and does not constitute a regulation.

This advisory circular (AC) describes an acceptable means for showing compliance with the requirements of Title 14, Code of Federal Regulations (14 CFR), 25.1419(e), (f), (g), and (h), Ice protection. Part 25 contains the airworthiness standards applicable to transport category airplanes a. Installing a primary ice detection system; b. Developing visual cues and installing an advisory ice detection system to alert the flightcrew that the airframe ice protection system (IPS) must be activated; c. Identifying conditions conducive to airframe icing through the use of temperature and visible moisture cues; and d. Including in the airplane flight manual (AFM) procedures for activating and deactivating the airframe IPS.

Provides guidance to airplane manufacturers, modifiers, foreign regulatory authorities, and FAA transport airplane type certification engineers and their designees.