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Advisory Circulars

Lister below are Advisory Circulars that i have found helpful through the years. These are Circulars that every Mechanic, Repairman and Aircraft Owner should have at hand for review, or know where to easily find, before conducting anything Major or Minor on an aircraft.  Just click the title and it will take you to the Advisory Circular on the FAA's website.

Can't find what you are looking for? Conduct your own search. the link below takes you to the FAAs website where you can conduct a search.


Advisory Circulars Search:

AC 20-62E

Eligibility, Quality, & Identification of Aeronautical Replacement Parts

Office: AFS-300

This advisory circular (AC) provides information and guidance for use in determining the quality, eligibility and traceability of aeronautical parts and materials intended for installation on U.S. type-certificated (TC) products and articles, and to enable compliance with the applicable regulations.

Status: Activess.

AC 21-47 

Submittal Of Data To An ACO, A DER Or An ODA For A Major Repair Or Major Alteration

Office: AIR-100


This advisory circular (AC) provides guidance for creating a complete data package when data is submitted to a Federal Aviation Administration (FAA), aircraft certification office (ACO) or to FAA designees, to support a major repair or major alteration.


Status: Active

AC 21-44 

Issuance of Export Airworthiness Approvals Under 14 CFR Part 21 Subpart L

Office: AIR-100


This advisory circular (AC) provides guidance on how to show compliance with Title 14 of the Code of Federal regulations (14 CFR) part 21, subpart L, Export Airworthiness Approvals. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to comply with these requirements. However, if you use the means described in this AC, you must follow it in all important respects.

Status: Active

AC 21-47

Acceptable Methods, Techniques, and Practices - Aircraft Alterations

Office: AFS-300

AC 43.13-2B.pdf (PDF, 6.1 MB)

Status: Active

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Fabrication of Aircraft parts by Maintenance Personnel

Office: AFS-300


This advisory circular (AC) ensures that parts fabricated during maintenance and alteration have an equivalent level of safety as those parts produced under the original design holder’s production certificate. This AC provides one means of complying with the requirements of Title 14 of the Code of Federal Regulations (14 CFR) parts 21 and 43 for the design and fabrication of parts by persons performing maintenance and alterations using methods, techniques, and practices acceptable to the Administrator. As required by regulations, such parts fabrication and their implementation must be accomplished "in such a manner...that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition." This AC is not mandatory and does not constitute a regulation. It outlines one method (but not the only method) of compliance with the rules. A person may elect to follow an alternative method, provided the Federal Aviation Administration (FAA) finds the alternative method to be an acceptable means of complying with the applicable requirements of 14 CFR.


Status: Active



AC 120-87C

Use of Child Restraint Systems on Aircraft

Office: AFS-200


This advisory circular (AC) provides information and practices regarding the use of child restraint systems (CRS) on aircraft. The Federal Aviation Administration (FAA) intends for operators to use this as a resource during the development, implementation, and revision of an air carrier’s standard operating procedures (SOP), Web sites and training programs regarding the use of CRSs. FAA Initiatives. This AC is one of several FAA initiatives designed to address safety concerns of the National Transportation Safety Board (NTSB). It is a part of the FAA’s ongoing commitment to educate and inform aircraft operators, crewmembers, and airline passengers regarding the use of CRSs on aircraft in order to encourage and increase the use of approved CRSs. For more information, refer to the following FAA Web site:


 http://www.faa.gov/passengers/fly_children/.

Regulatory Requirements. In addition, this AC provides information to air carriers conducting Title 14 of the Code of Federal Regulations (14 CFR) part 121 operations about the requirement to make available on their Web sites the width of the narrowest and widest passenger seats in each class of service for each make, model, and series (M/M/S) of airplane used in passenger-carrying operations. If an air carrier does not have a Web site, the air carrier is not required to establish a Web site in order to comply with this regulation.


Status: Active

AC 20-154

Guide for Developing a Receiving Inspection System for Aircraft Parts and Material - Change 1

Office: AFS-300


This advisory circular (AC) provides guidance and information for incorporation into operators’ existing receiving/inspection systems to help prevent the introduction of unairworthy parts into inventories. The aim is to establish sufficient traceability to establish that the part(s) were manufactured under Title 14 of the Code of Federal Regulations (14 CFR) part 21, were previously determined to be Airworthy under 14 CFR part 43, and produced to established industry or U.S. Government standards or accepted foreign standards. Like all AC material, this AC is not mandatory and does not constitute a regulation. It is issued for guidance and to outline a method of compliance with the rules. This is one means but not the only means for developing a receiving inspection system. In lieu of following the method(s) prescribed herein, the applicant may elect to follow an alternate method. .


Status: Active

AC 21-47 

Instructions for Completion of FAA Form 337

Office: AFS-300


This AC provides instructions for completing Federal Aviation Administration (FAA) Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance).


Status: Active

AC 43-11

Reciprocating Engine Overhaul Terminology and Standards - Including Change 1

Office: AFS-340


This advisory circular (AC) discusses engine overhaul terminology and standards used in the aviation industry. This AC will: a. Inform owners or operators of the variety of terms used to describe types of reciprocating engine overhaul; b. Clarify the standards used by the industry during reciprocating engine overhaul; an c. Review Title 14 of the Code of Federal Regulations (14 CFR) regarding engine records and standards.

Status: Active

AC 65-24 

Certification of a Repairman (General)

Office: AFS-350


This advisory circular (AC) provides information and guidance to the aviation p.1blic on the procedures for certification of a repairman. It also introduces a new ooncept for certification, wherein formal training may be substituted for experience


Status: Active

AC 43-6D 

Altitude Reporting Equipment and Transponder System Maintenance and Inspection Practices

Office: AFS-300


This advisory circular (AC) provides information concerning acceptable methods of testing altimeters, static systems, altitude encoders, and air traffic control (ATC) transponder systems (ATCTS). This guidance also applies to the above articles, but does not include all requirements for testing the article, when part of 1090 megahertz (MHz) Extended Squitter (ES) or Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) systems. Like all advisory material, this AC is not in itself mandatory and does not constitute a regulation. It provides a means, but not the only means, of testing at the time of original installation, after performing repairs, or during scheduled recertification. Where indicated, this AC ensures compliance with regulatory requirements. Operators may elect to follow an alternative method that the Federal Aviation Administration (FAA) has found acceptable.


Status: Active

AC 43-18

Fabrication of Aircraft parts by Maintenance Personnel

Office: AFS-300


This advisory circular (AC) ensures that parts fabricated during maintenance and alteration have an equivalent level of safety as those parts produced under the original design holder’s production certificate. This AC provides one means of complying with the requirements of Title 14 of the Code of Federal Regulations (14 CFR) parts 21 and 43 for the design and fabrication of parts by persons performing maintenance and alterations using methods, techniques, and practices acceptable to the Administrator. As required by regulations, such parts fabrication and their implementation must be accomplished "in such a manner...that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition." This AC is not mandatory and does not constitute a regulation. It outlines one method (but not the only method) of compliance with the rules. A person may elect to follow an alternative method, provided the Federal Aviation Administration (FAA) finds the alternative method to be an acceptable means of complying with the applicable requirements of 14 CFR.


Status: Active

AC 00-68

Aircraft Certification Service Voluntary Disclosure Reporting Program

Office: AIR-150


This advisory circular (AC) provides information and guidance to Federal Aviation Administration (FAA) Aircraft Certification Service (AIR) Production Approval Holders (PAHs), Design Approval Holders (DAHs), and Organization Designation Authorization Holders (ODA Holders) who choose to voluntarily disclose apparent noncompliance with Title 14 of the Code of Federal Regulations (14 CFR). The procedures and practices outlined in this AC generally apply when PAHs, DAHs or ODA Holders voluntarily disclose noncompliance with regulatory requirements. These procedures and practices do not apply, however, to those persons who: (1) violate 14 CFR 21.2, Falsification of Applications, Reports, or Records; (2) are required to report failures, malfunctions, and defects pursuant to 14 CFR 21.3, but fail to make those reports in the timeframe required by the regulations; or (3) fail to report unsafe conditions pursuant to 14 CFR 183.63, Continuing Requirements: Products, Parts or Appliances. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means to voluntarily disclose an apparent noncompliance. If you use the AC to voluntarily disclose noncompliance, the processes and requirements in this AC must be followed.


Status: Active

AC 65-32a LSA

Certification of Repairmen (Light-Sport Aircraft)

Office: AFS-300


This advisory circular (AC) provides the public with information regarding the certification of repairmen (light-sport aircraft (LSA)) with maintenance and inspection ratings, the acceptability of training courses, and the continued airworthiness of LSA. The guidance contained in this AC is based on the Final Rule, Certification of Aircraft and Airmen for the Operation of Light-Sport Aircraft, which was published in the Federal Register (FR) on July 27,2004. The rule became effective September 1,2004.


Status: Active

AC 00-1.1B

System Safety Analysis and Assessment for Part 23 Airplanes

Office: ACE-100


This advisory circular (AC) sets forth an acceptable means of showing compliance with Title 14 of the Code .of Federal Regulations (14 CFR), § 23.1309, through Amendment 23-6.2: for equipment, systems, and installations in 14 CFR part 23 airplanes. 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. An applicant may elect to follow an alternate method, provided the FAA finds it to be an acceptable means of complying with the applicable requirements of 14 CFR. However, if the applicant uses the means described in the AC, they must follow it in all important respects.


Status: Active

AC 120-117

Voluntary Disclosure Reporting Program for Apparent Violations of the Drug and Alcohol Testing Regulations

Office: AAM-800


Any employer or contractor regulated under Title 14 of the Code of Federal Regulations (14 CFR) part 120 may voluntarily disclose to the Federal Aviation Administration (FAA) violations of the drug and alcohol testing regulations under the voluntary disclosure reporting program (VDRP) described in this Advisory Circular (AC). This AC provides the information and guidance material an employer or contractor needs in order to voluntarily disclose an apparent violation of the drug and alcohol testing regulations listed in paragraph 3 of this AC.


Status: Active

AC 23-2A 

Flammability Tests

Office: ACE-100


This advisory circular (AC) sets forth an acceptable means of showing compliance with Title 14 Code of Federal Regulations (14 CFR) part 23 and Civil Air Regulations (CAR) 3 for the flammability testing of systems and equipment in normal, utility, acrobatic, and commuter category airplanes and airships. This AC applies to Subparts D and F of part 23 and applicable sections of CAR 3 as listed in Paragraph 6a. The revision addresses systems and equipment and references other general ACs that provide guidance for other subparts of part 23.


Status: Active



AC 21-25B

Approval of Modified Seating System Initially Approved Under a Technical Standard Order

Office: AIR-100


This advisory circular (AC) provides information, clarification, and procedural guidance for the approval and installation of modified technical standard order (TSO)approved seating systems in U.S. type-certificated aircraft. In this AC, we address modifications that result from design changes, repairs, and alterations pursuant to Title 14 of the Code of Federal Regulations (14 CFR) parts 21 and 43. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to modify TSO seating systems. However, if you use the means described in this AC, you must follow it in all important respects.


Status: Active

AC 121-37A

Voluntary Disclosure Reporting Program - Hazardous Materials

Office: AXH-1


This advisory circular (AC) provides guidance to holders of certificates under Title 14 of the Code of Federal Regulations (CFR) parts 119 and 125 and foreign air carriers issued operations specifications under 14 CFR part 129 (operators) who voluntarily disclose to the Federal Aviation Administration (FAA) their violation(s) of certain hazardous materials regulations (HMR) under this voluntary disclosure reporting program (VDRP). This also provides guidance on the new process used to submit hazmat-related voluntary disclosures, which is now closely aligned with the process used by the F AA's Flight Standards Service (AFS).


Status: Active

AC 20-27G​

Certification and Operation of Amateur-Built Aircraft

Office: AIR-200


This Advisory Circular (AC) provides information about Title 14, Code of Federal Regulations (14 CFR) part 21, Certification Procedures for Products and Parts, § 21.191(g) for the purpose of operating amateur-built aircraft.


Status: Active

AC 20-33B 

Technical Information Regarding Civil Aeronautics Manuals 1, 3, 4a, 4b, 5, 6, 7, 8, 9, 13, and 14

Office: AIR-100


Advises the public that policy information contained in the subject Civil Aeronautics Manuals may be used in conjunction with specific sections of the Federal Aviation Regulations.


Status: Active

AC 20-37E 

Aircraft Propeller Maintenance

Office: AFS-350


Provides information and suggested procedures to increase service life and to minimize blade failures of metal propellers.


Status: Active

AC 20-42D

Hand Fire Extinguishers for Use in Aircraft

Office: AIR-120


This advisory circular (AC) gives you guidance for the fire-fighting effectiveness, selection and safe-use of hand fire extinguishers in airplanes and rotorcraft. In it we will also show you how to gain Federal Aviation Administration (FAA) approval of hand fire extinguishers for aircraft.


Status: Active

AC 20-77B

Use of Manufacturers’ Maintenance Manuals

Office: AFS-300


This advisory circular (AC) informs owners and operators about the usefulness of manufacturer’s maintenance manuals for servicing, repairing, and maintaining aircraft, engines, and propellers.


Status: Active

AC 20-106

Aircraft Inspection for the General Aviation Aircraft Owner

Office: AFS-340


Describes techniques used in aircraft inspections. Designed to familiarize owner, pilots, student mechanics, and others with inspection procedures, it does NOT qualify an individual to make airworthiness determinations.


Status: Active

AC 21-31A 

Quality Control for the Manufacature of Non-Metallic Compartment Interior Components

Office: AIR-200


a. This advisory circular (AC) 1) Provides information about Title 14, Code of Federal Regulations (14 CFR), part 21, Certification Procedures for Products, Articles, and Parts. 2) Provides information for both an applicant for, and a holder of, a production approval, and refers to both as a production approval holder (PAH). 3) Is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to comply with these requirements. However, if you use the means described in the AC, you must follow it in all important respects. b. The Federal Aviation Administration (FAA) will consider other methods of compliance that the applicant elects to present. More so than metallic articles, non-metallic articles obtain the majority of their attributes directly from their manufacturing process. Many quality systems established for the manufacture of metallic articles may be unable to provide the additional controls necessary to ensure conformance to design requirements of non-metallic articles. This AC addresses those areas of a quality system that may require expansion to adequately accommodate the manufacture of non-metallic compartment interior articles.


Status: Active

AC 23-27

Parts and Materials Substitution for Vintage Aircraft

Office: ACE-100


This advisory circular (AC) provides guidance for substantiating parts or materials substitutions to maintain the safety of old or out-of-production general aviation (GA) aircraft, or other GA aircraft where the parts or materials are either difficult or impossible to obtain. This AC also provides guidance about the data required to gain Federal Aviation Administration (FAA) approval for making these substitutions. This AC does not include specific approvals for installations. It provides guidelines to follow when collecting information needed for an FAA approval. The material in this AC is neither mandatory nor regulatory in nature and does not constitute a regulation. You may follow an alternate FAA-approved method. However, if you use the means described in this AC, you must follow it in all respects. Mandatory words such as "must" apply only to those who seek to show compliance to a specific rule by use of a method prescribed in this AC without deviation.


Status: Active

AC 33-6

Weld Repair of Aluminum Crankcases and Cylinders of Piston Engines - Including Change 1

Office: ANE-110


This advisory circular (AC) provides guidance to demonstrate compliance with the requirements of Title 14, Code of Federal Regulations (14 CFR) part 33, Airworthiness Standards: Aircraft Engines. It addresses development of weld repairs which are not contained in the engine manufacturer's "Instructions for Continued Airworthiness" (Maintenance Manual). It provides guidance to clarify the areas which should be addressed by an applicant's repair procedure, and/or substantiating data when seeking an approval for weld repair of aluminum crankcases or cylinders of piston engines. This advisory circular also includes information on critical areas of welding, qualifications of welder's, inspection techniques, the thermal processes, and technical data required. This advisory circular references industry and military specifications which are acceptable for use by repair stations as approved data.


Status: Active

AC 21-45 

Commercial Parts

Office: AIR-100


This advisory circular (AC) explains how you can use the new provision in Title 14 of the Code of Federal Regulations (14 CFR) §§ 21.1(a)(3), 21.8, 21.9(a)(4), and 21.50(c) for commercial parts. This AC is not mandatory and does not constitute a regulation. In it, we describe an acceptable means, though it is not the only means, to comply with 14 CFR §§ 21.8, 21.9(a)(4), and 21.50(c) for commercial parts. However, if you use the means described in this AC, you must follow it entirely.


Status: Active

AC 39-10

Alternative Methods of Compliance

Office: AIR-100


This advisory circular (AC) presents guidance for persons seeking approval of an alternative method of compliance (AMOC) to an airworthiness directive (AD). This AC also provides answers to common questions regarding AMOCs.


Status: Active

AC 43-9C

Maintenance Records

Office: AFS-340


Describes methods, procedures and practices determined to be acceptable for showing compliance with the general aviation maintenance record-making and record-keeping requirements of Title 14 of the Code of Federal Regulations (14 CFR) parts 43 and 91. This material is issued for guidance and outlines several methods of compliance with the regulations.


Status: Active

AC 43-4B

Corrosion Control for Aircraft

Office: AFS-300


This advisory circular (AC) is a summary of the current available data regarding identification and treatment of corrosive attack on aircraft structures and engine materials. Corrosion inspection frequency, corrosion identification, and especially corrosion treatment continues to be the responsibility of the operator. These inspections should be accomplished per this AC, the manufacturer’s recommendations, or the operator’s own maintenance program. The procedures in this AC are an acceptable means, but not the only acceptable means, of corrosion treatment. The information in this AC is applicable to aircraft for which the manufacturer has not published corrosion control information. Where the airframe or engine manufacturer has published a recommended corrosion inspection schedule and treatment program, the applicable program must take precedence over the recommendation of this AC.

Status: Active

AC 23.1309-1E

System Safety Analysis and Assessment for Part 23 Airplanes

Office: ACE-100


This advisory circular (AC) sets forth an acceptable means of showing compliance with Title 14 of the Code .of Federal Regulations (14 CFR), § 23.1309, through Amendment 23-6.2: for equipment, systems, and installations in 14 CFR part 23 airplanes. 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. An applicant may elect to follow an alternate method, provided the FAA finds it to be an acceptable means of complying with the applicable requirements of 14 CFR. However, if the applicant uses the means described in the AC, they must follow it in all important respects.


Status: Active

AC 43-210A

Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations -
 Change 1

Office: AFS-300


This advisory circular (AC) describes a standardized procedure for requesting approval of technical data associated with major repairs/major alterations. This AC also provides information that can help determine if a proposed repair/alteration requires approved data, guidance and standardized procedures for obtaining field approval (or approval by other means) of data, and instructions for completing the field approval checklist. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to obtain approved data for a major repair or major alteration. However, if you—whether you’re an aircraft owner, operator, or Aviation Maintenance Technician (AMT), collectively termed an applicant—use the means described in the AC, you must follow it in all important respects.


Status: Active

AC 43-215

Standardized Procedures for Performing Aircraft Magnetic Compass Calibration

Office: AFS-300


This advisory circular (AC) describes procedures for calibrating an aircraft magnetic compass to minimize the effect of aircraft-induced magnetic fields. These procedures are often referred to as “swinging the compass” or a “compass swing.” This AC is not mandatory and does not constitute a regulation. These means are not the only means to perform aircraft compass calibration. However, if you use one of the means described in this AC, you must follow it in all important respects. The content of this AC may be of interest to aircraft technicians performing compass swings or to users of aircraft compass systems.


Status: Active

AC 43-213A 

Parts Marking Identification - Including Change 1

Office: AFS-300


This advisory circular (AC) provides information and guidance on developing procedures for part marking and part re-marking when performing maintenance, alteration, and fabrication, including the fabrication of owner- or operator-produced parts.


Status: Active

AC 61-65H

Certification: Pilots and Flight and Ground Instructors

Office: AFS-800


This advisory circular (AC) provides guidance for pilot and instructor applicants, pilots, flight instructors, ground instructors, and examiners on the certification standards, knowledge test procedures, and other requirements in Title 14 of the Code of Federal Regulations (14 CFR) part 61.


Status: Active

AC 91-44A

Operational and Maintenance Practices for Emergency Locator Transmitters and Receivers - Change 1

Office: AFS-300


Combines and updates material in several Advisory Circulars on the subject of emergency locator transmitters (ELT) receivers for airborne service.


Status: Active

AC 91-91

Maintaining Public Aircraft

Office: AFS-300


This AC is intended to provide guidance for developing maintenance and inspection programs for aircraft operated as public aircraft. The recommendations in this AC were developed using industry best practices, depending on the aircraft being operated. The AC describes methods for maintaining aircraft in order to maximize both a safety and economic benefit.


Status: Active

AC 107-2A 

Small Unmanned Aircraft System (Small UAS)

Office: AFS-800  


This AC provides guidance in the areas of airman (remote pilot) certification, aircraft registration and marking, aircraft airworthiness, and the operation of small Unmanned Aircraft Systems (UAS) in the National Airspace System (NAS) to promote compliance with the requirements of Title 14 of the Code of Federal Regulations (14 CFR) part 107.


Status: Active.

AC 120-72A

Maintenance Human Factors Training

Office: AFS-300


1.Provides descriptions of references and training materials to ensure that thereader can assemble a Maintenance Human Factors (MxHF) training programmatched to the applicable needs of their specific organization. 2.Provides many sources of current information to develop, implement,reinforce, and assess MxHF training materials. 3.Streamlines MxHF training development at the local level. 4.Is not mandatory, like any AC, and does not constitute a regulation


Status: Active

AC 120-77

Maintenance and Alteration Data

Office: AFS-300


This advisory circular (AC) provides one means, but not the only means, of ensuring that the contemplated maintenance, alteration, or continue-in-service condition is in compliance with applicable regulations and existing policy.


Status: Active

AC 145-4A 

Inspection, Retread, Repair, and Alterations of Aircraft Tires - Including Change 2

Office: AFS-309


Provides guidance for the development, qualification, and approval of aircraft tire repair and retread process specifications, and the use of special nondestructive inspection (NDI) techniques. The information sets forth an acceptable means, but not the only means of developing a process specification for approval.


Status: Active

AC 145-9A 

Guide for Developing and Evaluating Repair Station and Quality Control Manuals

Office: AFS-300


This advisory circular (AC) provides informational material for all repair station certificate holders and/or applicants under Title 14 of the Code of Federal Regulations (14 CFR) part 145 to develop and evaluate a Repair Station Manual (RSM) and Quality Control Manual (QCM). This AC describes an acceptable, but not the only means, to develop a manual and comply with the referenced regulations.


Status: Active

AC 21-29D

Detecting and Reporting Suspected Unapproved Parts

Office: AIR-600


This advisory circular (AC) provides guidance to the aviation community for detecting suspected unapproved parts (SUP) and reporting them to the Federal Aviation Administration (FAA). Appendix A contains FAA Form 8120-11, Suspected Unapproved Parts Report, (with instructions) which serves as a standardized means of reporting. See appendix B for definitions specific to this AC.


Status: Active

AC 20-105B

Reciprocating Engine Power-Loss Accident Prevention and Trend Monitoring

Office: AFS-340


Updates statistical information and brings to the attention of aircraft owners, operators, manufacturers, and maintenance personnel the circumstances surrounding engine power-loss accidents with recommendations on how those accidents can be prevented.


Status: Active

AC 20-135

Powerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards and Criteria with change 1

Office: AIR-600


Provides guidance for use in demonstrating compliance with the powerplant fire protection requirements of the Federal Aviation Regulations (FAR). Included in this document are methods for fire testing of materials and components used in the propulsion engines and APU installations, and in areas adjacent to designated fire zones, as well as the rationale for these methods.


Status: Active

AC 20-105B

Reciprocating Engine Power-Loss Accident Prevention and Trend Monitoring

Office: AFS-340


Updates statistical information and brings to the attention of aircraft owners, operators, manufacturers, and maintenance personnel the circumstances surrounding engine power-loss accidents with recommendations on how those accidents can be prevented.


Status: Active


AC 21-34

Shoulder Harness-Safety Belt Installations

Office: AIR-120


Provides information and guidance pertinent to an acceptable means, but not the only means, for installation of shoulder harness and safety belt restraint systems at all seat locations on all previously type-certificated aircraft.


Status: Active

AC 21-25B

Approval of Modified Seating System Initially Approved Under a Technical Standard Order

Office: AIR-100


This advisory circular (AC) provides information, clarification, and procedural guidance for the approval and installation of modified technical standard order (TSO)approved seating systems in U.S. type-certificated aircraft. In this AC, we address modifications that result from design changes, repairs, and alterations pursuant to Title 14 of the Code of Federal Regulations (14 CFR) parts 21 and 43. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to modify TSO seating systems. However, if you use the means described in this AC, you must follow it in all important respects.


Status: Active

AC 23-21

Airworthiness Compliance Checklists Used to Substantiate Major Alterations for Small Airplanes with Change 1

Office: ACE-100


This change revises existing material in four paragraphs. First, it adds a reference to FAA Order 8300.10. Second, it indicates that no further FAA approval is required when 100 percent of the data is DER approved. Third, it includes a reference to the FSDO/ASI for signature on FAA Form 337. Fourth, it includes a requirement to submit ICA’s to the FSDO/ASI for acceptance. The change number and the date of the changed material are shown at the top of each changed page. Vertical bars in the margin indicate the changed material. Pages having no changes retain the same heading information.


Status: Active

AC 43-210A

Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations -
Change 1

Office: AFS-300


This advisory circular (AC) describes a standardized procedure for requesting approval of technical data associated with major repairs/major alterations. This AC also provides information that can help determine if a proposed repair/alteration requires approved data, guidance and standardized procedures for obtaining field approval (or approval by other means) of data, and instructions for completing the field approval checklist. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to obtain approved data for a major repair or major alteration. However, if you—whether you’re an aircraft owner, operator, or Aviation Maintenance Technician (AMT), collectively termed an applicant—use the means described in the AC, you must follow it in all important respects.


Status: Active

AC 21-41A

Replacing MIL-S-8879C With SAE AS8879

Office: AIR-110


Provides information, clarification, and procedural guidance concerning the Inactivation of MIL-S-8879Cm Screw Threads, Controlled Radius Root with Increased Minor Diameter, as it relates to the civil aviation industry.


Status: Active

AC 23.607-1