Aviation maintenance is built upon performance standards that ensure the safety, reliability, and airworthiness of aircraft. FAR 43.13 serves as the foundation for these standards, outlining the acceptable methods, techniques, and practices that mechanics, repair stations, and operators must follow when performing maintenance, preventive maintenance, or alterations. This regulation emphasizes that maintenance must be conducted using methods acceptable to the FAA or, in their absence, those that provide an equivalent level of safety. However, inconsistencies arise when multiple FAA directives, such as FAA Orders (e.g., 8900.1, 8010.2A), the Flight Standards Information Management System (FSIMS), Advisory Circulars (ACs) such as 43.13-1B and 43.13-2B, Special Airworthiness Information Bulletins (SAIBs), and Designated Engineering Representative (DER) approvals under FAA Order 8110.37F, create conflicting interpretations of acceptable maintenance practices.

A critical issue within FAR 43.13 is the disparity between legally binding regulations and advisory guidance. FAA Orders such as 8900.1 and FSIMS provide policy guidance for FAA inspectors, often leading to stricter interpretations than what is outlined in AC 43.13-1B and AC 43.13-2B. While ACs provide FAA-accepted methods, they are not legally binding unless incorporated into a regulation or airworthiness directive. At the same time, DER approvals under FAA Order 8110.37F allow for alternative repairs and alterations, but these may still face scrutiny if they differ from FSIMS expectations or AC guidance. Maintenance providers must be diligent in documenting compliance with FAR 43.13(b) to demonstrate that any alternative method ensures an equivalent level of safety.

Another major source of conflict in FAR 43.13’s performance standards comes from the interplay between Airworthiness Directives (ADs), manufacturer’s Instructions for Continued Airworthiness (ICA), and FAA guidance materials. ADs are legally binding and take precedence over all other maintenance instructions. However, ICAs developed by manufacturers under FAR Part 21 may mandate maintenance procedures that differ from those outlined in FAA-approved ACs or DER authorizations. For example, a manufacturer may specify a corrosion inspection process not detailed in AC 43.13-1B, creating discrepancies during FAA audits. Additionally, SAIBs, which offer non-mandatory safety recommendations, may sometimes contradict both ICA and FAA Orders, further complicating compliance efforts for maintenance personnel striving to meet FAR 43.13 standards.

To ensure compliance with FAR 43.13’s performance standards, maintenance providers must take a structured approach. Legally binding regulations such as FAR 43.13 and ADs should always take precedence over advisory materials. When alternative methods are used, they must be thoroughly documented under FAR 43.13(b), demonstrating equivalent safety. Additionally, cross-referencing multiple sources—including FSIMS, ACs, ICA, and DER approvals—before performing major repairs or alterations is crucial to preventing regulatory disputes. Seeking pre-approval from FAA Flight Standards District Office (FSDO) inspectors can further ensure compliance when adopting alternative maintenance techniques.

Ultimately, compliance with FAR 43.13’s performance standards requires a clear understanding of the regulatory hierarchy and how various FAA guidance materials influence maintenance practices. FAA Orders and FSIMS shape how inspectors interpret regulations, but they do not hold the same legal authority as FARs or ADs. While Advisory Circulars provide best practices, they are not legally enforceable unless incorporated into an AD or specific regulation. Maintenance providers must recognize these distinctions and maintain thorough documentation to support their compliance decisions. By staying informed on regulatory updates, legal interpretations, and FAA enforcement trends, maintenance professionals can effectively uphold safety, avoid compliance violations, and maintain the highest standards of aircraft maintenance.

Aviation Maintenance Performance Standards

Code of Federal Regulations (CFR) - Legally Binding

• 14 CFR 43.13 - Performance Rules for Maintenance

  • Establishes FAA-mandated performance standards for aircraft maintenance, requiring the use of FAA-accepted methods or alternative methods that ensure equivalent safety.

2. FAA Orders (Legally Binding for FAA Personnel)

These orders define FAA inspector policies, certification procedures, and airworthiness directives (ADs).

• FAA Order 8010.2A

  • Defines FAA policies for Airworthiness Directive (AD) enforcement and compliance verification.

• FAA Order 8110.54A

  • Governs engineering approvals for aircraft modifications and repairs.

FAA Order 8900.1 - Flight Standards Information Management System (FSIMS)

The FAA’s inspector handbook, outlining regulatory enforcement and compliance policies.

• Vol.2, Ch4, Sec8 – Defines FAA airworthiness determinations.

• Vol.20, Ch1, Sec1 – Covers Safety Management System (SMS) policies for maintenance organizations.

• Vol.3, Ch15, Sec1 – Outlines FAA oversight of major repairs and alterations.

• Vol.6, Ch11, Sec2 – Describes FAA airworthiness compliance inspections.

• Vol.6, Ch14, Sec1 – Establishes Part 145 repair station performance evaluations.

• Vol.6, Ch2, Sec26 – Discusses Part 135 operator maintenance requirements.

• Vol.6, Ch9, Sec15 – Covers aircraft maintenance recordkeeping.

• Vol.6, Ch9, Sec8 – Defines mechanic responsibilities under FAA oversight.

3. Advisory Circulars (ACs) - FAA-Approved Guidance (Non-Regulatory)

ACs provide FAA-accepted methods for compliance with FAR 43.13, but they are not legally binding unless incorporated into a regulation or AD.

• AC 43.13-1B CHG 1

  • The primary maintenance guidance document detailing FAA-accepted methods, techniques, and practices.

• AC 43.13-2B

  • Provides aircraft alterations and modification guidance under FAR 43.13.

• AC 20-109B

  • Defines composite aircraft repair procedures.

• AC 20-45

  • Covers Aircraft Certification and Conformity.

• AC 20-74

  • Defines Non-Destructive Testing (NDT) methods.

• AC 25-19A

  • Maintenance guidance for Part 25 (Transport Category) aircraft.

• AC 33.4-1

  • Provides engine maintenance standards.

• AC 120-16G

  • Details operational maintenance responsibilities under FAR 121 and 135.

• AC 135-7B Ed Update

  • On-demand operator maintenance requirements under FAR 135.

• AC 43-206 CHG 1

  • Aging aircraft inspection and maintenance procedures.

• AC 43-4B Ed Update 2

  • Guidelines for corrosion control and prevention.

• AC 43-6D Ed Update

  • Addresses electrical system maintenance and wiring safety.

5. FAA Legal Interpretations

(Clarifying FAR 43.13 Enforcement)These interpretations clarify how the FAA applies regulations and guidance in enforcement cases.

• Inter_AC_43-13-1B_AEA-200_2010

  • Determines whether ACs are enforceable in FAA actions.

• Meyer_2015 Legal Interpretation

  • Clarifies legal obligations of mechanics under FAR 43.13.

• Siilats_2015 Legal Interpretation

  • Discusses FAA enforcement perspectives on maintenance compliance.