2.1 14 CFR Parts 43, 65, and 91 Regulatory Framework

2.1 14 CFR Parts 43, 65, and 91 Regulatory Framework

Aviation safety in the United States is anchored by Title 14 of the Code of Federal Regulations (14 CFR), colloquially known as the Federal Aviation Regulations (FARs). For the aviation maintenance technician (AMT), three primary regulatory parts establish the daily operating environment: Part 43 (Maintenance, Preventive Maintenance, Rebuilding, and Alteration), Part 65 (Certification: Airmen Other Than Flight Crewmembers), and Part 91 (General Operating and Flight Rules). Mastery of these interlocking regulations is essential for passing the FAA General exam and exercising the legal privileges of an Airframe and Powerplant (A&P) mechanic.

1. Structure and Scope of 14 CFR Part 43

Part 43 prescribes the rules governing the maintenance, preventive maintenance, rebuilding, and alteration of any aircraft having a U.S. airworthiness certificate, as well as foreign-registered civil aircraft used in common carriage or commercial operations under 14 CFR Part 121 or 135.

                         TITLE 14 CFR REGULATORY TRIAD
  ┌─────────────────────────┐   ┌────────────────────────┐   ┌─────────────────────────┐
  │       14 CFR PART 43    │   │      14 CFR PART 65    │   │      14 CFR PART 91     │
  │  Maintenance Standards  │   │  Mechanic Privileges   │   │  Owner / Operator Rules │
  │  - Scope & Performance  │   │  - Subpart D: Mechanic │   │  - Subpart E: Maint.    │
  │  - Appendices A, B, D   │   │  - Ratings (A&P)       │   │  - Airworthiness Duty   │
  │  - § 43.9 / § 43.11 Log │   │  - Currency (§ 65.83)  │   │  - Log Retention Rules  │
  └────────────┬────────────┘   └───────────┬────────────┘   └────────────┬────────────┘
               │                            │                             │
               └───────────────────► PRACTICING AMT ◄────────────────────┘

Key Sections of Part 43

• § 43.1 (Applicability): Applies to civil aircraft registered in the United States, including their airframes, aircraft engines, propellers, appliances, and component parts.
• § 43.3 (Persons Authorized to Perform Maintenance): Explicitly lists who may perform maintenance:
  1. Certificated mechanics (A&P) within their rating limitations.
  2. Certificated repairmen working at a certificated repair station.
  3. Persons working under the direct supervision of a certificated mechanic or repairman.
  4. Certificated Part 145 repair stations.
  5. Aircraft manufacturers holding a type or production certificate.
  6. Pilots, under § 43.3(g) — except holders of a sport pilot certificate, the holder of any pilot certificate issued under Part 61 may perform preventive maintenance on an aircraft owned or operated by that pilot that is not used under Part 121, 129, or 135. Note what the rule actually says: it is keyed to holding a Part 61 pilot certificate and to ownership/operation, not to holding "at least a private pilot certificate." A sport pilot may perform preventive maintenance only on an aircraft owned or operated by that pilot and issued a special airworthiness certificate in the light-sport category.
• § 43.5 (Approval for Return to Service): No person may return to service an aircraft that has undergone maintenance, preventive maintenance, rebuilding, or alteration unless:
  1. The appropriate maintenance record entry has been executed per § 43.9 or § 43.11.
  2. The repair or alteration form authorized by the FAA (e.g., FAA Form 337) has been executed if required.
  3. If the work changed flight characteristics or in-flight operation, an operational flight check was conducted per § 91.407.
• § 43.7 (Persons Authorized to Approve for Return to Service): Strictly limits who can sign the return-to-service release. A non-certificated person working under supervision may perform work under § 43.3, but ONLY a certificated individual (A&P, IA), repair station, or manufacturer may approve the work for return to service under § 43.7.
• § 43.13 (Performance Rules - General): Mandates that maintenance be performed using methods, techniques, and practices acceptable to the Administrator, utilizing the tools, equipment, and test apparatus necessary to ensure completion of work in accordance with accepted industry practices.

The Critical Appendices of Part 43

Core Rule — Appendix D Checklists: Under 14 CFR § 43.15(c), each person performing a 100-hour or annual inspection MUST use a checklist. The checklist may be of the mechanic's own design, the manufacturer's checklist, or one provided by another entity, but it must include all the scope and detail items listed in Part 43 Appendix D.

2. 14 CFR Part 91 Subpart E: Owner vs. Mechanic Responsibilities

A critical distinction tested on the FAA General exam is the legal division of responsibility between the aircraft owner or operator and the certificated mechanic.

Primary Responsibility of the Owner/Operator (§ 91.403)

Under 14 CFR § 91.403(a), the owner or operator of an aircraft is primarily responsible for maintaining that aircraft in an airworthy condition, including compliance with all applicable Airworthiness Directives (Part 39).

• The owner/operator must ensure that maintenance personnel make appropriate logbook entries indicating the aircraft has been approved for return to service (§ 91.405).
• The owner/operator must ensure that discrepancy items are repaired between mandatory inspections (§ 91.405(a)).
• The owner/operator must ensure that all mandatory placards and Airworthiness Limitations are complied with (§ 91.403(c)).

Responsibility of the Certificated Mechanic

While the owner has primary responsibility for the aircraft's airworthiness status, the certificated mechanic is legally responsible for the work they perform and/or approve:

• The mechanic must perform maintenance in accordance with approved/acceptable data and 14 CFR § 43.13 standards.
• The mechanic must ensure that all records required by § 43.9 or § 43.11 are properly prepared and executed.
• The mechanic does NOT have the legal authority to force an owner to make repairs; if an owner refuses to fix a grounding defect discovered during an inspection, the mechanic's legal duty is to log the inspection as unairworthy and provide the owner with a signed discrepancy list per § 43.11(b).

Comparative Matrix: Legal Duties and Roles

3. Operation After Maintenance & Flight Checks (§ 91.407)

When maintenance, preventive maintenance, rebuilding, or alteration has been performed on an aircraft:

1. § 91.407(a): No person may operate that aircraft unless it has been approved for return to service by an authorized person, and the maintenance record entry required by § 43.9 or § 43.11 has been made.
2. § 91.407(b) (Operational Flight Check): If the maintenance or alteration has appreciably changed its flight characteristics or substantially affected its operation in flight, no person may carry passengers until an appropriately rated pilot (holding at least a private pilot certificate) flies the aircraft, performs an operational flight check, and logs the check in the aircraft records.
   • The flight check entry must include: date of flight check, pilot signature, pilot certificate number, and rating.