Definition
14 CFR Part 43 is the primary FAA regulation establishing the legal framework for all maintenance performed on U.S.-registered civil aircraft. Its applicability under §43.1 covers every civil aircraft with a U.S. airworthiness certificate, with a narrow exclusion for aircraft holding only experimental certificates and certain ultralight vehicles. The regulation defines both the procedural standards for performing maintenance and the documentation requirements that must accompany every completed task — the two pillars on which all aircraft airworthiness ultimately rests.
§43.3 enumerates the persons authorized to perform maintenance, each with distinct scope limits. A certificated A&P mechanic may perform maintenance and alterations within the scope of the mechanic's ratings, but may not return an aircraft to service after an annual inspection. A certificated pilot holding at least a private certificate may perform preventive maintenance (as defined in Appendix A) on aircraft they own or operate that are not used in air carrier service — tasks such as oil changes, landing gear lubrication, replacing safety wire, and similar owner-maintainer activities. An Inspection Authorization (IA) holder is required to perform annual inspections under §91.409(a) and to approve major repairs and major alterations by signing FAA Form 337. Certificated repair stations under Part 145 and air carriers under their own approved programs are also authorized persons under §43.3.
§43.9 establishes the legal recordkeeping standard that every maintenance entry must satisfy. Each record must contain: a description of the work performed (or a reference to acceptable technical data); the date of completion; the aircraft or component's total time in service; the signature and certificate number of the person approving the work; and a statement that the aircraft, airframe, engine, propeller, appliance, or component part is approved for return to service. This five-element requirement is frequently cited in enforcement actions when logbook entries omit certificate numbers or total-time entries. §43.11 extends similar requirements to records for inspection programs — annual, 100-hour, and progressive — and specifies how discrepancies discovered during an inspection must be noted if the aircraft is not released to service.
§43.13 Performance Rules establish the technical standard for all work. Maintenance must use methods, techniques, and practices prescribed in the manufacturer's current maintenance manual or Instructions for Continued Airworthiness (ICA), or in FAA Advisory Circulars AC 43.13-1B (Acceptable Methods, Techniques, and Practices — Aircraft Inspection and Repair) and AC 43.13-2B (Acceptable Methods, Techniques, and Practices — Aircraft Alterations). The aircraft must be returned to its original or properly altered condition after completion of work. §43.15 specifies additional performance rules for inspections: 100-hour and annual inspections must follow the scope and detail listed in Part 43 Appendix D, which catalogs the items requiring inspection across 34 categories including the aircraft structure, flight controls, powerplant, landing gear, radio equipment, and emergency equipment.
Appendix A is the definitional backbone of Part 43: it lists major alterations, major repairs, and preventive maintenance, drawing the line between what an A&P can approve versus what requires an IA or manufacturer data. Appendix B specifies how major repairs and major alterations must be recorded — specifically, via FAA Form 337, with one copy filed with the FAA Aircraft Records Branch in Oklahoma City and one retained in the aircraft's maintenance records. Appendix E and Appendix F prescribe the altimeter/pitot-static system test and ATC transponder test procedures that must be performed by appropriately rated persons every 24 calendar months under §91.411 and §91.413 respectively. §43.16 makes compliance with Airworthiness Limitations mandatory: if the type's Airworthiness Limitations section specifies a mandatory inspection interval or life limit for a structural element, that limit is not optional — it has the force of an airworthiness directive. §43.17 addresses Canadian persons performing maintenance on U.S. aeronautical products under the bilateral Canada–U.S. Bilateral Aviation Safety Agreement (BASA) framework, allowing Transport Canada–certificated AMEs to perform maintenance on U.S.-registered aircraft in accordance with the TCCA–FAA BASA agreement.
Why It Matters for Flight Schools
For flight schools, Part 43 defines the entire legal maintenance chain from the moment a technician picks up a wrench to the moment the aircraft is signed off for flight. The 100-hour inspection requirement of §91.409(b) — applicable to all aircraft operated for hire, including flight training — runs squarely through Part 43's scope: every 100-hour inspection must comply with Appendix D's checklist, be performed by an authorized person under §43.3, and be recorded per §43.9. A school whose mechanic signs off a 100-hour inspection with an incomplete logbook entry — missing the certificate number, omitting total time, or using a vague work description — has an immediately actionable §43.9 violation that can surface during any FSDO ramp check or surveillance inspection. Schools that perform their own preventive maintenance through certificated pilot-owners must document those tasks identically to professional maintenance entries.
The major repair and major alteration framework in Appendix A is especially relevant when training aircraft sustain prop strikes, hard landings, or ground damage. Determining whether a repair is major or minor is the first decision the IA or A&P must make after assessing damage — and that determination controls whether a Form 337 must be filed, whether field approval from the FSDO is needed, and which approved data sources are acceptable. Getting this determination wrong in either direction creates legal exposure: treating a major repair as minor means no Form 337 and potentially no return to service; treating a minor repair as major generates unnecessary administrative burden and cost.
How Aviatize Handles This
Aviatize's maintenance control module tracks every recurring Part 43 inspection interval — including the 100-hour clock under §91.409(b) and the 24-month altimeter/transponder certification intervals required by §91.411 and §91.413 — against live flight-time accumulation. Warning thresholds are configurable per aircraft so the maintenance team receives alerts before limits are reached rather than after. When a 100-hour or annual inspection is opened as a work order, the system applies the Appendix D checklist as the standard task card template, ensuring that all 34 inspection categories are addressed and that no items are inadvertently skipped during high-workload periods.
For §43.9 documentation compliance, Aviatize's maintenance execution module enforces structured logbook entries: each work order closure requires the technician's certificate number, rating, signature, total time in service, work description, and return-to-service statement before the record can be finalized. The platform also maintains a centralized Form 337 repository within digital data and records, linking each major repair or major alteration document to the specific aircraft and work order, so that the complete Appendix B file is available on demand for FSDO audits, pre-purchase inspections, or aircraft sales without manual logbook searches.