FAR 91.401 — Maintenance Applicability
FAR 91.401 sets the scope of Part 91 Subpart E, covering maintenance, preventive maintenance, and alterations for U.S.-registered civil aircraft.
FAR 91.401 is the opening section of Part 91, Subpart E — the subpart that lays out the rules for maintenance, preventive maintenance, and alterations on U.S.-registered civil aircraft, whether you're flying inside or outside the United States.
As a pilot, this section tells you which aircraft the Subpart E rules apply to, and just as importantly, which aircraft are carved out:
- Continuous airworthiness maintenance programs: Aircraft maintained under a continuous airworthiness maintenance program per Part 121, Part 129, §91.1411, or §135.411(a)(2) are not subject to §§ 91.405, 91.409, 91.411, 91.417, and 91.419.
- Part 125 airplanes: Airplanes inspected under Part 125 are not subject to §§ 91.405 and 91.409.
Why it matters: most general aviation aircraft you'll fly as a student or private pilot fall squarely under Subpart E, meaning you as PIC are responsible for verifying annual inspections, 100-hour inspections (when required), ELT checks, transponder/altimeter checks, and proper maintenance records before every flight.