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Commercial pilot · ACS CA.I.B · lesson pack

Airworthiness Requirements (Commercial)

Why this one matters

Passengers who pay for a flight trust that the airplane has been looked after. The 100-hour inspection exists because airplanes flown for hire are flown hard and often. A commercial pilot who checks the records and refuses an airplane that isn’t right protects people who can’t check for themselves.

1 · Know these cold

  • •On board: the airworthiness certificate (displayed), registration, the operating limitations (POH/AFM, placards, markings) and weight and balance data.(14 CFR 91.9; 91.203)
  • •Annual inspection within the preceding 12 calendar months (signed by an IA). A 100-hour inspection too (an A&P may sign it) if the airplane carries any person other than a crewmember for hire, or is provided by the person giving flight instruction for hire. An annual counts as a 100-hour; a 100-hour never counts as an annual. A progressive inspection program can replace both.(14 CFR 91.409(a), (b), (d); 65.95)
  • •The 100-hour may be overflown by up to 10 hours only to reach a place where it can be done; the extra time counts toward the next one.(14 CFR 91.409(b))
  • •Airworthiness Directives are mandatory, including recurring ones; the logbooks must show compliance. SAIBs are advisory.(14 CFR Part 39; 91.417)
  • •A pilot who owns or operates the airplane may do only the preventive maintenance listed in Part 43 Appendix A(c), with no complex assembly (not on aircraft used under Part 121, 129 or 135), may approve it for return to service, and must log it.(14 CFR 43.3(g); 43.7(f); 43.9)
  • •Inoperative equipment without an MEL (91.213(d)): it may be inoperative only if it is not required by the VFR-day type certificate, not on the equipment list or KOEL, not required by 91.205 or another rule for the flight, and not required by an AD. Then it is removed (placard, record) or deactivated and placarded "Inoperative", and a pilot or mechanic determines it isn't a hazard.(14 CFR 91.213(d))
  • •An airplane that isn’t airworthy may be flown to a repair base only under a special flight permit from the FAA.(14 CFR 21.197)

2 · The lesson

Certificates, inspections and ADs
  • The airworthiness certificate stays valid while maintenance and inspections are done as required. Registration expires after 7 years and must be renewed.(14 CFR 21.181; 47.40)
  • Inspections, with when they apply: annual (12 calendar months); 100-hour for hire; the transponder may not be used unless tested within the preceding 24 calendar months; altimeter and static system within 24 calendar months to fly IFR in controlled airspace; a VOR check within the preceding 30 days to use the VOR under IFR.(14 CFR 91.171; 91.409; 91.411; 91.413)
  • ELT: inspected every 12 calendar months (installation, battery corrosion, controls and crash sensor, a radiated signal). Replace or recharge the battery after more than 1 cumulative hour of use or when 50% of its useful life (or of its charge, if rechargeable) has passed; mark the new expiration date on the transmitter and in the records.(14 CFR 91.207(c)-(d))
  • ADs fix unsafe conditions and are mandatory; check one-time and recurring ADs in the logbooks. SAIBs recommend action but don’t require it.(14 CFR Part 39)
  • Special flight permit (a "ferry permit"): to fly an airplane that isn’t airworthy but is safe for a specific flight, such as to a repair base. Apply on FAA Form 8130-6 to the responsible Flight Standards office (or a DAR), stating the purpose, itinerary, crew, how the airplane doesn't comply, and the restrictions proposed. Fly only under the limitations issued with it, with essential crew only.(14 CFR 21.197; 21.199)
Preventive maintenance
  • Preventive maintenance is a closed list in Part 43 Appendix A(c) (oil changes, tire servicing, replacing bulbs and the other listed items), and only where no complex assembly is involved. If it isn’t on the list, a mechanic does it.(14 CFR Part 43, Appendix A)
  • A certificated pilot who owns or operates the airplane may do it, except on aircraft used under Part 121, 129 or 135.(14 CFR 43.3(g))
  • Doing it and approving it are separate: you may approve your own preventive maintenance for return to service, and log it with a description, the date, your name, certificate number and kind, and signature. The airplane flies only after that approval.(14 CFR 43.7(f); 43.9; 91.407(a))
Required and inoperative equipment
  • Day VFR (91.205(b)): airspeed indicator, altimeter, magnetic direction indicator, tachometer, oil pressure and temperature gauges, manifold pressure gauge for an altitude engine, a fuel gauge for each tank, gear position indicator if retractable, anticollision lights (airplanes certificated after March 11, 1996), seat belts and shoulder harnesses as required, an ELT, and flotation and a pyrotechnic signal if for hire over water beyond gliding distance.(14 CFR 91.205(b))
  • Night VFR adds (91.205(c)): position lights, anticollision lights, an adequate source of electrical energy, and spare fuses; and an electric landing light if operated for hire. IFR adds more.(14 CFR 91.205(c)-(d))
  • An MEL is specific to the airplane (developed from the MMEL), comes with an FAA letter of authorization that must be on board, and you fly under all its conditions. An MMEL alone authorizes nothing for Part 91. An MEL can't defer items required by the type certificate, an AD (unless it says so), or Part 91 for the flight.(14 CFR 91.213(a)-(b))
  • Without an MEL, 91.213(d) applies, using the KOEL or equipment list in the POH/AFM.(14 CFR 91.213(d))
  • Placard inoperative items "Inoperative" and record the discrepancy. A paying passenger shouldn’t discover it.(14 CFR 91.213(d))
  • Found something broken at preflight? Legal and safe are separate questions; answer both before you go.(Risk Management Handbook (FAA-H-8083-2A))
Special airworthiness certificates
  • Aircraft with special airworthiness certificates (experimental, restricted, limited, light-sport) fly under their own operating limitations. Read them before flying.(14 CFR 91.9)
  • An experimental aircraft may not carry persons or property for compensation or hire.(14 CFR 91.319(a)(2))

Want it all on one page, with scenarios? Read the full lesson.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “When does an airplane need a 100-hour inspection?”

  2. Understand Explain why

    “Why may you overfly the 100-hour by up to 10 hours, and what happens to that time?”

  3. Apply Use it on a flight

    “Before a paid sightseeing flight you find the airplane is at 102 hours since its last 100-hour, and the landing light is out. What do you do?”

4 · Common mistakes

  • Ignoring the 100-hour.

    Required when flying for hire.

    Instead: Check it every time you fly someone for pay.

  • Treating SAIBs as ADs, or ADs as advice.

    Only ADs are mandatory.

    Instead: Know the difference.

  • Missing the logbook entry for preventive maintenance.

    It’s required.

    Instead: Log it per 43.9.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What documents must be on board?

  2. 2. How long is aircraft registration valid?

  3. 3. By how much may a 100-hour be exceeded?

  4. 4. Are SAIBs mandatory?

  5. 5. Who may do preventive maintenance?

  6. 6. How do you fly an unairworthy airplane to a repair shop?

  7. Scenario7. Before a paid flight, the fuel gauge on one tank doesn’t work. What do you do?

Trained it? Now prove it: practice airworthiness requirements (commercial) out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Preflight Preparation

A week after your checkride, a friend's company offers to pay you to fly three employees to a meeting in a rented 172. They want to leave at 6 a.m.; you have a full workday before.

Can you take the job, and what else matters? Decide, then see the worked answer

It turns on who provides the airplane and who has operational control. If you rent the 172 and provide the company pilot plus airplane, that's carrying persons for compensation, and offering it (holding out, under AC 120-12A) makes it common carriage. That needs an operator certificate under Part 119, with the flight run as an on-demand Part 135 operation, so decline. The lawful version is the company renting or leasing the airplane in its own name, holding operational control, and paying you only to fly it. That's a Part 91 flight, and your commercial certificate lets you be paid as its pilot (the FAA's Green (1993) and Ferris (1990) interpretations draw this line). None of the 119.1(e) exceptions, such as student instruction, nonstop commercial air tours under 91.147, ferry or training flights, or aerial work like banner towing, covers flying a company's employees to a meeting. 91.409(b) requires a 100-hour inspection for an aircraft carrying any person, other than a crewmember, for hire, or used for flight instruction for hire in an airplane the instructor provides. Company employees flown on the company's own business, without being charged, aren't passengers for hire in that sense, so it doesn't automatically apply to the Part 91 version; check the airplane's inspections either way. Then check yourself: a second-class medical for commercial privileges, a current flight review, and three takeoffs and landings in the last 90 days to carry passengers. Without an instrument rating, 61.133(b)(1) bars carrying passengers for hire on cross-countries over 50 NM or at night. Part 91 has no duty or rest limits, so fatigue is yours to manage: run IMSAFE honestly, and a 6 a.m. report after a full workday needs a real sleep opportunity first. If you won't get one, decline or move the departure. Pressure to please a client makes the call harder, not different.

14 CFR 61.23, 61.56, 61.57, 61.133, 91.409(b), 119.1; AC 120-12A; Risk Management Handbook (FAA-H-8083-2A)

Brings together: Pilot Qualifications · Airworthiness Requirements · Human Factors

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: 14 CFR; Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C); Commercial Pilot ACS (FAA-S-ACS-7B). Checked against current sources 2026-11-13.