Commercial pilot · ACS CA.I.B
Airworthiness Requirements (Commercial)
As a commercial pilot you’re responsible for knowing the airplane is airworthy, and for the extra inspection rules that apply when you fly for hire.
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.
Can’t miss
- •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)
What you should know
Certificates, inspections and ADs K1
- 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 K2
- 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 K3 · R1
- 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 K4
- 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))
Scenarios
Decide what you would do first, then see the worked answer.
A recurring AD on the airplane was due 5 hours ago.
Can you fly it? See the worked answer
No. It’s unairworthy until the AD is complied with, unless the AD itself allows a ferry flight or you get a special flight permit.
14 CFR Part 39
You change the oil on a rental airplane that flies Part 135 charters.
Was that allowed? See the worked answer
No. Pilot preventive maintenance isn’t allowed on aircraft used under Part 135 (with limited exceptions under an approved program).
14 CFR 43.3(g)
The airplane’s registration expired last month.
Can you fly? See the worked answer
No. It isn’t validly registered; renew it first.
14 CFR 47.40; 91.203
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.
Now train it
Say it out loud, hear it asked, and take the quick check in this lesson’s practice pack. It tracks your shaky spots.
Got it?
When it feels solid, practice airworthiness requirements (commercial) out loud with our examiner.
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Sources
- 14 CFR: 21.181, 21.197, Part 39, 43.3, 43.9, Part 43 Appendix A, 47.40, 91.9, 91.203, 91.205, 91.207, 91.213, 91.319, 91.409, 91.411, 91.413, 91.417
- Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C): Aircraft documents, maintenance and inspections
- Commercial Pilot ACS (FAA-S-ACS-7B): Area I, Task B
Study aid, not FAA guidance. Regulations change; check the current text at eCFR and the ACS. Checked against current sources 2026-11-13.