Private pilot · ACS PA.I.B

Airworthiness Requirements

Before every flight you decide whether this airplane is airworthy: legally, and actually safe to fly.

That means the right documents on board, inspections up to date in the logbooks, ADs complied with, and a clear process for anything that's broken.

Why this one matters

An airplane can look fine on the ramp and still not be safe or legal: an overdue inspection, an unaddressed AD, a broken instrument you need at night. Knowing how to check the documents and how to handle inoperative equipment is how you avoid flying a problem into the air.

Can’t miss

•The pilot in command decides whether the airplane is in condition for safe flight; the owner or operator keeps it airworthy.(14 CFR 91.7, 91.403)
•On board: the airworthiness certificate (displayed), the registration certificate, the operating limitations (POH/AFM, placards, markings) and weight and balance data.(14 CFR 91.203, 91.9)
•Annual inspection within the preceding 12 calendar months; a 100-hour inspection too if the airplane carries people for hire or is provided for flight instruction for hire.(14 CFR 91.409)
•ELT inspected every 12 calendar months; transponder checked every 24 calendar months; the altimeter/static check (24 months) is for IFR in controlled airspace.(14 CFR 91.207, 91.411, 91.413)
•Airworthiness Directives are mandatory; Special Airworthiness Information Bulletins are advisory.(14 CFR Part 39)
•Inoperative equipment without an MEL: if it isn't required, deactivate or remove it, placard it "Inoperative", and decide it isn't a hazard.(14 CFR 91.213(d))
•As a private pilot you may do preventive maintenance on an airplane you own or operate, and you must log it.(14 CFR 43.3(g), 43.9, Part 43 Appendix A)

What you should know

Certificates and who is responsible K1 · K4

The owner or operator is primarily responsible for keeping the airplane airworthy, including AD compliance.(14 CFR 91.403(a))
The pilot in command is responsible for deciding the airplane is in condition for safe flight, and must end the flight if it isn't.(14 CFR 91.7)
The airworthiness certificate must be on board and displayed at the cabin or cockpit entrance, visible to passengers. A standard airworthiness certificate stays valid as long as the airplane is maintained and operated as required.(14 CFR 91.203(b), 21.181)
The registration certificate must be on board. Registrations now expire after 7 years.(14 CFR 91.203(a)(2), 47.40)
Standard airworthiness certificates cover normal, utility, acrobatic, commuter and transport categories. Special airworthiness certificates (experimental, light-sport, restricted, special flight permit and others) carry their own operating limitations, which you must follow.(14 CFR 21.175, 91.319)
The POH/AFM, placards and markings are the operating limitations and must be on board and followed. Weight and balance data must be current.(14 CFR 91.9)
Special certificates carry real limits. An experimental airplane (91.319): no carrying persons or property for compensation or hire, day VFR only unless the FAA authorizes otherwise, no flight over densely populated areas or in a congested airway unless authorized, and you must tell each person on board that it is experimental.(14 CFR 91.319(b)-(e); 21.175)

Inspections and the logbooks K1

Annual inspection within the preceding 12 calendar months.(14 CFR 91.409(a))
100-hour inspection if the airplane carries any person (other than crew) for hire, or is provided by the person giving flight instruction for hire. You may exceed it by up to 10 hours to reach a place where it can be done; that time counts toward the next one.(14 CFR 91.409(b))
ELT: inspected within the preceding 12 calendar months; battery replaced after 1 cumulative hour of use or half its useful life.(14 CFR 91.207)
Transponder: tested within the preceding 24 calendar months to use it.(14 CFR 91.413)
Altimeter and static system: within the preceding 24 calendar months, required for IFR in controlled airspace.(14 CFR 91.411)
Inspections, AD compliance and alterations are recorded in the airframe, engine and propeller logbooks. Check them; don't assume.(14 CFR 91.417)
Who signs: an annual must be performed and approved by someone authorized under 43.7, in practice a mechanic with an Inspection Authorization (A&P/IA), an appropriately rated repair station or the manufacturer. A 100-hour can be done and approved by an A&P without an IA. Both use the same Appendix D scope. An annual counts as a 100-hour; a 100-hour counts as an annual only if done by someone authorized to do annuals and entered as an annual.(14 CFR 91.409(a)-(b); 43.7; 65.95(a); Part 43, Appendix D)
The ELT is required only where 91.207 requires it. Exceptions include training flights conducted entirely within 50 nm of the airport where the local flight began, and aircraft with only one seat; an airplane may also be ferried for ELT repair or removal without one. Where an ELT is installed, the 12-month inspection and battery rules apply.(14 CFR 91.205(b); 91.207(a), (c)-(f))

ADs, SAIBs and special flight permits K1

Airworthiness Directives address unsafe conditions and are mandatory. Some are one-time; recurring ADs need compliance at set intervals. Compliance is recorded in the logbooks.(14 CFR Part 39, 91.417)
Special Airworthiness Information Bulletins (SAIBs) are recommendations, not requirements.(PHAK (FAA-H-8083-25C), Aircraft Documents, Maintenance, and Inspections)
A special flight permit (a "ferry permit") lets an airplane that doesn't currently meet airworthiness requirements, but is capable of safe flight, fly to a place where it can be repaired or inspected. You get it from the FAA (a Flight Standards office or designee) before the flight.(14 CFR 21.197, 21.199)
The special flight permit process: the application states the purpose, the required crew, how the airplane doesn't comply, and the restrictions needed for safe operation. The FAA may inspect or require a mechanic's or repair station's finding that the airplane is safe for the route. The permit comes with operating limitations you must follow: essential crew only, no persons or property for hire, and the permit carried as specified.(14 CFR 21.197; 21.199(a)-(b))

Preventive maintenance K2

A certificated pilot (not a student pilot) may perform preventive maintenance on an airplane they own or operate that isn't used under Part 121, 129 or 135.(14 CFR 43.3(g))
Preventive maintenance is the list in Part 43 Appendix A: simple jobs like changing oil, replacing tires, servicing landing gear struts, or replacing safety belts.(14 CFR Part 43, Appendix A(c))
Log it with the full 43.9(a) entry: a description of the work (or a reference to acceptable data), the date it was completed, the name of the person who did it if not the approver, and, if the work was done satisfactorily, the signature, certificate number and kind of certificate of the person approving it. That signature is the approval for return to service for that work only.(14 CFR 43.9(a); 43.7(f))
Performing and approving are separate steps. A Part 61 pilot certificate holder may perform preventive maintenance on an airplane they own or operate that isn't used under Part 121, 129 or 135 (a sport pilot only on a light-sport aircraft they own or operate). Only someone holding at least a private pilot certificate may approve it for return to service.(14 CFR 43.3(g); 43.7(f))
Adding oil is servicing and needs no maintenance entry. Changing the oil (and filter or screen work in Appendix A) is preventive maintenance and needs the full entry. Replacing position and landing light bulbs, reflectors and lenses is also preventive maintenance.(14 CFR Part 43, Appendix A(c); 43.9)

Required equipment and inoperative equipment K3 · R1

Day VFR equipment includes: airspeed indicator, tachometer, oil pressure and oil temperature gauges, manifold pressure gauge (altitude engines), altimeter, temperature gauge (liquid-cooled engines), fuel gauges, landing gear position indicator (retractable gear), anticollision lights (airplanes certificated after March 11, 1996), a magnetic direction indicator (the compass), an ELT if 91.207 requires one, safety belts for each occupant 2 years or older (metal-to-metal latching), shoulder harnesses for each front seat in small airplanes made after July 18, 1978 (all seats if made after December 12, 1986), and, if operated for hire over water beyond power-off gliding distance from shore, flotation gear for each occupant and at least one pyrotechnic signaling device.(14 CFR 91.205(b))
Night VFR adds position lights, anticollision lights, a landing light if operating for hire, an adequate source of electrical energy, and spare fuses if fuses are used.(14 CFR 91.205(c))
With an approved MEL (a letter of authorization for that specific airplane), follow it.(14 CFR 91.213(a))
Without an MEL, inoperative equipment is allowed only if it isn't required by the VFR-day type certification, the equipment list or kinds of operation equipment list (KOEL), 91.205 or other rules, or an AD. Then it must be removed or deactivated and placarded "Inoperative", and the pilot must decide it's no hazard.(14 CFR 91.213(d))
Many POHs include a KOEL listing what must work for day VFR, night VFR, IFR and icing.(PHAK (FAA-H-8083-25C), Aircraft Documents, Maintenance, and Inspections)
A discrepancy found before flight is recorded and placarded; it is not just ignored.(14 CFR 91.213(d)(3), 43.11)
91.213(d) applies only to the aircraft listed in (d)(1): rotorcraft, non-turbine-powered airplanes, gliders and lighter-than-air aircraft (small ones only, if a master MEL has been developed for the type). If an item is removed, placard the cockpit control and record the maintenance under 43.9; if deactivated, placard it "Inoperative", and any deactivation that is maintenance must be done and recorded under Part 43. The no-hazard decision is made by a certificated, appropriately rated pilot or by an appropriately rated maintenance person.(14 CFR 91.213(d)(1)-(4))

Scenarios

Decide what you would do first, then see the worked answer.

The airplane's last annual was signed off 13 months ago, on the 3rd of the month. Today is the 28th.

Can you fly it? See the worked answer

No. An annual is due by the end of the 12th calendar month. Thirteen months later it's overdue. The airplane needs its annual, or a special flight permit to get to where it can be done.

14 CFR 91.409(a), 21.197

You rent a 172 for flight training. The tach shows 98 hours since its last 100-hour inspection, and your lesson will take 2 hours.

Is that a problem? See the worked answer

The lesson would take it past 100 hours, and the 10-hour allowance is only for flying to a place where the inspection can be done, not for finishing a lesson. Get the inspection done first, or keep the lesson short enough to stay under 100.

14 CFR 91.409(b)

You find the alternator inoperative before a day VFR flight. The airplane has no MEL.

How do you decide? See the worked answer

Check whether it's required by the type certificate, the equipment list or KOEL, 91.205, or an AD. If it is required, you don't go. Even if it weren't, with no charging system the battery is your only electrical power, which is a hazard for a trip that needs radios and a transponder. Ground it and get it fixed.

14 CFR 91.213(d)

An AD on your engine requires a recurring inspection every 100 hours. The logbook shows the last one 110 hours ago.

Is the airplane airworthy? See the worked answer

No. ADs are mandatory; an overdue recurring AD means the airplane isn't airworthy until it's done and logged.

14 CFR Part 39, 91.403

Your oil is low and you want to add a quart and replace a worn landing light bulb before your flight.

Can you do it yourself? See the worked answer

Yes, if you're a certificated pilot operating the airplane and it isn't used under Part 121, 129 or 135. Adding a quart is servicing: no maintenance entry. Replacing the landing light bulb is preventive maintenance: log it with a description of the work, the date, and your signature, certificate number and kind of certificate, which approves it for return to service.

14 CFR 43.3(g), Part 43 Appendix A

Common mistakes

Treating the 24-month altimeter/static check as required for VFR.
91.411 applies to IFR in controlled airspace.
Instead: Know which inspections apply to this flight: annual, 100-hour if for hire, ELT, transponder; altimeter/static only for IFR.
Listing a radio station license as always required.
It's only needed for international flights.
Instead: Use the required list: airworthiness, registration, operating limitations, weight and balance.
Flying with broken equipment because "it's not on the 91.205 list".
91.213(d) also checks the type certificate, the equipment list/KOEL and ADs, and requires deactivating and placarding.
Instead: Walk through every step of 91.213(d), then decide whether it's a hazard on this flight.

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Sources

14 CFR Part 91: 91.7, 91.9, 91.203, 91.205, 91.207, 91.213, 91.403, 91.409, 91.411, 91.413, 91.417
14 CFR Parts 21, 39, 43, 47: 21.175, 21.181, 21.197; ADs; 43.3, 43.9, Appendix A; 47.40
Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C): Aircraft Documents, Maintenance, and Inspections
Your airplane's POH/AFM: limitations, equipment list / KOEL

Study aid, not FAA guidance. Regulations change; check the current text at eCFR and the ACS. Checked against current sources 2026-11-12.