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Airworthiness Requirements

The certificate in the cabin says the airplane met a standard once. Whether it still meets it this morning is a determination 14 CFR 91.7 hands to you, every flight.

Preflight Preparation — FI.III.B

Airworthy is a decision, not a sticker

The word has two halves, and both have to be true at the same moment: the aircraft conforms to its approved type design, and it is in a condition for safe operation. A worn tire breaks the second without touching the first. An unapproved part breaks the first while everything runs beautifully. Break either one and the airplane is not airworthy.

14 CFR 91.7 puts the rest on you. No person may operate a civil aircraft unless it is in an airworthy condition, and the pilot in command is responsible for determining whether it is in condition for safe flight. The mechanic signs the inspection and the owner keeps the records, but the determination on the morning of the flight is yours — and the rule also requires you to discontinue the flight when an unairworthy condition appears. Regulations change, so everything below cites a rule by number: the current CFR, not this page, is the authority, and you should read the section itself before you rely on it.

The certificate, and what it covers

A standard airworthiness certificate is issued under 21.175(a) for aircraft type certificated in the normal, utility, acrobatic, transport and commuter categories, and also for manned free balloons and for the special classes of aircraft the FAA designates. It has no expiration date. It stays valid only as long as the aircraft is maintained, inspected and operated the way the rules require, and it must be displayed at the cabin or cockpit entrance so that it is legible to passengers or crew (91.203(b)).

Aircraft that cannot qualify for one are certificated for specific kinds of operation under a special airworthiness certificate. 21.175(b) gives the set: primary, restricted, limited, light-sport, provisional and experimental certificates, plus special flight permits. That is what homebuilts, crop dusters, factory light-sport aircraft and airshow airplanes fly on — safe for what they are approved to do, and limited to it.

The inspections that keep it valid

The annual is the baseline: every twelve calendar months (91.409(a)), subject to the exceptions the rule itself lists in 91.409(c) — among them aircraft carrying a special flight permit, a current experimental certificate or a light-sport certificate, and aircraft inspected under an approved inspection program. The sign-off comes from a person authorized under 43.7, which is usually a mechanic holding an Inspection Authorization but also includes an appropriately rated certificated repair station and the manufacturer of the aircraft. Calendar months run to the end of the month, so an annual signed in March is good through March 31 the following year.

The 100-hour applies to hire. If the aircraft carries persons for hire, or is used for flight instruction for hire and the instructor provides the airplane, it needs a 100-hour on top of the annual (91.409(b)) — which is why the rental trainer has both and your own airplane has only the annual. You may run up to ten hours over, and only to reach a place where the inspection can be done, and those hours come off the next interval. An annual satisfies a 100-hour; a 100-hour does not satisfy an annual. A progressive inspection (91.409(d)) splits the same work into scheduled segments under an FAA-accepted program.

Other items come due on the clock. AVIATES is the memory aid:

• Airworthiness Directives — at the interval the AD sets
• VOR check — within the preceding 30 days for IFR (91.171)
• Inspections — annual, 100-hour, progressive
• Altimeter — every 24 calendar months for IFR (91.411)
• Transponder — every 24 calendar months (91.413)
• ELT — inspected every 12 calendar months; battery replaced after one cumulative hour of use or at half its useful life (91.207)
• Static system — the static pressure system, checked under that same 91.411 test along with the altimeter instruments and the automatic pressure altitude reporting equipment. The pitot side is not part of the 91.411 inspection, whatever the shop calls the sticker.

Airworthiness directives

An AD is the FAA's official notification that a known unsafe condition exists in an aircraft, engine, propeller or appliance, and that something must be done about it. Compliance is legally required. It may require an inspection, a repair, a modification or an operating limit, one-time or recurring — cracked structure, an avionics software revision and a fuel system change have all arrived as ADs. Recurring ones are what get missed, because they come due between annuals. Their status lives in the maintenance records.

The paperwork that flies with the airplane

Four documents have to be aboard for a domestic flight, and a fifth once you leave the country. ARROW is how everyone remembers the set:

• Airworthiness certificate — good as long as the aircraft is kept airworthy
• Registration — check the expiration date; the term was extended to seven years, but older certificates were issued for three
• Radio station license — the fifth item, an FCC requirement that applies only to flights outside the United States
• Operating limitations — the AFM or POH with the placards and instrument markings, all specific to that tail number
• Weight and balance — current data for that individual airplane

Required equipment

Day VFR equipment is 91.205(b), remembered as ATOMATOFLAMES: airspeed indicator, tachometer, oil pressure gauge, manifold pressure gauge, altimeter, temperature gauge, oil temperature gauge, fuel quantity indicator, landing gear position indicator, anticollision lights, magnetic compass, ELT and seat belts. Night VFR adds FLAPS from 91.205(c): fuses, landing light, anticollision lights, position lights and an adequate source of electrical power.

Read the acronyms as prompts, not as the rule: several items apply only to certain airplanes or certain operations, and the section says which.

What if something is broken

91.213 starts with the Minimum Equipment List. If the aircraft has an approved MEL, that document and 91.213(a) govern the flight. Without one you may be on the path in 91.213(d) — but that paragraph is not open to every airplane. 91.213(d)(1) limits it to rotorcraft, non-turbine-powered airplanes, gliders, lighter-than-air aircraft, powered parachutes and weight-shift-control aircraft, with a further limit to small aircraft where a Master Minimum Equipment List exists. A turbine airplane never arrives here. The trainer you teach in does, which is why this is the paragraph you will actually use — and why it is worth reading (d)(1) in the CFR rather than assuming the absence of a MEL is the only gate.

Then 91.213(d)(2) sets four checks, and it states them as four things the inoperative instrument or equipment must not be:

• part of the VFR-day type certification instruments and equipment prescribed in the airworthiness regulations under which the aircraft was type certificated;
• indicated as required on the aircraft's equipment list, or on the Kinds of Operations Equipment List for the kind of flight operation being conducted;
• required by 91.205 or any other rule of Part 91 for the specific kind of flight operation being conducted;
• required to be operational by an airworthiness directive.

The first two are separate criteria and get counted separately on a checkride: the VFR-day type certification list comes from the certification basis, the equipment list and KOEL come from the AFM. If it clears all four, 91.213(d)(3) and (d)(4) give the rest:

1. The item is removed from the aircraft, the cockpit control placarded, and the maintenance recorded in accordance with 43.9 — or it is deactivated and placarded Inoperative, and if that deactivation involves maintenance, the work is done and recorded under Part 43 by someone authorized to do it, not by you.
2. A determination is made that the inoperative item does not constitute a hazard to the aircraft, by a pilot certificated and appropriately rated under Part 61, or by a person certificated and appropriately rated to perform maintenance on the aircraft.

Telling maintenance is not in the rule, and it belongs in the story anyway: a write-up on record outlasts your memory of the squawk and lets the shop schedule the fix. Keep it as practice, and keep it separate from what 91.213 requires.

The determination is the step that matters. The rule will let you go with a great deal inoperative that you would not want to launch with, and it hands that call to a certificated person on purpose. Your personal minimums live here.

Special flight permit

Sometimes an aircraft is not airworthy but is still capable of safe flight for one specific trip — the annual has lapsed, or the repair has to happen somewhere else. That is a special flight permit, often called a ferry permit, under 21.197, and 91.213(e) points you to it. It covers flying to a base for repairs, maintenance or storage; delivery or export; production flight testing; evacuation from impending danger; and demonstration flights in new production aircraft.

21.199 is how you get one: a statement to the FAA giving the purpose, the itinerary, the crew needed, the ways the aircraft does not comply, and any restriction needed for safety. Apply through your local Flight Standards District Office or a Designated Airworthiness Representative — and the FSDO will want an appointment.

What you may legally fix yourself

Preventive maintenance is defined in 1.1 as simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations. The list is Part 43, Appendix A(c) — servicing landing gear, changing tires, oil and spark plugs, replacing safety wire, seat belts and side windows, and more. It is closed: if the job is not on it, it is not preventive maintenance.

Under 43.3(g) the holder of a pilot certificate issued under Part 61 may perform preventive maintenance on an aircraft owned or operated by that pilot, as long as it is not being flown under Part 121, 129 or 135; some items carry extra conditions of their own. 43.9(a) requires a record of the work — a description, the date of completion, the name of the person who did it, and that person's signature, certificate number and kind of certificate — and 43.7(f) lets a pilot holding at least a private pilot certificate approve that work for return to service. And the part in no regulation: be honest about whether you can do the work satisfactorily and safely.

Records

91.417 splits the records in two. Under 91.417(a)(1), records of maintenance, preventive maintenance and alterations are kept until the work is repeated or superseded by other work, or for one year after the work is performed — the clock starts at the work, not at the next inspection. The records in 91.417(a)(2) transfer with the aircraft when it is sold: time in service of airframe, engine and propeller; life-limited parts and time since overhaul; inspection status; the status of applicable ADs; and the forms for major alterations.

Where you meet it next

On the practical test this is a ground task: the logbooks land on the table and you are asked to show this airplane is legal today. Find the annual, the transponder and static checks, show the ADs are current, then locate the ARROW documents in the airplane and the equipment list and Kinds of Operations Equipment List in the handbook. The mnemonics get you started; the records give the answer.

It also shows up on every preflight. The walkaround is the second half of 91.7, and an inoperative item you find out there drops you into the 91.213 decision with somebody waiting on you. Knowing the criteria in advance is what keeps that decision honest. The rest of the preflight preparation ground subjects — weather, performance and cross-country planning — are in the Learn library, and the report you will be handed on the same oral is taken apart in decoding METARs. When the numbers come next, the density altitude tool and the crosswind calculator do the arithmetic you will be checked on.