Airworthiness Requirements

Two conditions, both required: the aircraft conforms to its type certificate (including STCs and applicable ADs), and it is in condition for safe operation.

The owner/operator is responsible for maintaining it in airworthy condition and for required inspections (91.403). The PIC is responsible for determining it is airworthy before each flight and for discontinuing the flight when an unairworthy condition occurs (91.7). Signing for a customer's airplane does not transfer that determination away from you.

• Airworthiness certificate — displayed at the cabin or cockpit entrance, legible to passengers and crew. No expiration as long as inspections are current, the aircraft conforms to type design, and registration is valid (91.7, 91.203).
• Registration — valid 7 years, extended from 3 effective January 23, 2023.
• Operating limitations — AFM/POH, placards, markings, and any STC supplements.
• Weight and balance — the current equipment list and W&B data in the AFM.

An AD is a regulation issued under 14 CFR part 39 defining the FAA's authority to require correction of an unsafe condition in a product — a condition that exists because of a design defect, maintenance, or other causes, and is likely to exist or develop in other products of the same design (PHAK ch. 9).

Compliance is mandatory and recorded in the applicable maintenance log. Emergency ADs must be complied with before further flight; one-time and recurring ADs by their stated deadline or interval. There is no overfly allowance and no MEL relief — AD-required equipment cannot go on an MEL unless the AD itself says otherwise (91.213(b)(2)).

A Special Airworthiness Information Bulletin is FAA-issued and non-regulatory — it flags a condition the FAA has evaluated and decided does not warrant an AD. Compliance is voluntary. A manufacturer's service bulletin is the factory's equivalent recommendation.

Either can be the precursor to an AD. Under Part 91 you are not required to comply with either, but as a commercial operator flying someone else's revenue airplane, "voluntary" is a maintenance-program decision, not a preflight one — know which ones your operator has adopted.

The aircraft has to be one of the classes 91.213(d)(1) lists, and the class test splits on whether an MMEL exists. Where no MMEL has been developed: rotorcraft, non-turbine-powered airplane, glider, lighter-than-air, powered parachute, or weight-shift-control (91.213(d)(1)(i)). Where an MMEL has been developed: only small rotorcraft, small non-turbine-powered airplane, glider, or lighter-than-air (91.213(d)(1)(ii)). For your ASEL that means a non-turbine airplane either way. Then take off with the item inoperative only if all of the following hold (91.213(d)):

1. It is not part of the VFR-day type certification instruments and equipment
2. It is not indicated as required on the aircraft's equipment list or on the KOEL for the kind of operation being conducted
3. It is not required by 91.205 or any other rule of Part 91 for this specific kind of flight
4. It is not required to be operational by an airworthiness directive

Then: remove it (cockpit control placarded, maintenance recorded per 43.9) or deactivate it and placard it INOPERATIVE; and a pilot or a certificated mechanic determines the inoperative item does not constitute a hazard.

An FAA-approved, aircraft-specific list of equipment that may be inoperative. You cannot simply download one. 91.213(a) requires:

• An approved MEL exists for that aircraft
• A letter of authorization from the responsible Flight Standards office is carried in the aircraft — obtained by written request of the airworthiness certificate holder
• The MEL and the LOA together constitute a supplemental type certificate for the aircraft
• The aircraft records available to the pilot include an entry describing the inoperative equipment
• The aircraft is operated under all conditions and limitations in the MEL and the LOA

Operators under subpart K, Part 121, 125, or 135 who hold an MEL must use it (91.213(c)).

• Instruments and equipment required by the airworthiness requirements under which the aircraft was type certificated and essential for safe operation under all operating conditions
• Instruments and equipment required by an airworthiness directive to be operable, unless the AD provides otherwise
• Instruments and equipment required for specific operations by Part 91

The Kinds of Operations Equipment List lives in the AFM/POH — it is the manufacturer's table of what must be installed and operative for each kind of operation: day VFR, night VFR, day IFR, night IFR, and sometimes flight into known icing.

Difference that matters: the MEL is FAA-approved, aircraft-specific, and relieves you (it permits dispatch with items inoperative); the KOEL restricts you and is a mandatory gate even when no MEL exists (91.213(d)(2)(ii)). Most light airplanes have a KOEL and no MEL — so the KOEL is the list you will actually read.

A special flight permit (a ferry permit) is a form of special airworthiness certificate issued for an aircraft that does not currently meet applicable airworthiness requirements but is capable of safe flight, to move it to a place where repairs or inspection can be performed. 91.213(e) is the Part 91 hook — it lets you operate under such a permit notwithstanding the rest of 91.213 — and the permit itself is issued under 21.197 and 21.199 (PHAK ch. 9, 91.213(e), 21.197).

Practical path: contact the FSDO; the permit is issued by the FAA or by a DAR (Designated Airworthiness Representative). A critical catch — all applicable ADs that are due must be complied with before the flight, even under the permit (PHAK ch. 9).

Special airworthiness certificates are pink (PHAK ch. 3, ch 9). They cover:

• Primary, restricted, and limited category aircraft
• Light sport aircraft
• Provisional airworthiness certificates
• Special flight permits
• Experimental aircraft

The operating limitations attached to a special certificate are part of the certificate, and they can bite a commercial pilot hard: restricted-category aircraft — the crop dusters and survey airplanes of 119.1(e)(4) — generally may not carry persons or property for hire beyond the special purpose for which they are certificated. Read the limitations before you accept the airplane.

Yes, if it is being used to carry any person (other than a crewmember) for hire, or is provided for flight instruction for hire (91.409(b)). The trigger attaches to the use of the aircraft, not to today's flight — so a school or rental airplane must be within its 100-hour whether or not the leg you are flying is for hire.

An annual satisfies a 100-hour, but never the reverse. The 10-hour overfly is permitted only to reach the place where the inspection is done, and the overage comes off the next interval.

14 CFR part 43, appendix A lists what counts as preventive maintenance (PHAK ch. 9), including:

• Servicing landing gear tires and wheel bearings
• Replenishing hydraulic fluid
• Changing oil
• Replacing safety wire and cotter keys
• Replacing spark plugs
• Changing batteries
• Simple fabric patches

Whoever does the work must make an entry in the maintenance record: description of the work, date, and the signature, certificate number, and kind of certificate held (43.9). Undocumented preventive maintenance leaves the airplane unairworthy on paper.

Work the ladder, then work the pressure.

• Legality: the annunciator is not in the 91.205(b) day-VFR list by name, but its function is tied to the source of electrical power in 91.205(c) for night. Check the equipment list, the KOEL row for the kind of operation, and any AD. If the KOEL requires it for night VFR, the night leg is off regardless of what the day leg permits.
• Airworthiness reasoning: the item's purpose is to tell me about a failure I cannot otherwise see quickly. Losing the warning does not degrade the alternator — it degrades my detection of an alternator failure. That is exactly the risk the "does not constitute a hazard to the aircraft" determination is asking about (91.213(d)(4)).
• The pressure: state out loud that the passenger, the schedule, and the revenue are the hazard here. My mitigation is a personal rule decided on the ground: I do not depart on a night or IFR leg with a degraded electrical-monitoring path, whatever the placard says.

Three separate records: airframe, engine, and propeller. Inspections and AD compliance are signed off in the applicable log, and recurring ADs carry a next-due date or interval that you should be able to find and read.

For a commercial oral, be ready to open the actual logs and point to:

• The most recent annual (and 100-hour if the aircraft is used for hire)
• The AD compliance list with recurring items and next-due
• The ELT battery replacement date
• The transponder and static-system checks
• The current W&B and equipment list

The Type Certificate Data Sheet is generated when the FAA issues a Type Certificate and specifies the important design and operational characteristics of the aircraft, engine, or propeller (PHAK ch. 3). It is public and available from the FAA.

You care because the TCDS plus the aircraft's equipment list are how you answer whether something counts as VFR-day type certification equipment for an airplane you did not grow up in (91.213(d)(2)(i)). It is also where you confirm engine and propeller models, fuel grade, and placard requirements when you take delivery of an unfamiliar aircraft.

An annual must be performed by an A&P holding an Inspection Authorization (IA), by the aircraft manufacturer, or by a certificated and appropriately rated repair station. The scope is identical to a 100-hour; only the authorization differs — any certificated A&P may sign a 100-hour (PHAK ch. 9, 91.409).

The aircraft may not be operated unless the annual has been performed within the preceding 12 calendar months, and a calendar month runs from any day of a month to the last day of that month the following year. An aircraft overdue for an annual may be operated only under a special flight permit to reach the inspection location (PHAK ch. 9).

• 100-hour inspection attaches (91.409(b)) whenever the aircraft carries a person other than a crewmember for hire or is provided for flight instruction for hire.
• Landing light becomes required equipment for night operations for hire (91.205(c)).
• The ELT exception in 91.207(f) for training flights within 50 NM does not cover a revenue flight.
• Special-category limitations matter — restricted, limited, provisional, and experimental certificates each carry operating limitations that can prohibit carrying persons or property for hire.
• If the operation runs under Part 119 with 121/125/135 opspecs, an approved MEL is mandatory where one is held (91.213(c)), and the operator's maintenance program — not 91.213(d) — governs dispatch.

This is a ferry flight, one of the 119.1(e)(3) exceptions, so my commercial certificate covers the operation. What it does not cover is the airworthiness: an aircraft past its annual is unairworthy and cannot legally fly without a special flight permit.

The sequence:

1. Confirm the aircraft is capable of safe flight
2. Contact the FSDO or a DAR for the permit
3. Ensure all due ADs are complied with first
4. Fly only the route and conditions the permit specifies — commonly day VFR, no passengers, minimum crew
5. Carry the permit in the aircraft as its special airworthiness certificate