A company buys a business jet, hires two pilots, and starts flying its executives to plants and customer sites. No tickets are sold, no strangers board, and the flight department holds no air carrier certificate. That operation lives in a specific corner of the regulations — Subpart F of 14 CFR Part 91 — and it carries a recordkeeping burden that surprises a lot of first-time flight-department managers.
The reason is that Part 91 corporate flying looks, from the outside, almost identical to Part 135 charter: a turbine airplane, professional crew, passengers in the back. What separates them is not the aircraft — it is who exercises operational control, whether anyone paid for the flight, and how much. And the FAA reconstructs all three from documents. Get the §91.501 agreements, the §91.501(d) charge records, the §91.503 onboard documents, and the §91.417 maintenance records right, and the operation is plainly non-commercial. Get them wrong, and a flight that felt like a routine company trip can be recharacterized as unlicensed charter.
This guide walks through what Subpart F is, the §91.503 flying-equipment and operating-information list, the §91.505 familiarity rule, the three §91.501(c) cost-recovery agreements and the §91.501(d) charge limits, and the maintenance, inspection, and truth-in-leasing records every corporate flight department has to keep.
What Subpart F Is — and Which Aircraft It Governs
14 CFR §91.501 opens Subpart F, the set of additional operating rules for larger and more complex airplanes flown for business and corporate purposes. Section 91.501(a) applies the subpart to three categories — all of U.S. registry: large airplanes, turbojet-powered multiengine civil airplanes, and fractional ownership program aircraft. (Fractional aircraft are operated under Subpart K, which layers its own rules on top of Subpart F.) A piston twin or a light single does not fall under Subpart F; a large turboprop that meets the large-airplane definition does.
The §91.501(b) Operations — Non-Commercial by Design
Section 91.501(b) lists the operations a person may conduct under the operating rules of this subpart. They are deliberately non-common-carriage — the corporate flying that does not require a charter certificate, including:
- Ferry or training flights
- Aerial work operations such as aerial photography or survey, or pipeline patrol, but not including fire fighting operations
- Flights for the demonstration of an airplane to prospective customers (with no charge except as provided in paragraph (d))
- Flights conducted for the carriage of company officials, employees, and guests when the carriage is within the scope of, and incidental to, the business of the company (other than transportation) and no charge is made except as provided in paragraph (d)
- Carriage of company officials, employees, and guests under a time sharing, interchange, or joint ownership agreement as defined in paragraph (c)
- Carriage of property (other than mail) on a flight conducted for, or to further, a business (other than transportation) when the carriage is within the scope of, and incidental to, that business and no charge is made except as provided in paragraph (d)
The list above is paraphrased and abbreviated; §91.501(b) also covers airplane demonstration to prospective buyers, carriage of athletic teams or groups, and certain sales-demonstration flights. Read the full text before relying on any one category.
The thread running through every §91.501(b) operation is that the flying is incidental to a non-transportation business, or is a carefully bounded cost-sharing arrangement. The moment a flight crosses into holding out transportation to the public for compensation, it leaves Subpart F and enters the world of Part 119/135 certification and operations specifications. That boundary is policed almost entirely through records — which is the rest of this guide.
Operational control is defined in §1.1 — and proven by documents
Operational control is defined in 14 CFR §1.1 as the exercise of authority over initiating, conducting, or terminating a flight. In a Subpart F operation it decides who is the operator and who is accountable. The FAA reconstructs it after the fact from the agreement, the flight release, the crew employment and pay records, and the §91.501(d) expense documentation. When those records conflict, the agency can conclude an unauthorized commercial operation occurred.
§91.503 — Flying Equipment and Operating Information
14 CFR §91.503(a) places the obligation on the pilot in command to ensure that specific equipment and operating information is aboard and available before flight. Three of the five items are physical documents a flight department has to maintain and version-control — which makes §91.503 as much a recordkeeping rule as an equipment rule.
Flashlight
A flashlight having at least two size "D" cells, or the equivalent, that is in good working order.
Cockpit checklist
A cockpit checklist containing the procedures required by paragraph (b) of this section — see the seven procedure categories below.
Aeronautical charts
Pertinent aeronautical charts.
IFR / night charts
For IFR, VFR over-the-top, or night operations, each pertinent navigational en route, terminal area, and approach and letdown chart.
OEI climb data
In the case of multiengine airplanes, one-engine-inoperative climb performance data.
§91.503(b) — The Cockpit Checklist Must Cover Seven Phases
Section 91.503(b) requires the cockpit checklist required by §91.503(a)(2) to contain procedures for:
§91.505 — Familiarity with Operating Limitations and Emergency Equipment
Closely paired with §91.503 is 14 CFR §91.505. Under §91.505(a), each pilot in command of an airplane must, before beginning a flight, become familiar with the Airplane Flight Manual for that airplane (if one is required) and with any placards, listings, instrument markings, or any combination thereof containing each operating limitation prescribed for that airplane by the Administrator, including those specified in §91.9(b). Under §91.505(b), each required crewmember must, before beginning a flight, become familiar with the emergency equipment installed on the airplane to which that crewmember is assigned and with the procedures to be followed for the use of that equipment in an emergency.
For a flight department, §91.505 turns the AFM, its supplements, and the emergency-equipment documentation into controlled records: the current revision of the AFM and any flight manual supplements from installed STCs has to be the one on the airplane, and the crew must be able to show familiarity. A superseded AFM revision or a missing supplement for an installed modification is a documentation gap an inspector can find on a ramp check.
§91.501(c) — Time Sharing, Interchange, and Joint Ownership Agreements
Section 91.501(c) defines three arrangements that let a Subpart F operator recover certain costs without becoming a commercial operator. Each is a specific legal structure with its own charge rules, and the written agreement is the primary document the FAA examines when it tests whether a cost-sharing arrangement is genuine. The definitions below track the regulation closely.
Time Sharing Agreement — §91.501(c)(1)
An arrangement whereby a person leases his airplane with flight crew to another person, and no charge is made for the flights conducted under that arrangement other than those specified in paragraph (d). In other words: the aircraft owner provides the airplane and the crew, the other party pays, and the only permissible charges are the §91.501(d) expense categories. This is the most common structure when one company lets a related or unrelated company use its flight department occasionally.
Interchange Agreement — §91.501(c)(2)
An arrangement whereby a person leases his airplane to another person in exchange for equal time, when needed, on the other person's airplane, and no charge, assessment, or fee is made, except that a charge may be made not to exceed the difference between the cost of owning, operating, and maintaining the two airplanes. Two operators essentially swap aircraft time; the only money that may change hands is the cost difference between the two airplanes — making the cost-accounting records for both airplanes part of the compliance trail.
Joint Ownership Agreement — §91.501(c)(3)
An arrangement whereby one of the registered joint owners of an airplane employs and furnishes the flight crew for that airplane and each of the registered joint owners pays a share of the charge specified in the agreement. The defining features are that the parties are registered joint owners, one of them supplies the crew, and the cost split is set in the written agreement — which ties the arrangement to the Part 47 aircraft registration records.
These agreements usually trigger truth-in-leasing under §91.23
Because a time sharing, interchange, or joint ownership agreement is a lease of a U.S.-registered large civil aircraft, it generally must contain the §91.23 truth-in-leasing clause — naming the person responsible for operational control, identifying the maintenance/inspection regulations followed in the prior 12 months, with a copy carried aboard, a copy mailed to the FAA Aircraft Registration Branch within 24 hours of execution, and the responsible Flight Standards office notified before the first flight under the lease.
§91.501(d) — The Closed List of Chargeable Expenses
Section 91.501(d) is the dollar boundary of Subpart F. It provides that the following may be charged, as expenses of a specific flight, for transportation as authorized by the relevant paragraphs of §91.501(b). The word that matters is closed: if an expense is not on this list, it cannot be charged without pushing the flight toward commercial carriage. The ten categories are:
| Item | Chargeable Expense |
|---|---|
| (d)(1) | Fuel, oil, lubricants, and other additives |
| (d)(2) | Travel expenses of the crew, including food, lodging, and ground transportation |
| (d)(3) | Hangar and tie-down costs away from the aircraft’s base of operation |
| (d)(4) | Insurance obtained for the specific flight |
| (d)(5) | Landing fees, airport taxes, and similar assessments |
| (d)(6) | Customs, foreign permit, and similar fees directly related to the flight |
| (d)(7) | In-flight food and beverages |
| (d)(8) | Passenger ground transportation |
| (d)(9) | Flight planning and weather contract services |
| (d)(10) | An additional charge equal to 100 percent of the expenses listed in paragraph (d)(1) of this section |
The (d)(10) Trap — and What You Cannot Charge
Item (d)(10) lets an operator add a charge equal to 100 percent of the fuel and oil in (d)(1) — effectively, double the fuel cost. That is the ceiling, and it is the single most misread line in Subpart F. What is not on the list cannot be charged on these flights:
- ×A profit margin or an open-ended "per flight hour" rate
- ×Recovery of fixed costs — crew salaries, training, aircraft depreciation, financing, or base hangar rent
- ×Management or administrative fees not tied to a (d) category
- ×Anything that, in substance, charges for the transportation itself rather than the enumerated specific-flight expenses
The records that prove you stayed inside §91.501(d) — invoices, the expense breakdown billed under each agreement, fuel receipts — are exactly what an FAA inspector or, in a dispute, opposing counsel will ask to see.
Note that several other Subpart F operations in §91.501(b) — such as carrying company officials within the scope of and incidental to the company's non-transportation business — permit no charge at all except the §91.501(d) expenses. The agreements in §91.501(c) are the structures that let a second party be billed those expenses at all; outside an agreement, the default is the company simply absorbing the cost of its own flying.
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Run the FAA Readiness Score — FreeMaintenance and Inspection Records Still Apply — §91.417 and §91.409
A corporate flight department does not escape the Part 91 maintenance and recordkeeping rules just because it is non-commercial. A Subpart F airplane is a U.S.-registered civil aircraft, so §91.417 aircraft records apply in full.
§91.417(a)(1) — Maintenance Records (1-Year Floor)
Records of maintenance, preventive maintenance, and alteration, and records of the 100-hour, annual, progressive, and other required or approved inspections, kept until the work is repeated or superseded by other work, or for one year after the work is performed. Each entry is made under §43.9 (or §43.11 for inspection entries).
§91.417(a)(2) — Life-of-Aircraft Permanent Records
The six permanent items retained for the life of the aircraft and transferred with it on sale: total time in service (airframe, engines, propellers, rotors); current status of life-limited parts; time since last overhaul of items required to be overhauled on a specified time basis; current inspection status; current status of applicable Airworthiness Directives (including method of compliance, AD number, and next-due dates for recurring ADs); and copies of FAA Form 337 for major alterations to the airframe and installed engines, rotors, propellers, and appliances.
Because most Subpart F airplanes are large or turbine-powered multiengine airplanes, §91.409(f) requires the operator to select one of four inspection programs rather than relying on a simple annual:
Continuous airworthiness inspection program
A continuous airworthiness inspection program that is part of a continuous airworthiness maintenance program currently in use by an air carrier under part 121 or 135.
Approved aircraft inspection program (AAIP)
An approved aircraft inspection program approved under §135.419 and currently in use by a person holding an operating certificate under part 135.
Manufacturer-recommended program
A current inspection program recommended by the manufacturer.
Owner/operator-developed program
An inspection program established by the registered owner or operator and approved by the FAA under §91.409(g).
Whichever program the operator selects, the documents that prove the airplane is current within it become the inspection-status backbone of the §91.417(a)(2) permanent set. For a turbojet flight department, that usually means a manufacturer-recommended program (often administered through a tracking service) plus rigorous records-retention discipline. Separately, the §91.411 altimeter/static and §91.413 transponder tests recur on a 24-calendar-month cycle and, while expressly excepted from §91.417 recordkeeping, are kept in practice because they gate IFR and transponder-airspace operations — and because RVSM-equipped jets layer on additional altimetry documentation.
The Corporate Flight Department Records Stack
Pulling it together, a Part 91 Subpart F operation has to be able to produce a coherent set of documents on demand — for a ramp check, an insurance audit, a lender's diligence, or an FAA inquiry into whether a flight was commercial. The stack spans agreements, onboard documents, crew records, and maintenance records.
| Document | Authority | Why It Matters |
|---|---|---|
| Time sharing / interchange / joint ownership agreement | §91.501(c) | Defines the cost-recovery structure and who exercises operational control |
| Per-flight expense documentation (invoices, fuel receipts) | §91.501(d) | Proves charges stayed inside the closed list — including the (d)(10) ceiling |
| Truth-in-leasing clause + filing/notification proof | §91.23 | Names the operational-control party; copy aboard, mailed to Registry, FSDO notified |
| Cockpit checklist (7 phases) | §91.503(a)(2), (b) | Required onboard; must be current and cover all seven procedure categories |
| One-engine-inoperative climb performance data | §91.503(a)(5) | Required onboard for multiengine airplanes |
| Airplane Flight Manual + STC supplements | §91.505(a) | Current revision must be aboard; crew must show familiarity with limitations |
| Pilot currency / recency records | §61.57 | Landings, instrument experience, and flight reviews underpinning each crewmember |
| §91.417(a)(1) maintenance & inspection entries | §91.417(a)(1), §43.9 | Kept until repeated/superseded or 1 year |
| §91.417(a)(2) permanent records | §91.417(a)(2) | Total times, life-limited parts, AD status, Form 337s — life of aircraft |
| Selected inspection program + currency proof | §91.409(f) | The inspection-status backbone for large/turbine multiengine airplanes |
Crew records deserve a specific note. Even under Part 91, each pilot has to satisfy §61.57 recency of experience — takeoffs and landings, instrument experience, and the flight review cycle — and the second pilot in a two-crew jet has to meet the SIC qualification rules, including the type-rating path that flows from §61.55(d) where a type rating is required. These are pilot-side records distinct from the aircraft logbooks, and they round out the personnel half of the stack. A flight department that wants to operate cleanly keeps both halves indexed and current — and keeps the distinction between a pilot's personal logbook and operator records clear.
How FileFlo Sits in the Subpart F Records Stack
FileFlo is a compliance document intelligence platform — a read-only proof layer that sits alongside a flight department's existing systems and keeps the documents audit-ready. It classifies 600+ document types against the governing CFR section, indexes the §91.501 agreements and §91.23 truth-in-leasing paperwork next to the §91.417 maintenance records, and tracks expirations so a 24-calendar-month transponder test, an upcoming inspection, or a recurring AD due date surfaces 90/60/30 days out.
FileFlo does not exercise operational control, hold any certificate, perform maintenance, fly the airplane, or render legal advice about whether a given charge or arrangement is commercial. It keeps the documents that prove the operation is what it claims to be — organized, indexed against the relevant CFR, and ready for an FAA inspector, an insurer, or a lender's diligence team.
Check Your Flight Department's ReadinessRelated Aviation Compliance Guides
Part 91 Aircraft Records Requirements
The full §91.417 permanent vs temporary records framework
Part 91K Fractional Ownership Records
How Subpart K layers onto Subpart F for fractional aircraft
Truth-in-Leasing Aircraft Lease Records (§91.23)
The clause your time-sharing agreement almost certainly needs
What Is Operational Control?
The §1.1 definition the FAA reconstructs from your documents
Part 91.409 Annual Inspection Requirements
The inspection cycle and the four §91.409(f) programs
Aircraft Flight Manual & AFM Supplements
The §91.505 documents that must be current and aboard
Operations Specifications (OpSpecs) Explained
What changes when an operation crosses into Part 119/135
What Records Must a Part 135 Operator Keep?
The certificated-charter comparison point
Frequently Asked Questions
What is 14 CFR Part 91 Subpart F and which aircraft does it apply to?
Subpart F of 14 CFR Part 91 (§§91.501-91.535) prescribes additional operating rules for corporate and business flying that does not require a charter certificate. Section 91.501(a) states that the subpart governs the operation of large airplanes of U.S. registry, turbojet-powered multiengine civil airplanes of U.S. registry, and fractional ownership program aircraft of U.S. registry. It does not apply to piston twins, light single-engine airplanes, or turboprops below the large-airplane threshold unless they are operated under a fractional program managed under Subpart K. The practical audience is the corporate flight department flying a business jet (or a large turboprop that meets the large-airplane definition) under Part 91 in non-commercial operations — carrying company executives, not paying charter passengers. Because Subpart F operations are non-commercial, the operator does not hold an air carrier certificate, which makes its own records discipline the only thing standing between it and an operational-control or recordkeeping finding.
What flying equipment and operating information must a Part 91 corporate PIC have on board under §91.503?
Under 14 CFR §91.503(a), the pilot in command of a Subpart F airplane must ensure five items are aboard and available: (1) a flashlight having at least two size D cells, or the equivalent, that is in good working order; (2) a cockpit checklist containing the procedures required by §91.503(b); (3) pertinent aeronautical charts; (4) for IFR, VFR over-the-top, or night operations, each pertinent navigational en route, terminal area, and approach and letdown chart; and (5) in the case of multiengine airplanes, one-engine-inoperative climb performance data. Section 91.503(b) requires the cockpit checklist to contain procedures for before starting engines, before takeoff, cruise, before landing, after landing, stopping engines, and emergencies. Note that several of these — the cockpit checklist and the one-engine-inoperative performance data — are documents a flight department must maintain, version-control, and produce on request, not just carry once.
What is the difference between a time sharing, interchange, and joint ownership agreement under §91.501(c)?
Section 91.501(c) defines three distinct cost-recovery arrangements for Subpart F aircraft. A time sharing agreement (§91.501(c)(1)) is an arrangement whereby a person leases his airplane with flight crew to another person, and no charge is made for the flights conducted under that arrangement other than those specified in paragraph (d). An interchange agreement (§91.501(c)(2)) is an arrangement whereby a person leases his airplane to another person in exchange for equal time, when needed, on the other person’s airplane, and no charge, assessment, or fee is made, except that a charge may be made not to exceed the difference between the cost of owning, operating, and maintaining the two airplanes. A joint ownership agreement (§91.501(c)(3)) is an arrangement whereby one of the registered joint owners of an airplane employs and furnishes the flight crew for that airplane and each of the registered joint owners pays a share of the charge specified in the agreement. The agreement itself, and the documentation supporting the charges billed under it, are the records the FAA looks at when it questions whether an arrangement is genuine cost-sharing or disguised commercial carriage requiring a Part 119/135 certificate.
What charges can a corporate operator collect under a §91.501 time sharing agreement?
Section 91.501(d) sets the closed list of expenses that may be charged, as expenses of a specific flight, for transportation authorized under the listed Subpart F operations. The items are: (1) fuel, oil, lubricants, and other additives; (2) travel expenses of the crew, including food, lodging, and ground transportation; (3) hangar and tie-down costs away from the aircraft’s base of operation; (4) insurance obtained for the specific flight; (5) landing fees, airport taxes, and similar assessments; (6) customs, foreign permit, and similar fees directly related to the flight; (7) in-flight food and beverages; (8) passenger ground transportation; (9) flight planning and weather contract services; and (10) an additional charge equal to 100 percent of the expenses listed in paragraph (d)(1) of this section. The (d)(10) item is the one most often misunderstood: an operator can charge actual fuel cost plus an amount equal to 100 percent of that fuel cost — but nothing beyond the enumerated categories. Charging a profit margin, an hourly rate, or recovering fixed costs like crew salaries or aircraft depreciation falls outside §91.501(d) and pushes the flight toward commercial carriage.
Does a corporate flight department under Part 91 have to keep maintenance and inspection records?
Yes. A Subpart F aircraft is still subject to the Part 91 maintenance and recordkeeping rules. Section 91.417 requires the registered owner or operator to keep maintenance, preventive maintenance, and alteration records (§91.417(a)(1), retained until the work is repeated or superseded or for one year) and the life-of-aircraft permanent records in §91.417(a)(2) — total time in service, life-limited part status, time since last overhaul, current inspection status, current Airworthiness Directive status, and copies of major alterations. Because most Subpart F airplanes are large or turbine-powered multiengine airplanes, §91.409(f) requires the operator to select an inspection program — a continuous airworthiness inspection program, an approved aircraft inspection program under §135.419, a current manufacturer-recommended inspection program, or a program the owner or operator establishes and the FAA approves. The selected program, and the records proving the aircraft is current within it, are the inspection-status backbone of the §91.417(a)(2) permanent set.
Is a corporate flight department aircraft subject to truth-in-leasing under §91.23?
Often, yes. 14 CFR §91.23 requires a written truth-in-leasing clause in any lease or conditional sales contract for a U.S.-registered large civil aircraft, and time sharing, interchange, and joint ownership agreements under §91.501(c) are leases of the aircraft and therefore generally must contain the clause when the aircraft is a large civil aircraft (the §91.23 text does not name those arrangements; the FAA treats them as leases in its truth-in-leasing guidance, AC 91-37). The clause must identify the FAA regulations under which the aircraft has been maintained and inspected during the prior 12 months, name the person responsible for operational control, and certify that person understands their responsibilities. The lessee or operator must also carry a copy of the lease aboard the aircraft, mail a copy to the FAA Aircraft Registration Branch within 24 hours of execution, and notify the responsible Flight Standards office before the first flight under the lease (per the rule, at least 48 hours in advance for the first flight). Truth-in-leasing is therefore a document-creation and document-retention obligation that sits directly on top of the §91.501 agreement.
What does operational control mean for a Part 91 corporate operation, and why does it matter for records?
Operational control is defined in 14 CFR §1.1 as the exercise of authority over initiating, conducting, or terminating a flight. In a Subpart F operation it determines who is legally the operator — and therefore who is accountable for compliance with the operating and maintenance rules. The reason it matters for records is that the FAA reconstructs operational control after the fact from documents: who signed the time sharing or interchange agreement, who scheduled and released the flight, who employed and paid the crew, who held the operating certificate of authority, and who paid for the flight under §91.501(d). When those documents tell a consistent story, operational control is clear. When they conflict — for example, a passenger entity that pays for fuel, schedules the crew, and directs the flight while claiming the flight is the aircraft owner’s Part 91 operation — the FAA may conclude that an unauthorized commercial operation occurred, exposing the parties to civil penalties.
How is a Part 91 corporate flight department different from a Part 135 charter operator for recordkeeping?
A Part 135 charter operator holds an air carrier certificate and operates under a detailed, FAA-approved system: required management personnel, an approved training program, drug and alcohol testing, operations specifications, and prescriptive recordkeeping for pilots, training, and maintenance. A Part 91 Subpart F corporate flight department holds no certificate and is not commercial — it carries the company’s own people and property, recovering only the §91.501(d) expenses where an agreement permits. Its recordkeeping obligations are narrower: §91.417 maintenance records, the §91.409 inspection program, §91.503 flying equipment and operating information, §91.505 operating-limitations familiarity, pilot currency under §61.57, and any §91.23 truth-in-leasing paperwork. The risk is different too: Part 135’s exposure is in the depth of its required system, while Part 91 corporate’s exposure is in proving that what looks like charter is genuinely non-commercial — which is almost entirely a documentation question.
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Written by Chad Griffith, Founder, FileFlo — compliance document intelligence · Reviewed June 13, 2026 · Primary sources: eCFR 14 CFR §91.501, §91.503, §91.505, §91.409, §91.417, §91.23