Ask a group of GA pilots when their aircraft needs its next inspection and most will say "the annual." Ask when a 100-hour applies. Ask what a progressive inspection actually changes. Ask whether an AAIP replaces the annual or supplements it. The answers reveal how much confusion surrounds 14 CFR §91.409 — one of the most operationally consequential sections in Part 91.
§91.409 doesn't create a single inspection requirement. It creates four distinct regimes with different intervals, different triggering conditions, different authorization levels for who can sign off, and different records implications. Flying under the wrong assumption about which regime applies — or flying with an expired inspection because you misread the calendar-month rule — can make an aircraft legally unairworthy on departure.
This guide disentangles all four. We cover what each regime requires, who can legally perform and sign off each type, what records each produces, and how inspection status feeds into the §91.417 permanent record set that travels with the aircraft for its entire service life.
The Four §91.409 Inspection Regimes at a Glance
§91.409's core prohibition is straightforward: no person may operate a U.S.-registered civil aircraft unless, within the preceding 12 calendar months, the aircraft has had an inspection and been approved for return to service by a person authorized under Part 43 — unless an approved inspection program is in effect. The four regimes are the ways that "unless" clause gets filled in.
| Regime | CFR | Interval | Applies When | Sign-Off Authority |
|---|---|---|---|---|
| Annual Inspection | §91.409(a) | 12 calendar months | All aircraft not under approved program | IA or rated repair station |
| 100-Hour Inspection | §91.409(b) | 100 hours TIS (+10 ferry) | Pax-for-hire, or instruction for hire in an aircraft the instructor provides | Any certificated A&P (no IA required) |
| Progressive Inspection | §91.409(d) | Approved program intervals | Owner/operator elects an FAA-approved progressive program | Per the approved program |
| AAIP (Approved Program) | §91.409(e)/(f) | Per program schedule | Large airplanes + turbojet/turboprop multiengine (required); turbine rotorcraft (may elect) | Per the approved program |
Calendar Months vs. Flight Hours — A Critical Distinction
The annual inspection interval is measured in calendar months, not flight hours. An aircraft that received its annual on June 15, 2025 is current through the end of June 2026 — not 365 days from June 15, but through the last day of the 12th calendar month following the inspection month. An aircraft that flew zero hours in that period still needs its annual by June 30, 2026. The 100-hour inspection, by contrast, is measured in aircraft total time in service (flight hours), not calendar time. These two measuring systems run in parallel for for-hire operators and can expire at different points.
Annual Inspection — 14 CFR §91.409(a)
The annual inspection under §91.409(a) is the default inspection requirement for U.S.-registered civil aircraft that are not operating under an approved inspection program. It applies regardless of how many hours the aircraft has flown. A C172 that sat in a hangar all year still needs its annual.
The 12-Calendar-Month Window
§91.409(a)(1) uses the phrase "preceding 12 calendar months." A calendar month ends on the last day of that month. An aircraft inspected on March 5, 2025 has an annual current through the end of March 2026 (March 31, 2026). The inspection does not expire on March 5, 2026 — it expires at the end of the 12th calendar month. This grace window is real and frequently used: an aircraft can fly legally throughout March 2026 even if the annual was completed on March 1, 2025. Note that the new annual, if performed any time in March 2026, resets the clock to the end of March 2027 — not 12 months from the date of the new inspection.
Scope of the Annual Inspection
The scope and detail of the annual inspection is governed by 14 CFR Part 43 Appendix D, which lists the items that must be inspected. Appendix D covers the aircraft powerplant, propeller, fuel and oil systems, landing gear, flight control surfaces, and structural components. The IA or repair station conducting the annual must inspect each item to determine that it meets the applicable airworthiness standards — not merely that it passed last year.
An expired annual makes the aircraft immediately unairworthy
Under §91.409(a), an aircraft with an expired annual is not approved for flight. This is not a paperwork technicality — it is an airworthiness condition. An aircraft that has not had an annual within the preceding 12 calendar months cannot legally be flown for any purpose except ferrying to an inspection facility under a special flight permit (if the aircraft is otherwise airworthy). An owner who discovers an expired annual on the ramp must ground the aircraft until the annual is completed, not reschedule at the next convenient time.
What the Annual Inspection Logbook Entry Must Contain (§43.11)
Per 14 CFR §43.11 (content and form of inspection records), each person who performs an annual inspection must make an entry in the maintenance record that contains:
- The type of inspection performed (e.g., "annual inspection per 14 CFR Part 43 Appendix D")
- The date of the inspection
- Total time in service of the aircraft at the time of inspection
- The signature, certificate number, and kind of certificate (IA) held by the person approving the aircraft for return to service
- Either a statement that the aircraft has been approved for return to service, OR a list of all discrepancies and unairworthy items that prevent return to service
Missing any of these elements creates a logbook defect under §43.11. An annual entry that reads "aircraft airworthy — returned to service" without the total time in service and the IA certificate number fails the standard.
100-Hour Inspection — 14 CFR §91.409(b)
The 100-hour inspection under §91.409(b) is an additional inspection requirement layered on top of the annual for aircraft used in specific commercial operations. It does not replace the annual — both requirements run in parallel for affected aircraft.
Exactly Which Operations Trigger the 100-Hour Requirement
§91.409(b) triggers for aircraft carrying any person (other than a crewmember) for hire, and for flight instruction for hire when the person giving the instruction provides the aircraft. Ownership is not the test. If a flight school provides a Cessna 172 and its CFI gives instruction in it for hire, the 100-hour requirement applies to that aircraft. If a CFI gives instruction for compensation in an aircraft the CFI provides — owned or rented — the requirement applies; instruction in an aircraft the student provides does not trigger it. For Part 135 charter aircraft type certificated for nine or fewer passenger seats, §135.411(a)(1) keeps maintenance under Parts 91 and 43, so the annual and 100-hour requirements apply directly unless the operator uses an approved aircraft inspection program under §135.419 — only aircraft type certificated for ten or more passenger seats must instead follow the §§135.415–135.443 maintenance-program regime.
The +10-Hour Ferry Allowance
§91.409(b) includes an explicit overrun allowance: the aircraft may exceed the 100-hour limit by up to 10 hours to ferry it to a location where the inspection can be performed. However — and this is the detail most operators get wrong — the next 100-hour interval starts from the inspection that was exceeded, not from the ferry-arrival inspection. If an aircraft's last 100-hour was at 1,200 hours total time and it was ferried in at 1,208 hours (8 hours over), the next 100-hour is due at 1,300 hours (100 hours from 1,200), not 1,308 hours. The overrun is "consumed" in the next interval.
No IA Required — But the Same §43.11 Entry Standard Applies
Unlike the annual, a 100-hour inspection can be performed and approved for return to service by any certificated A&P mechanic. No Inspection Authorization is required. The inspection scope follows the same Part 43 Appendix D checklist as the annual, and the logbook entry must meet the same §43.11 content requirements: type of inspection, date, total time in service, A&P certificate number, and return-to-service statement or discrepancy list. An A&P who performs a 100-hour but writes "100-hr insp completed" with no total time in service creates the same logbook defect as an IA who does so on an annual.
Annual and 100-hour run in parallel — both can be expired simultaneously
A flight school aircraft used for instruction for hire must satisfy both the annual (12 calendar months) and the 100-hour (100 hours TIS) — and the two interact. §91.409(b) accepts an annual or a 100-hour inspection within the preceding 100 hours of time in service, so a completed annual restarts the 100-hour clock: if an aircraft had its last 100-hour at 1,000 hours TIS and then received its annual in January 2026, the next 100-hour compliance point is 100 hours of time in service after the annual — not a fixed 1,100 hours TIS. The reverse is narrower: a 100-hour does not reset or extend the annual due date unless it was performed by a person authorized to perform annual inspections and entered in the required records as an annual inspection (§91.409(a)). Both requirements must remain current simultaneously.
Progressive Inspection — 14 CFR §91.409(d)
The progressive inspection program under §91.409(d) allows an aircraft owner or operator to satisfy the §91.409 inspection requirement through a series of partial inspections spread over a defined schedule, rather than a single comprehensive annual event.
How a Progressive Inspection Works
A progressive program divides the required inspection items into groups inspected in rotation on a defined schedule. §91.409(d) requires that the frequency and detail of the progressive inspection provide for the complete inspection of the aircraft within each 12 calendar months. The program begins with a written request that the registered owner or operator submits to the responsible Flight Standards office (the local FSDO), supported by a current inspection procedures manual and enough housing and equipment for necessary disassembly and proper inspection. The practical benefit: maintenance downtime is distributed throughout the year rather than concentrated in a single annual event, which suits high-utilization operators.
Personnel, Manual, and Discontinuance Requirements
§91.409(d)(1) requires the progressive inspection to be supervised or conducted by a certificated mechanic holding an Inspection Authorization, a certificated airframe repair station, or the aircraft manufacturer; §91.409(d)(2) requires a current inspection procedures manual; and §91.409(d)(3) requires enough housing and equipment for necessary disassembly and proper inspection. If at any point the owner/operator decides to discontinue the progressive program, they must immediately notify the responsible Flight Standards office in writing — and the first annual inspection is due within 12 calendar months after the last complete inspection under the progressive program. The aircraft's current inspection status under the program is part of the §91.417(a)(2)(iv) inspection-status record.
Approved Aircraft Inspection Program (AAIP) — 14 CFR §91.409(e) and (f)
For larger and turbine-powered aircraft, §91.409 moves beyond calendar-month and flight-hour intervals into manufacturer- and operator-developed inspection programs. These programs replace both the annual and 100-hour requirements entirely.
§91.409(e) — Large Airplanes and Turbojet/Turboprop Multiengine Airplanes (Mandatory Program Selection)
For U.S.-registered large airplanes (over 12,500 lbs maximum certificated takeoff weight) to which Part 125 is not applicable — piston or turbine — and for turbojet and turbopropeller-powered multiengine airplanes, §91.409(e) makes inspection-program selection mandatory. These operators cannot simply do an annual — the owner or operator must select, identify in the aircraft maintenance records, and use one of the four inspection programs listed in §91.409(f). Turbine-powered rotorcraft may use a §91.409(f) program or may instead elect the inspection provisions of §91.409(a), (b), (c), or (d).
Corporate flight departments operating under Part 91 Subpart F with large or turbine-powered aircraft are operating under this regime. The selected program must be identified in the aircraft maintenance records (§91.409(f)), and the aircraft's current inspection status under that program is a §91.417(a)(2)(iv) permanent record that must be maintained and available to the FAA.
§91.409(f) — The Four Selectable Inspection Programs
§91.409(f) lists the inspection programs an owner or operator may select as an alternative to the annual: (1) a continuous airworthiness inspection program currently in use by a Part 121 or Part 135 air carrier; (2) an aircraft inspection program approved under §135.419 and currently in use by a Part 135 operator — this is the Approved Aircraft Inspection Program (AAIP); (3) a current inspection program recommended by the manufacturer; or (4) any other inspection program established by a registered owner or operator and approved by the FAA Administrator. Each of these programs eliminates the annual and 100-hour requirements in favor of the program's own maintenance schedule.
Transferring aircraft between inspection programs is a compliance-gap risk
When a large or turbine aircraft moves from one selected inspection program (such as a CAMP-based carrier program at a previous operator) to a different §91.409(f) program, §91.409(h) requires the time in service, calendar times, and cycles of operation accumulated under the previous program to be credited to the new program in determining inspection due times. An aircraft that exits a CAMP without a selected successor inspection program is not compliant with §91.409(e) until the new program is established. This is a recurring source of compliance gaps in turbine aircraft transactions.
Who Can Sign Off Each Inspection Type
The sign-off authority question is where the most consequential logbook errors occur. Inspections approved by the wrong authority are not legal return-to-service approvals — they are logbook defects that can make an aircraft legally unairworthy even though the inspection work was performed correctly.
Annual Inspection: IA or Rated Repair Station Only
Under 14 CFR §43.7(b) through (d), an annual inspection can be approved for return to service only by:
- A certificated A&P mechanic holding a current Inspection Authorization (IA) — issued under 14 CFR §65.91 through §65.95
- A certificated repair station appropriately rated to perform the inspection for that category and class of aircraft (14 CFR Part 145)
- The aircraft manufacturer (for their own type) in specific circumstances
The IA must perform (or directly conduct) the annual inspection itself — an A&P without an IA may perform maintenance and repairs found during the inspection, but not the inspection or the return-to-service approval. An annual signed solely by an A&P (without IA authority) is not a valid annual approval. See the A&P and IA certification guide for the difference between the two certificates.
100-Hour Inspection: Any Certificated A&P
A 100-hour inspection may be approved for return to service by any certificated A&P mechanic with the appropriate airframe and powerplant ratings for the aircraft being inspected. No Inspection Authorization is required. This is the legally operative difference between the annual and the 100-hour — same Appendix D scope, different authorization level for the sign-off.
Progressive Inspection and AAIP: Per the Approved Program
The sign-off authority for progressive and AAIP inspections is defined by the approved program itself and the applicable Part 43 rules for the specific maintenance tasks performed. A Part 145 certificated repair station performing AAIP work signs off under its repair station certificate and the applicable §43.7 authority. Individual IA sign-offs remain required for any tasks within the program that specifically require IA authority.
Records Each Inspection Produces — and How They Feed §91.417
Every inspection under §91.409 produces records that become part of the §91.417 permanent record set. Understanding which records are produced — and what the FAA requires them to contain — determines whether the aircraft's inspection history is legally documented.
How §91.409 Inspection Records Flow Into §91.417
§43.11 Logbook Entry
Every inspection generates a §43.11 entry: type, date, total time, sign-off, return-to-service or discrepancy list. This entry is the legal evidence the inspection was completed.
§91.417(a)(2)(iv) Permanent Record
The inspection entry feeds the "current inspection status" — the inspection program the aircraft is maintained under and the time since the last required inspection. That status record is a life-of-aircraft permanent record.
Discrepancy List = Grounding Notice
If the IA/A&P cannot approve return to service, they must provide a signed list of discrepancies under §43.11. That list grounds the aircraft until the discrepancies are resolved and a new sign-off is issued.
Transfer on Sale (§91.419)
The inspection status record — including the most recent annual or AAIP entry — must transfer to the new owner. A buyer who cannot locate the last inspection entry cannot confirm legal currency.
The interplay between §91.409 and §91.417 is direct: §91.409 determines when the inspection must happen and who can sign off; §91.417 determines how the resulting record must be maintained. The §43.11 logbook entry is the bridge — it is the evidence that the §91.409 requirement was satisfied, and it feeds the current-inspection-status record that §91.417(a)(2)(iv) requires to be retained for the life of the aircraft and transferred with it.
Don't Forget the Adjacent 24-Month Inspection Records
Two additional inspection records run alongside the §91.409 annual and must remain current and documented as part of the §91.417 permanent set:
- §91.411 — Altimeter / Static System Test: Every 24 calendar months before IFR flight in controlled airspace. The test and record must be performed per Part 43 Appendix E.
- §91.413 — ATC Transponder Test: Any ATC transponder specified in §91.215(a), §121.345(c), or §135.143(c) may not be used unless it has been tested and inspected within the preceding 24 calendar months and found to comply with Part 43 Appendix F (the test standard).
Both records are frequently missing or undated in pre-purchase inspections. A buyer's due-diligence check should confirm that both are current and documented alongside the annual inspection record.
Track every §91.409 inspection due date before it lapses
FileFlo is a compliance document intelligence platform — a read-only proof layer that classifies and tracks the records §91.409 produces. Upload your annual inspection logbook entries, §91.411 altimeter test records, and §91.413 transponder test records and FileFlo:
- Classifies each document against the governing CFR (§91.409, §91.411, §91.413, §43.11)
- Extracts the inspection date and auto-calculates the next-due date (12 calendar months for annual, 24 for altimeter and transponder)
- Sends 90/60/30-day expiration alerts before any inspection lapses — not the day after
- Generates an audit-ready inspection record binder organized by section for any FAA inquiry or pre-purchase review
FileFlo sits alongside your maintenance provider and logbooks — it does not replace an A&P, IA, or Part 145 repair station. It keeps the documents that prove your compliance audit-ready. Starter $89/mo · Professional $299/mo · 5-day free trial, no credit card required.
Check Your FAA Inspection ReadinessFrequently Asked Questions
What does 14 CFR §91.409 actually require for most general aviation aircraft?
14 CFR §91.409(a) prohibits any person from operating a U.S.-registered civil aircraft (unless excepted under §91.409(c) — for example, aircraft operating under an FAA-approved inspection program, carrying a special flight permit, or holding a current experimental, light-sport, or provisional airworthiness certificate) unless the aircraft has had an annual inspection within the preceding 12 calendar months and been approved for return to service. The inspection must be performed by a certificated airframe and powerplant (A&P) mechanic who holds an Inspection Authorization (IA), or by a certificated repair station that is appropriately rated. The completed annual produces a §43.11 logbook entry — the type of inspection, the date, the total time in service, and either a return-to-service approval or a discrepancy list. That entry evidences compliance and feeds the aircraft's current inspection status, which is the §91.417(a)(2)(iv) permanent record that must remain with the aircraft and transfer with it on sale.
When is a 100-hour inspection required, and who can perform it?
14 CFR §91.409(b) requires a 100-hour inspection on any aircraft carrying persons (other than crewmembers) for hire, or used for flight instruction for hire when the person giving the instruction provides the aircraft. The 100-hour interval is measured in aircraft total time in service, not calendar time. Unlike an annual inspection, a 100-hour inspection can be performed by any A&P mechanic — an Inspection Authorization (IA) is not required. The 100-hour limit can be exceeded by up to 10 hours to ferry the aircraft to a location where the inspection can be performed, but the next 100-hour interval starts from the inspection that was exceeded, not the ferry-arrival point. The resulting logbook entry follows §43.11 content requirements: type of inspection, total time in service, date, return-to-service approval or discrepancy list, and the A&P's certificate number and kind of certificate.
What is a progressive inspection and how does it differ from an annual?
14 CFR §91.409(d) allows an aircraft owner or operator to substitute a progressive inspection program for the annual inspection requirement. A progressive inspection divides the required inspections into scheduled partial inspections covering different aircraft systems in rotation, and the frequency and detail of the program must provide for the complete inspection of the aircraft within each 12 calendar months. To use one, the registered owner or operator must submit a written request to the responsible Flight Standards office and provide for a certificated mechanic holding an Inspection Authorization, a certificated airframe repair station, or the aircraft manufacturer to supervise or conduct the inspection; a current inspection procedures manual; enough housing and equipment for necessary disassembly and proper inspection; and appropriate current technical information for the aircraft. The key operational difference: an annual produces one comprehensive inspection event per 12-month calendar cycle; a progressive produces rolling partial inspections on a continuous schedule. Both satisfy the §91.409 prohibition on flying without a current inspection.
What is an AAIP and which operators use it?
Strictly, an Approved Aircraft Inspection Program (AAIP) is the §91.409(f)(2) program option: an aircraft inspection program approved under §135.419 and currently in use by a person holding a Part 135 operating certificate. It is one of four programs §91.409(f) allows an owner or operator to select in place of the annual and 100-hour requirements: (1) a Part 121 or 135 air carrier's continuous airworthiness inspection program; (2) a §135.419 AAIP in current use; (3) a current inspection program recommended by the manufacturer; or (4) any other program established by the owner or operator and approved by the Administrator. Under §91.409(e), large airplanes (to which Part 125 is not applicable), turbojet multiengine airplanes, and turbopropeller-powered multiengine airplanes must select, identify in the aircraft maintenance records, and use one of these programs; turbine-powered rotorcraft may do so or may instead elect the inspection provisions of §91.409(a), (b), (c), or (d). Under a selected program, neither the annual nor the 100-hour inspection intervals apply — the aircraft is inspected according to the program's own schedule (often task-card based). A corporate flight department running a carrier's CAMP-based continuous airworthiness inspection program is selecting option (f)(1) rather than an AAIP in the strict sense. The selected program must be identified in the aircraft maintenance records, and the aircraft's current inspection status under it is part of the §91.417(a)(2)(iv) permanent record.
Who can sign off an annual inspection — and can a standard A&P do it?
Only a certificated A&P mechanic who holds a current Inspection Authorization (IA) — or an appropriately rated certificated repair station (or, in specific circumstances, the manufacturer) — may approve an aircraft for return to service after an annual inspection. A standard A&P without an IA cannot perform the annual inspection or issue its return-to-service approval — the IA must perform (or directly conduct) the annual inspection itself, although an A&P may perform maintenance and repairs found during it. This is established by 14 CFR §65.95(a)(2), which defines IA authority, and §43.7(b) through (d), which list who may approve return to service after an annual. A 100-hour inspection differs: any certificated A&P (without an IA) can approve the aircraft for return to service after a 100-hour inspection. This is a common point of confusion that results in logbook entries signed by an A&P for what was effectively an annual — creating an inspection-record defect under §43.11.
How long must inspection records be retained under 14 CFR §91.417?
The permanent tier under 14 CFR §91.417(a)(2)(iv) is the current inspection status of the aircraft — including the time since the last inspection required by the inspection program under which the aircraft is maintained. That status record must be retained and transferred to the new owner under §91.419 on any change of ownership. The inspection entries themselves — records of the 100-hour, annual, progressive, and other required or approved inspections — fall under §91.417(a)(1) and must be retained until the work is repeated or superseded by other work, or for one year after the work is performed. The annual entry evidences compliance and feeds the permanent §91.417(a)(2)(iv) inspection-status record; keeping every inspection entry for the life of the aircraft is best practice and what buyers expect, but the rule's permanence requirement attaches to the inspection-status record, not to each logbook entry.
Related Aviation Compliance Guides
Part 91 General Aviation Operations
Full Part 91 compliance overview — operating rules, equipment requirements, and records obligations
14 CFR §91.411 — Altimeter System Tests
24-calendar-month altimeter and static system test requirement and records
14 CFR §91.413 — ATC Transponder Tests
24-calendar-month transponder test requirement and performance standards
A&P Mechanic + IA Certification
What an IA is, how it differs from a standard A&P, and when each is required
Part 145 Repair Station Compliance
Certificate requirements, QC manual obligations, and FSDO surveillance preparation
Airworthiness Directives Compliance
Part 39 AD compliance workflow, applicability rules, and the §91.417 tracking obligation
Know when your next inspection is due — before it lapses
FileFlo classifies your inspection records against 14 CFR §91.409, §91.411, and §91.413, extracts due dates, and sends 90/60/30-day alerts before any inspection window closes. Keep every annual, 100-hour, altimeter test, and transponder test documented and current — all in one compliance record set organized by CFR section.
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