# Aircraft Required Inspections: Dates and Hours > Compare annual, 100-hour, ELT and avionics requirements, work calendar and travel-overrun examples, and verify the actual maintenance records. - Source: https://firstsolo.ai/blog/aircraft-required-inspections - Author: Ellie Navarro, Student Pilot - Published: 2026-11-02 - Updated: 2026-11-02 - Last reviewed: 2026-11-02 **Aircraft required inspections depend on the airplane, its inspection program and the intended operation: check annual, applicable 100-hour, required ELT and applicable avionics requirements separately.** Calendar-month intervals and time-in-service limits are different clocks, and maintenance can trigger additional tests. Read the records and approvals for the actual aircraft; a current annual alone does not establish readiness for flight. This guide uses a conventional small, nonturbine U.S.-registered airplane with a standard airworthiness certificate under Part 91. Special certificates and alternative inspection programs can change the answer. Start with the [airworthiness requirements hub](https://firstsolo.ai/blog/airworthiness-requirements) for the wider decision; this spoke teaches how to apply common inspection intervals. ## Which required inspections should you check first? Identify applicability before calculating a due date or copying a number from a school dispatch sheet. | Inspection or test | Recurring interval | Applicability or separate condition | Source | | --- | --- | --- | --- | | Annual | Preceding 12 calendar months | Ordinary annual-inspection program, subject to the rule's alternatives and exceptions | [91.409(a), (c)](https://www.ecfr.gov/current/title-14/section-91.409) | | 100-hour | Preceding 100 hours of time in service | Non-crewmember carried for hire, or paid instruction when the person giving it provides the aircraft | [91.409(b)](https://www.ecfr.gov/current/title-14/section-91.409) | | Required ELT | Inspection within 12 calendar months after the last inspection | Battery replacement/recharge has additional triggers | [91.207(c)–(d)](https://www.ecfr.gov/current/title-14/section-91.207) | | Altimeter, static and altitude-reporting systems | Preceding 24 calendar months | Airplane or helicopter operated under IFR in controlled airspace; specified work also triggers checks | [91.411](https://www.ecfr.gov/current/title-14/section-91.411) | | Applicable ATC transponder | Preceding 24 calendar months | Use of a transponder covered by the rule; specified work also triggers checks | [91.413](https://www.ecfr.gov/current/title-14/section-91.413) | These rows are a starting point, not the aircraft's complete maintenance program. Dates, hours and the operation all matter. ## How do the annual and 100-hour requirements differ? The annual uses calendar months; an applicable 100-hour requirement uses time in service and depends on the operation. The [FAA PHAK, Chapter 9](https://www.faa.gov/sites/faa.gov/files/11_phak_ch9.pdf), explains the annual's month-end calculation. In a fictional example, an annual completed November 18, 2026, remains within its ordinary interval through November 30, 2027. December 1 is outside that interval unless another qualifying inspection or applicable authorization changes the situation. This is not a 365-day anniversary calculation. An annual can satisfy a required 100-hour inspection. The reverse requires the inspector to be authorized for annual inspections and the record to identify it as an annual; merely having a recent 100-hour entry does not reset the annual clock. See [91.409(a)](https://www.ecfr.gov/current/title-14/section-91.409). For instruction, the [FAA's Pipitone interpretation](https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/Data/interps/2016/Pipitone_2016_Legal_Interpretation.pdf) distinguishes who actually provides the airplane. Instruction for hire in an instructor-provided aircraft triggers the requirement; an owner furnishing an airplane for instruction is a different arrangement. Ownership labels and separate invoices do not settle every case: the FAA may examine whether the instructor or represented entity effectively supplied the aircraft. “Every rental needs a 100-hour” is an unreliable shortcut. [1.1](https://www.ecfr.gov/current/title-14/section-1.1) defines time in service for maintenance records by the aircraft's airborne interval, from leaving the surface until the next landing. Do not silently substitute billed Hobbs time or a displayed tach value without knowing how that aircraft's required time is recorded. ![An annual calendar-month example and a 100-hour time-in-service example use different clocks](https://s3.doublegis.com/firstsolo/blog/aircraft-required-inspections/inspection-calendar-versus-hours.svg?v=7d33efca) *Fictional records: the annual reaches November 30, 2027; a qualifying inspection at 2,340.0 hours produces an ordinary 2,440.0-hour limit when the 100-hour requirement applies. These do not resolve other inspection or airworthiness requirements.* ## How does the 100-hour travel allowance affect the next limit? Up to 10 additional hours may be used only while en route to a place where the inspection can be done, and that excess is counted in the next interval. [91.409(b)](https://www.ecfr.gov/current/title-14/section-91.409) provides this limited allowance; it is not extra lesson time or an annual-inspection extension. The [FAA maintenance handbook](https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/amt_general_handbook.pdf) also explains deducting the excess from the following interval. Suppose the fictional 100-hour limit is 2,440.0 hours and four additional hours of qualifying en-route travel lead to inspection at 2,444.0. With no other schedule-changing event assumed, the next limit is 2,540.0, leaving 96.0 hours after that inspection. Moving it to 2,544.0 would incorrectly forgive the overrun. Confirm the real operation and records before applying this arithmetic. ![Four qualifying travel hours beyond a 2440-hour limit leave 96 hours before the next 2540-hour limit](https://s3.doublegis.com/firstsolo/blog/aircraft-required-inspections/hundred-hour-extension-example.svg?v=08d1473a) *This worked example assumes the limited travel allowance applies. It does not authorize a flight, extend an annual or create a general 110-hour inspection interval.* ## What must you check for the ELT besides its inspection date? A required ELT has both an inspection requirement and separate battery rules. Under [91.207(d)](https://www.ecfr.gov/current/title-14/section-91.207), its inspection covers installation, battery corrosion, controls/crash-sensor operation and an adequate radiated antenna signal. The recurring inspection is within 12 calendar months after the previous one. Under [91.207(c)](https://www.ecfr.gov/current/title-14/section-91.207), replace or recharge the battery after more than one cumulative hour of transmitter use, or when half its manufacturer-established useful life or charge life has elapsed. The new battery expiration must appear on the transmitter and in the maintenance record. The storage-life provision has an exception for essentially unaffected batteries, such as water-activated types. A recent ELT inspection date does not erase a battery trigger. The section contains operational exceptions, so this article says “required ELT” rather than claiming every flight has identical requirements. Ask qualified maintenance personnel about the actual unit and operation; this is not a transmitter-testing procedure. ## Are the two 24-calendar-month avionics checks interchangeable? No: equal recurring intervals do not make the applicability, tested systems or work-related triggers identical. [91.411](https://www.ecfr.gov/current/title-14/section-91.411) addresses static pressure, altimeter and automatic pressure-altitude-reporting systems for controlled-airspace IFR operation. Opening and closing the static system can trigger a test, except normal use of drain and alternate-static valves. Certain altitude-reporting-system work also triggers integrated-system testing. [91.413](https://www.ecfr.gov/current/title-14/section-91.413) governs use of the ATC transponders it covers, rather than only IFR flight. Installation or maintenance that could introduce data-correspondence error triggers additional integrated-system testing. A VFR plan therefore does not automatically excuse an overdue applicable transponder test. Use the actual entries to establish what was tested, by whom and when. Do not infer that one “avionics checked” note establishes both rules, or that maintenance has no effect until the next recurring date. ![Two 24-calendar-month rules differ in their operating trigger and affected systems](https://s3.doublegis.com/firstsolo/blog/aircraft-required-inspections/inspection-avionics-applicability.svg?v=38e5ad36) *Read 91.411 and 91.413 separately. This comparison is a study aid, not a complete testing standard or authority to perform the work.* ## What evidence should you find in the inspection records? Find the completed inspection and its approval status, then reconcile the status with subsequent maintenance and use. [43.11](https://www.ecfr.gov/current/title-14/section-43.11) specifies inspection-entry information, including inspection type/extent, date, aircraft total time in service, the approving or disapproving person's credentials, and the applicable return-to-service or discrepancy statement. A scheduled appointment or unsigned worksheet is not the same evidence. | Record question | Why it changes your answer | | --- | --- | | Is this entry for the correct aircraft and item? | Another airplane's log cannot establish this one's status | | What was completed, and was return to service approved? | “Inspected” alone can conceal an unresolved discrepancy list | | What date or time controls this requirement? | Calendar deadlines and time-in-service limits cannot be interchanged | | What happened after that entry? | Later work, use or a recurring requirement may change the status | [91.417](https://www.ecfr.gov/current/title-14/section-91.417) requires current inspection and applicable AD-status records, including the next action for recurring ADs. A dispatch summary helps locate evidence; it does not explain an ambiguous maintenance entry. Resolve gaps with the owner/operator and appropriately authorized maintenance personnel before departure. ## What does an inspection mnemonic leave out? A memory aid cannot replace the aircraft's program, additional mandatory requirements or the PIC's present-condition assessment. [91.403](https://www.ecfr.gov/current/title-14/section-91.403) places primary airworthiness-maintenance responsibility on the owner/operator and addresses mandatory airworthiness-limitations requirements. An annual date is not a universal answer to every component interval or directive. The VOR check sometimes included in inspection mnemonics is another distinct rule: [91.171](https://www.ecfr.gov/current/title-14/section-91.171) addresses IFR operation using VOR, with an approved-procedure alternative or a qualifying operational check within the preceding 30 days. It is not a 30-calendar-month check required merely because a VOR receiver is installed. Finally, [91.7](https://www.ecfr.gov/current/title-14/section-91.7) keeps the PIC responsible for determining condition for safe flight. Current inspection records do not make a damaged tire or a new leak disappear. ## Check yourself **A fictional annual was completed November 18, 2026. Is December 1, 2027 within that ordinary annual interval?** No. The 12-calendar-month interval reaches November 30, 2027. Do not use the exact anniversary or add the 100-hour travel allowance to an annual. This answer addresses only the stated annual example ([91.409](https://www.ecfr.gov/current/title-14/section-91.409), [FAA PHAK](https://www.faa.gov/sites/faa.gov/files/11_phak_ch9.pdf)). **A 100-hour limit was 2,440.0. Qualifying travel used four excess hours before inspection at 2,444.0. What is the next limit, with no other change assumed?** 2,540.0 hours, leaving 96.0 hours after inspection. The four-hour excess counts toward the next 100 hours; 2,544.0 incorrectly resets the schedule as though the excess had not occurred ([91.409(b)](https://www.ecfr.gov/current/title-14/section-91.409)). **A VFR flight will use a transponder covered by 91.413. Its last qualifying test was 25 calendar months ago. Does the VFR plan fix that?** No. The covered transponder's recurring test is not an IFR-only requirement. The similar 91.411 interval has a different operating trigger; do not substitute one rule's applicability for the other ([91.413](https://www.ecfr.gov/current/title-14/section-91.413)). ## Frequently asked questions **Does a 100-hour inspection replace an annual?** Not automatically. It must meet the annual inspector-authorization condition and be recorded as an annual. Conversely, an annual can satisfy the applicable 100-hour requirement. **Does every rental airplane need a 100-hour inspection?** Rental alone is not the complete trigger. Apply 91.409(b) to the actual carriage-for-hire or aircraft-provided instruction arrangement, with the rule's exceptions and inspection program considered. **Does an annual automatically reset every ELT or avionics interval?** No. Read the records for the specific required inspection or test. An annual entry alone does not establish completion of each separate ELT, battery or avionics requirement. **Can I fly normally with an overdue annual using the 10-hour allowance?** No. That allowance belongs to the qualifying 100-hour en-route situation. An overdue annual requires a different resolution; a special flight permit may be relevant, but it is not automatic permission for ordinary operations. ## Sources and review Last reviewed **November 2, 2026**. The current eCFR provisions were checked for this draft; their detailed applicability and exceptions control over mnemonic summaries. - FAA/eCFR: [91.409](https://www.ecfr.gov/current/title-14/section-91.409), [91.207](https://www.ecfr.gov/current/title-14/section-91.207), [91.411](https://www.ecfr.gov/current/title-14/section-91.411), [91.413](https://www.ecfr.gov/current/title-14/section-91.413), [43.11](https://www.ecfr.gov/current/title-14/section-43.11), [91.417](https://www.ecfr.gov/current/title-14/section-91.417), [91.403](https://www.ecfr.gov/current/title-14/section-91.403), [91.7](https://www.ecfr.gov/current/title-14/section-91.7), [1.1](https://www.ecfr.gov/current/title-14/section-1.1) and [91.171](https://www.ecfr.gov/current/title-14/section-91.171). - [FAA PHAK, Chapter 9](https://www.faa.gov/sites/faa.gov/files/11_phak_ch9.pdf), printed pages 9-8–9-9, for instructional context; use the current rules for precise applicability. [Current FAA chapter page](https://www.faa.gov/regulationspolicies/handbooksmanuals/aviation/phak/chapter-9-flight-manuals-and-other-documents). - [FAA maintenance handbook](https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/amt_general_handbook.pdf), printed page 2-22, for inspection-interval context; [FAA Pipitone interpretation](https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/Data/interps/2016/Pipitone_2016_Legal_Interpretation.pdf), May 4, 2016, for who provides the aircraft. ## What should you study next? Return to the [airworthiness requirements hub](https://firstsolo.ai/blog/airworthiness-requirements), connect operation and equipment with [airspace classes](https://firstsolo.ai/blog/airspace-classes-explained), and pair the records review with the [preflight weather briefing checklist](https://firstsolo.ai/blog/preflight-weather-briefing-checklist). [Practice aircraft-inspection and airworthiness concepts on FirstSolo.ai](https://firstsolo.ai/login). Explain the trigger and evidence before reciting an interval. FirstSolo.ai is solely a study tool and does not issue FAA endorsements.