asset: aircraft-inspection-and-test-intervals

asset_type: lifecycle

body: How often each required aircraft inspection, test or check must be done under Part 91, in the unit the regulation actually uses. Each record is one item with its interval, the anchor the interval runs from, and the consequence of letting it lapse. Covers the annual and 100-hour inspection (14 CFR 91.409), the altimeter and static pressure system test (91.411), the ATC transponder test (91.413), the emergency locator transmitter inspection and battery replacement (91.207), and the VOR equipment check for IFR (91.171). Answers 'does an ELT battery have to be replaced every year', 'how often does a transponder need to be checked', 'is the pitot static check 24 months', 'does a 100 hour inspection reset the annual', and 'how often do I need a VOR check for IFR'. Every one of these is expressed in a different unit - 12 calendar months, 100 hours, 24 calendar months, 30 days, 1 cumulative hour of transmitter use or 50 percent of useful life - which is why the neighbouring ones get swapped: the ELT 12-month item is the inspection, not the battery.

key_field: item

licence: Facts extracted from the US Code of Federal Regulations, a US government work not subject to copyright. Records quote the official eCFR text via its versioner API (the eCFR HTML pages block our fetcher; law.cornell.edu copies were read as a cross-check but carry inline definition links that break verbatim quoting); each record quotes a short verbatim span and links back to the section.

title: Aircraft inspection and test intervals under 14 CFR Part 91

type: dataset


body:
**Inspection or test item:** 100-hour inspection

**Interval:** within the preceding 100 hours of time in service

**Applies to:** aircraft carrying any person (other than a crewmember) for hire

**Consequence if lapsed:** no person may operate an aircraft carrying any person (other than a crewmember) for hire

**Regulation section:** § 91.409

> no person may operate an aircraft carrying any person (other than a crewmember) for hire, and no person may give flight instruction for hire in an aircraft which that person provides, unless within the preceding 100 hours of time in service the aircraft has received an annual or 100-hour inspection and been approved for return to service in accordance with part 43 of this chapter or has received an inspection for the issuance of an airworthiness certificate in accordance with part 21 of this chapter. The 100-hour limitation may be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.409>

item: 100-hour inspection

title: 100-hour inspection — Aircraft inspection and test intervals under 14 CFR Part 91

type: lifecycle


body:
**Inspection or test item:** Altimeter instrument

**Interval:** Within the preceding 24 calendar months

**Applies to:** airplane, or helicopter, in controlled airspace under IFR

**Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR

**Regulation section:** § 91.411

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter;

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411>

interval: Within the preceding 24 calendar months

item: Altimeter instrument

title: Altimeter instrument — Aircraft inspection and test intervals under 14 CFR Part 91


applies_to: aircraft

body:
**Inspection or test item:** Annual inspection

**Interval:** within the preceding 12 calendar months

**Applies to:** aircraft

**Consequence if lapsed:** no person may operate an aircraft

**Regulation section:** § 91.409

> no person may operate an aircraft unless, within the preceding 12 calendar months, it has had— (1) An annual inspection in accordance with part 43 of this chapter and has been approved for return to service by a person authorized by § 43.7 of this chapter

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.409>

consequence: no person may operate an aircraft

interval: within the preceding 12 calendar months

item: Annual inspection

title: Annual inspection — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** ATC transponder

**Interval:** within the preceding 24 calendar months

**Applies to:** ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter

**Consequence if lapsed:** No persons may use an ATC transponder

**Regulation section:** § 91.413

> No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with appendix F of part 43 of this chapter; and

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.413>

consequence: No persons may use an ATC transponder

interval: within the preceding 24 calendar months

item: ATC transponder

title: ATC transponder — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Automatic pressure altitude reporting system

**Interval:** Within the preceding 24 calendar months

**Applies to:** airplane, or helicopter, in controlled airspace under IFR

**Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR

**Regulation section:** § 91.411

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter;

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411>

title: Automatic pressure altitude reporting system — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Batteries used in the emergency locator transmitters

**Interval:** When the transmitter has been in use for more than 1 cumulative hour; or (2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired

**Applies to:** emergency locator transmitters required by paragraphs (a) and (b) of this section

**Consequence if lapsed:** must be replaced (or recharged, if the batteries are rechargeable)

**Regulation section:** § 91.207

> Batteries used in the emergency locator transmitters required by paragraphs (a) and (b) of this section must be replaced (or recharged, if the batteries are rechargeable)— (1) When the transmitter has been in use for more than 1 cumulative hour; or (2) When 50 percent of their useful life (or, for rechargeable batteries, 50 percent of their useful life of charge) has expired, as established by the transmitter manufacturer under its approval.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.207>

title: Batteries used in the emergency locator transmitters — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Emergency locator transmitter

**Interval:** within 12 calendar months after the last inspection

**Applies to:** Each emergency locator transmitter required by paragraph (a) of this section

**Consequence if lapsed:** must be inspected within 12 calendar months after the last inspection

**Regulation section:** § 91.207

> Each emergency locator transmitter required by paragraph (a) of this section must be inspected within 12 calendar months after the last inspection for— (1) Proper installation; (2) Battery corrosion; (3) Operation of the controls and crash sensor; and (4) The presence of a sufficient signal radiated from its antenna.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.207>

item: Emergency locator transmitter

title: Emergency locator transmitter — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Installation or maintenance on an ATC transponder

**Interval:** Following any installation or maintenance on an ATC transponder where data correspondence error could be introduced

**Applies to:** ATC transponder where data correspondence error could be introduced

**Consequence if lapsed:** No persons may use an ATC transponder

**Regulation section:** § 91.413

> No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or § 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with appendix F of part 43 of this chapter; and (b) Following any installation or maintenance on an ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.413>

title: Installation or maintenance on an ATC transponder — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder

**Interval:** Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder

**Applies to:** airplane, or helicopter, in controlled airspace under IFR

**Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR

**Regulation section:** § 91.411

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter; (2) Except for the use of system drain and alternate static pressure valves, following any opening and closing of the static pressure system, that system has been tested and inspected and found to comply with paragraph (a), appendix E, of part 43 of this chapter; and (3) Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411>

title: Installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Opening and closing of the static pressure system

**Interval:** following any opening and closing of the static pressure system

**Applies to:** airplane, or helicopter, in controlled airspace under IFR

**Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR

**Regulation section:** § 91.411

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter; (2) Except for the use of system drain and alternate static pressure valves, following any opening and closing of the static pressure system, that system has been tested and inspected and found to comply with paragraph (a), appendix E, of part 43 of this chapter; and

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411>

title: Opening and closing of the static pressure system — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Progressive inspection

**Interval:** within each 12 calendar months

**Applies to:** aircraft

**Regulation section:** § 91.409

> The frequency and detail of the progressive inspection shall provide for the complete inspection of the aircraft within each 12 calendar months and be consistent with the manufacturer's recommendations, field service experience, and the kind of operation in which the aircraft is engaged.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.409>

interval: within each 12 calendar months

item: Progressive inspection

title: Progressive inspection — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** Static pressure system

**Interval:** Within the preceding 24 calendar months

**Applies to:** airplane, or helicopter, in controlled airspace under IFR

**Consequence if lapsed:** No person may operate an airplane, or helicopter, in controlled airspace under IFR

**Regulation section:** § 91.411

> No person may operate an airplane, or helicopter, in controlled airspace under IFR unless— (1) Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter;

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.411>

item: Static pressure system

title: Static pressure system — Aircraft inspection and test intervals under 14 CFR Part 91


body:
**Inspection or test item:** VOR equipment

**Interval:** within the preceding 30 days

**Applies to:** civil aircraft under IFR using the VOR system of radio navigation

**Consequence if lapsed:** No person may operate a civil aircraft under IFR

**Regulation section:** § 91.171

> No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless the VOR equipment of that aircraft— (1) Is maintained, checked, and inspected under an approved procedure; or (2) Has been operationally checked within the preceding 30 days, and was found to be within the limits of the permissible indicated bearing error set forth in paragraph (b) or (c) of this section.

Source: <https://www.ecfr.gov/api/versioner/v1/full/2026-08-01/title-14.xml?part=91&section=91.171>

interval: within the preceding 30 days

item: VOR equipment

title: VOR equipment — Aircraft inspection and test intervals under 14 CFR Part 91