FAR 21.181 — Airworthiness Certificate Duration
FAR 21.181 explains how long airworthiness certificates remain valid, including standard, special, light-sport, and experimental certificates.
In Plain English
FAR 21.181 tells you how long an airworthiness certificate stays valid. The short answer: as long as the aircraft is registered in the U.S. and you keep up with the rules — but the specifics depend on the type of certificate.
- Standard and special airworthiness certificates (primary, restricted, or limited category): effective as long as maintenance, preventive maintenance, and alterations are performed per Parts 43 and 91.
- Special flight permit (ferry permit): valid only for the time period stated on the permit.
- Light-sport special airworthiness certificate: valid as long as the aircraft still meets the LSA definition, conforms to its original configuration (except for approved alterations), and has no unsafe condition.
- Experimental certificates for R&D, showing compliance, crew training, or market survey: 3 years from issue or renewal (or shorter if FAA specifies).
- Experimental certificates for exhibition, air racing, amateur-built, kit-built, and light-sport operations: unlimited unless FAA sets a specific period.
Why it matters: as PIC you're responsible for the aircraft being airworthy. If maintenance lapses or the aircraft is altered outside the rules, the certificate is no longer in effect — even though the paper is still in the aircraft. The owner must also make the aircraft available for FAA inspection on request, and surrender the certificate if it's suspended or revoked.
Regulation Text
14 CFR § 21.181§ 21.181 Duration.
(a) Unless sooner surrendered, suspended, revoked, or a termination date is otherwise established by the FAA, airworthiness certificates are effective as long as the aircraft is registered in the United States and as follows:
(1) Standard airworthiness certificates and special airworthiness certificates issued for aircraft certificated in the primary, restricted, or limited category are effective as long as the maintenance, preventive maintenance, and alterations are performed in accordance with parts 43 and 91 of this chapter.
(2) A special flight permit is effective for the period of time specified in the permit.
(3) A special airworthiness certificate in the light-sport category is effective as long as—
(i) The aircraft meets the definition of a light-sport aircraft;
(ii) The aircraft conforms to its original configuration, except for those alterations performed in accordance with an applicable consensus standard and authorized by the aircraft's manufacturer or a person acceptable to the FAA; and
(iii) The aircraft has no unsafe condition and is not likely to develop an unsafe condition.
(4) The duration of an experimental airworthiness certificate issued for research and development, showing compliance with regulations, crew training, or market survey is effective for 3 years from the date of issue or renewal unless the FAA prescribes a shorter period.
(5) The duration of an experimental airworthiness certificate issued for exhibition, air-racing, operating amateur-built aircraft, operating primary kit-built aircraft, operating light-sport aircraft, operating light-sport category kit-built aircraft, operating former light-sport category aircraft is unlimited, unless the FAA establishes a specific period for good cause.
(b) The owner, operator, or bailee of the aircraft must, upon request, make it available for inspection by the FAA.
(c) Upon suspension, revocation, or termination by order of the FAA of an airworthiness certificate, the owner, operator, or bailee of an aircraft must, upon request, surrender the certificate to the FAA.
[Amdt. 21-21, 33 FR 6858, May 7, 1968, as amended by Amdt. 21-49, 44 FR 46781, Aug. 9, 1979; Amdt. 21-70, 57 FR 41368, Sept. 9, 1992; Amdt. 21-85, 69 FR 44861, July 27, 2004; Amdt. 21-109, 90 FR 35205, July 24, 2025]
Link to an amendment published at 90 FR 35205, July 24, 2025.
Oral Exam Questions a DPE Might Ask
Q1How long is a standard airworthiness certificate valid?
Per FAR 21.181, a standard airworthiness certificate is effective as long as the aircraft is registered in the U.S. and maintenance, preventive maintenance, and alterations are performed in accordance with Parts 43 and 91.
Q2How long is a special flight permit good for?
FAR 21.181(a)(2) states a special flight permit is effective only for the period of time specified in the permit itself.
Q3What conditions must a light-sport aircraft meet for its special airworthiness certificate to remain in effect?
Under FAR 21.181(a)(3), the aircraft must continue to meet the definition of a light-sport aircraft, conform to its original configuration (except for properly authorized alterations under a consensus standard), and have no unsafe condition or likelihood of developing one.
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Related Sections in Part 21