Primary Category Aircraft Airworthiness Certification

Primary category airworthiness certification is governed by FAR 21.184 .

General Information

FAR 21.24(b) allows a person to submit a special inspection and preventive maintenance program as part of the aircraft’s type design or supplemental type design. The submitted program is reviewed by the Kansas City, Missouri, Aircraft Evaluation Group (MKC-AEG). Programs for primary category rotorcraft are submitted to the Fort Worth, Texas, Aircraft Evaluation Group (FTW-AEG).

An applicant for a primary category certification can obtain a special airworthiness certificate for primary category aircraft (PCA) when the provisions of FAR 21 are met. PCA are not eligible for multiple category airworthiness certificates.

An applicant can obtain a special airworthiness certificate for an imported PCA, if the Civil Aviation Authority of the country of manufacture certifies that the aircraft meets the criteria of FAR 21.24(a)(1) and that the aircraft is in a condition for safe operation. The FAA must also perform an inspection of the aircraft to confirm that it meets the requirements.

Aircraft Conversions

An applicant can exchange a standard airworthiness certificate for a special airworthiness certificate in the primary category. The conversion will be made through the normal STC process. The only benefit for making a conversion is so the pilot/owner can perform preventive maintenance beyond what is already allowed under FAR 43, Appendix A .

If there is not already an approved inspection and preventive maintenance program for the aircraft, or if any additional preventive maintenance items are to be added, the applicant must submit the program or additional items as part of the STC design data to be approved.

Only a properly qualified pilot/owner can perform preventive maintenance under the special inspection and preventive maintenance program. To be properly qualified, a pilot/owner must successfully complete an FAA-approved course given by an approved aviation maintenance technician school, the aircraft manufacturer (production certificate holder), or another entity approved by the FAA.

The same aircraft cannot be reissued a standard airworthiness certificate again unless the aircraft is shown to meet all the criteria for a standard airworthiness certificate. Such a showing historically has been difficult when an aircraft has remained in a different classification or category for a lengthy period.

To facilitate the return to a standard airworthiness certificate, the aircraft records should indicate, among other requirements, that the aircraft has been maintained according to the manufacturer’s instructions, and that any modifications to the aircraft either were removed or approved by the FAA.


The duration of a primary category airworthiness certificate is unlimited as long as the requirements of FAR 21.181(a)(1) are met. FAR 91.325 identifies the operating limitations unique to Primary Category Aircraft.

Back to the Special Airworthiness Certification Page

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