Authority
FAA
Applicability
14 CFR Part 21 establishes FAA procedural requirements for type, production and airworthiness approvals. For powered-lift, the FAA uses the special-class pathway under § 21.17(b), with AC 21.17-4 providing current guidance and airworthiness criteria for certain powered-lift.
Status
Current
Plain-English Explainer
14 CFR Part 21 is the FAA's procedural framework for approving aircraft designs and production. It covers type certificates, changes to type certificates, production approvals and airworthiness certification.
Powered-lift are type certificated as a special class under § 21.17(b). FAA AC 21.17-4, issued in 2025, provides current guidance for type, production and airworthiness certification of powered-lift and identifies Appendix A airworthiness criteria as an acceptable, but not the only, means of showing compliance for certain powered-lift.
Part 21 is the approval-process framework. It should not be confused with technical consensus standards such as DO-160, which provide test methods or development-assurance practices used within a wider compliance showing.
Primary source: eCFR Part 21 · Powered-lift guidance: FAA AC 21.17-4
