FAA’s new eVTOL certification advisory circular provides long-awaited clarity for OEMs
On 18 July 2025, the FAA published Advisory Circular (AC) 21.17‑4, offering comprehensive guidance for certifying powered‑lift aircraft, including electric vertical take‑off and landing (eVTOL) designs. …
July 30, 2025
On 18 July 2025, the FAA published Advisory Circular (AC) 21.17‑4, offering comprehensive guidance for certifying powered‑lift aircraft, including electric vertical take‑off and landing (eVTOL) designs.
This marks the first time the FAA has issued an airworthiness framework tailored to a new category of civil aircraft since helicopters were introduced in the 1940s.
Powered‑lift aircraft use engine-driven devices or specific propulsion systems to take off and land vertically or hover, then transition to rigid-wing lift during forward flight. This hybrid design makes prior regulations (aeroplane or rotorcraft categories) inadequate.
The FAA had originally intended to certify eVTOLs under Part 23 rules, as with other small aircraft. However, in 2022, the administration reversed course, deciding that eVTOLs would be certified as ‘powered lift’ aircraft under 14 CFR § 21.17(b).
The publication of Advisory Circular 21.17‑4 completes the FAA’s foundational regulatory framework for eVTOLs, following the earlier release of Special Federal Aviation Regulations (SFAR) in October 2024, which addressed pilot training and operational requirements.
What does the new Advisory Circular on eVTOL certification say?
The published document, AC 21.17-4, provides detailed guidance on how manufacturers can achieve type certification under 14 CFR § 21.17(b). It doesn’t add anything new or different to the existing regulations, but instead outlines how existing airworthiness standards can be adapted and applied to eVTOLs.
It outlines how applicants can use performance-based means of compliance, supported by a newly defined set of airworthiness criteria in Appendix A, to streamline their certification without requiring a lengthy public rulemaking process.
Critically, AC 21.17-4 introduces the concept of two performance levels: ‘essential’ and ‘increased’. This allows flexibility for manufacturers depending on the intended mission profile of the aircraft.
For example, a cargo drone with simpler performance needs might pursue essential compliance, while a passenger-carrying eVTOL operating in dense urban airspace would be expected to meet the increased level.
The AC moves away from rigid minimum performance metrics like stall speed, instead focusing on flight profile-based evaluations, ensuring that aircraft are judged on their specific handling and safety characteristics.
It also introduces additional requirements for systems critical to vertical flight, such as enhanced fatigue tolerance and reliability testing for propellers and actuators, as well as safeguards against resonant vibrations or instabilities during transition or ground operations.
The document gives clarity to OEMs pursuing type certification, helping to standardise expectations while retaining flexibility for innovation in design.
What does this FAA circular mean for eVTOL developers?
The FAA circular brings long-awaited regulatory clarity to the eVTOL market.
Until now, most eVTOL developers have operated under interim guidance, working closely with the FAA through custom-built certification plans and G-1 issue papers. While this case-by-case approach allowed progress, it also introduced uncertainty, especially for newer entrants or investors seeking predictable timelines.
With AC 21.17-4 in place, eVTOL companies now have a transparent, performance-based framework that defines what the FAA will accept as an airworthy powered-lift aircraft, significantly reducing regulatory ambiguity.
Practically, this means developers like Joby, Archer, Beta, and others can align their certification strategies with a consistent and publicly available standard.
For the broader ecosystem, such as battery suppliers, simulation providers, and MRO partners, it also unlocks opportunities by defining the baseline technologies and support infrastructure these new aircraft will require.
