The FAA’s new advisory circular covering type, production, and airworthiness certification of powered-lift aircraft (AC 21.17-4) has been widely welcomed among companies aiming to launch new eVTOL vehicles. Released on July 18, the document landed more than halfway into the year in which several of the advanced air mobility sector’s frontrunners have been aiming to complete U.S. certification, ending several years of uncertainty around the regulatory landscape.
While the agency’s long-awaited initiative doesn’t guarantee certifications will now be completed in short order, it does at least appear to clear a path to the finish line for what is set to be the first new class of aircraft since the first half of the 20th century. It applies to powered-lift, battery-electric aircraft being certified under Part 21.17 (b) rules weighing no more than 12,500 pounds and carrying six or fewer passengers.
Crucially, the AC removes the need for advanced air mobility (AAM) manufacturers to resort to so-called special rulemaking provisions as the basis for meeting airworthiness requirements. The rules are also aligned with Special Federal Aviation Regulations (SFAR) covering operational rules and pilot certification for powered-lift aircraft that the FAA issued in October 2024.
Several eVTOL manufacturers, most notably Joby and Archer, opted not to wait for the AC before securing the G-1 issue papers that establish the basis for certification. In theory, companies in that situation could now approach the FAA with requests to adjust their G-1 documentation to take account of the fully-formed rules, which are reckoned to cover two dozen or more changes.
Beta Technologies, which is developing both the A250 eVTOL aircraft and its conventional takeoff and landing sibling, the CX300, purposely deferred finalizing the G-1 for the A250 to enable continued direct negotiation with the FAA on airworthiness criteria, which also form part of the AC. Along with other companies, Beta gathered industry feedback for the FAA to ensure the AC took into account data being gathered by learnings from the more advanced powered-lift applicants. The Vermont-based start-up believes the now-standardized rules as being well aligned with the G-1 for the A250.
Could Joby and Archer Reboot Their G-1s?
Neither Joby nor Archer has said whether they will seek to revise their G-1 papers. Nonetheless, both welcomed the arrival of the AC for their four-passenger vehicles.
“Along with their commitment to continued global leadership in aviation certification through the NAA Network, this guidance reinforces the FAA’s focus on bringing advanced air mobility to market,” said a Joby spokesperson. “The new guidance aligns with our approach to certification and will help streamline the certification process of powered-lift aircraft generally. Our specific FAA certification continues to make industry-leading progress, and we are excited to be pushing through the final stages towards type certification.”
The National Aviation Authorities Network announced in April represents a shared certification roadmap agreed by the U.S. regulator with its counterparts in Australia, Canada, New Zealand, and the UK. Meanwhile, Joby and Archer have started flight testing eVTOL prototypes in the UAE, where the government is very eager to support the launch of the world’s first commercial services based on compliance with FAA standards.
“Establishing a streamlined pathway to certification lowers barriers for new entrants and accelerates innovation,” said an Archer spokesperson. “That’s a big win for the entire industry. Archer is one of only two companies that has finalized its certification basis for an eVTOL aircraft with the FAA. Given that, we don’t expect this will impact Midnight’s program. Still, it’s great that the FAA continues to streamline the certification process.”
Beta Now Ready To Accelerate
According to Beta, the AC establishes a much clearer baseline for certification, clearing the way to a shorter path to certification. It avoids the need to propose rules specific to each aircraft and then wait out a drawn-out public comment period.
A member of the company’s airworthiness team briefing AIN on background said the AC’s new rules provide coverage for its eVTOL design. While each manufacturer will make their own detailed safety requirements in the G-2 issue paper, the FAA appears to have moved to a more performance-based approach to rule-making that prioritizes safety intent while not unduly constraining individual designs.
Beta now expects to be able to close its G-1 soon and is already working to establish which prescriptive rules it will be required to meet. The company's electric propulsion system, which will be power both versions of the Alia, will be certified under FAA’s Part 33 rules.
“In addition to providing clear guidance, it [AC 21.17-4] is helping to create a more predictable path to certification for all eVTOL aircraft, while maintaining the high safety standards that are foundational to any certification project,” Beta said in a written statement. “This is another important step forward, bringing the AAM industry to commercial operations, and our collective effort to maintain American leadership in aviation.”
This week, Beta unveiled the first electric charging station as part of a network to be installed at airports across Michigan. The first unit is now operational at Capital Regional International Airport in Lansing.
According to independent industry consultant Sergio Cecutta, Joby and Archer may choose to resubmit their G-1 documentation with a view to aligning it with the fully defined regulations. However, he does not expect FAA to require them to take this step.
In his view, the publication of the AC is a very positive final step towards the entry into service for eVTOL aircraft, representing a concrete commitment to removing the regulatory uncertainty that the AAM sector has faced. That said, there will still be another SFAR covering post-certification regulations.
“We see this AC as very significant as it sets the final rules for all powered-lift certifications with no more special papers to describe a specific aircraft, so certification by regulation, not exception,” Cecutta told AIN. “It also brings the clarity needed by OEMs to give them confidence in moving forward full-speed with their aircraft design and certification.”