EASA intends to publish phase two of the means of compliance (MoC) requirements for its Special Condition-VTOL (SC-VTOL) type certification rules by the end of June. Confirming the European safety agency’s next steps in finalizing the SC-VTOL regulations during a presentation to the Vertical Flight Society’s Forum 77 event on May 13, David Solar, head of EASA’s general aviation and VTOL department, said that phase three of the MoC document will be made public in November.
During his presentation, however, Solar also reported that EASA’s operational rules will not likely be confirmed in time for the first urban air mobility services using eVTOL aircraft. European manufacturers, such as Volocopter and Lilium, have been targeting the start of commercial flights in 2023 or 2024. He indicated that EASA will probably allow some local exemptions so early operations can get underway.
The further MoC details will be eagerly awaited by eVTOL aircraft developers seeking to certify their products under the new SC-VTOL rules. These are based on the CS-23 Amendment 5 rules for light fixed-wing aircraft. EASA recently released the phase-one MoC requirements, which cover factors such as minimum acceptable handling qualities, the structural design and strength envelopes, load limits, and emergency landing capability.
The planned requirements for the eVTOL category cover aircraft of the same size and capacity as the existing CS-27 rules for small rotorcraft, with nine or fewer passenger seats and a maximum takeoff weight of 3,175 kg (7,000 pounds) or less. It is anticipated that under the Special Condition, there will be requirements for “enhanced” and “basic” categories of operation, depending on the purpose of flights and the operating environment.
The enhanced category will apply for the protection of third parties in commercial flights over congested areas, as envisioned by the so-called on-demand taxi urban air mobility business model. This will cover factors such as requirements for continued safe flight and landing, including the possibility of having to divert from the planned destination.
The basic category will likely apply for private operations and in less congested airspace. Aircraft operating in this mode will have to be able to make a controlled emergency landing through means similar to a controlled glide for a fixed-wing aircraft or autorotation for a helicopter.
The phase-two MoC requirements will cover aspects of eVTOL aircraft such as structures, hydro-mechanical systems, flight and human factors, electrical systems, avionics, fire protection, and cabin safety. The phase-three MoC document will be presented at the next EASA Rotorcraft and VTOL Symposium, which is to be held as part of the European Rotors trade show in Cologne, Germany, from November 16 to 18.
According to Solar, industry-standards group Eurocae is expected to publish around 15 new standards related to eVTOL type certification during 2021. He said that EASA will step up efforts to support training needs for eVTOL aircraft operators and recently qualified the first virtual reality training device developed by VRM Switzerland for helicopter pilots. In April, the agency published the final version of the SC-VTOL rules covering electric and hybrid-electric propulsion systems that will power the new class of aircraft.
While EASA’s work on the certification of eVTOL aircraft appears to be closely aligned with the approach taken in the U.S. by the FAA, Solar indicated that other international safety agencies might not be on the same track. FAA is basing its approach to eVTOL certification on its Part 23 Amendment 23 rules.
“One big question mark is China, because we have very low visibility [of the Civil Aviation Administration of China’s approach to certifying eVTOL aircraft] and they may have some very local agreements we are not aware of,” Solar told the Forum 77 audience. This comment would appear to be a reference to Chinese eVTOL aircraft manufacturer EHang, which has enjoyed a high degree of cooperation from CAAC, allowing it to conduct extensive trial operations with its EH216 aircraft ahead of certification, which may come as soon as late 2021 or 2022.
According to Lowell Foster, director of global innovation and engineering with the General Aviation Manufacturers Association, industry and regulators are generally making good progress in establishing the certification path for eVTOL aircraft, while cautioning that more work lies ahead. “We’re about midway through the process and still have some huge challenges,” he told the Forum 77 audience, “It took the airline industry around 100 years to get the level of safety and efficiency that they have today and we’re doing it all in a very short time.”
Foster maintained that complete requirements for operations and training will need to be worked out once the first eVTOL models are certified and ready to start operating. “This work will have to be done concurrently; otherwise the initial operations could be severely limited,” he said.
GAMA’s Electric and eVTOL Certification Progress committee is bringing together member companies to focus on challenges around certification, operations, training, infrastructure, and airspace challenges. Lowell said the committee is encouraged by the willingness of FAA and EASA to take a performance-based approach to aircraft certification and that around two-thirds of MoCs for existing aircraft will be applicable for eVTOL designs with no changes.
However, he expressed concern that the approach taken to type certification may still be too rooted in requirements for aircraft powered by fossil fuels, rather than the new modes of electric propulsion. “I’m concerned that we may miss an electric-specific safety issue this way,” he warned.
Foster also advocated for a strong emphasis on human-factors issues, such as the need to closely scrutinize the design of flight displays used by pilots. He indicated that lessons learned from two fatal accidents involving Boeing’s 737 Max airliner could have a bearing on how eVTOL aircraft are treated. “In the fallout from the Max [accident investigations], the human-factors folks have an even bigger magnifying glass now,” he concluded.
