E-Fan X’s technologies will challenge FAA’s and EASA’s certification rules

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Heavyweight companies’ plan for hybrid plane ‘a stepping stone to electric flight’

Airbus, Rolls-Royce, and Siemens developing a hybrid-electric propelled aircraft


The Innovation will test EASA and FAA

Airbus’ press release:

“Airbus, Rolls-Royce, and Siemens have formed a partnership which aims at developing a near-term flight demonstrator which will be a significant step 
forward in hybrid-electric propulsion for commercial aircraft.

The three companies together announced the groundbreaking collaboration, bringing together some of the world’s foremost experts in electrical and 
propulsion technologies, at the Royal Aeronautical Society in London.

The E-Fan X hybrid-electric technology demonstrator is anticipated to fly in 2020 following a comprehensive ground test campaign, provisionally 
on a BAe 146 flying testbed, with one of the aircraft’s four gas turbine engines replaced by a two megawatt electric motor. Provisions will be made 
to replace a second gas turbine with an electric motor once system maturity has been proven.

“The E-Fan X is an important next step in our goal of making electric flight a reality in the foreseeable future. The lessons we learned from a 
long history of electric flight demonstrators, starting with the Cri-Cri, including the e-Genius, E-Star, and culminating most recently with the 
E-Fan 1.2, as well as the fruits of the E-Aircraft Systems House collaboration with Siemens, will pave the way to a hybrid single-aisle commercial 
aircraft that is safe, efficient, and cost-effective,” said Paul Eremenko, Airbus’ Chief Technology Officer. “We see hybrid-electric propulsion as 
a compelling technology for the future of aviation.”

The E-Fan X demonstrator will explore the challenges of high-power propulsion systems, such as thermal effects, electric thrust management, altitude 
and dynamic effects on electric systems and electromagnetic compatibility issues. The objective is to push and mature the technology, performance, 
safety and reliability enabling quick progress on the hybrid electric technology. The programme also aims at establishing the requirements for future 
certification of electrically powered aircraft while training a new generation of designers and engineers to bring hybrid-electric commercial aircraft 
one step closer to reality.

EFANX systems


That’s an announcement which will test aircraft certification standards, as presently written. It is improbable that many existing FAA or EASA regulations address high-power propulsion systems, such as thermal effects, electric thrust management, altitude and dynamic effects on electric systems and electromagnetic compatibility issues.

Well, actually there are recent revisions to the electromagnetic interference, but the testing will be stretched by a two megawatt motor engine.  There is also current experience with lithium ion batteries as part of an aircraft support system, but not as the primary source of power.

If the FAA is only able to use its existing prescriptive Part 25, the development of airworthiness standards will be laborious and may delay approval. The Part 23 standards have been revised to authorize “performance-based’ standards and reliance on expert panels such as ASTM  to devise appropriate testing regimes for these innovations. If Part 25 is amended by the time E-Fan X is ready for review, the certification review can focus on the new elements and rely on past actions for approving prior established safety bases. Perhaps, most importantly this Airbus, Rolls-Royce, and Siemens project would be benefited most significantly by EASA and FAA jointly and simultaneously updating the criteria and processes, like they did for Part 23.


The environmental gains which potentially come from the E-Fan X merit the regulators’ devoting time to bringing the rules into a contemporary time frame with the technology.






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