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The Pax Cabin Demonstrator — developed under the Clean Sky 2 Regional Aircraft (REG) Integrated Aircraft Demonstrator Platform (IADP) — showcases sustainable, passenger-focused cabin innovations for regional turboprop aircraft, combining lightweight structures, environmentally friendly materials and human-centric design. Results include:

• A weight reduction of 8% for major cabin components, which contributes to long-term fuel savings — up to 22% over a 30-year aircraft lifespan — and direct reduction in CO_â‚‚ emissions.
• Successful Integration of eco-friendly, biocomposite panels met stringent aviation flammability and safety standards, offering a low-impact alternative to conventional materials. These panels would reduce 75 megatons of CO_â‚‚ emissions over 20 years for next-gen aircraft.

CW reported on this development in 2018. With completion of the Pax Cabin Demonstrator, this program’s success is now reported in . This ground-based test platform simulates the real-world interior environment of a regional turboprop aircraft and showcases how future cabins can enhance passenger wellbeing while slashing environmental impact.

“The Passenger Cabin Demonstrator is a full-scale, 7.3-meter-long, 3.4-meter-diameter fuselage barrel, equipped with major structural elements including: composite-stiffened panels, frames, pressure bulkheads, window frames and doors, as well as passenger and cargo floor grids,” explains Vittorio Ascione, Clean Sky 2 – REG IADP project manager at of Leonardo (Rome, Italy), the topic manager for this project. “The [Pax Cabin] Demonstrator is fitted with five seats per row, and though it was structurally similar to the Fuselage Structural Demonstrator, this one went further: it included interior components and systems, making it much more complete and complex.”

The fully integrated interiors and systems were also designed using a human-centric approach, focusing on increasing comfort through noise and vibration reduction while applying environmentally friendly materials to reduce cabin weight and minimize emissions.

A cabin concept built for the future

The Pax Cabin Demonstrator is an immersive mock-up that enables rigorous testing to assess noise levels, vibration, thermal comfort, air quality and overall passenger wellbeing, all critical elements in developing the necessary cabin environment for next-gen aircraft.

To validate innovations, the demonstrator underwent two test campaigns. Acoustic and vibrational tests were conducted at Leonardo VEL facilities in Pomigliano d’Arco, Italy, using external sources to replicate realistic cruise conditions. Vibrations were measured using accelerometers embedded within the seats, while “shakers” were used externally to simulate the effects of real in-flight dynamics.

Afterward, comfort and wellbeing tests were conducted at the Fraunhofer Institute facility in Holzkirchen, Germany. A group of 73 participants were subjected to simulated flight conditions — including noise, vibration, thermal environment and lighting. In response to questionnaires about their comfort levels and overall wellbeing, 94.5% said they would be willing to fly on such an aircraft in real life.

Biocomposite interior panels

A defining feature of the Pax Cabin Demonstrator is its use of advanced, eco-compatible materials and manufacturing processes. Cabin components including biocomposite panels contribute to an 8% weight reduction compared to interiors based on early-2000s technology. 

By applying these lightweight designs, significant fuel savings could be achieved over a 30-year service life. Use of bio-based materials — which was shown to outperform conventional interior panels in environmental impact categories such as climate change — could impact >75 megatons of CO_â‚‚ emissions across the global aviation sector in the next two decades.

A key challenge for new aircraft cabin interiors is the stringent flammability regulations. The biocomposite cabin panels passed multiple rounds of flammability, smoke and toxicity (FST) testing. Fire-retardant coatings, partially composed of renewable constituents, were developed to ensure compliance without relying on halogen-based chemicals.

A key step toward technology readiness

The project’s scope was designed to achieve TRL 6. Instead of isolated component testing, the demonstrator offered an integrated platform to measure system-wide performance, enabling realistic evaluation of interior architecture and environmental systems. All tests confirmed that the demonstrator met or exceeded the expected benchmarks, confirming that the proposed solutions are technically mature and ready for further development toward in-flight application.

Ascione notes this project had many key achievements, including integration of all myriad parts — structural, systems and interiors — from multiple partners into one cohesive unit. “This demonstrator brought together a high level of complexity, cross-functional collaboration and real-world performance in both physical and passenger comfort terms,” he adds.

Looking forward, the Pax Cabin Demonstrator provides a solid foundation for next-generation cabin innovation. It acts as a reusable platform to explore further advancements in aircraft systems, from enhanced thermal management to next-gen sensor technologies for onboard climate control. It also opens the door to deeper studies into crew interfaces, passenger feedback loops and modular interior configurations.

Fraunhofer and Leonardo are indeed already collaborating on a thermal management project called the that leverages the facility of the Pax Demonstrator. The project aims to demonstrate the dissipation of heat for systems and for power storage/generation in batteries, and for use in APU and fuel cells in hybrid-electric regional aircraft.

Collaboration and leadership

The success of the Pax Cabin Demonstrator is the result of extensive collaboration across leading aerospace organizations in Italy and Germany with links to stakeholders in France, the Netherlands and the U.K. The complementary grant agreements of COFRARE 2020, FUSINBUL, WINFRAME 4.0, TOD and SPARE contributed to structural components including frames, pressure bulkheads, window frames, doors and floor grids under the REG IADP WorkPackage 3.2. Key cabin components were developed under the CASTLE core partner agreement, coordinated by Geven S.p.A.

“This demonstrator was not only in the Clean Sky 2 Regional Innovative Aircraft Demonstrator Platform [REG], it also incorporated a lot of contributions from the Airframe Integrated Technology Demonstrator, which developed the panels and various elements of the cabin interiors,” says Clean Aviation project officer Costin-Ciprian Miglan. “We had many challenges, successfully mitigated by the consortium.” He adds that even though having the final demonstration spread across two platforms made it more complex, having “multiple platforms, countries and organizations contributed to the project’s success.”