A new European research project called SUSTAINair has launched that will apply circular economy principles to the design, manufacturing, operations and end-of-life phases of aircraft, and develop solutions to increase resource efficiency and aircraft performance while cutting down on waste, emissions and material costs throughout the aircraft life-cycle. Spanning a period of 3.5 years and a budget of €5 million ($6m), the Horizon 2020 project aims to make the aviation supply chain ecosystem greener in line with the EU’s Circular Economy Action Plan, one of the main blocks of the European Green Deal. It is a collaboration of 11 European research organisations and industrial partners that will be coordinated by the Center for Low-Emission Transport at the Austrian Institute of Technology (AIT-LKR), Austria’s largest research and technology establishment. The circular economy is an approach to make the most out of resources by keeping them in use for as long as possible, so increasing their total value throughout their life cycle.

“SUSTAINair will address all phases of the aircraft component value chain, from circular design to manufacturing, maintenance and repair, as well as assembly and recycling,” explained Jürgen Roither, a research engineer at AIT-LKR who is coordinating the project.

A challenge for the aerospace industry is the high-quality material – both metal alloys and composites – used in the manufacturing process is typically accompanied by large amounts of waste. SUSTAINair will develop novel upcycling and recycling methods to reduce waste incurred during the manufacturing and end-of-life processes, including upcycling solutions for carbon and glass fibre thermoset materials as well as high-performance thermoplastic composites.

The project will aim to develop components to be manufactured to the size and shape of the finished product to reduce the ‘buy-to-fly’ ratio as close as possible to 1, which is imperative, said Roither, if more material is utilised along the chain rather than discarded. This is obtained by using recently invented nano-eutectic aluminium alloys at AIT-LKR in combination with advanced high-pressure die casting technologies, he said.

“Such processing is known in the automotive industry as ‘quick and efficient,” he added. “SUSTAINair’s adapted technique and materials will make the manufacturing of aerospace components ‘quick, efficient and clean.”

Novel metal alloys and composite materials, such as carbon fibre reinforced polymers, are used to reduce mass and increase aerodynamic efficiency, so improving fuel consumption and reducing emissions during flight operations. Minor changes to the materials or aircraft structure can therefore result in further significant reductions in fuel and emissions. With that in mind, the project will develop novel aerospace structures to reduce weight and also techniques for the integration of sensors in the material used in such aircraft components.

“What is unique about SUSTAINair is that the design process will be formed to allow for innovative techniques along the value chain that will give the material a longer life with more value, accounting for end-of-life disassembly and upcycling,” said Chiara Bisagni, Professor in Aerospace Structures and AIAA Fellow at TU Delft in the Netherlands.

Aircraft consist of many parts from various materials that need to be joined. Currently, the joining is done by using rivets, which not only make the aircraft heavier and so less fuel efficient but are difficult to remove and can make the efficient recycling of aircraft components challenging and costly to the point of being not economically viable. The project partners will bring their expertise in welding and other joining techniques to find solutions that could ultimately eliminate the need for rivets.

Introducing Industry 4.0 technology in aircraft end-of-life processing, the project will develop a robot head that automatically detects and removes rivets, allowing for alloy separation and hence higher value recycled aircraft material.

The European Aviation Safety Agency (EASA) is contributing to the project by providing advice on certification and regulatory aspects, as well as risk assessments.

SUSTAINair has launched a month-long digital campaign, #CircularAviation, to raise awareness about the circular economy in the aerospace and aviation sectors.

Photo: An autonomous robot for visual inspections accompanied by real-time, onboard, continuous structural health monitoring with novel sensors developed in the SUSTAINair project (credit: NLR)