In the 70s the construction of aircraft was revolutionized. With the start of the construction of Airbus A300, not only costs were saved but also time due to the introduction of separate component production. In 2006, when the first Airbus A300 had reached the end of its service life, it also triggered a major upheaval in the aviation industry. It was the first plant that tested innovative processes for scrapping and recycling end-of-life aircrafts.
The PAMELA (Process for Advanced Management of End of Life of Aircraft) project was intended to demonstrate that the components of an aircraft could be dismantled without harming the environment and then reused in aviation or other sectors. The success of the project, co-funded by the EU LIFE-Environment program, led to the establishment of aircraft recycling companies offering high quality materials for reuse in aircraft construction.
Aircraft recycling – A life after death also for airplanes
Aircraft have a normal service life of 20 to 30 years. At the end of their life cycle, commercial aircrafts are usually either converted to cargo aircraft or parked in “aircraft cemeteries” or airports – often under inadequate safety conditions.
In case of increased demand, these aircraft can be put back into service or disassembled into parts for reuse. This resulted in a rather haphazard scrapping process leading to about 45% of the mass of an aircraft being dumped in landfills before PAMELA. Furthermore, aircraft recycling might have been a poorly monitored process involving insufficient attention to the handling of potentially hazardous waste and the re-introduction of used parts into the supply chain without a suitable inspection.
The aim of the PAMELA project was a demonstration that end-of-life aircraft do not have to “end up” in this way and that an aircraft could be dismantled. Furthermore, it was shown that an aircraft could be dismantled without environmental hazard and that its components could be reused or recycled as secondary raw materials.
However, although aircraft are made of materials that can be recycled or reused in various ways, a standardised procedure did not exist before PAMELA. Therefore, the project was designed to fill this gap and to ensure that relevant waste regulations were complied with. In addition, a recycling rate target of 85% was to be achieved on a voluntary basis, comparable to the EU Directive 2000/53/EC on end-of-life vehicles, which does not yet apply to aircraft.
A three-stage process for aircraft recycling
Within the framework of PAMELA, a three-stage procedure was applied for the systematic recycling of aircraft that had been taken out of service: decommissioning, dismantling of components and intelligent selective disassembly. The first stage included cleaning and decontamination of the aircraft, i.e. removal of hazardous substances and flammable or explosive materials.
At this stage, which had not been foreseen in the previous procedures for aircraft scrapping, the test object, a first-generation Airbus A300, was also subjected to a thorough inspection in which the parts were listed and assessed as reusable or not. At the end of the first phase, the weight reduction of the aircraft was approximately 18 tonnes, mainly due to the removal of liquids such as fuel and water, which are not included in the recycling quota.
During the second stage, reusable components such as engines and landing gear were removed. Those were then tested and certified to be suitable for use as spare parts for aircraft in service. The weight of the test aircraft was reduced by a further 13.5 tons during this phase.
After completion of the first two stages, an aircraft could, in principle, be put back into service. However, this is only possible if the necessary flight certification is granted. It should be noted, that the decision to disassemble the aircraft is irreversible, as the aircraft will be officially declared as waste from that moment on.
Breakthrough in material recycling
Although a more systematic and comprehensive approach to decommissioning and dismantling was applied under PAMELA than before, a real innovation occurred in the third stage, where the entire aircraft hull was dismantled as planned. Aluminium accounted for the majority of the materials recovered; titanium alloys, steel, copper, plastics, foam and textiles were also recovered.
The waste streams were thoroughly sorted, aluminum was also separated into different alloys. These alloys were then melted in a special melting process to produce aluminium of a sufficiently high quality to be reused in aircraft construction. And this was the decisive innovation, as it had previously been assumed that aluminium from old aircraft could not be used to manufacture new aircraft.
When the aircraft was finally dismantled, a total of 61 tonnes of recyclable material was recovered. At the end of the three phases, only 13% of the original aircraft mass had to be declared as non-recyclable waste and landfilled.
Permanently conserving resources through recycling
The PAMELA project has successfully demonstrated that the environmental impact of aircraft scrapping can be significantly reduced. Thanks to a comprehensive and selective sorting process, more than 85% of the recoverable materials were sold for regulatory recycling – up to 70% of the material was returned to industry, including the aviation industry, thus creating its first closed production cycle (“cradle-to-cradle”).
However, “composite materials such as CFRP (carbon fibre reinforced plastic), which cannot currently be recycled, are still problematic today. The reason for this is that the quantities recovered are too small and the technical performance of the materials still needs to be improved. Today, these materials account for a much larger proportion of aircraft production. The goal is therefore quite clear: in the next three to five years we need recycling processes for production waste, which can then be used in 20 years’ time for aircraft at the end of their life cycle.