Pilot Robin Evans reports on how the aviation industry is dealing with its redundant aircraft.
Between 500 and 600 commercial aircraft are dismantled each year worldwide as carriers renew their fleets and slake their thirst for efficiency. But this need not be the components’ final destination, as Air Salvage International (ASI) is showing.
The work of this aircraft decommissioning company is in contrast to conventional sustainability practice in the sector, which has tended to focus on reduction of noise, fuel consumption and carbon emissions. Indeed, in the past reuse or recycling of high-value parts was limited and many older aircraft were abandoned in the corners of airports while others were grounded, pending disassembly. But in 2006 an expert group of 11 companies, including ASI, founded the Aircraft Fleet Recycling Association (AFRA) to define an approach towards aircraft recycling and anticipate the potential market for an activity that was unbound by regulation. They created management practices that have informed an accreditation programme and engagement of new members. The aim is to return quality components to the supply chain to keep fleets airborne, maximise the recycling of materials, some hazardous, and deal with the evolving nature of aircraft construction.
Sum of its parts
Aircraft are much more than the sum of their parts. Many individual components can be more valuable. Aircraft succumb not only to the effects of gravity over time but to the constant cycle of market forces: recessions, fuel price, fleet ageing, ever-more stringent regulation and competing models. In a financial recovery mechanism, many older or less cost-effective models are stripped for compatible parts. Without cradle-to-grave support from the original equipment manufacturer (OEM), parts must be sourced new or – given their robust design, servicing intervals and serial number traceability – second hand. If an OEM has stopped producing spares or discontinued the type, there will always be a need for a rolling stock of salvaged parts.
Taking a chance
In 1992, British Airways bought the ailing Dan-Air, retaining only the route slots. Former engineer Mark Gregory took a chance, investing his redundancy package on an old Hawker 748 turboprop, a mainstay of short-haul domestic and European routes. Gregory single-handedly took apart the Hawker, reselling the cabin doors for several times that he had paid for the entire aircraft. Identifying an opportunity, he then won a contract to disassemble 12 similar aircraft. A site within Cotswold Airport (formerly RAF Kemble) was the perfect venue for a larger enterprise, arriving in the form of an ex-Virgin Boeing 747. Twenty years on, ASI is a family-run, British business with 47 staff, disassembling between 50 and 60 aircraft a year – a significant share of an unsung but crucial global market.
‘The industry has fundamentally changed inside 20 years. You can’t just arrive by car and take the engines off any more,’ says Gregory, who maintains a practical, hands-on approach as ASI chief executive. Aviation is a 24–7, global operation, but behind the scenes lies an equally complex web of financial ties: given the massive costs involved in buying new aircraft – the latest generation Airbus A350 retails for around $350m – it is often banks, investors and hedge funds that own them. Those that end up at ASI from distant operators tend to be aircraft with connections to UK lessors, or when the company is appointed to work on their behalf.
The number of parts returned to the supply chain varies with aircraft age and model. Generally, newer models have the greatest potential and rarer aircraft can be more valuable. The parts of the Embraer E-Jet, a Brazilian, short-haul jet from 2002, are relatively more valuable than components from the Boeing 737, which typically returns around 1,800 parts to the supply chain. Spares for older aeroplanes, such as the 747, tend to have less value, so it is worth harvesting only between 300 and 400 specific parts.
The dismantling process has often started before an aircraft arrives at somewhere like ASI. They land ‘de-branded’ with livery markings obscured, keeping the disassembly anonymous. ‘There are no passengers flying from here – but it is not good psychologically for passengers going on their holidays to see an aircraft in bits,’ says Gregory. The first step is to assess the aircraft on behalf of the owner or lessor. The engines are always scrutinised first since they represent about 80% of the value. Passengers tend to consider aircraft as a single unit but the engines are separate assets, owned or leased independently and easily swapped or removed for servicing.
A maximum power assessment (MPA) is carried out and a borescope is directed into the engine core to confirm an engine’s integrity. ‘With its performance established, we report to the owner or lessor,’ says Gregory. ‘Once satisfied, they sign off and can walk away; the aircraft is now with their representatives.’
Engines can be shipped or stored, a giant stack occupying one corner of a hangar at ASI. If stored, fluids are drained and a preservative circulated, each unit shrink-wrapped with humidity monitoring. Using preserving agents has implications under dangerous goods regulations so some preparation is required to ready an engine for dispatch.
Not all aircraft make one-way trips to ASI. Some are placed in storage and return to service should the circumstances of the operator change: two immaculate regional jets are parked aside awaiting a return to the skies. Storage is short-term in the UK due to the damp climate, unlike the vast, desert ‘boneyards’ in the US. A recent arrival for storage, although it could end up being dismantled, is a 20-year-old Asian-registered Boeing 777 – an extremely successful, wide-body, long-haul airliner. Its British-made, Rolls-Royce engines are assets best kept within Europe, but its appearance at ASI is significant, signalling the onset of retirement for advanced ‘third-generation’ models built in the late 1990s.
All fluids are collected in a pre-decommissioning phase. An approved supplier collects hazardous materials for treatment in accordance with COSHH procedures. One of these is Skydrol, a proprietary brand of hydraulic fluid whose additives are dissolved into a fire-resistant, corrosion-inhibiting phosphate ester base. Historically, materials have been more hazardous: Boeing used depleted uranium as a counterweight in early versions of the 747. Because aviation fuel has a tax exemption, it is controlled by HMRC and recycled through a local fuelling company, much of it being resold as domestic heating oil. Fuel tanks are vented and all systems depressurised. The Civil Aviation Authority and the Environment Agency regulate aircraft or parts and ‘waste’ respectively.
Looking after the values
Only the parts that are deemed economical to extract are salvaged. All the major systems are targeted, such as air conditioning units and flight controls. Seats, radios and instruments are first out. ‘We have a phase one hit-list of parts to harvest and so on,’ says Gregory. ‘We rotate narrow-bodied aircraft very quickly and it only takes two weeks to make that initial hit. An Airbus A320 can take between two and ten weeks, depending on age, type and customer. A 747 takes between ten and 15 weeks, but it’s always a variable process.’
Hydraulic components are last to be extracted because they often include the landing gear. Once the landing gear is salvaged, aircraft are fitted with a basic ‘slave gear’ to wheel them on to the storage line, making way for the next patient. Parts collect in bays, either for ‘parting out’ to specific clients or are inventoried in-house (see panel, right).
A wall of shipping containers at ASI indicates the entrance to the yard for final disassembly. On my visit, a 747 sits on sleepers awaiting its fate. With surgical precision, the flight deck has been removed and the landing gear set aside. ‘It takes around one day to dismantle a tube,’ says Gregory. Aircraft are dismantled tail-first and the remains sent for industrial separation, with only the purest grades of metal remaining in the aviation industry. There is little waste. Around 95% of the metal in the fuselage of an aircraft built since 2002 is reused or recycled, compared with 70% for those produced in the 1980s. In contrast to the polluting reputation of aviation, there is an industry target of 100% recyclability.
The fuselage is not always torn apart: the forward section – wings to the forward cabin doors – is most valuable. There are many airport trades that benefit from recycled fuselage sections, most obviously flight decks and cabin sections for simulators. Wing sections are used as rigs for training engineers on engine-fitting and fuel tanks are retained to help workers practise in confined spaces. Cargo holds are used for baggage and loading training, and various sections are used in security: running deportee drills, destructive testing or as simulators for hijack and fire training.
Innovative uses are made of other parts. Engine pylons were converted into vehicles for the latest Star Wars film, while a fuselage sits in Thorpe Park theme park in Surrey as part of its Swarm rollercoaster. There is also a flourishing market in upcycled ‘fallen furniture’ thanks to the iconic design of fan blades, engine cowlings and seatbelts. Smaller components such as extinguishers are serviced for reuse or drained for recycling. Lifejackets are punctured, often stamped ‘not for use’, and sold on to training establishments. ‘A 747 has 400 lifejackets so, on a scale that vast, it’s an incredible operation,’ says Gregory.
There is also a range of associated applications. ASI is a licensed provider of maintenance, repair and overhaul (MRO) services, including engine borescoping or nondestructive testing (NDT) of spars, the main structural member of a wing. Aircraft, including two Concordes, have been disassembled, transported and rebuilt for museums. Salvage teams from ASI have been deployed to locations as diverse as Guernsey, Kolkata and Khartoum to either disassemble aircraft damaged beyond economic repair or help to recover them after incidents. But opportunities abroad are restricted by the permit system. Gregory says: ‘The whole industry requires permits to work. It could take six months to acquire the necessary permits abroad. It’s easier to bring aircraft on to site and work on them under our own permit.’
There are three established issues that cause difficulties for aircraft recyclers: wood, old aircraft, and the plastic in cabin interiors. Wood from the interiors of business jets and the oldest generations of commercially obsolete aircraft (retained as freighters or privately owned) are relatively small in scale. However, the use of plastics in passenger cabins is widespread. A fourth challenge has started to emerge: composites, in particular carbon fibre and especially when the material is ‘dirty’ (riveted, painted or otherwise impure). ‘Plastics are definitely where the development needs to go; we need recycling companies to get a grip,’ says Gregory.
Driven by demand, in turn motivated by fuel price, OEMs are turning to ‘lightweighting’. Small margins for many flights amount to significant economic and green gain. Carbon fibre maintains great strength for weight reduction and can be repaired easily in situ. The latest ‘fourth generation’ Boeing Dreamliner and Airbus A350 are 50% composite by weight, using between 30 and 1,000 3D-printed parts that minimise waste during production. How to separate and recycle composites on a commercial and energy-efficient scale is a significant challenge. Composite recycling is still in its infancy. There is a great cost and energy embedded in carbon fibre, so unlocking commercial viability by reclaiming and reusing these fibres is key to the 100% recyclability target. ‘Either on their own or in combination with virgin carbon fibre, these materials extend the envelope where the use of composites can be economically justified,’ says Frazer Barnes, managing director of ELG Carbon Fibre, the world’s first and largest carbon fibre recycling plant.
Commercialised carbon fibre recycling heats a raw feedstock to release the binding matrix (typically epoxy resin) and retrieve the fibres. Recycled fibres retain their stiffness but, as the feedstock is chopped to begin with, they are shorter, dictating lower-grade reuse. The returned product is available in powdered, pelleted, filament or non-woven mat forms. Within aerospace the main waste sources are scrap and laminate trim generated from the manufacturing process and known as pre-preg. This is partly cured, ‘preimpregnated’ assemblies of fibres and binding matrix that is prepared for handling and shaping. Barnes says: ‘We have carried out studies for the aerospace industry that demonstrate the viability of end-of-life recycling of carbon fibre-intensive structures. However, more work is required to industrialise these processes.’ Research at the University of Nottingham is under way on the fluidised bed and supercritical fluid processes. These produce cleaner, longer fibres that can be aligned within a weave, a key factor for highgrade, load-bearing applications such as wings. The supercritical fluid process can also recover some of the binding matrix that is otherwise lost.
Boeing and Airbus have both funded research into recycling processes and applications for recycled products, such as seat backs, tooling and interior panels. Technically, 100% recyclability of carbon fibres alone could be achieved, but the critical issue is the cost of implementing it. Given an average 25-year aircraft lifespan, can the industry’s understanding catch up before the latest models start to be retired?
Back at ASI, newly arrived by road is an elderly Boeing 727 fuselage for final disposal. Going out is a wing for industrial testing. ‘Manufacturers might call up for a wing section of a certain age for post-service testing,’ says Gregory. The results will help to inform future design and so the cycle continues. The Cotswold Airport represents the end of the runway for some, but for others, it is just the beginning.
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