Detail Leading Edge scanner

This content is password protected. To view it please enter your password below:

Detail Leading Edge scanner

This content is password protected. To view it please enter your password below:

Composite Manufacturing Technologies

The use of composite materials has become a new norm in the aerospace and mobility sectors. While the weight, strength and usability benefits are clear, there are still some big gaps to fill – namely a knowledge gap in knowing how to inspect, repair and extend the life cycle of such material. To fill this void, NLR is teaming up with material and technology experts to launch the DCMC, aimed at enhancing knowledge and technology to keep the composites world moving.

If you’ve driven a car over the last few decades, you’ve probably noticed a change in construction. While bodies remain largely steel, more and more of the structural parts come from composite materials like carbon fiber. Similarly, the aerospace sector has also adopted the use of composites, as it cuts down on weight and subsequently, fuel. And with all eyes on fighting climate change, wider use of these durable and lightweight composite materials is certain to be a big piece of the puzzle in lowering emissions.

However, according to composites expert Bert Thuis of the Royal NLR – Netherlands Aerospace Centre, at least one big challenge remains. “It’s clear that the use of composites is increasing, which is great. However, what we’ve encountered is that there exists a real gap in knowledge when it comes to inspecting and repairing composite structures,” describes Thuis.

That’s where NLR is looking to shake things up and is teaming up with aerospace specialists GKN Fokker, Specto Aerospace and the TU Delft to establish the Development Center for Maintenance of Composites (DCMC) – a new research centre completely devoted to the development of new technologies and enhancing knowledge to extend the life cycles of composite materials and parts.

For nearly half of his 30+ years of working at NLR, Thuis, now serving as Technical Director of the DCMC, has been immersed in the structured technology department of NLR. In his roles, he’s been involved with a number of OEMs as they’ve set out to launch new development programs. Their goal, according to him, is simple. They want to sell airplanes, helicopters, or drones. Upon delivery, they also send a structural repair manual with repair instructions.

“What we see, however, is that these manuals are very thin and don’t offer much in the way of instructions,” Thuis describes. “In order to increase the operation level of an airplane or helicopter, new inspection and repair procedures have to be developed and made available – either to enable operator repairs in-house, or by setting up a dedicated channel of communication with proposed repair suggestions and instructions from OEMs.”

Adding another layer of complexity is the fact that, when dealing with composites, the damage can often times be easily overlooked, or invisible altogether. “If you take a hammer and bang your car, you’ll see a dent. It’s a visible damage, which is easy to both see and normally easily repaired. Composites, on the other hand, especially the high specification, high-tech materials like thermoplastics (materials which can be reheated, molded and cured multiple times) or carbon-fiber-reinforced thermosets (composites that cure only one time at elevated temperatures), which are used in the aerospace and automotive industries don’t have the same plasticity. That means there may be no visible damage, but it’s still there and has the potential to be serious.”

Kissing bond
The problem is current methods of inspection and repair are antiquated and labour intensive. The most commonly used technique to investigate for damage is known as the woodpecker, where someone goes across the entire surface of the aircraft with a pointed hammer, tapping on the composite to listen for hollow sounds. When a troubled spot is found, the solution is to cut the material around the damage, drill holes into the surface and then attach a patch with rivets.

“Inspection and repair technology has been stuck at the same level since the 90s, with very little improvement. Essentially, to repair damage, technicians have to create more damage to the structure by drilling holes. And at the moment, that’s the only acceptable solution,” illustrates Thuis. “Up to now, sort of the holy grail was to create a bonded patch to fill the problem areas. But the problem becomes, how do you know if the bond is strong enough, or if it’s what we call a kissing bond – where the bond seems to be strong and holding, but then with some sort of tap, it falls off. And if it is good, how long can it last? These points are crucial to know, but at this time, we just don’t.”

Opening such a centre offers the Netherlands the opportunity to be internationally recognized in the field of composites maintenance

This is where Thuis and NLR believe the DCMC can make a real and lasting difference. In its role as the technology institute, NLR is arming the DCMC with the knowledge and researchers to get the centre up and running. Additionally, NLR will supply the DCMC with experts to provide training and assessment of potential technologies in the field.

“Together with our partners, we’re definitely focused on modernizing and automating the approach to inspection and maintenance composite materials. We have established a pretty comprehensive technology roadmap, looking at different techniques and approaches ranging from ultrasonic solutions to thermal image scanning like shearography or thermography and more,” describes Thuis. “We also want to enable other experts and innovators to not only learn from our expertise, but also to share theirs. For that, the DCMC will be rolling out a development box, where members of the center can test and validate their technology on a number of different composite modules and models and perhaps get assistance from DCMC to help optimize their solutions.”

According to Thuis, opening such a centre offers the Netherlands the opportunity to be internationally recognized in the field of composites maintenance, and is quick to point out, opening the DCMC is just the start. NLR’s bigger goal is to keep that leading edge and to stay at least one step ahead of the industry.

“Companies are often focusing on the problems they foresee over the next year. But we’re really thinking about this with a longer-term vision and want to really push technology developments in the domain. We’ve got a lot of ground to cover, especially since we anticipate a boom in the use of composites in the next 5-10 years,” express Thuis. “But we believe that the DCMC has the potential to be a real centre of excellence in advancing composite material technologies in aerospace and beyond – including automotive, maritime and even wind turbines in the energy sector.” Adding, “Basically, if it moves, we think we can help.”

Partners of DCMC are Fokker Services, Royal NLR, TU Delft, Specto Aerospace, Rewin, BOM, Dutch Terahertz, Damen, TiaT Europe, and supported by EFRO, the European Fund for Regional Development and the Province of Noord-Brabant.

For additional information see the website of DCMC:

For those passionate about aviation, 2020 has been a roller-coaster of emotions. The year started off with seemingly unlimited opportunities for the aviation industry. But within few weeks, due to the spreading of COVID-19, airlines all over the world started to ground aircraft, until reaching a never-before standstill of flights in April and May. Airlines started filing for bankruptcy and retiring iconic aircrafts such as the 747-400, while hoping to recover fast and go back to normal as soon as possible. On the other hand, as aviation was already committed to become a more sustainable industry, many saw this disruption as an opportunity to speed up such transition.

In a recent interview discussing the impact of the COVID-19 emergency on the aviation sector, Michel Peters, CEO at Royal NLR, mentions how recovery goes hand in hand with greater attention to the sustainability objectives. He states that NLR will therefore be helping the sector to achieve these longer-term objectives for climate-neutral aviation, with the ultimate aim of making flying completely ‘circular’ (closed-cycle) and not burdening the environment.

Michel is not the only one claiming that the recovery following the COVID-19 emergency will need to go hand in hand with meeting environmental and sustainable development goals. In June, a joint statement has been signed by politicians and CEOs of several worldwide companies and published by the Financial Times which supports the claim that circular economy would be fundamental to the recovery of post-COVID-19. Aviation will join many other industries (from food and fashion, to civil construction and furniture) that plan to turn to circular economy to recover from the current economic downfall.

But how can circular economy be beneficial to many different industries in their post COVID-19 recovery? And what lessons can the aviation industry learn from circular economy, not only to recover but, more fundamentally, to transform into a sustainable aviation?

“Circular economy leads to resilient environments”

Circular economy’s principles of reduce, reuse, and recycle can easily be associated to a strategy towards a more sustainable way of working, but they also have proven to lead to more resilient and flexible environments. Circular economy considers waste and end-of-life products as a resource, which reduces the dependency on import of raw materials or on remotely located supply chains. This circular economy enables local economies to operate in a self-sufficient way, while connecting them to a larger, global network. Products can be manufactured locally, with local, renewable or second-stream resources. By encouraging reuse and repair solutions, the need or request for new products are reduced, which translates in less impact on personal economic situations. By supporting and favouring local employment, fewer jobs are at risk, in case of lockdown or international travel ban. By producing locally, being able of repurposing local resource or products, and introducing new ownership  models, markets could react more promptly to specific and constantly changing demands, by generating more availability of the (temporarily) needed products.

The aviation industry has grown into a worldwide, interconnected entity, where aircraft are assembled out of components manufactured in different countries across the globe. Though this supports national economies all around the world, it means the supply chain can be susceptible of interruptions when import/export trade has to be suspended. Also the aviation sector depends on massif infrastructures (airports) and expensive and incredibly optimised, single purpose vehicles (airplanes).

By transitioning to local, on demand production, the aviation industry could absorb the economic downturn by adjusting aviation-specific production as requested and enabling to transition more smoothly to different products. Applying design for disassembly and modularity concepts could help to repurpose airports and aircraft depending on actual needs; modular concepts would allow adjusting assets for different number of passengers, different health restrictions, or purpose, for example, enabling a simpler turnover from passenger into cargo. Modularity could help to reuse the materials and resources embedded in them. At an OEM level, aircraft manufactures are suffering the consequences of airlines bankrupting or delaying taking delivery of freshly produced vehicles. By designing and manufacturing aircraft in a more circular way, unsold aircraft could be easily dismantled, with components destined to different products, or reconfigured and simply sold to different airlines. Modularity can also lead to a reduction in time and cost for maintenance, repair and overhaul activities.

“Circularity as a full value-return on investment to feed a local market”

A consequence of the decline in air traffic and passenger numbers is that airlines have been forced to retire older and less efficient aircraft types to reduce costs; retired aircraft are taken apart, with valuable components sold as spare parts (for example engines). Unfortunately currently only a minimal part of the entire aircraft ends up in a second hand market, due to strict regulations and limited demand. Selling scrap parts for recycling the material simply does not generate enough return. With a more circular approach and the integration of aviation into a circular ecosystem, access to the resources of retired aircraft could provide a full return on investment, and such resources could feed a local market. As the expectations are that there will be no return to previous traffic numbers for many years to come, the airport infrastructure will also suffer from overcapacity for some time to come, leading to costs for the airport.  By building airports in a circular, modular way, the sections of airports not used could be disassembled and moved where needed. Airports also will need alternatives to passenger-related revenues; incorporating the airports with their surrounding communities and infrastructures in so-called “Airport cities” is seen as a possible solution. If this Airport City were to be built with circularity principles in mind, this transformation could generate several opportunities for all stakeholders involved.

Circularity principles can generate their maximum impact, in terms of environment impact and economic profit, if applied from the earliest stage of product development. Therefore introducing such principles in the design of new aircraft and airports would be the ideal situation. Nonetheless much can be done on existing assets, to minimise the environmental impact of abandoned airplanes wrecks and disused airport buildings.And creating the mind-set for the aviation industry to embrace a transition to circularity business models, not only in favour of an environmental agenda, but because such new models open new opportunities for business.

About the author

 Ligeia Paletti works at Royal NLR’s Aerospace Vehicles Division. She is a passionate aeronautical engineer with a strong background in structural analysis and structural integrity. Ligeia is deeply committed to making aviation more sustainable, with the dream of making the first circular aircraft fly.  Setting up NLR’s Circular Economy Team is a great start to achieve that! Check NLR Circular Economy capabilities. Questions? If you have any questions about this blog post, please feel free to contact Ligeia by email at or +31 885 11 43 61

Metal Additive Manufacturing

Join our Metal Additive Manufacturing certification programme

After the first successful metal Additive Manufacturing programme, the Netherlands Aerospace Centre now offers a follow-up programme to support participants in their ambition to introduce certified metal AM parts.

A new four years Additive Manufacturing (AM) technology programme has started at the Metal Additive Manufacturing Technology Centre (MAMTeC) at NLR in Marknesse. Royal NLR will work with a consortium of partners on certification of critical metal AM components. The new programme is a follow-up of the successful first metal AM programme which ran from 2015 to 2018 and was focussed on the laser powder bed fusion method (L-PBF). For the new programme, the MAMTeC will be extended with a BeAM Modulo 400 machine dedicated to manufacture and repair parts according to the Directed Energy Deposition (DED) process.

Video: New BeAM machine for MAMTeC

The new programme focuses on the certification of critical AM components for instance for aerospace, oil & gas, high-tech/high-spec industry, defence, and automotive applications. Especially these markets will have a great benefit from reduced weight, increased performance and higher efficiency that metal-AM can offer. To fulfil the stringent certification requirements, a qualified and stable manufacturing process is required. Therefore, research into the application of in-situ process monitoring systems will be an important part of the programme.

Another important part of the work during the programme will be related to the metal AM process simulation (virtual manufacturing) for both L-PBF and DED in order to gain insight into the temperature profile during processing. As a result, the residual stresses in the AM product can be predicted and an optimal AM production approach can be designed. Main target of the simulation is to establish a “first time right” manufacturing procedure.
Various materials will be investigated and test programmes will be executed to define the material properties of high performance materials such as Titanium and Nickel based Super alloys.

Participants of the new Public Private Partnership project are Oerlikon, Shell, Patria (Finland), BeAM (France), The Dutch Ministry of Defence, Thales, Aeronamic, KIMS (Korea) and Mokveld Valves. Participation is still open for other parties. Parties interested in this four years project are invited to contact the NLR program manager (t: +31 88 511 4204, e:

For more information also visit our Metal Additive Manufacturing capability page and read our Large-scale application of metal additive manufacturing article.

19 June 2019, Amsterdam – KLM Engineering & Maintenance and Royal Netherlands Aerospace Centre (NLR) have launched a joint venture, NUVEON, for the development of new Augmented Reality (AR) products for MRO (maintenance, repair & overhaul). NUVEON will integrate AR throughout the MRO chain to improve everyday performance in maintenance. The new partnership was signed at the Paris Airshow by Olaf Hoftijzer, Director Training E&M KLM, and Marja Eijkman, Division Manager Aerospace Operations, Royal NLR.

After a successful pilot, AFI-KLM E&M and NLR are now developing several maintenance training applications using Hololens AR goggles. The advantages have proven numerous, it makes training more attractive, more effective and more efficient. Trainees are actively involved in the instruction session, get a better insight into how the system works and are better able to put what they have learned into practice. And a virtual aircraft is available any place, any time. In addition to the development of further training applications, applications using combinations of different AR/VR devices are studied, as well as remote access through Maintenance Control Centres (MCC), visualization of complex 3D data and more.

In NUVEON, NLR is developing Augmented Reality applications and didactic concepts, and AFI-KLM E&M is delivering the subject matter experts and the commercial activities for the augmented reality technology for MRO aircraft maintenance applications. NUVEON aims to address MRO related companies that seek to improve and make their aircraft and aircraft components more efficient and more effective.

Olaf Hoftijzer, KLM: “Augmented Reality enables us to train on the aircraft while it is not actually there. This gives us a huge advantage especially for aircraft configurations not easily available. It is time to start developing new applications not only for training, but also to assist maintenance staff in their day-to-day work.”

Marja Eijkman, Division Manager Aerospace Operations, Royal NLR: “NLR is a frontrunner when it comes to aviation training, simulation, and the application of AR. Together with KLM, we wanted to create an innovative training solution that outperforms existing training in terms of efficiency and effectiveness. We recommended using HoloLens, in a collaborative way. NLR is able to model all complex mechanical systems in the aircraft, including systems that normally cannot be demonstrated in an aircraft on the ground. A key element in achieving excellent training effectiveness is to organise the training differently and to make it more interactive, because that is the only way to leverage the full added value of Augmented Reality. It’s not enough simply to use a new technology and leave everything else as it was.”

Current NUVEON solutions in MRO training

  • EASA part 147, B777 ATA’s Fuel System, Equipment Cooling and Air-conditioning
  • EASA part 147, B787GE to B787RR engine difference practical in full ( July 2019)
  • EASA part 147, B777GE to B777RR and PW engine difference in full ( November 2019)

NLR Division Manager Aerospace Operations Marja Eijkman and Director Training E&M KLM Olaf Hoftijzer shake hands on the new partnership, accompanied by NLR Business Manager Michel Piers and Wanda Manoth-Niemoller, Commercial Development Manager of Training E&M KLM.

Also visit our augmented and virtual reality and MRO pages.


Royal NLR and Ultimaker start collaboration on printing high performance (fibre) reinforced polymers

NLR’s Smart Industry field lab for Automated Composites, Metal Manufacturing and Maintenance ACM3, supports companies in the development of lightweight systems made of composite materials and/or metal. Additive manufacturing of high performance metals and polymers is one of the key areas ACM3 is focusing on.

Ultimaker, the global leader in desktop 3D printing, has an open material strategy which makes it possible to print applications with different materials with specific properties such as heat, impact and chemical resistance, flexibility, strength and more. Ultimaker 3rd party material suppliers deliver a wide range of reinforced (e.g. carbon or glass fibre) high performance plastics. These materials are delivered with optimised printing profiles from the Ultimaker Marketplace.

Besides processing fibre reinforced composites and additive manufacturing of high performance metals like aluminium, titanium, magnesium and inconel, ACM3 is expanding its reach on additive manufacturing by printing high performance (fibre reinforced) polymers like PEEK and PEKK and metal filaments. It is for this reason that NLR and Ultimaker decided to collaborate on this topic.

The collaboration will focus on improving the processability and material properties of these materials and will address topics like reproducibility and printing accuracy.

This combination of NLR industrialisation expertise and Ultimaker print process knowledge will open up new possibilities for creating strong, multifunctional and lightweight parts. It will contribute to the establishment of 3D printing as a mature manufacturing technology, which can be made available to SME’s and industry.

More info on ACM3 can be found at

NLR and Ultimaker team with the Ultimaker S5 professional 3D printer

Airforce operations

Maintaining aircraft means balancing budgets and resources to achieve the best aircraft availability. This balancing act is complicated by uncertainty; maintenance is inherently unpredictable.

AARE or aircraft availability and resource estimator offers a management decision support tool to determine the impact of changes to budgets and resources on the fleet availability (and vice versa) based on realistic reliability data, and it is specifically tailored to cope with uncertainty.

It provides the user with valuable insights into the relation between fleet availability, resources and budget.  It supports you with your financial planning, and set realistic availability targets, such as your On Time Performance.

AARE serves different purposes. It can help you with your financial and operational planning in an existing operation. However, you can also use it if your operations change or of you prepare for fleet changes, such as the introduction of a new aircraft type. It also offers an interesting learning experience for managers and management trainees.

AARE can be tailored to your needs. If you have specific questions, for example about the impact of condition-based maintenance or performance-based contracts, we can discuss the options to tailor aare to your needs.


Aircraft availability and resource estimator