Safe. Reliable. Efficient. These are the fundamental requirements for any commercial airline fleet in operation around the globe today. Those objectives rely heavily on maintenance, repair and overhaul (MRO) services, which ensure that planes remain in optimum condition.
Advanced surface finishing is playing an increasingly important role in modern MRO strategies. Technologies such as high velocity oxyfuel (HVOF) thermal spray, in particular, can deliver both component strength and high resistance to wear and corrosion to fulfil design requirements.
Furthermore, when advanced surface finishing is delivered locally by specialist providers, it can reduce turnaround times and eliminate long-distance transportation costs — ultimately enhancing sustainability objectives.
Repairing rather than replacing aircraft parts
So, let’s have a look at such strategies in action, focusing on how advanced surface technologies extend the life of critical components on the A380 superjumbo. This 575-ton aircraft is the undisputed giant of the skies, capable of taking between 500 and 850 passengers halfway round the world.
The A380’s landing gear is critical to its safe performance. Made from high-strength steel, aluminium, and titanium, it is a highly engineered assembly that combines enormous strength with the low weight essential to modern aircraft design. Configured as a multi-bogie system comprising both four- and six-wheel assemblies, the landing gear relies on the precise interaction of numerous mechanical and hydraulic systems, including the shock absorber piston, main fitting (outer cylinder), bogie beams and the sliding elements of the retraction mechanism.
Dozens of cylindrical components from the A380 landing gear assembly require tungsten carbide coating renewal to maintain durability and control wear. The process itself is highly specialized, involving stripping, inspection, surface preparation, robotic HVOF coating application and precision post-processing, all performed to exacting aerospace specifications.
HVOF thermal spraying on the A380
The process starts when worn parts are received by manufacturers, such as Bodycote, as an example. The degraded tungsten carbide coating is removed using a controlled electrochemical stripping process, in which the parts are submerged in a solution with an applied current that attacks the metallic binder phase within the coating, allowing it to be safely removed without damaging the base material.
Further NDT checks are then performed on the base material to ensure there is no heat damage. Degreasing is then performed to prepare for the application of the new tungsten wear-resistant coating, and grit blasting roughens the surface before the new coating.
The HVOF coating material is heated and accelerated at supersonic speed by a gas stream to a component’s surface to attain better properties. In the tungsten carbide coating process, the gas stream is produced by mixing and igniting oxygen and a fuel (gas or liquid) in a combustion chamber, then allowing the high-pressure gas to accelerate through a nozzle. A powder is introduced into this stream, where it is heated and accelerated towards a component’s surface. Spraying is an entirely automated process using a programmable robot, with the parts mounted on customized jigs and rotated in a sealed chamber.
The gun traverses many times over the area that needs coating, resulting in the thermal spray being applied in thin overlapping platelets in a highly controlled manner, slowly building up the tungsten carbide coating.
The process takes between one and six hours, depending on the size of the parts. Some of the A380 parts that vary in size can be held in the hand, while others are several meters long. Batch sizes are relatively small in MRO, with the A380 run rate typically accounting for one landing gear per month.
The coating is applied with sufficient build-up for finish machining, then ground back to meet the required tolerance and surface finish. A diamond belt polishing process is then performed to get the desired finish. Finally, an NDT process is conducted to detect any surface defects, such as tiny cracks or holes. The A380 parts are then handed back to the MRO specialist for refitting and repainting, fully renewed in terms of strength and high resistance to wear and corrosion.
The advantages of outsourced services
There is growing recognition that such highly specialized processes, such as thermal spraying, are better delivered as an outsourced service. HVOF capacity requires significant investment, both in equipment and expertise. Engineering knowledge and process control are critical to achieving the tight tolerances and selective coating required for landing gear applications. Specialist providers tend to have better access to in-house skills, making outsourcing a more efficient and less costly option for many MRO providers.
These surface-finishing activities must also be completed as quickly as possible to minimize aircraft downtime. Aircraft operators are under pressure to streamline supply chains and reduce turnaround times, and do not want to be transporting parts long distances, sometimes overseas, as part of MRO strategies.
Increasingly, then, fleet operators look to collaborate with surface finishing organizations that can offer a global but local service. This means parts can be repaired regionally, without delay. Bodycote, for example, operates 50 National Aerospace and Defense Contractors Accreditation Program (NADCAP)-accredited sites globally, ensuring a local solution is always available.
Where next for thermal spraying?
Finally, environmental regulations could also lead to increased thermal spraying, as the aerospace sector accelerates the transition to safer, more sustainable processes. For example, hexavalent chromium, also known as chromium (VI), has been widely used across industries for its exceptional corrosion resistance and durability. However, its toxic nature poses significant risks to human health and the environment.
To address these concerns, HVOF-applied tungsten carbide has emerged as a Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH)-compliant alternative, offering performance that exceeds customer requirements while minimizing environmental impacts. By adopting HVOF technology, companies can adhere to REACH regulations and promote a safer working environment. This shift aligns with broader industry goals around sustainability and responsible material use.
Supporting the next generation of aerospace MRO
Aerospace MRO is as much about effective restoration as it is about replacement, giving flight-critical parts a second life. For high-value components, advanced surface technologies such as HVOF can help extend in-service operation, reduce logistical complexity and support more sustainable maintenance strategies.
As applications expand beyond landing gear into other aircraft systems, providers such as Bodycote with deep process expertise and global yet local capacity will be well placed to support the next generation of aerospace MRO.
Ultimately, MRO providers can scale with confidence, ensuring safe, reliable and efficient aircraft fleets that are ready to take to the sky.
This article was originally published in Fabricating & Metalworking, September 2026