Whether as works of art or brand adverts, the way an aircraft looks – not to mention the way it is able to withstand a variety of challenging conditions – is the result of the hard work of the aircraft painting and coatings industry. Jason Holland assesses developments from both a manufacturing and maintenance perspective

[This article first appeared in MRO Management September 2021, which you can read in full here.]

The outer skin of an aircraft is the brand ambassador and identifier for every airline – it is what everyone notices first whether at the airport or in the sky.

But aircraft paint, in addition to these important aesthetic requirements, must above all be able to withstand the toughest technical challenges, notes René Lang, executive managing director aviation at Mankiewicz Germany. Strong temperature fluctuations, maximum UV exposure, durability and contact with harsh chemicals are just a few of these challenges. “Exterior paint must be intact, have a high gloss and colour depth, and match the airline’s colour tone very accurately,” he says.

For AkzoNobel’s global product management and commercial marketing manager aerospace & film Jill Kokkinen, quality and consistency are the foundations for manufacturing aircraft paint. “As a company, you cannot be successful without these fundamental pieces as they determine your reliability as a supplier to the industry,” she says.

“Aircraft paint is subjected to some of the harshest conditions you can imagine. Whether it be temperature, speed or weather, our partners dictate the parameters of product performance to protect and maintain their aircraft. They expect that we meet or exceed their criteria for performance every single time. Performance requirements also go beyond protection of the aircraft, other key elements include colour, durability as well as reduced application time and weight.”

After the original paint job, commercial aircraft exteriors are repainted and refurbished every five to six years throughout their operational lives, estimates PPG’s Vignesh Palanivel, global product manager, aerospace coatings. Exterior products include adhesion promotor, primer layer and topcoat, he notes.

The products used during the OEM’s initial coating process are not significantly different from those used in the refurbishment coating process though. The only exception, says Mankiewicz’s Lang, is the level of automation, which is somewhat different for OEM coatings. Here, mixing, application and drying are more often done in automated processes, he notes.

Sherwin-Williams Aerospace Coatings’ global marketing manager Julie Voisin says that when it comes to a quality aircraft refinish project, going back to basics is key – “the entire paint job is only as good as it’s foundation”. Looking at the stages involved, she adds: “Pre-treatment is designed to prepare the substrate to receive the subsequent coatings and provides adhesion to get paint to stick; then primer to create corrosion (and/or primer-surfacer for filling resistance); next topcoat to provide colour and branding, but more so protection from chemicals, the elements and VOCs; and finally – in some cases – there is a clearcoat layer or layers, which is also an effective means of topcoat and colour protection. Today’s new basecoat clearcoat systems not only provide increased production, but also provide easier repairs.”

When an MRO company begins an aircraft painting project, says Addev Materials’ international sales manager, aerospace & defense Philip Lutteroch, an incoming damage survey is carried out to ascertain the condition of windows, composites, fluid leaks and the general condition of the airframe (Addev Materials is Sherwin-Williams Aerospace’s UK-based distributor).

“All windows, composites static ports, leading edges and areas not to be stripped are masked,” he says. “We then apply an environmentally advantaged and PH neutral paint remover. The paint and remover residue is removed and the airframe jet is washed. We then undertake a solvent wash and an eco-friendly surface treatment. All the paint removal and surface preparation is started within our preparation booth which has ‘bunded’ drainage to allow any waste liquid to be collected and not enter any public drainage.”

The aircraft is then moved into the clean environment of the paint booth and a chrome-free primer is applied as a three-coat system to allow sanding for a smooth finish. “Panel joints which require sealant will receive application and surface imperfections and in composites will have a filler application,” adds Lutteroch. “After sanding we apply another single coat of chrome-free primer, inspect the finish for imperfections and then prepare to apply a topcoat.”

US-based MRO Constant Aviation – which services a variety of business and private jets – recently announced major improvements at its aircraft painting operation at Orlando Sanford International Airport. Director of painting Sandy McPherson says that a quality paint job consists of “completely stripping off the old paint, treating the entirety of the aircraft’s exterior for corrosion, priming the bare metal and composites, sanding to a smooth finish, painting the entire aircraft with the chosen base colour, applying approved customer livery, and detailing the aircraft after paint completion”.

The most important considerations for an MRO company when it comes to painting an aircraft, he says, are customer satisfaction, regular communication, on-time delivery and “ensuring the cost figure given in the estimate stage is what the customer is presented with upon the completion of their aircraft’s refinish”.

McPherson notes that customers are getting bolder and bolder in their designs and colour schemes “which we love because it keeps our creative juices flowing. Right now, the trend is more elaborate paint schemes with mostly pearls and mica paints.” He thinks the use of pearl and mica finishes is directly related to the complexity of the livery design. “Customers are trending away from a solid white basecoat on their aircraft,” he says. Many manufacturers continue to push the envelope providing these and other available speciality finishes.

For flag carriers and major airlines, colour accents tend to be placed more on the horizontal stabilizer, notes Lang. “These often reflect the corporate colours and are still commonly in the red and blue range. Low-cost carriers and start-ups are much more likely to go bold. Be it red, orange or purple, the imagination has no limits.”

Aerocare Aviation Services is an established Part-145 provider with facilities based in Chester, UK, and is noted for its ability to handle all aircraft paint requirements, from custom designs to current factory paint schemes, registration number changes, refreshes and touch ups to both fixed-wing and rotary aircraft in its paint facility.

For MRO companies, a successful painting project means achieving what the customer wants and “making sure we can deliver”, explains Graham Davidson-Guild, of Aerocare’s sales, estimating & planning department. “It’s all about meeting customer expectations, and more so making sure it’s all within their timeframe and budget,” he says. “Oftentimes they are looking for a very special final result; one that would best be reflected by using a higher-end coating.”

The painting part of an MRO project serves as the finishing touch that is not only what is seen first, but ties everything else together, explains Aerocare’s commercial manager Ruth Roberts. “If you see an aircraft that looks great, the owner feels good about it; they feel like all the mechanics, the avionics, everything that was done to the aircraft was done first class. That’s why it’s worth investing in a premier paint system because the final paint appearance is what’s going to be seen first, and from far away. Plus, it means it’s not going to have to be repainted in just 3-4 years down the road.”

Picking a quality paint and coatings supplier is therefore “one of the most important decisions you make as an MRO”, states Davidson-Guild. For its part, Aerocare works closely with Sherwin-Williams Aerospace and Addev Materials.

Assessing the future

The paint manufacturing companies interviewed for this article work constantly to improve their products and innovate in anticipation of new demands from airlines and MROs.

“Environmental compliance, improved performance and reduced application time are the biggest drivers in our innovation efforts,” says AkzoNobel’s Kokkinen. “As the leader in primers for aluminium structures in aerospace, we dedicate a significant portion of our R&D resources to developing chromate-free options. This is a difficult and lengthy task as these products are expected to provide protection for a minimum of 30 years. Based on the synergies of our patented inhibition technologies and [AkzoNobel-owned French aerospace coatings manufacturer] Mapaero’s significant research into this area, we expect to be ready for field trials in 2021.

“Improving performance and reducing application time are a constant challenge for our R&D team.  We are constantly pushing ourselves and our products to be better; this includes looking outside of our traditional coatings. We are currently leveraging other internal technology platforms to create coatings that could be applied to composite parts in the mold, as they are being built. The goal is to yield a completed part with the protective coating built in to provide better UV resistance, adhesion, flexibility and durability compared to traditional application methods.”

PPG’s Palanivel notes that reducing coatings weight on painted aircrafts has long been on the aerospace industry’s radar and remains a top priority. “Lowering the weight of an aircraft improves fuel efficiency that can result in significant operating cost savings and reduced greenhouse gas emissions when translated across a fleet,” he says. “One specific weight reducing product is ‘PPG Aerocron’ chrome-free, electrocoat (e-coat) primer, which is used to coat structural parts by electrodeposition instead of a traditional spray process and provides a more uniform film thickness on the part. This can result in up to 75 per cent weight savings on highly complex parts.”

New pre-treatments and primers are also being developed that offer many attributes, says Palanivel, supporting customer needs “to eliminate use of chrome and provide environmentally sustainable products while offering potential for reducing weight, increasing productivity and decreasing the total cost of ownership”.

Turning to current innovations and demands in the MRO space, Palanivel says customers are looking for products “that are lighter, have desirable environmental, health and safety qualities, wide range of colour capability including solid and special effect colours and are cost effective. Therefore, our innovation and research are based around these concepts.”

Products need to be suitable for more automated processes and offer faster curing times, he notes. “An aircraft in the hangar is an immobilised asset that is not generating revenue for the customer. There is an opportunity for us to help customers increase revenue by reducing the cycle time through better application processes and faster-drying products.

“Our customers will also require more services such as product training, technical service and support, marketing support and coatings services. Through closer partnerships, we will be able to deliver higher value to our customers and better protect their assets that millions of individuals use every day.”

There has been an industry-wide move to becoming more environmentally friendly. “New technology in equipment as well as coatings has given design groups and paint facilities the opportunity to think outside the box and get very creative with paint schemes and colours,” says Constant Aviation’s McPherson. “For example, our recently expanded paint facility at Orlando Sanford has been fitted with a three-stage filtration system to minimise the particulates that enter the environment. The filtration system is monitored, and alarms advise if emissions levels are exceeded. In addition, all wastewater used during our paint process runs through an in-house water treatment facility before it goes on for further treatment by the city.”

Besides offering durable and productive topcoats and interior coatings, Sherwin-Williams has recently introduced a new maintenance product called ‘JetPen’, Voisin says. “This product allows users to touch up chips, dings and scratches quickly and easily in a one-time use on aircraft. This two-component touch up pen contains actual Sherwin-Williams aerospace coatings that can be used on aircraft exteriors and cabins at any point during the paint process.

“JetPen can be used at the maintenance facility when doing some quick touch ups and used at the customer site later. It provides a perfect match with previous primers, clearcoats and a variety of topcoat colours for systems.”

Finally, AkzoNobel’s Kokkinen says that the entire industry is being impacted by global raw material and freight carrier shortages. “MROs are driven by speed and uncontrollable supply issues cause aircraft to be out of service longer than originally scheduled,” she says. “This hurts the MRO financially, so the focus has shifted to improving processes. Currently, our technical service representatives are on-site working side by side with our MRO customers to get aircraft flying again.”

Conclusion

As with any industry or sector currently, everything must be seen in the context of the Covid-19 crisis. Like every other industry, paintings and coatings was severely impacted “but we are pleased to see that in some regions of the world there is almost as much air traffic again as there was before the crisis, and with it the demand for coatings”, notes Mankiewicz’s Lang.

“Because we have always placed great emphasis on enabling our customers to implement lean and efficient processes, our customers appreciate our products despite the crisis. Many airlines have also taken advantage of the time to integrate maintenance, which was also accompanied by coatings. Even when leasing returns were on the agenda, we were able to help our customers.”

Aircraft that are put back into service after such a long time, of course, require special care and preparation, and painting and coatings companies will remain vital to applying those finishing touches.

Lang sees a “settling down period” as airlines align services to meet demand and travel starts to pick up again. “It is expected that there will be a change in aircraft types and size in order to meet route demand and this will take time to settle and whilst it does, aircraft will need to come out of storage or have liveries applied, as well as others leaving fleets and go through transitioning to storage or new customers. The past shows, crises often bring rebrandings – and rebrandings also mean a change of the livery.”

AkzoNobel too has a “very positive” outlook on the future for the aerospace market. “We are starting to see signs of recovery as airlines have started placing order for new, more economical aircraft and OEMs are increasing rates,” reports Kokkinen. “Additionally, air traffic is picking back up and the repaint market is following suit. While not all regions are recovering equally, we see improvements in the macro picture.

“This is a resilient industry fuelled by passionate people. We look at previous challenges, such as 9/11 and the economic crisis of 2008, as proof of the industry’s ability to climb back and grow.”