The finishing touch

As one of the world's most advanced and dedicated plasma electrolytic oxidation (PEO) treatments for light alloys, the Keronite process produces ceramic surface layers which enhance the durability of components by delivering wear resistance and corrosion protection in the most demanding of applications.

The performance of Keronite also offers the potential for greater service life. Rather than routine refurbishment or scrappage, landing gear bearing carriers can be returned to service after scheduled maintenance inspection. The possibility of increased service life offers reduced costs, simplified logistics during outages and improved aircraft availability.

MROs send the used bearing carriers to one of Keronite's service centres, where the remains of the old surface treatment are removed. The parts are then processed in accordance with the Boeing Aircraft Company (BAC) standard and a precisely engineered layer of Keronite is applied.

“PEO is an electrolytic immersion process that requires an electrical current to pass through the surface of a light metal part,” begins Keronite's CEO, Matt Hamblin. “This oxidises the surface of the metal and generates a plasma in the oxide layer, which converts it into a hard yet flexible ceramic layer, growing both into and outwards from the surface of the metal. Our customer base is predominantly MROs located outside the US. It costs the customer a lot of money every time they have an aircraft on the ground (AOG), so turnaround time is our biggest selling point. Our customers value the fact that we can turn parts around in 2-3 days.”

Get going with Boeing

At a scheduled landing gear overhaul, MROs reported premature wear of the titanium bearing carriers fitted to Boeing 737 NG aircraft. To overcome this problem, Keronite collaborated with Boeing to develop its own patented PEO technology to improve the wear characteristics of the 737 NG's main and nose bearing carriers.

With the release of Boeing's Service Letter, MROs can specify Keronite for the refurbishment of the bearing carriers. This new cost-effective service provides MROs with rapid turnaround times and operators with the potential for reduced service life costs.

“The Boeing 737NG landing gear bearing carrier is virtually the last part that is removed from the landing gear assembly. Being the last part off, it's one of the first parts back onto the landing gear, which is why fast turnaround is so important. The Boeing parts are made ‘fit for assembly' back into the landing gear. We apply Keronite that grows the appropriate layer of coating, then we apply a friction modifier and the parts are returned to the MRO for reassembly into the landing gear.

“The reality is that Keronite isn't specified on the original equipment (OE) drawing; this is done by a competitor of Keronite and we are approved as part of the MRO cycle. The landing gear goes through many take-offs and landings and is overhauled as part of the routine maintenance of the aircraft. Certain customers use Keronite under our Boeing approval as opposed to returning it to the OEM.”

Hamblin adds that purchasing brand new bearings would run into thousands of pounds, because it's machined from a solid piece of titanium.

“Using refurbished carriers with a new coating is a more cost-effective solution for airlines. The reality is that it's not Boeing we are doing business with, but the airline itself or the recommended company they choose to use. Ideally, we need Keronite to be stated on the original equipment drawing by Boeing. This would allow us to compete for new build aircraft as a viable alternative to the incumbent as well as grow our network of business with overhaul shops.

“We handle on average 1-2 landing gear sets every month. The reason the MROs do business with us is our turnaround time. If these parts were shipped to the US, it could take 2-3 weeks to turnaround, whereas we can do it in 2-3 days. This is where we really come into our own. Our size and flexibility means we're able to accommodate short turnaround times for the airlines that want to do business with us.

“We've undertaken an intense validation process where Keronite was tested against the same criteria as the OE coating, and it's been proven that Keronite is equivalent to what they currently put on. In an ideal world we want to get Keronite on multiple Boeing OE drawings across numerous aircraft programmes. This isn't quite where our journey is yet, but I'm confident of getting there.”

Legislation within reach

With environmental legislation changes, such as the EU's REACh directive driving technology changes in traditional industries, there are real opportunities to develop new markets for Keronite, particularly as aerospace OEMs now need to review how they produce certain components.

“The REACh compliance issue is where Keronite will come into its own in the next couple of years. Many of the traditional coating processes contain potentially harmful substances for example, whereas Keronite electrolyte can be flushed down the drain once it is used.

“As the REACh compliance deadline gets closer the option of using Keronite's technology will become more attractive to aerospace businesses. From 2017, suppliers will be forced to register, control or remove restricted substances. We're working with many major OEMs to qualify and test Keronite on their applications in place of some of the traditional coatings containing these restricted substances.”

I'm interested to know what aerospace components the Keronite process is most suitable for. Are we talking about purely bearing components or subassemblies like entire landing gear?

“At present we are only specified on the bearing carrier repair and overhaul. This is the first sweet spot Boeing has identified. Subject to some strict NDAs, we're working more generally with leading aerospace manufacturers to qualify other materials for future aircraft and engine programmes: for example, the investigation of using more light alloys to support the drive for lighter weight and more efficient aircraft. Here, Keronite is an ideal solution for applications requiring corrosion and wear protection as well thermal and electrical management.

“Many airframers and engine makers are aware of Keronite and have an awareness of its ‘clean' merits. One of the biggest challenges to overcome is getting the industry to understand that it can be competitive with traditional processes too,” Hamblin concludes.

“Our biggest challenge is communicating the commercial viability and scalability of our offering, alongside the proven technical benefits. We've demonstrable evidence of high volume production in other markets so we are confident of being able to do the same here in the aerospace sector.”

www.keronite.com