“With this mobile, autonomous cold spray system, we’ll be bringing repair capabilities closer to the aircraft,” she explained. “We will be able to make repairs in the shadow of the aircraft that were previously not possible using existing, approved cold spray systems. And there’s flexibility in that the system can be programmed to run autonomously, or be used in-hand by qualified artisans.
“The system will save time, because the artisans won’t have to fully disassemble the aircraft in order to complete these specific, approved repairs,” Templeton continued. “We’ll save on time and costs associated with transporting certain parts and components from one location to another. And we’ll further save on costs by returning to use some components that would have been scrapped before, but can now be salvaged through the cold spray process. There are so many benefits to having this system approved for use.”
The cold spray process bonds metal to metal in a relatively low-heat environment in order to deposit a coating onto a surface, or substrate. Solid metal powders are accelerated through a heated gas and directed toward a metallic substrate; the moving particles impact the surface and embed on the substrate, forming a strong bond. In aviation applications, cold spray is used to repair aircraft components like shafts, gearboxes and skid tubes by depositing a durable metallic alloy coating to surfaces. This coating can fill abrasions or gouges in some cases, or provide protective coverage in others.
Most cold spray systems currently used by the Navy are located in booths, which creates size limitations, Templeton said. There are finite limits to the size of the components that can be treated in the booths, which means that parts often have to be removed from aircraft before spraying, or the components cannot be sprayed at all due to their size. The mobile nature of this system mitigates those size constraints and also lends itself to the possibility of on-aircraft repairs in locations that don’t have permanent cold spray booths.
Templeton and her team have been working for years with the Naval Aviation Enterprise Cold Spray Integrated Products Team to make the vision of a mobile, autonomous cold spray system a reality for aircraft maintainers at the depot level. In late 2019, FRCE hosted the first U.S. field demonstration of an on-aircraft structural repair using a mobile, autonomous cold spray metallization system funded under the Office of the Secretary of Defense Foreign Comparative Test Program. Over the course of the two-day trials, the team demonstrated an on-aircraft repair to the windowsill of a V-22 Osprey, and also conducted an off-aircraft repair to a surplus H-1 skid tube.
The H-1 program was the first within NAVAIR to adopt the new system, Templeton said, and has approved it to make specific repairs to the helicopter’s combining gearbox and skid tube. It’s gratifying to see the team’s work come to fruition, she added.
“It takes a lot of time, a lot of effort and a lot of supporters within NAVAIR; however, it is all worth it when we implement a technology that will ultimately benefit our warfighters,” Templeton said.
Tim McCardle, a support equipment logistics management specialist with NAVAIR’s Marine Corps Light/Attack Helicopters Program Office (PMA-276), said officials anticipate the system will have a positive impact on readiness by helping ensure components reach their full service life, rather than being scrapped early due to wear, as is the case with the H-1 combining gearbox. The system has also been fielded at the Fleet Readiness Center Southwest field site at Marine Corps Base Camp Pendleton, California.
“Gearboxes have an expected service life based on flight hours, and when they come up with wear or chafing to the outer case, they’re pulled out of service long before they were ever meant to be. There’s a tremendous cost to that, both fiscally and in terms of component availability,” he said. “What this system does is allow artisans to make repairs to many of those outer cases, so those gearboxes can be put back into service and used for their planned life.”
McCardle agreed the unit’s mobile nature will also boost readiness by reducing aircraft movement, thereby reducing downtime during the maintenance process.
“The cold spray system being previously used to make these repairs is not mobile,” he said. “With this version, you can take the tools to the aircraft rather than having to wait to bring the aircraft to the tools. You save a lot of motion that way by not having to move an entire aircraft.”
Kevin Conner, H-1 Drives and Diagnostics manager for NAVAIR’s H-1 Fleet Support Team at FRCE, said using a mobile system allows for more flexibility in processes that were formerly confined to depot industrial spaces, which will help improve the H-1 program’s responsiveness to needs of the Fleet.
“The new system will help cut the time the assets are out of service for repairs, and greatly improve the range of repairs that can be completed,” Conner said. “This capability affords the opportunity to execute in-service repairs in place of transferring the entire aircraft out of the squadron and into the depot, which reduces the aircraft’s time out of service and increases mission readiness.”
While the H-1 program is an early adopter of this system, there are potential use cases for the technology that exist for other aircraft platforms throughout the naval aviation community, Templeton noted. For example, the system has been tested as a possible solution for repairing a fitting on a V-22 Osprey that currently requires major disassembly of the aircraft to address.
The properties of the cold spray process make it especially adaptable to a wide variety of uses, Conner noted.
“Cold spray technology is shifting the scope of repair to address metal repair and restoration with a solution that surpasses existing adhesive-based repairs, weld repairs and mechanical fastening repairs,” he explained. “Cold sprayed material mechanically and metallurgically bonds to the substrate, effectively becoming part of the damaged material. Cold spray is superior to welding in that it does not dramatically degrade the material process with a large heat-affected zone, and material properties are maintained without requiring a follow-on process like annealing or heat treating. This opens up future capabilities for all types of applications that are yet to be imagined.”
FRCE is North Carolina's largest maintenance, repair, overhaul and technical services provider, with more than 4,000 civilian, military and contract workers. Its annual revenue exceeds $1 billion. The depot provides service to the fleet while functioning as an integral part of the greater U.S. Navy; Naval Air Systems Command; and Commander, Fleet Readiness Centers.