Following years of rigorous testing and evaluation, a cold spray metallization technology that was initially demonstrated at Fleet Readiness Center East (FRCE) is now being fielded on the H-1 line at the depot’s detachment on board Marine Corps Air Station New River.

The new system will aid in reducing aircraft maintenance turnaround times and decreasing costs, said Jessica Templeton, the Air Vehicle and Materials Engineering lead with the Naval Air Systems Command Fleet Support Team’s Advanced Technology and Innovation Team at FRCE.

“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,

“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.”

The U.S. Air Force recently selected Fleet Readiness Center East (FRCE) as the stateside depot source of repair (DSOR) for the HH-60W Jolly Green II, the air service’s new combat rescue platform. FRCE will conduct all helicopter airframe programmed depot maintenance for Jolly Green II aircraft located within the continental United States, which represents about 70% of the platform’s total expected workload.

“I’m honored the Air Force has selected FRC East to support a core platform that performs critical search and rescue operations,” said FRCE Commanding Officer Capt. James M. Belmont. “Since the depot began operations in 1943, we have been a vital asset to national defense, and new workload like the Jolly Green II will allow us to continue to support our warfighters well into the future.

“It’s exciting to see the future of FRC East come into focus as we add capabilities that will enable us to support military aviation readiness for years to come,” Belmont continued. “FRC East is a pillar of the eastern North Carolina community and economy, and the success our team has seen in securing new workload on emerging platforms only helps cement our reputation as the premier vertical-lift depot within the Department of Defense.”

Matt McCann, director of the Business Development Division within FRCE’s Central Coordination Department, said the first Jolly Green II is scheduled to arrive at FRCE for maintenance in fiscal year 2027. Once programmed maintenance operations for the aircraft have ramped up to full capacity, the projected workload represents at least 210,000 direct labor hours annually – the equivalent of more than 100 full-time positions. Adding that number of jobs to the depot’s workforce would have a substantial impact on the local economy, McCann said.  

“The HH-60W represents new workload above and beyond what FRC East currently maintains, rather than being a replacement for existing aircraft workload that is scheduled to sun down in the future,” McCann said. “There is a wide range of possibilities on what the final direct labor hours will look like annually, but this additional workload stands to bring a significant financial benefit to the area.”

The dual-piloted, multi-engine vertical takeoff and landing aircraft is the Air Force’s replacement for the HH-60G Pave Hawk, and is used to perform critical combat search and rescue and personnel recovery operations, said Del Bennett, capability establishment lead within the Capability Management Branch of FRCE’s Central Coordination Department.

The Jolly Green combat rescue platform has a long and storied history, running from 1967-2008. From the Vietnam War though the Global War on Terror, the aircraft was deployed in high-stakes scenarios to rescue individuals in dangerous or remote areas that weren’t accessible by ground transportation. The HH-3E Jolly Green Giant and HH-53 Super Jolly Green Giant – and later the HH-60G Pave Hawk – were used to rescue downed Airmen and other service members in hostile or denied territory, day or night, in adverse weather conditions, with threats ranging from terrorist to chemical, biological, radiological or nuclear. The aircraft were called upon to conduct humanitarian missions, civil search and rescue, and medical evacuations. The Jolly Greens and Pave Hawk were welcome sights to those awaiting their arrival, and the Jolly Green II will fulfill these functions with improved communication, navigation and defense systems, along with an upgrade in weapon systems. 

FRCE’s work on the platform will include disassembly, inspection, repair, assembly, ground check and flight testing, Bennett said. Commercial repair operations will provide the same services for HH-60W aircraft located outside the continental United States.

In order to get FRCE and its workforce ready to support the new platform, a Depot Maintenance Activation Working Group will begin operation soon. The working group will focus on ensuring the capabilities needed to support the platform are in place, and artisans are trained and qualified to perform required tasks prior to the first Jolly Green II’s arrival, Bennett said.

“We have started laying the groundwork to be able to support the platform with regard to infrastructure, logistics and maintenance,” he said. “There’s a lot of effort that goes into making sure FRC East can hit the ground running when it’s time to induct that first airframe. It’s important that everything is in place so we can turn these aircraft around and get them back on mission as quickly and efficiently as possible, while still ensuring the best possible quality product for the warfighter.”

FRCE’s commitment to quality played a large part in the depot securing the new HH-60W workload, Bennett added.

“FRC East has a proven track record of providing service to the Air Force with the UH-1N platform, and they’ve been very happy with the performance of our production line,” he said. “They know we’re reliable. They know we produce a quality product. They know we can deliver on time. They know we’re constantly in pursuit of process improvements to ensure the quality of the product stays high while we strive to reduce cycle time.

“Securing a DSOR designation is a very competitive process, and they take into account a lot of factors. It’s not just a matter of drawing a name out of a hat,” Bennett continued. “The work FRC East has done on the UH-1N has made the depot a name the Air Force can depend on, and it’s a real testament to the skill and dedication of the FRC East workforce that they have placed their trust in us.”

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. 

Fleet Readiness Center East (FRCE) recently secured designation as the Depot Source of Repair (DSOR) for 81 major structural and dynamic components of the U.S. Air Force MH-139A Grey Wolf helicopter, the planned replacement for the UH-1N Huey. FRCE performs maintenance, repair and overhaul of the legacy UH-1N platform at its North Carolina Global TransPark detachment in Kinston. Current projections place the start date for the new work in fiscal year 2028.

“I’m proud that our counterparts at the Air Force have recognized the caliber of service FRC East provides, and have chosen to expand our relationship by selecting our depot to support the MH-139A through sustainment of many of the platform’s components,” said FRCE Commanding Officer Capt. James M. Belmont. “Our workforce has long maintained a stellar reputation for producing the best quality products for our nation’s military aviators, and securing workload on emerging platforms like the Grey Wolf will allow us to continue that tradition for many years to come.

“Our selection as the DSOR for these components is a direct reflection of the ability and commitment of the FRCE workforce,” Belmont continued. “Our people continue to be our greatest asset as we shape the future of the depot.”

The planned workload includes major components like gearboxes, rotor blades, hubs, actuators and engines, said Del Bennett, capability establishment lead within the Capability Management Branch of FRCE’s Central Coordination Department. The Air Force plans to use the dual-piloted, multi-mission aircraft to support security for intercontinental ballistic missile sites, and transport U.S. government and visiting officials and security forces, he explained.

The Air Force has not yet fielded the Grey Wolf platform, which is currently in the engineering and manufacturing development phase of the defense acquisition process and is undergoing military unit testing. Bennett said current data does not provide final projections on the effort required to sustain the platform; however, depot officials are planning for a substantial workload.

“This DSOR provides FRC East with the lion’s share of the major structural and dynamic component workload,” he explained. “Because the platform is new, we don’t yet have projections on the final number of labor hours the component work will involve, but we know that it will be significant.”

Depot Activation Maintenance Working Groups will begin operations this summer in order to ensure the FRCE’s facilities and workforce are prepared when the first Grey Wolf components arrive. Bennett said the lengthy process guarantees that all logistical elements are in place to support sustainment of the new workload, including technical data from the manufacturer; required facilities and infrastructure; necessary support and test equipment; supply support; and artisan training on maintenance, repair and overhaul processes.

With the maintenance work that FRCE’s UH-1N line does at the Global TransPark detachment, pursuing the workload related to the legacy aircraft’s replacement was a natural fit, Bennett said. The depot’s long history of providing quality products for military aviators helped secure the nod.

“The Air Force Program Office selected FRC East based on our substantial knowledge and experience in the maintenance, repair and overhaul of helicopter, tilt-rotor and fixed wing airframes and components, including engines, drive shafts, rotor heads, fuel pumps and electronics,” Bennett said. “We are the Department of Defense Vertical Lift Center of Excellence, and that shows in the breadth and depth of understanding our artisans, engineers, logisticians and support staff have of military aircraft.

“The selection process is pretty competitive when you’re considering these major aircraft platforms for all their workload, and the Air Force has been very happy with the service that we have provided on the UH-1N platform,” he continued. “Their support of FRC East and the work we’ve done on those aircraft is now flowing down through other programs, and it gives us a competitive edge.”

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. 

Since Fleet Readiness Center Southeast (FRCSE) inducted its first F-5N Tiger II, the depot has forged forward despite the challenges associated with standing up a new product line. 

The F-5s were initially purchased in the 1970s by the Air Force and then sold through foreign military sales to Switzerland. In 2002, the Department of Defense decided to repatriate many of these aircraft back to the Navy. The F-5 is a twin-engine tactical fighter aircraft that provides air-to-air combat training for Navy and Marine Corps pilots. Its reliability and low operating costs result in savings to the Navy each year in maintenance and unnecessary wear on current strike fighter aircraft like the F/A-18 Super Hornet and F-35 Lightning II without sacrificing essential pilot training in a formidable aircraft.

In 2019, the depot-level maintenance and repair of the F-5 airframe transitioned from the original equipment manufacturer to organic support, and FRCSE was designated as the U.S. Navy depot source of repair. Currently, FRCSE performs Phased Depot Maintenance (PDM). This process includes replacing certain high time structural and system components and thoroughly inspecting the aircraft in known corrosion and metal fatigue areas. Artisans use various means, including non-destructive inspection (NDI) methods to look for corrosion and/or cracks caused by wear and stress fatigue.

“The maintenance we conduct at the depot extends the service life of the aircraft, as each phase of the PDM addresses time-limited component inspections and replacements at certain flight hours,” said Cris Baldwin, FRCSE’s F-5 Production Line Director.

Planned structural component replacements include the upper cockpit longeron (UCL) and the vertical stabilizer (V-stab). The UCLs, approximately six-foot beams that run down either side of the cockpit, are the main structural components of the airframe and provide fundamental rigidity to the aircraft around the cockpit. The V-stab, another critical component, is the static part of the vertical tail that stabilizes and balances the aircraft in yaw. These load-bearing sections of the aircraft are replaced at regular intervals, but before recent process innovations, the work was not able to be done concurrently.

“One of the innovative time reduction efforts was the idea to perform the UCL and V stab work concurrently,” said Lt. Cmdr. Ryan McNulty, FRCSE’s F-5 Production Line Military Director. “Originally, these were done separately because each is a critical structural element. With one or the other removed, there is a risk that the airframe could be permanently damaged due to twisting. Fortunately, we have an in-house engineering support team and a dynamic manufacturing division that provided sound, innovative thinking in an effort to conduct these efforts concurrently.”

Concurrent work would significantly reduce the time needed to return the aircraft back to adversary operations, but the team faced risks associated with the stability of the aircraft. To conduct the UCL and V stab repairs simultaneously, the airframe had to be adequately supported.  FRCSE’s engineering and manufacturing teams designed robust shoring to sit beneath the aircraft and prevent twisting, which illustrates the level of ongoing innovation at the depot.

“The F-5 engineering team devised and performed a test to determine if and how much the airframe would flex when the UCL and V stab work was performed at the same time,” McNulty said. “The results proved that by using the shoring, the two repairs could be performed together.”

While the concurrent work for UCLs and V stabs are the most beneficial of the F-5 production line efforts to reduce the time the aircraft is at the depot, they are far from the only ones. There have been more than 45 innovative solutions proposed to help turn aircraft around faster. More than half of those solutions came from artisans on the production floor, and include V stab work stands, flight control rigging tool test kits, and a mobile, hand-held, E-drill® system to remove hard metal fasteners more than 20 times faster than twist drills. These technological advancements should provide increased productivity as the team continues to get more adept.

“The F-5 team is an amazing group of professionals with many challenges to overcome to meet the Fleet’s demand,” said Baldwin. “Over the last year, I have seen incredible improvements, and I know this line will soon become the best-performing product line at FRCSE. I’m proud of their performance and continued dedication to the warfighter.”