Will Improve Restorations Of Specialized Coatings On Engine Inlets

Robotic technology developed through the Air Force Small Business Innovation Research program will soon make the process of restoring specialized coatings on F-22 Raptor engine inlets more efficient for aircraft maintenance personnel during depot maintenance at the Ogden Air Logistics Complex, located at Hill Air Force Base, Utah.

The initiative has been a team effort, led by engineers from the Air Force Research Laboratory and the Air Force Life Cycle Management Center’s F-22 System Program Office both here at Wright-Patterson AFB and Hill AFB.

Aerobotix, a small business located in Madison, Alabama, was selected as the SBIR Phase II winner for the project. The company specializes in providing turn-key robotic systems for aerospace, military, NASA, and general industrial applications, while providing a range of solutions for robotic and automated coating needs.

The robotics project has three goals: reducing the number of hours aircraft maintainers are required to work in confined spaces while wearing full personal protective equipment, improve consistency and overall quality of the coatings applied, and to reduce the overall hours required to restore the inlets for the lifecycle of the aircraft, said Colin Allen, an AFLCMC F-22 structures and system safety engineer at Hill AFB. As part of the $1.5 million SBIR contract, Aerobotix developed the robotic system, a complex multi-axis system with a long carbon fiber arm to reach deep into the engine inlet ducts.

The AFLCMC F-22 System Program Office at Hill AFB is in charge of managing the F-22 fleet from both an engineering and logistics perspective and is the lead agency for this effort. “We’re at a position within our F-22 fleet where we are restoring the intakes of the fleet here at the Hill AFB depot facility,” Allen said.

Currently, this is a manual process where maintainers have to don a Tyvek suit and respirator as required PPE in order to crawl into the intakes and recoat manually. “It’s not an easy process. It’s kind of an awkward position to be in for a lengthy amount of time where the environment is actually considered a confined space here at Hill, so you need another person watching the person manually restoring the intakes,” Allen said.

The ergonomics issues involved present a less than ideal situation for the depot maintainers to be in all day so one of the goals of the program is to reduce the amount of time that a maintainer is exposed to that environment, Allen added. “The depot F-22 maintainer’s workload is challenging and this project will help speed up that restoration process and ultimately the throughput of the depot. The number of F-22s to go through the restoration process on a yearly basis will be based on mission requirements and depot availability, but the objective remains to get the aircraft back into the warfighter’s hands as quickly as possible,” Allen said.

“The actual removal of coatings from the F-22 inlets remains a manual process where maintainers go inside the intakes and strip the coatings using hand tools,” said Tech. Sgt. Justin Daywalt, the low observable/structures integrated support manager for the F-22 System Program Office at Hill AFB.

The coatings removal process is manual and an automated process has not yet been qualified.

For Phase three of the SBIR process, AFLCMC has partnered with the Small Business Office at Hill AFB to procure Aerobotix robots for three of the bays at Hill AFB. “We’ve gone through a validation verification of several of these booths by using the robots to coat one of our trainer aircraft – a ground-based aircraft that the air battle damage repair group here loaned us for the purposes of our program. It’s actually a representative of a production intake so we can go through the full gamut of things that we need to do for production aircraft as far as bringing the aircraft in, jacking it up, locating it, positioning the robots and actually physically applying the coatings we need to restore the intakes,” said Allen.

The next step is to receive and analyze test results of the robot sprays, followed by depot personnel being trained to use the robots by Aerobotix personnel, Allen said. Based off that, the engineering group will get together and decide when to push forward with a full-production aircraft in the depot for the intake coating restoration operation. “From the engineering perspective, we like what we see. There are some issues we’re working through, but any project has its issues that need to be smoothed out,” he said. “In addition to the ergonomics issues maintainers must face when restoring coatings inside an F-22 intake, another important factor that comes into play are the tolerance requirements of the application process,” Strunk said.

“We will see consistency from jet to jet. With manual application involving different technicians applying the coatings through a spray gun, it’s very hard to (meet the application requirements) the first time. With a robot, we’re expecting to meet those requirements more consistently, reducing the additional time needed to manually work in the inlets. The second part of that are the hazards associated with the materials we’re applying. Once we remove an individual out of the intake, they’re not going to be exposed to those materials to the same degree that we are currently with manual application,” Strunk added.

“If there’s any concern right now that we have on the production side of it, it’s just our schedule. We’ve gotten very good at what we do with this intake coating restoration process over the last three years or so. Now that we’re introducing the robots, we want to still be able to see the schedule maintain at the same rate and get better. However, there’s always that concern of being able to meet that tempo utilizing a new piece of equipment. Ultimately, I think we will see some hiccups, but in the end, it will be all for the better,” he said.

The project has included the use of computing power using modeling and simulation to accomplish the objectives for the depot F-22 maintenance team, said Carl Lombard, a materials research engineer with the Electronics & Sensors Branch, Manufacturing & Industrial Technologies Division, Materials & Manufacturing Directorate at AFRL. “This enables the maintainers to avoid collision with the inlets and the plane while developing the fastest paths to correctly apply the coatings,” he said. “We’re producing fifth generation aircraft maintenance capabilities for fifth-generation fighters,” said Allen.

According to the project team, Aerobotix personnel have utilized their experience with the process to make the transition to F-22 robotic intake coating restoration as smooth as possible for all involved. “One of the reasons Aerobotix was chosen is because they’re certainly an industry leader as far as aircraft robotics goes in their use of robotics for aircraft maintenance on the F-22 and F-35 (Lightning II) programs. They have certainly been more than accommodating, to not only the AFRL and the SPO’s needs, but also the depot’s needs, as far as maintaining their schedule and reevaluating when they need to be in the depot doing work and during the validation process,” said Allen.

The exact amount of time saved by using the robots for F-22 intake coating restoration is not yet known. “There’s definitely going to be areas where we shorten the time span. However, we are going to have to change our processes quite drastically and that may cause some additional time that we are not normally used to. Once we get technicians in there working with it, they’re going to find those ways to make things faster,” Strunk said.

(Images provided with USAF news release and from file)

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