Navy Gearing Up to Prolong Lifespan of Its Preeminent Strike Fighter
In an effort to extend the service life of its aging fleet of F/A-18E-F Super Hornets into the 2040s, the U.S. Navy is preparing to begin a comprehensive modification program that will enable the fighter jets to fly more than 50-percent longer than originally intended.
When it debuted in theater in 2002, the F/A-18E-F’s lifespan of 6,000 flight hours was expected to last about 20 years. But delays to the F-35 Lightning II program and unplanned squadron transitions from the F/A-18A-D Hornet to the F/A-18E-F mean the Navy needs the Super Hornet to last longer than initially planned.
The platform having never known peacetime and racking up flight hours more quickly than anticipated over 15 years of constant combat operations in the Middle East exacerbates the problem. The first Super Hornet to reach 6,000 flight hours is projected to do so in April, just ahead of its 15th birthday in June.
The Navy’s answer to this challenge—extending the life of a platform that is aging faster than expected—is a Service Live Modification (SLM), which will authorize the Super Hornet to fly past 9,000 flight hours while also delivering major modifications and capability upgrades.
The process begins next year with the arrival of four Super Hornets at a Boeing facility in St. Louis. By 2023, Boeing expects to induct about 50 Super Hornets into the program each year—10 in St. Louis, and 40 in San Antonio at a former C-17 hangar currently being retrofitted for the SLM.
At first, the aircraft will take about 18 months to move through—the first six Super Hornets are projected for delivery in fiscal 2020—but as Boeing nails down the process it anticipates cutting down that timeline to 12 months.
The SLM program is the result of lessons learned from the Hornet’s own Service Life Extension Program (SLEP), which is pushing the legacy fleet’s lifespan from 6,000 flight hours beyond 8,000 and, in some cases, up to 10,000 flight hours. Under SLEP, the Hornet aircraft have received high-flight-hour (HFH) inspections and necessary repairs at Navy and commercial maintenance depots. But those repairs have oftentimes had to wait for engineering solutions and for parts to be ordered from and delivered by a commercial manufacturer.
“Under the legacy SLEP, we had to go through multiple parties—when the Navy depot found a failed part, it had to order a replacement from industry and wait for the part to be shipped, and most of those parts have not been produced for decades,” said Scott Dailey, the F/A-18 & EA-18G Program Office deputy program manager for air vehicle systems.
The Super Hornet began its required 10-year Service Life Assessment Program (SLAP) in 2008, midway through its expected 20-year service life. At the time, the plan was for the platform to transition straight into a SLEP, but in an effort to expedite the process, the program office decided in 2016 to give the F/A-18E-F a more-comprehensive SLM, with Boeing—the aircraft’s manufacturer—responsible for the entire process. By having the aircraft, engineering resources, replacement parts and technology modifications all in the same location, the program office is expecting a significant uptick in aircraft throughput.
Under SLM, the Super Hornet will receive capability upgrades meant to counter future threats that they may not have gotten in a SLEP, along with life-extending modification “kits.”
“If it was just extending the life of the aircraft, it would be called SLEP,” Dailey said.
Throughout the SLAP, Boeing engineers have predicted which modifications and upgrades each Super Hornet will need and placed the jets into “bins” based on fatigue life—how stressed the airframe has been by its mission set—and the amount of maintenance it’s expected to require. Thus, each Super Hornet will receive a tailored SLEP kit.
But because the aircraft are aging faster than expected, the process of extending their lifespan is also beginning sooner than planned.
“Ideally, you want the first SLEP kits ready at 6,000 hours, but that was not possible due to the Super Hornets’ high use,” Dailey said. “We have accelerated the program to accommodate as much as possible.”
Full SLEP kits will not be available until fiscal 2023; in the meantime, the Super Hornets that reach 6,000 flight hours will require a Service Life Extension Authorization (SLEA), which permits the aircraft to fly up to 7,500 hours before requiring a full SLEP kit. Super Hornets inducted before fiscal 2023 will get a partial SLEP kit, followed by a full modification post-2023.
The program office also hopes to avoid the “waves” of inspections and retrofits that could sometimes bog down the legacy Hornet’s SLEP. If the program office notices a glut of Super Hornets approaching 6,000 flight hours, it will shift some of them into SLM ahead of schedule in order to maintain a steady flow of aircraft through Boeing’s hangars.
In preparation for the SLM, Boeing engineers recently despliced—or split in half—two retired, high-use Super Hornets to examine their interior structures for anomalies and signs of fatigue—such as cracks that validate SLAP predictions. They will also inspect and analyze material condition of the aircraft, checking for things like corrosion, frayed wiring and damage to hydraulic and fuel tubing. One of the despliced jets retired with the most carrier takeoffs, landings and flight hours in the fleet, while the other accumulated the most total landings.
Boeing is examining the forward fuselage and wings, while Northrup Grumman is looking at the center aft fuselage. As of September, a total of 190 areas on the two aircraft had been accessed with no major negative findings, though minor corrosion was found on one of their dorsal decks.
“SLM is a new approach to extending the life of a platform and its initial success is receiving positive feedback from the acquisition community, and now similar initiatives are following suit,” Dailey said.
Jeff Newman is a staff writer for Naval Aviation News.