AIR STATION NAVAL LEMOORE, California — The sound of fighter engines is unavoidable from the air control tower located at the heart of the biggest jet base operated by the U.S. Navy.

It originates from the rows of F/A-18E/F Super Hornets on the flight line, undergoing standard maintenance before taking to the skies, together with a growing number of F-35C Joint Strike Fighters.

It originates from the runway as well, as jets hurtle past at breakneck speed after rehearsing formations over the nearby farms.

Navy chiefs find comfort in the sound, which indicates that the maintainers of the squadrons and the depot artisans at Fleet Readiness Center West are reversing the jets so pilots may resume flying for training and deployment preparations.

However, the Navy and a government oversight body are concerned that the Joint Strike Fighters won’t be available for missions frequently enough as the service’s F-35C fleet grows here in Lemoore. The cost of maintaining the aircraft is much higher than anticipated, which is bad news for the fleet.

Unlike most other military aircraft programs, Lockheed Martin has a significant role in maintaining jet readiness for the Joint Strike Fighter program. The company is in charge of engineering, maintenance training, maintenance planning and management, and supply distribution. The government’s F-35 Joint Program Office, or JPO, is in charge of managing the personnel and infrastructure needed to sustain maintenance for the F-35 aircraft worldwide.

As a result, the services have limited ability to guarantee their own preparedness. However, the Joint Strike Fighter Wing in Lemoore, which is in charge of all Navy F-35Cs, is going above and above by learning from the F/A-18E/F Super Hornets of the service in order to directly increase readiness.

U.S. Navy sailors perform maintenance on an F/A-18F Super Hornet assigned to a squadron from Naval Air Station Lemoore, Calif., during a weapons system evaluation program at Tyndall Air Force Base, Fla.

In 2018, then-Defense Secretary Jim Mattis ordered the military branches to hit an 80% mission-capable rate for all fighters in fiscal 2019. With Super Hornet mission-capable rates barely above 50% for much of 2008 through 2018, the Navy kicked off a data-driven effort to analyze its processes, facilities, supply practices and more, dubbed Naval Sustainment System-Aviation. By the end of FY19, the service surpassed 80% and has sustained that readiness since.

Now, the Joint Strike Fighter Wing is working with its F-18 counterparts to adopt proven practices on operation-level maintenance to boost readiness and lower costs. As part of this effort, the Navy is particularly bolstering its data collection and communication efforts.

Those efforts are yielding results: The Navy’s F-35C community has higher readiness rates and fewer aircraft awaiting supply parts than the rest of the global F-35 fleet’s average, a service leader told Defense News.

That improvement on readiness and cost matters, given the threat of a high-end fight in the Pacific and mushrooming procurement costs.

“From a budget standpoint, it is simple economics: The more it costs to buy and maintain aircraft, the fewer we can procure in a tight fiscal environment and the more onerous it will be to repair them,” Rep. Rob Wittman, R-Va., the vice chairman of the House Armed Services Committee, told Defense News.

“We also cannot go to war, especially against an adversary with advanced [anti-access/area-denial] capabilities, without our most advanced fifth-generation aircraft,” he added.

Slow repair times, lower aircraft readiness

In a September report, the Government Accountability Office detailed the failures in Joint Strike Fighter maintenance and availability of spare parts.

The watchdog’s report noted that in March 2023, 55% of planes were considered mission capable, meaning they were able to fly and conduct at least some warfighting missions. It attributed this low readiness to maintenance challenges at the squadron and depot levels.

The report detailed the unique maintenance setup: Other programs like the Navy’s Super Hornets are repaired through operational-level maintenance by squadrons, intermediate-level work by the Navy’s fleet readiness centers located at the jet bases, and depot-level work at select fleet readiness centers.

But the F-35 program does not include any intermediate-level maintenance; instead squadrons must undertake more work on the flight line with help from contractors, while farming out more work to industry at depot locations and at the original builder’s facilities.

This rate is the percentage of time during which aircraft in the possession of F-35 units are unable to conduct any of their assigned missions because of maintenance.

In the case of the Super Hornet, the Navy controls all three levels of maintenance and signs its own contracts for support and parts. In contrast, the F-35 program gives significant responsibility to manufacturer Lockheed Martin and to the Joint Program Office, leaving the services with little ability to change or improve the supply system and contractor-led maintenance.

At the operational level, the GAO report noted, squadrons lack some technical data and training experience needed to efficiently conduct maintenance — a challenge that will only grow if the JPO decides to shift more work from industry to the services by adding intermediate-level maintenance to the plan.

At the depots, it noted the JPO is now 12 years behind schedule in standing up some of its repair capabilities, or “workloads.” As of last spring, 44 of 68 workloads were activated.

“Delays in standing up the F-35 program’s depot repair capacity has had several effects, including slow repair times, a growing backlog of components needing repair, and lower aircraft readiness,” the report found.

GAO projects the total fleet’s mission-capable rate could have been at 65% instead of 55% last spring if not for the lack of depot repair capacity.

The lack of depot capacity is also increasing the cost.

With the depots now facing a backlog of 10,000 components to repair, “the F-35 Joint Program Office has purchased new parts instead of repairing the parts it already has in inventory. According to [Department of Defense] officials, this is a practice that program officials do not believe is a sustainable solution.”

Those officials said the approach keeps the aircraft flying, but it results in “higher sustainment costs because buying new parts generally costs more than repairing existing parts.”