A new study by the Government Accountability Office (GAO) cites depot and organizational maintenance challenges as being partly responsible for a lagging mission capable (MC) rate for the Lockheed Martin [LMT] F-35 fighter.

“The F-35 fleet mission capable rate—the percentage of time the aircraft can perform one of its tasked missions—was about 55 percent in March 2023, far below program goals,” said the GAO study, F-35 Aircraft: DOD and the Military Services Need to Reassess the Future Sustainment Strategy (GAO-23-105341).

“This performance was due in part to challenges with depot and organizational maintenance,” the report said. “The program was behind schedule in establishing depot maintenance activities to conduct repairs. As a result, component repair times remained slow with over 10,000 waiting to be repaired—above desired levels. At the same time, organizational-level maintenance has been affected by a number of issues, including a lack of technical data and training.”

More than two decades ago, the Pentagon Joint Requirements Oversight Council approved key performance parameters (KPPs) for the Joint Strike Fighter (JSF) that set the availability rate at more than 90 percent, a rate that would make the operations of the entire F-35 fleet, not just front-line squadrons, as routine as that of commuter cars (Defense Daily, Apr. 17).

Availability rates are calculated by dividing the number of hours that aircraft are both mission capable and in the possession of operational squadrons by the total number of aircraft hours for the entire fleet, including aircraft undergoing depot-level maintenance. F-35 availability rates have been more than 30 percentage points below the KPPs.

On the MC rate side, the goals are now 70 percent for the U.S. Air Force F-35A and 75 percent for the U.S. Marine Corps F-35B and U.S. Navy F-35C. The MC rate is the percentage of time that a squadron aircraft can fly and perform at least one mission.

The current F-35 fleetwide MC rate is 56 percent, a one percentage point increase from the March rate cited in the new GAO report. Lockheed Martin officials have said that deployed F-35As, Bs, and Cs have seen MC rates between 80 and 90 percent, and the F-35 program has said that the deployed F-35 MC rate is significantly higher than the average MC rate for the more than 450 F-35s in the U.S. fleet.

To improve F-35 availability and reduce costs, DoD is considering awarding Lockheed Martin a five-year Performance-Based Logistics contract for the F-35 this year, if the program is able to meet conditions set out in the fiscal 2022 National Defense Authorization Act (Defense Daily, Feb. 17).

The new GAO report said that the agency had visited three F-35 installations–Hill AFB, Utah; Marine Corps Air Station Yuma, Ariz.; and Naval Air Station Lemoore, Calif.

“Maintainers at all three installations we visited told us that support equipment was breaking too frequently and, due to the proprietary nature of most of the equipment, they were not able to repair it themselves,” the study said. “As a result, contractor representatives either have to come to the installation to repair the equipment, or the equipment is sent back to the original equipment manufacturer.”

“Like components, support equipment can take original equipment manufacturers months to repair,” the report said. “Maintainers we spoke to at one installation said that they have the capability to repair a lot of the broken support equipment at their installation; however, they are not able to do so. They stated that their inability to repair the equipment is having a negative effect on readiness; however, they could not provide the degree.”

Air Force Lt. Gen. Michael Schmidt, the head of the F-35 JPO, said in a Sept. 21 statement that the JPO  “will work with, and be part of, the Sustainment Implementation Working Group (SUSWG) to drive improvements in sustainment across the F-35 enterprise.”

“We are pursuing a more resilient sustainment structure,” he said. “We must grow our sustainment capacity and efficiency around the world.  To do so, we must stand up our global repair, transportation, and warehousing network at a faster pace, incentivize industry behavior toward desired availability and affordability outcomes, and remain laser focused on increasing all aspects of Mission Capable rates for fielded aircraft.”

The DoD SUSWG is to guide transferring acquisition and sustainment responsibilities for the F-35 from the F-35 JPO to the military services in the coming years.