WASHINGTON — The F-35 joint strike fighter is still struggling to meet its mission capable rate goals, with current figures well below the military’s target, the Pentagon’s outgoing acquisition chief told reporters on Jan. 19.

The Lockheed Martin-made F-35′s mission capable rate — which describes the percentage of aircraft that can meet at least one of its assigned missions — currently sits at 69 percent, falling short of the military’s longstanding 80 percent goal, said Ellen Lord, whose time as the undersecretary for acquisition and sustainment ended Jan. 20 at noon after Joe Biden was inaugurated as president.

When looking at fully mission capable aircraft able to perform all of the F-35′s assigned missions, “we’re currently at 36 percent fully mission capable, and we are striving to be at 50 percent for the fleet,” she added.

Lord attributed the low percentage of fully mission capable jets to ongoing issues with the F-35′s canopy and the F135 engine’s power module.

Although she did not elaborate, the program has grappled with a longstanding problem with “transparency delamination,” where outer layers of the canopy begin to peel away from the base. In 2019, an F-35 joint program office spokesman told Defense News that the department was working with canopy supplier GKN Aerospace to improve the design and increase the supply of canopy transparencies.

Although the F-35′s mission capable rate has improved in recent years, the latest figures presented by Lord show that progress be stagnating.

In testimony to the House Oversight and Reform Committee in July, Lord noted that the mission capable rate for the F-35 increased from about 60 percent in January 2020 to nearly 70 percent in June of that year. Full mission capable rates improved from below 40 percent to nearly 50 percent over the same time period, she wrote.

A similar jump had been documented in Lord’s testimony to the House Armed Services Committee in November 2019, where she wrote that mission capable rates for combat-coded squadrons had increased from 55 percent in October 2018 to 73 percent in September 2019.

It’s not always easy to chart the trajectory of whether the F-35′s readiness is improving due to a host of factors.

Although Pentagon officials like Lord have, at times, provided updates about the jet’s mission capable rates, it is often unclear whether the numbers cited reflect a single point in time — an especially good month where more F-35s are ready to fly, for example — or a sustained trend. Officials also sometimes talk specifically about “operational” or “combat-coded” squadrons, which leaves out a lot of the early model F-35s used by training and test squadrons, which are more prone to breaking down and needing repairs.

Other times, the department has made mission capable rate data inaccessible to the public. In a November report on aircraft readiness, the Government Accountability Office reported that mission capable rates of all three F-35 variants had been moving upwards since fiscal 2018, but did not provide specific figures because the Defense Department designated such information as sensitive.

Between fiscal years 2012 through 2019, the F-35A was able to meet mission capable rate goals in two years, the GAO reported. The F-35B hit its objective in only one year from fiscal 2013 to 2019, and the F-35C met its target two years over the same period.

The GAO noted that spare parts shortages had contributed to the F-35 not being able to meet readiness objectives.

“Specifically, the F-35 supply chain does not have enough spare parts available to keep aircraft flying enough of the time necessary to meet warfighter requirements,” the GAO stated. “Several factors contributed to these parts shortages, including F-35 parts breaking more often than expected, and DOD’s limited capability to repair parts when they break.”

Valerie Insinna is Defense News' air warfare reporter. She previously worked the Navy/congressional beats for Defense Daily, which followed almost three years as a staff writer for National Defense Magazine. Prior to that, she worked as an editorial assistant for the Tokyo Shimbun’s Washington bureau.

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