Update: This story now includes comments from the F-35 Joint Program Office that were provided after initial publication.

WASHINGTON — The Pentagon’s chief weapons tester fears a crucial test for the F-35 program is in danger of slipping further, perhaps into fiscal 2024.

And even the best-case scenario for carrying out the series of tests in the Joint Simulation Environment means the chances of an F-35 full-rate production decision happening in fiscal 2023 are rapidly dwindling.

The F-35 program hopes to finish a series of complex tests in the Joint Simulation Environment by the end of August, the office of the director of operational test and evaluation said in its latest report, released Friday. Those 64 test trials in the JSE have to happen before the fighter’s initial operational test and evaluation phase can close, allowing the F-35 Joint Program Office to move the fighter into full-rate production.

But the JSE is still not ready, even after years of work. And that late August goal for finishing the trials is considered “at risk” by the DOT&E because more problems and delays with the verification, validation and accreditation process could still be found.

In an email to Defense News after press time, the JPO confirmed it expects to run the tests in August and said it expects to reach the full-rate production milestone by the end of the calendar year.

The August goal already represents a delay from the program’s plans. In March 2022, former F-35 program executive officer Lt. Gen. Eric Fick told reporters the weeks-long JSE testing process was expected in spring or early summer 2023.

After those tests are complete, their results have to be validated to create a report necessary for the full-rate production decision.

Asked in March whether such a short timetable effectively ruled out a decision on full-rate production in fiscal 2023, Fick said it wasn’t impossible — but further test slips would leave “not a lot of leeway.”

Dan Grazier, a military analyst for the Project on Government Oversight who has been critical of the management of the F-35 program, said the new timetable rules out a full-rate production decision by the end of September — and said calendar year 2024 is a more likely scenario. He pointed to a passage in the DOT&E report that said the results of effectiveness testing during IOT&E would be reported within 90 days of the testing’s completion in the JSE to explain why next January or later is more likely.

This will place the decision on full-rate production decision at least four years behind schedule. The Defense Department originally hoped to make that decision in December 2019, but the deadline has repeatedly slipped due to delays in setting up the Joint Simulation Environment testing.

“That’s how complex [F-35 manufacturer Lockheed Martin and the Defense Department] made this thing,” Grazier said. “They spent years trying to develop a simulator to test it, and they still can’t deliver that.”

The report said the F-35 program made “steady progress” in fiscal 2022 to get ready for the JSE’s 64 test trials, and is near the end of the lengthy IOT&E process.

The Joint Simulation Environment, which is being prepared at Naval Air Station Patuxent River in Maryland, will test the fighter on a variety of scenarios, including defensive counter-air, cruise missile defense, and combined offensive counter-air, air interdiction, and destruction of enemy air defense trials, the report said.

The tests will be in-depth and close to the kind of scenarios and latest threats the F-35 would face in combat, the report said, and include all three variants of the fighter.

The team setting up the JSE has been working to find and fix problems with the testing environment, and the DOT&E report said that there were two “must-fix” problems remaining at the end of October. Also in October, the report said, nearly three-quarters of the JSE’s components were likely to pass accreditation, with the team working on finishing the rest.

But as the verification, validation and accreditation process continues, the report said, more problems are likely to be found that need to be fixed before the tests can be run.

“The time required to fix these deficiencies and update the analysis in the final system-level [verification validation and accreditation] documentation will be key indicators of additional schedule pressures,” the report said.

However, the document sounded a note of optimism about the JSE’s ability to provide reliable data on the fighter’s performance.

“Assuming any remaining key deficiencies are addressed and no significant uncorrectable discoveries occur, the JSE will be on track to provide a well-documented, accredited test venue with sufficient threat and system-under-test fidelity to determine F-35 effectiveness against a near-peer adversary in an operationally representative environment,” the report said.

So far, it said, 540 F-35s have been produced for the U.S. military, and Lockheed Martin said it has delivered more than 890 of the fighters worldwide.

Grazier said the F-35 program has continued producing new fighters as if it were already in full-rate production.

But if problems are found in the testing needed before the full-rate production decision, he said, hundreds of already-built and in-use fighters may need to undergo retrofitting.

“The problem is, we’re pushing underdeveloped F-35s onto operational units,” Grazier said. “This is a really horrible precedent for future acquisition programs. Federal acquisition law was written for a reason.”

The report also said availability of the F-35 fleet is below what the military hoped, and that availability rates were flat in 2022 after declining for most of fiscal 2021.

U.S. F-35s of all variants and missions — including training and test aircraft — had average monthly availability rates below the military’s goal of 65%.

Combat-coded aircraft are doing better, however. The report said those fighters, which tend to be the newest and get priority when it comes to spare parts for maintenance, hit the 65% target on average throughout 2022.

In a statement on the report to Defense News, Lockheed Martin said combat-operational F-35As have made progress in improving availability.

“The F-35 is the fighter of choice among the U.S. and its allies, allowing pilots to execute their missions and come home safely,” Lockheed Martin said in a Tuesday email. “The world’s most survivable and connected fighter is an advantage against any adversary, and combat operational F-35A deployments and exercises have demonstrated a combined mission capable rate above 80% during the past 15 months.”

This DOT&E report did not release the number of open deficiencies in the F-35 program in 2022; this figure was also not released in the public version of the 2021 report.

A controlled but unclassified version of the 2021 report, which POGO obtained and posted online, said there were 845 open deficiencies in the program, including six Category 1 deficiencies, which are the most serious.

By March 2022, the JPO said last year, that number had grown to 873 total open deficiencies, including five Category 1B deficiencies, which can keep a mission from being accomplished. The JPO said last year that as of March, there were no open 1A deficiencies, which pose a risk to the pilot’s life or a loss of the aircraft.

The JPO and Lockheed Martin declined to address a Defense News question about how many total open deficiencies there were in 2022.

Lockheed Martin only said that as of Jan. 12, there were no open 1A deficiencies, and five open 1B deficiencies.

Lockheed Martin said it has delivered to the government plans to fix and close two of those open 1B deficiencies in the near term and it is waiting for the government to verify its software works.

The JPO is now conducting a study to figure out if a solution to a third problem is feasible, Lockheed Martin said and the remaining two problems need more funding and requirement updates.

Lockheed said details of the deficiency reports, including their names, cannot be released because it’s controlled unclassified information.

Software problems persist

The report also criticized the F-35 program for its track record on rolling out software needed for its Block 4 upgrades, and for having “not adequately planned” for operational testing of the new upgrades known as Technology Refresh 3.

The DOT&E report called the Block 4 mission systems software the program is sending to units in the field “immature, deficient and insufficiently tested,” and said operational test teams keep finding bugs in the software.

The JPO’s software development process for the Block 4 modernization effort, called Continuous Capability Development and Delivery or C2D2, aims to develop, test and roll out small batches of capability updates or fixes every six months, as opposed to taking several years to develop and deliver a large package of updates.

But this “agile software” concept, patterned after commercial practices, doesn’t adhere to industry’s best practices, such as clearly defined capabilities, focused testing, and full delivery of the specified capabilities, the DOT&E report said. Because the program has not been able to deliver the full set of capabilities, this has led to delays, the report said.

The report said the F-35 program still has “a large number” of cybersecurity discrepancies, and none were resolved in fiscal 2022.

It also said the JPO “has not adequately planned” for TR3, which is expected to start being delivered with the lot 15 fighters scheduled for later this year. The Air Force conducted the first test flight of an F-35 loaded with TR3 on Jan. 6.

And a shortage of fully functional F135 engines used by the fighters — which is most acutely felt in the F-35As flown by the Air Force and worsened by a lack of depot repair capacity — has also hit aircraft availability, the report said.

DOT&E said the military has taken steps to expand depots’ resources and make them more efficient as well as to toughen key engine components so they last longer. But without more steps, the report said, “a lack of propulsion spares will result in some aircraft not having a functional engine through at least 2028.”

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.

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