WASHINGTON — Lagging availability rates, flareups of new software problems, and a stubborn number of open deficiencies plagued the troubled and repeatedly delayed F-35 fighter in 2021, according to a newly-revealed version of the Pentagon’s weapons tester’s report.

For the first time, the Office of the Director, Operational Test and Evaluation in January only released to the public an “uncontrolled” version of its annual report. Details about shortfalls in key programs were relegated to a “controlled” — but still unclassified — edition kept from the public.

The watchdog group Project on Government Oversight obtained, and last week posted online, the controlled report, which fleshes out some of the problems hinted at in the publicly released version.

Dan Grazier, a military analyst for POGO and a vocal critic of the F-35 program, said in a March 11 interview the Pentagon’s secrecy on this report is troubling and undermines the effectiveness of its testing office.

“The Pentagon did go to really extraordinary lengths to try to hide these details,” Grazier said. “That’s not the way this is supposed to work.”

And in a March 9 post on POGO’s blog, Grazier said the report reveals “stagnation and even backsliding” in some areas used to measure the fleet’s reliability.

Lt. Gen. Eric Fick, program executive officer for the F-35 Joint Program Office, said in a March 8 roundtable with reporters, before POGO posted the full report, that 2021 was “a pretty good year for the program, despite all of the chaos that seemed to surround it.”

He pointed to the 142 F-35s the program delivered in 2021, beating the goal of 139 fighters, as an example of progress — but acknowledged issues remained with engine production and the ability to perform critical simulation tests necessary for a decision on full-rate production.

Some of the F-35′s biggest remaining problems highlighted by the full DOT&E report were:

  • The F-35′s availability is still lagging, and a lack of spare parts and fully-functional engines has hurt it.

The F-35 saw a “program high peak” in aircraft availability in January 2021, the controlled version of the report said, when it hit 70%. But during the year, the report said, availability rates “plateaued,” and in June started to slide before hitting a low of 53% in September. Throughout fiscal 2021, the entire F-35 fleet averaged 61% availability, below its target of 65%. The F-35 has consistently stayed above 50% availability since December 2018.

Of the average 39% unavailable at any given time, 15% were down for maintenance, 16% were waiting on spare parts and another 8% were undergoing depot maintenance.

The report said the progress the F-35 made before June was due to two factors: an influx of new aircraft that didn’t require time in the depots, and a program effort focusing on increasing the availability of spare parts.

That spare parts increase didn’t last, however, and the report said the post-June decline was largely because spare parts weren’t available when they needed. In a newly-revealed passage, the DOT&E report said 15% of the F-35 fleet was sidelined due to a lack of spare parts in May 2021. By December, a full quarter of the fleet was down for that reason.

Grazier wrote on POGO’s site this has very troubling implications for the military’s ability to consistently keep the F-35 ready to fly.

“What that means is the F-35 did not suddenly become a more reliable aircraft in 2021,” Grazier wrote. “It means that it takes extraordinary effort to keep the fleet operating even close to the required levels and suggests that those availability rates are not sustainable long-term.”

Fick acknowledged the drop in F-35 mission capable rates March 9 at the McAleese Defense Programs Conference in Washington March 9, but pledged to address the root causes of the problems that led to that readiness decline, including a shortage of F135 power modules.

Fick also said at the event the F-35 program is taking several actions to improve the health of the fleet, including keeping parts on the aircraft longer, ensuring enough spare parts are on hand when those parts fail, and bolstering repair capacity for a growing fleet.

“No program is perfect, and a program as complex as the F-35 will always have challenges,” Fick said. “But none of these challenges are insurmountable.”

The JPO declined to comment on information from the controlled version of the report.

But that non-public version went into further detail on the shortage of fully functional F135 engines, worsened by a lack of depot repair capacity, that further drove down availability rates. This was particularly felt by the F-35A, the report said.

One week in June, there were 38 F-35s down awaiting a working engine. By the last full week of the fiscal year, there were 52 F-35s waiting for an engine.

The services try to manage the shortage of engines by giving combat-coded units the priority to get spares over test and training units, the report said — but the shortage has nevertheless hit deployed units as well. The U.S. military’s 214 combat-coded F-35s averaged 70% availability throughout 2021, but that number dipped as low as 63% at one point.

After highlighting the progress made in aircraft production in the March 8 briefing, Fick acknowledged the propulsion side was “not quite as great of a story.” The program hoped to deliver 159 engines last year, but only produced 152, all but four of which were late.

Fick said none of the late engines led to late delivery of a production aircraft, but the program is working with Pratt & Whitney to get its engine deliveries back on schedule. Fick said the COVID pandemic — particularly higher rates of absenteeism — had a big effect on the program’s ability to deliver engines on time.

  • Its software programs aren’t being tested properly for hidden bugs — and, in at least one case, a system that was working fine got broken when a new capability was added elsewhere.

The F-35 program’s developmental test teams haven’t been funded enough to do the right tests, data analysis or regression tests on new software before it’s delivered, the report said.

In a passage omitted from the public version, the report said capabilities for the AIM-120 Advanced Medium-Range Air-to-Air Missile, or AMRAAM, that had been working on an earlier version of software broke when the development team tried to add capabilities for another weapon.

The F-35′s approach to software development in the Block 4 modernization effort, called Continuous Capability Development and Delivery, or C2D2, aims to develop, test and roll out software updates containing small batches of new capabilities or fixes to deficiencies every six months, instead of taking years to develop and deliver all the necessary capabilities at once.

But this approach has “proven unsustainable,” the report said, and the F-35 Joint Program Office extended that timeline of updates from every six months to once a year.

This process of incremental updates “often introduced stability problems,” or led to problems with other capabilities, the report said. This meant operational test units and field units in many cases were the ones to find the problems — sometimes significant operational deficiencies — with the software updates. Last year, operational test teams found problems with the F-35′s weapons, fusion communications and navigation, cybersecurity and targeting processes.

Grazier said this demonstrates the problem with fielding an aircraft whose design isn’t complete.

“If you’re going to have a software-driven design, you better make sure that original software is the 95% solution,” Grazier said. “Even with simple programs, when you start making changes in software in one place, you are very likely creating problems someplace else that were unanticipated. So you better make sure that your original version is pretty close to what you need — particularly before you start building hundreds and hundreds of them.”

Fick said that due to a holdup of funding in fiscal 2021, the program had to temporarily suspend most of the program’s Block 4 development, except for critical elements such as electronic warfare configurations. The arrival of funds in 2022 allowed the program to resume “the lion’s share” of Block 4 development, Fick said.

JPO spokeswoman Laura Seal said in a March 16 email the office “has delivered numerous new capabilities and sustainment improvements utilizing the C2D2 agile construct.”

“The JPO has taken feedback from our testers and customers and used it to improve the way we deliver software,” Seal said. “To this end, the F-35 enterprise has made significant progress in transforming into an agile delivery enterprise. Ultimately, the F-35 program delivers software on a warfighter-relevant timeline and our warfighters decide to take the software based on their review of the benefits of incorporating this software into their fleets.

  • The number of deficiencies has barely budged, because new problems keep popping up.

Last year, the DOT&E report tallied the number of open F-35 deficiencies at 871, 10 of which were Category 1 deficiencies, the most serious.

That improved in fiscal 2021 — but not by much. The F-35 had 845 open deficiencies, including six Category 1 deficiencies, at the end of the fiscal year. That number was not shared with the public until POGO released the controlled version of the report.

The report said F-35 program is working on addressing problems that have been identified during the system development and demonstration process. But the number of deficiencies isn’t shrinking significantly because new problems continue to be found.

By March 1, according to the latest figures from the JPO, that number had grown again to 873 total open deficiencies. That includes five Category 1B deficiencies, which can seriously affect mission readiness and keep a mission from being accomplished, although there are no open 1A deficiencies that pose a risk to the pilot’s life or a loss of the aircraft.

Seal said most of the new deficiency reports stem from issues that emerged in new capabilities added to the F-35. The JPO closed 171 deficiency reports in 2021, she said.

“Warfighters have assessed that acceptable mitigations exist for the remaining deficiencies,” Seal said. “Deficiency resolution is an ongoing effort, and deficiencies are resolved in concert with warfighters’ prioritization and resource allocation.”

She also said the potential effects of open deficiencies on missions or operations are documented in pilot manuals and training materials.

But Grazier said that the continual discovery of new problems means 2021′s decline to 845 open deficiencies shouldn’t be seen as a sign of success.

“It sounds like they’re making improvements, but really it’s one step forward and two-thirds of a step back,” Grazier said.

Stephen Losey is the air warfare reporter at Defense News. He previously reported for Military.com, covering the Pentagon, special operations and air warfare. Before that, he covered U.S. Air Force leadership, personnel and operations for Air Force Times.

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