WASHINGTON — For months, newly built F-35 Joint Strike Fighters have languished at Lockheed Martin’s facility in Fort Worth, Texas, awaiting the completion of a key upgrade that has stalled deliveries.
In 2024, the Pentagon and Lockheed hope that overdue modernization dubbed Technology Refresh 3, or TR-3, will be finished, allowing the government to accept these latest F-35s.
The jet’s TR-3 improvements include better displays, computer memory and processing power. They will lay the foundation for a more extensive upgrade, called Block 4, that will bring greater weapons capacity as well as improved electronic warfare and target recognition capabilities.
But persistent software troubles, including problems integrating it into the new TR-3 hardware, has stalled its completion. Originally, TR-3 upgrades were supposed to be ready in April 2023, but that deadline has repeatedly slipped and is now expected sometime between April and June 2024.
New F-35s equipped with TR-3 hardware started rolling off Lockheed’s production line in late July, but the government refused to accept their deliveries since they could not fly during the necessary acceptance flights. Since then, Lockheed Martin has stored an undisclosed number of F-35s at Fort Worth.
The Pentagon’s F-35 Joint Program Office in November said it is looking for a way to resume acceptance flights for the new fighters and deliveries before TR-3 is completely finished. That could involve a strategy of loading early, but incomplete, versions of the TR-3 software into new F-35s. The interim software would probably need upgrades down the road to get the rest of its capabilities, the Joint Program Office said.
In mid-November, a handful of production F-35s with interim TR-3 software flew for the first time at Fort Worth, Lockheed confirmed.
Top Air Force officials said at the Defense News Conference in September that the stalled deliveries could mean some units — which are in the process of transitioning from other aircraft — have to wait longer for promised F-35s.
That could have a cascading effect that hurts the Air Force’s ability to manage its forces worldwide, Air Combat Command head Gen. Mark Kelly said at the conference.
“When a unit converts to a new airplane, usually by the time they get their last airplane, the clock starts and they need to be ready to go a year or so later,” Kelly said in September. “That will delay and will impact … global force management.”
The Pentagon early in 2024 is also expected make a decision — itself years behind schedule — that formally moves the F-35 to full-rate production. However, since Lockheed is already building the fighter at almost full capacity, this milestone C decision will likely have a minimal effect on production.
The F-35 program in September finished a series of tests in the Joint Simulation Environment to collect data needed for the Pentagon to make that decision. The JSE tests put all three versions of the aircraft through several scenarios — including cruise missile defense, air interdiction, counter-air, and destruction of enemy air defense trials — designed to emulate what the fighter would likely encounter in combat.
And in early 2024, Pratt & Whitney is expected to receive the first in a series of sole-source contracts to upgrade the F-35′s existing F135 engines under the Engine Core Upgrade program. The engine upgrades are intended to give the F-35 more power and cooling ability so it can handle the needs of its Block 4 modernization.
Pratt said deliveries for the program are expected to start in early 2029, although that schedule could be pushed up to late 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.