US fighter manufacturer Lockheed Martin has completed assembly of the 1,000th F-35 Lightning II stealth fighter.

The company confirmed the milestone on 18 January, but says the aircraft in question has not yet been delivered. Lockheed did not provide additional details regarding the specific F-35 variant or intended customer of the aircraft in question.

The Pentagon stopped accepting most new F-35s in August 2023, as Lockheed works to complete airworthiness certification on the latest configuration of the stealth fighter, known as Technical Refresh 3 (TR-3).

F-35 factory

Source: Lockheed Martin

Lockheed completes final assembly of F-35s in Fort Worth, Texas. The company recently completed the 1,000th example of the advanced the stealth fighter, which still awaits delivery

The upgrades, which include a new flight computer and operating software, turn each F-35 into an airborne data centre capable of operating at 5G speeds. Such improvements will enable weapon, sensor and communications enhancements planned for the forthcoming Block 4 variant of the fifth-generation fighter.

TR-3 certification is significantly behind schedule. Lockheed chief executive James Taiclet described the process as being in the “very late innings” as far back as April 2023.

Flight testing of the TR-3 package began a year ago, in January 2023.

The delay in certification significantly reduced Lockheed’s F-35 delivery projections for 2023.

In the company’s final earnings call of the year, Taiclet said Lockheed expected to deliver only 97 jets in the calendar year – down from 141 examples in 2022.

While revenue has been impacted accordingly, F-35 production has continued at the normal rate and Lockheed expects to recoup the short-term losses when deliveries resume.

“We are producing F-35s at a rate of 156 per year,” Taiclet said in October. “[We] expect to continue at that pace while simultaneously working to finalise TR-3 software development and testing.”

Taiclet said the company expects to complete TR-3 certification sometime in the first half of 2024, with the first delivery of those aircraft coming sometime between April and June.

Lockheed is expected to provide an update on the F-35 programme on 23 January, during the company’s final earnings report covering 2023.

Although it has paused deliveries, the Pentagon remains enthusiastic about the potential of TR-3 configured F-35s.

“These capabilities provide the war fighter a combat edge to identify, track, engage, and survive against advanced air, ground and cyber threats,” the Pentagon’s F-35 Joint Program Office says.

US Air Force Lieutenant General Michael Schmidt, the Pentagon’s F-35 programme director, has expressed similar sentiments.

“TR-3 is the F-35’s critical computer processing electronics upgrade that will continue to provide all our pilots with the capability they need to be successful against any adversary,” he said at the start of flight testing.

The Pentagon continued to accept older TR-2 configured F-35s throughout 2023, as assembly of those models was completed.