Lockheed Martin flies first production F-35s equipped with TR-3 upgrade

US Air Force F-35A Lightning II. F-35 deliveries with TR-3 upgrades are scheduled to begin as soon as April 2024. (US Air Force/Staff Sgt Zade Vadnais)

Lockheed Martin has flown the first production F-35s equipped with Technology Refresh 3 (TR-3) hardware and software upgrades, the manufacturer confirmed on 28 November. F-35 deliveries to customers have been paused until TR-3 is judged to be sufficiently mature.

“We are now flying TR-3 software on F-35 production jets in Fort Worth and flight test continues at Edwards Air Force Base and Naval Air Station Patuxent River,” the company told Janes on 28 November.

The TR-3 software upgrade first flew in January 2023 aboard a US Air Force test aircraft at Edwards Air Force Base. The US Department of Defense's F-35 Joint Program Office (JPO) declined to specify the number of F-35s flying with TR-3 today, citing operational security.

“The JPO and Lockheed Martin agree that the acceptance of TR-3 aircraft should fall in the April 2024 to June 2024 timeframe based on risks as we understand them today,” the JPO told Janes on 28 November.

Deliveries of TR-3-equipped aircraft were paused in July 2023. Though the reasons behind the delivery pause have not been detailed, Lieutenant General Michael Schmidt, head of the JPO, told Congress in March, “The key risks ahead of us are centred around maturity and stability of the final integrated software, flight-test execution with an ageing fleet of test aircraft and infrastructure, and delivery of TR-3 hardware to the production line.”

The JPO declined to specify the number of TR-3-equipped jets that remain to be delivered.