The United States Department of Defense has expanded its support for the F-35 program by awarding Lockheed Martin a $177.49 million contract modification to produce three dedicated flight sciences test aircraft, aimed at accelerating Block 4 and future capability upgrades.
This builds on a prior $180 million award in April 2025 to convert three F-35 jets into test platforms, with the latest contract extending efforts to include design, engineering, and construction across all variants — F-35A, F-35B, and F-35C — for the US Air Force, Marine Corps, and Navy respectively.
The new aircraft will replace current test assets and ensure continuous testing capability, supporting comprehensive validation of advanced upgrades within the Joint Strike Fighter program. Initial funding of $37.67 million has been allocated, with contributions from US services and international partners.
Production activities will be spread across seven sites in three countries, with the majority of work in Fort Worth and El Segundo, supplemented by facilities in Warton (UK) and Grenaa (Denmark). Completion is targeted for April 2031.
Flight sciences aircraft serve as highly instrumented flying testbeds, designed to capture detailed data on aerodynamic characteristics, structural loads, and performance limits. Conversion typically includes adding equipment such as telemetry systems, sensors, and spin recovery tools, while removing unnecessary operational components.
The limited availability of such aircraft has previously slowed progress on Technology Refresh 3, a key enabler of Block 4 capabilities. To mitigate this, the F-35 Joint Program Office revised its plan, increasing the number of flight sciences aircraft from six to nine, drawing them from Lot 18 production.
