The United States Department of Defense has awarded Lockheed Martin a $177.49 million contract modification to build three F-35 flight sciences test aircraft, strengthening flight-testing capacity for Block 4 and future upgrades.
This award follows a separate $180 million contract issued in April 2025 to convert three existing F-35s into test platforms. The latest modification broadens the scope to include engineering, labor, and full development support for three aircraft spanning all variants: the F-35A for the US Air Force, the F-35B for the US Marine Corps, and the carrier-based F-35C for the US Navy.
These aircraft will replace aging test assets, prevent capability gaps, and enable detailed validation of Block 4 enhancements under the Joint Strike Fighter program. At the time of award, $37.67 million was obligated, including $18.83 million each from the US Air Force and Navy, along with $8.39 million contributed by international partners.
Work will be carried out across multiple locations, primarily in Fort Worth and El Segundo in the United States, with additional contributions from Warton in the UK (20%) and Grenaa in Denmark (5%). The program is scheduled for completion by April 2031.
Flight sciences test aircraft act as airborne laboratories, equipped with advanced instrumentation to assess aerodynamics, structural performance, and full flight envelope behavior. Converting such aircraft involves integrating specialized systems like spin chutes, telemetry, sensors, and cameras, while removing non-essential components.
A shortage of these test platforms has contributed to delays in the Technology Refresh 3 effort, which underpins Block 4 upgrades. To address this, the F-35 Joint Program Office increased its planned fleet of test aircraft from six to nine, sourcing them from Lot 18 production, as noted by Air & Space Forces Magazine.
