Fort Worth. Lockheed Martin has been awarded a $177 million contract by the United States Department of Defense (US DoD) for three F-35 Lightning II fighter jets configured for flight science and test work.
Approved on April 23, 2026, the contract covers one aircraft in each of the three F-35 variants: the conventional takeoff F-35A, the short takeoff and vertical landing F-35B, and the carrier-based F-35C.
As the Pentagon works to resolve persistent delays in the F-35 Block 4 upgrade programme, now estimated at over $6 billion above original costs and at least five years behind schedule, the order for these three jets is expected to close the gap arising due to a limited fleet of ageing test aircraft, identified as a key bottleneck in certifying new configurations.
Currently, the Pentagon operates only a small number of flight-science F-35s. Officials and auditors have repeatedly cited this limited test fleet as a factor behind delays in rolling out upgrades for the fifth-generation stealth fighter. Without sufficient test platforms, new hardware and software configurations face longer certification timelines, which push costs higher.
The latest contract follows the delivery of a test-instrumented F-35A to the United States Air Force (USAF) in September. The three new jets will replace older platforms and provide modern test infrastructure for current and future upgrade certification.
As per the Pentagon’s contract announcement, the aircraft will “support preventing a capability gap for flight test” and enable holistic testing of Block 4 capabilities and other future upgrades across the Joint Strike Fighter (JSF) programme.
As one of the most scrutinised defence acquisition efforts in recent years, the F-35 Block 4 upgrade programme encompasses a broad suite of upgrades to the jet’s weapons, sensors, and communications systems. These upgrades depend on the Technical Refresh 3 (TR-3) configuration, which provides improved onboard computing power.
Protracted delays at Lockheed Martin in certifying the TR-3 hardware has caused significant disruption. This led the Pentagon to halt all new F-35 deliveries for a full year between 2023 and 2024. That delivery pause affected production schedules and operational readiness across the US military and allied nations.
In a September report, the US Government Accountability Office (GAO) noted that Block 4 costs now exceed original estimates by more than $6 billion, with completion running at least five years late. Delivery of the first Block 4-configured F-35 is now projected for 2031.
Additionally, the Pentagon is pursuing multiple complex projects to upgrade the F-35’s electrical power generation and thermal management systems. Current power and cooling demands on the aircraft now exceed the original design parameters, creating a need for significant hardware improvements.
The Engine Core Upgrade (ECU) programme aims to re-core the jet’s Pratt & Whitney (PW) F135 engine. Pratt & Whitney is currently under contract and performing design work for the ECU, which would boost thrust and power generation capacity.
A separate effort targets the F-35’s Honeywell-made Power and Thermal Management System (PTMS). This upgrade is still under evaluation and has not yet received full commitment or funding from the Pentagon. Both the ECU and PTMS programmes will require dedicated test aircraft to validate new hardware in flight conditions.
The addition of three new flight-science jets addresses a structural weakness in the F-35 programme. The Pentagon’s decision to invest $177 million in dedicated test aircraft signals recognition that flight testing infrastructure is as important as the upgrades themselves. Without adequate test platforms, every major upgrade effort risks the same pattern of delays that plagued TR-3 and Block 4 certification.
