Pratt & Whitney finished the Risk Reduction Design Review to advance the F-35 modernization program toward production.
RTX announced on 15 September 2026 that its Pratt & Whitney business completed the F135 Engine Core Upgrade Risk Reduction Design Review. This milestone validates the maturity of the engine core design and advances the modernization program toward full production.
The review evaluated propulsion technologies, detailed design elements, integration aspects, and risk reduction work required to provide full engine life across all three F-35 Lightning II variants. The upgrade supplies the extra power and thermal management capacity needed for Block 4 and future capabilities, including advanced sensors and weapons. The assessment also confirmed supply-base readiness for future production and retrofits under a contract awarded in 2024.
Completing RRDR is an important milestone that demonstrates the maturity of the F135 Engine Core Upgrade and the progress our team is making to deliver this capability to the warfighter.
To date, Pratt & Whitney has delivered more than 1,500 F135 production engines to customers across 20 allied nations. The upgraded core serves as a drop-in modernization for both newly manufactured aircraft and fielded jets, which can be retrofitted at depot facilities.
Headquartered in Arlington, Virginia, RTX employs more than 180,000 people globally and reported 2025 sales exceeding $88 billion.
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