Program remains on track to enable F-35 Block 4 and beyond capabilities

EAST HARTFORD, Conn., Sept. 15, 2026 /PRNewswire/ -- Pratt & Whitney, an RTX (NYSE:RTX) business, has successfully completed the F135 Engine Core Upgrade (ECU) Risk Reduction Design Review (RRDR), a major program milestone that validates the maturity of the ECU design and advances the program toward production.

The review evaluated the detailed design elements, propulsion technologies, integration considerations and risk-reduction activities critical to delivering full engine life and providing the additional power and thermal management capacity needed to support advanced sensors, weapons and other Block 4 and beyond capabilities across all three F-35 Lightning II variants. The review further assessed the industrial base's readiness to support future production and retrofit.

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