Lockheed Martin / Chris Hanoch
Closeup view of F-135 turbofan engine.

Pratt & Whitney to Start F-135 Engine Upgrades in 2024

Dec. 4, 2023
A $700-million Pentagon award sets the start for the engineering and manufacturing phase of the F-135 Engine Core Upgrade, to improve the propulsion system ahead of DoD’s planned overhaul of the jets for new weapons systems.

The U.S. Dept. of Defense awarded $701.9 million to Pratt & Whitney to begin the “Engine Core Upgrade” project for F-135 engines installed in the F-35 Joint Strike Fighter jets. With more than 975 of the single-engine F-35s completed and in service with the U.S. Air Force, U.S. Navy, U.S. Marine Corps, and more than a dozen allied defense forces, the number of engines to be updated is close to that number, with work to begin in 2Q 2024 and continue through 2031.

The Engine Core Upgrade is Pratt & Whitney’s plan to improve the propulsion system capabilities for all three variants of the F-135 turbofan engine, in anticipation of the Pentagon’s plan to upgrade the three different F-35 aircraft models.

The full cost of the Engine Core Upgrade has not been announced, but a P&W official previously estimated it to cost as much as $2.4 billion.

DoD’s F-35 modernization, which is called the Block 4 upgrade, is largely focused on electronic hardware and software advances that will facilitate dozens of new weapons systems. Before the Block 4 update can be implemented, the jets’ core processor and memory will be updated in an effort called Technology Refresh 3 (TR3.)

Earlier this year the Pentagon decided against replacing the F-135 with a new engine model, favoring Pratt & Whitney’s approach to modifying the existing design. P&W has said the Engine Core Upgrade will be “the fastest, most cost-effective, and lowest-risk path to Block 4 capability for all global F-35 operators. It is optimized for all three F-35 variants and will yield $40 billion in lifecycle cost savings by avoiding disruptive and costly air vehicle changes and leveraging the current global sustainment infrastructure.”

The not-to-be-exceeded value of the new award will cover the Engine Core Upgrade’s engineering and manufacturing phase, which includes recurring engine sustainment, program management, propulsion integration, engineering, material management, configuration management, software sustainment, security management, equipment management, product management support activities, and spare replenishments.

It also provides for continued joint technical data updates, training, and depot level maintenance and repair for all fielded propulsion systems at F-35 production and operational locations for the USAF, U.S. Navy, USMC, and foreign operators.

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