THE SMART decision FOR THE F-35

The F135 Enhanced Engine Package (EEP): variant-common, combat-tested, coalition-assured and cost-effective. For full Block 4 capability and $40B savings over the lifecycle of the program to keep our military on the leading edge.


F135 EEP is the most cost-effective, lowest-risk propulsion modernization solution for the F-35 weapons system.
As the air vehicle grows, so must the engine. Designed with the knowledge that operational environments evolve and threats advance, the F135’s modular design and advanced digital architecture allow for spiral development and insertion of both hardware and software – ensuring the F-35 outpaces emerging threats.

Pratt & Whitney developed EEP, a block upgrade for the F135, with the objective of providing an affordable, low risk, and agile pathway to fielding meaningful propulsion capability for all F-35 customers. F135 EEP leverages Department of Defense investments in adaptive technology to deliver the capability needed for Block 4 aircraft, while maintaining the variant-commonality and international partnership approach that the joint program was built upon. Doing so maximizes affordability for all, with F135 EEP generating approximately $40B in lifecycle cost savings over the life of the program.

Additionally, low technical risk is a must for pilot safety on a single-engine fighter. Based on operational experience, today’s F135 is the safest fighter engine ever produced. As a derivative design, F135 EEP builds upon the same proven architecture that has more than one million flight hours of safe and dependable operation so pilots can complete their mission and return home safely.

F135 EEP meets the timeline and necessary requirements to support Block 4 aircraft without disrupting the program of record or driving increased cost and risk. 

  • Variant-Common

    F135 EEP is the only modernization solution that maintains variant commonality, a foundational element of the F-35 program’s design to drive economies of scale and reduce cost. As such, the F135 EEP upgrade leverages the existing production and sustainment infrastructure, and maintains the current cost share ratios with the Services and Partners. Additionally, F135 EEP is production cost neutral, retaining the sizable affordability investments that have been made to date.

    All told, F135 EEP saves the taxpayer approximately $40 billion in lifecycle costs over the life of the program, making it the most cost-effective modernization available for the F-35 enterprise. Those are substantial savings that can be put to use for other modernization priorities across the Department of Defense.

  • Combat Tested

    F135 EEP upgrades an engine that is combat-tested and serving the warfighter now, powering missions for more than a dozen customers around the world. As a derivative design, F135 EEP builds upon a proven architecture that has more than one million flight hours of dependable operation between the F135 and the F119, which powers the F-22 Raptor.

    Weight neutral and requiring minimal airframe integration testing, the F135 EEP upgrade was designed from the onset to be integrated into production and/or retrofit during engine overhaul – enabling the accelerated fielding of fully supported Block 4 capabilities in the capacity needed by the warfighter.

  • Coalition-Assured

    F135 EEP’s variant commonality strengthens the combat capability and capacity of key allies who serve as a vital pillar in U.S. national security and defense strategies at a time when geopolitical instability across the globe is increasing.

    The F135 EEP upgrade enables critical Block 4 capability for all F-35 operators, while maintaining the international partnership and alliance approach of the program -- preserving the ability to share cost and logistics over a broad enterprise to ensure F-35 interoperability and sustainability across multiple variants and users.

  • Advanced Capability

    F135 EEP leverages the Department of Defense’s investment in adaptive technology to deliver the required capability growth – all within the confines of the existing program construct. This means the F135 EEP upgrade incorporates the latest in propulsion technology to meet necessary requirements for Block 4, while retaining variant-commonality to maximize affordability.

    F135 EEP delivers performance improvements in range, thrust, and thermal management capacity for all variants as well as powered lift for the F-35B variant.

F135 Myth Busting

Separate fact from fiction regarding the F135 engine.

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