Pratt & Whitney's F135 Enhanced Engine Package (EEP) is the only cost-effective, variant-common modernization solution for the F-35 that can enable full Block 4 capability for the warfighter and reduce billions in sustainment costs for the taxpayer.


Growth in aircraft capability must be matched with propulsion modernization to ensure the full mission capability of the F-35 weapon system, now and in the future.

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.


Pratt & Whitney developed EEP for the F135 with the objective of providing the most cost-effective solution to meet future F-35 propulsion requirements. This includes inserting the latest technologies into the F135 without breaking variant commonality. Doing so would result in two development programs, two sustainment networks, increased production costs and significant air vehicle integration costs.


The Time is Now to Move Forward with Propulsion Modernization


As the air vehicle grows, so must the engine. To date, there is no propulsion growth requirement or funding commensurate to support planned Block 4 air vehicle upgrades. This needs to urgently change as planned air vehicle growth will exceed the current F135’s limits by the end of the decade.


Without propulsion modernization, there will be substantial operational impacts for F-35 warfighters and increased sustainment costs for the taxpayer. EEP is the only variant-common propulsion growth path that can close the Block 4 capability gap and reduce sustainment costs.

With room for growth for tomorrow’s missions, the F135 is uniquely postured to meet the evolving demands of the F-35.

F135 EEP: Cost Effective. Capable. Low Risk.

  • Cost effective

    EEP is the only solution that enables full Block 4 capability without driving billions of dollars into program costs and bifurcating the F-35 fleet. In accordance with program design, EEP is a variant-common modernization solution that leverages the existing production and sustainment infrastructure and maximizes cost share across all F-35 partners. EEP is production cost-neutral and will generate billions in sustainment cost savings over the life of the program.

  • Next-gen capability

    EEP leverages Department of Defense propulsion investments to provide next-generation capability to the F-35 at an affordable cost –  all within the confines of the existing program construct. EEP can provide double-digit improvements in range, thrust and thermal capacity and will meet the F-35 propulsion requirements necessary to fully enable Block 4 capabilities for the warfighter. Additionally, EEP can be optimized to further increase a specific propulsion performance parameter, such as fuel efficiency, should the customer desire.

  • Low risk
    EEP is by far the lowest risk propulsion modernization solution available for the F-35. It maintains a proven architecture that has over 900,000 flight hours between the F135 and F119, maintains the same weight, and requires minimal airframe integration. Low technical risk is a must on a single engine fighter jet.


More about the F135