Proven. Capable. Retrofittable.

Pratt & Whitney’s F135 Engine Core Upgrade (ECU) delivers the durability and performance needed to enable Block 4 capabilities and beyond. Easily retrofittable in all F-35 variants, ECU is the only engine that offers all global F-35 operators the additional power and thermal management capacity needed to enable next-generation weapons systems and sensors. Utilizing cutting-edge technologies developed for advanced programs, ECU ensures the F-35 Lightning II remains the most advanced fighter for decades to come.

Why ECU?

Proven track record

F135 updated exhaust plug

The ECU builds on the architecture of the F135 – a proven engine with over 860,000 recorded flight hours and 20 years of reliable performance.

Variant common

Three F-35 variants

Commonality enables agility within the F-35 program. The ECU is the only engine upgrade that supports all three variants of the F-35 while leveraging existing production, supply chain and maintenance infrastructure to ensure global readiness.

Advancing technology

F135 engine

ECU leverages proven technology from the Navy’s Fuel Burn Reduction program and other cutting-edge advanced development programs to support the modernization needs of the F-35.


F135 engine

As the only “drop in” propulsion modernization solution available to the F-35, ECU’s retrofittable design allows for upgrades to already fielded F-35s and new production F-35s, ensuring a common, capable fleet for all users.

Economically impactful

A technician on an assembly line

The F135 program sustains more than 57,000 domestic jobs, 255 U.S. suppliers, and contributed more than $2.2 billion to the U.S. economy in 2023. ECU for the F-35 protects existing U.S. infrastructure investments and creates new skilled labor and engineering jobs year-over-year to support program growth.