Twenty years ago, after extensive competition, the Pentagon awarded Lockheed Martin a contract to develop the Joint Strike Fighter (JSF), or the F-35. Since its inception, the Joint Strike Fighter (JSF) has emerged as the most advanced combat aircraft in history. Designed from the onset as common airframe platform able to support unique and challenging missions, the F35-A, F-35B, and F-35C all benefit from common maintenance, training, and supply chains that enable the global readiness of nearly 1,000 aircraft. But the heart of any aircraft is its engine. Similarly, there was extensive competition to develop the aircraft’s engine—one that would be interoperable for all three variants of the F-35.
In 2009, Pratt & Whitney delivered the first production version of the F135 engine, a variant-common propulsion system built upon the decades of proven combat experience of the F119 which powers the F-22 Raptor. The F135 was intentionally designed as a derivative to have a high degree of commonality with the F119 in order to improve performance by increasing durability, reliability and supportability while also reducing overall program cost, schedule, and risk.
By 2011 the F135s unparalleled performance combined with the program objective for commonality and cost effectiveness led to a broad, bipartisan majority in Congress voting to end a long-standing earmark for a second engine.
Today, the F135 remains a prime example of modern engineering as the world’s safest and most advanced fighter engine in the world. It is flown by the United States Air Force, Marine Corps, and Navy as well as 17 US allies around the globe and has a mature global sustainment network supporting multiple depot facilities, 32 bases and 12 ships internationally.
The F-35 aircraft has received several incremental updates over the last 20 years, but the F135 engine was not updated in parallel, causing a high degree of stress on the propulsion system. While the F135 is still performing above specification, F-35 operators have unanimously agreed an upgrade is needed to enable the future demands of the platform – known as Block 4. To meet these performance needs and ensure the F-35 maintains air superiority, Pratt & Whitney developed the F135 Engine Core Upgrade (ECU).
F135 ECU leverages learnings from a variety of cutting-edge propulsion engineering efforts completed over the last decade including the Navy Fuel Burn Reduction (FBR) high pressure compressor and high pressure turbine testing, as well as the Air Force’s sixth generation Adaptive Engine Transition Program (AETP). These technologies were incorporated into the F135 ECU design to modernize the fifth generation F-35 fleet with cutting-edge technology while building a bridge towards the full suite of AETP technologies intended for future sixth generation aircraft.
In 2023, the Department of Defense selected Pratt & Whitney’s F135 Engine Core Upgrade (ECU) to modernize the F-35 propulsion system and deliver the durability and performance improvements to enable Block 4 capabilities and beyond on all F-35s. Noting the importance of affordability, commonality, and availability, Congress then fully funded the ECU in the FY2024 Defense Appropriations bill and included language preventing government funds from being used to develop an alternate engine for the F-35, thereby acknowledging the importance of the legacy of the F135 and F119 designs that F135 ECU is built upon.