The F-35 Joint Strike Fighter (JSF), powered by Pratt & Whitney’s F135 engine, is the most advanced combat aircraft in history. Designed as a common airframe and propulsion platform able to support unique and challenging missions in any theater, all three variants – the F-35A, F-35B, and F-35C – benefit from common maintenance, training, and supply chains that enable the global readiness of more than 1,100 aircraft and over 1,300 engines.
Pratt & Whitney delivered the first production F135 engine in 2009. Since then, the program has grown considerably and as of 2025, powers the F-35 fleets for the United States Air Force, Marine Corps, and Navy as well as 20 U.S. allies around the globe. The F135 also benefits from a mature global sustainment network supporting multiple depot facilities, 32 bases, and 12 ships.
While the F135 has consistently outperformed it’s requirements throughout its lifetime, F-35 operators have unanimously agreed an upgrade is needed to enable the future demands of the platform while maintaining the original engine life specifications. To meet these performance needs and ensure the F-35 maintains global 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 Adaptive Engine Transition Program (AETP). These learnings were incorporated into the F135 ECU design to modernize the 5th Generation F-35 fleet with cutting-edge technologies while building a bridge toward the full suite of capabilities for the Next Generation Adaptive Propulsion (NGAP) program which will power 6th Generation aircraft.