The U.S. Dept. of Defense placed a contract with Pratt & Whitney that could be worth more than $8 billion for up to 518 F135 afterburning turbofan jet engines, to power Lots 15-17 of the F-35 Lightning II Joint Strike Fighter aircraft. Officially, the value of the order is $5.2 billion for 278 engines for Lot 15 and 16 engines, according to the Pentagon’s F-35 Joint Program Office.
The option covering Lot 17 will be exercised in the near future, reportedly, adding a further 240 engines and increasing the value of the order to the $8 billion figure reported by Pratt & Whitney.
The engine order follows a $30-billion agreement that DoD and Lockheed Martin reached at the end of 2022 for production and delivery of up to 398 new F-35s – covering Lots 15 and 16, plus an option for Lot 17 – for the U.S. Air Force, Navy, and Marine Corps, plus defense forces in more than a dozen allied nations.
Pratt & Whitney’s order assigns responsibilities for program management, engineering support, production support, and tooling to the engine manufacturer.
"This marks a major milestone for the program," stated Pratt & Whitney's Jen Latka, vice president for the F135 program. "This contract award enables us to continue delivering critical 5th Generation propulsion capability to the warfighter at a fair and reasonable cost for the taxpayer."
The F-35 is a single-engine, Stealth-enabled aircraft deployed for ground attack and combat, and available in three variants: F-35A, for conventional takeoff and landing (CTOL); F-35B, for short take-off and vertical-landing (STOVL); and the F-35C carrier-based variant for Catapult Assisted Take-Off But Arrested Recovery (CATOBAR) variant. Nearly 900 F-35s have been built since 2006, with Lot 15 already in production. Lot 17 would be completed in August 2026, according to the program schedule.
Pratt & Whitney’s F135 is a design derived from the F119 engine (for the F-22 Raptor fighter jet), and is described by manufacturer as “the most powerful and most advanced fighter engine in the world”.
Currently Pratt is collaborating with DoD on a “core upgrade” of the engine, in line with an extensive update to all three variants of the F-35 jet. That project is called the Block 4 upgrade, most of which concerns new electronic hardware and software, toward adoption of dozens of new weapons systems. Before the Block 4 update can be implemented, the jets’ core processor and memory will be updated in an effort called Technology Refresh 3 (TR3.)
The F135 engine core upgrade will be “the fastest, most cost-efficient, lowest-risk path to Block 4 capability for all global F-35 operators,” according to Pratt & Whitney. It calls the F135 ECU a “drop-in” project to improve the propulsion system for all three variants of the F135, in advance of the Block 4 program.
