The Pentagon on March 30 announced a a $3.8 billion contract modification to buy F135 engines for the F-35 Joint Strike Fighter from contractor Pratt & Whitney.
The modification finalizes—or “definitizes” in acquisition-speak—Lot 18 of the F135, as well as providing for the production of engines that will go in Lot 19 of the F-35, the Defense Department said in a contract announcement.
The F-35 Joint Program Office did not respond to queries from Air & Space Forces Magazine on how many engines the contract will cover. But the Pentagon awarded a contract last summer to Lockheed Martin for 296 airframes in Lots 18 and 19, and the department gave Pratt & Whitney a $2.88 billion undefinitized contract award for Lot 18 for the production of 141 engines around the same time.
That would suggest Lot 19 will include somewhere around 150 engines—a figure a JPO spokesperson confirmed to Breaking Defense.
RTX, of which Pratt & Whitney is a subsidiary, noted in a March 31 statement that the combined value of the contract for Lots 18 and 19 is $6.6 billion.
“The F135 is the most advanced military engine in the world, delivering unmatched thrust, reliability and mission readiness for the United States and its allies,” Jill Albertelli, president of military engines for Pratt & Whitney, said in the company’s statement. “Pratt & Whitney is investing heavily across our global production base and supply chain to increase production and accelerate engine delivery and sustainment to meet growing global demand for the F-35 program.”
The contract will allow Pratt & Whitney to keep manufacturing F135 engines uninterrupted, as well as ensuring it maintains the necessary capacity, tooling, and supply chain operations, RTX said. It covers full-rate production engines, initial spares, modules, engineering resources, program oversight, and dedicated production support services.
The Pentagon said work on the engines is expected to be finished in March 2028 and will take place in a variety of locations including in Connecticut and Indianapolis.
RTX said Pratt & Whitney has invested more than $1 billion over the last five years to expand and modernize its capacity to produce engines, which has boosted F135 production rates by 20 percent.
Presuming Lots 18 and 19 comprise around 296 engines, the average cost per powerplant would be around $22.6 million.
The Lot 18 and 19 contract for the F-35 airframe, meanwhile, was for $24.29 billion—putting the average cost of the airframe across all variants and customers at $82.4 million.
Combined, that puts the average cost of an F-35 for the lots at somewhere around $105 million. That cost, however, can vary significantly depending on the variant. The short takeoff and landing F-35B, for example, can cost upwards of $20 million more per airplane than the Air Force’s F-35A. The JPO has yet to break down costs by variant for the most recent lots.