Raytheon CEO Opposes XA101 For F-35As As Tests Continue

Pratt & Whitney will start altitude tests on its experimental XA101 engine in early 2022, though the CEO of parent company Raytheon Technologies warns it would be a difficult and expensive effort to install it on F-35As as some lawmakers are calling for and the U.S. Air Force is exploring.

The XA101, the company’s entry in the Air Force’s Adaptive Engine Transition Program (AETP), finished a series of ground tests in September. Raytheon Technologies CEO Gregory Hayes said during an Oct. 26 earnings call that flight tests would begin early next year. But a company spokesman clarified that the engine will in fact undergo tests at the Air Force’s Arnold Engineering Development Complex in Tennessee that simulates operating at altitude. 

The XA101, which is competing against the GE Aviation XA100, could replace Pratt’s F135 engine in the F-35 fleet. But Hayes said this plan is problematic for multiple reasons.

“The issue right now with the adaptive engine is it doesn’t fit on the carrier-based version, the Navy version or the Marine Corps version … so the Air Force would have to fund the entire development cost of a new engine,” Hayes said.

Air Force Secretary Frank Kendall in September said the fuel efficiency and thermal management improvements in the AETP would help the F-35 fleet and directed his staff to look into the affordability of installing an AETP powerplant if the Navy does not participate. 

The House Armed Services Committee’s version of the fiscal 2022 defense policy bill also calls for the Pentagon to produce a report on installing an AETP engine into the Air Force’s F-35A fleet.

Hayes said the re-engining plan in 2027-2028 is “extremely aggressive.” 

Another issue is the XA101’s brand-new technology, unlike the F135 which has millions of flight hours, Hayes said.

“You’re talking about a single-engine fighter,” he said. “I think it’s going to be a tough putt to think about putting a brand-new, paper engine on the F-35 in the near term.”

Pratt believes its AETP technology should be used for the Next Generation Air Dominance platform, and Hayes pushed Pratt’s proposed Engine Enhancement Package for the F-35, which would provide near-term upgrades that would improve cooling, thrust and fuel efficiency. This is significantly cheaper, Hayes said, and the company is working with the services on that proposal.

“I think it’s the thought of a brand-new engine that’s going to be a tough putt,” he said. “It’s not to say we’re not going to look for ways to improve the current version. I think that’s just a question of finding the funding because as the Block 4 [F-35] gets introduced, we are going to need more cooling, we are going to need more thrust. But we have a plan to address that with the [F-35 Joint Program Office].”