A bipartisan letter calling on the Defense Department to continue investing in adaptive propulsion technology in fiscal year 2024 has won support from 49 lawmakers, according to a final copy shared today with Inside Defense.
The effort, which Inside Defense reported on earlier this week after obtaining a draft copy, advocates for the quick delivery of those next-generation engines to the military services’ fighter fleets, with lawmakers arguing that failing to do so would “risk opening the door for U.S. adversaries to overtake our advantages in fielded engine technology.”
“We must make strategic funding decisions that bring us the technological leaps that will enable us to maintain our competitive edge,” reads the letter, which is dated Oct. 7 and addressed to Defense Secretary Lloyd Austin.
Among the signatories of the letter, led by Sen. Rob Portman (R-OH), are 10 other senators, including Appropriations Committee Chairman Patrick Leahy (D-VT), who is retiring at the end of the year.
Though the letter does not name a specific program or airframe, the call comes as Air Force officials are weighing next steps for their Adaptive Engine Transition Program, under which propulsion vendors Pratt & Whitney and General Electric are maturing prototypes compatible with an F-35A conventional-takeoff-and-landing variant.
AETP is nearing a potential engineering and manufacturing development stage, though it’s unclear whether the service will move forward with it, as such a decision is entangled with broader enterprise-level plans for F-35 re-engining. The Air Force, Navy and Marine Corps are facing a looming engine modernization decision that boils down to two options: incrementally upgrade the existing Pratt-manufactured F135 propulsion system, a path Pratt supports, or fund a full engine replacement using an offering developed through AETP, an alternative GE backs.
The letter pushes DOD “to capitalize on the investments made over the last 15 years” and fund an EMD phase for next-generation propulsion in the FY-24 budget proposal while swiftly working to “deliver adaptive technology to the services.”
The message comes in the months after a group of three-dozen lawmakers, led by Rep. John Larson (D-CT), penned a letter opposing “a complete engine replacement program” for the F-35. The Joint Strike Fighter fleet has need for an upgraded engine with more power and cooling due to forthcoming capabilities, with those features expected to result in more bleed air extraction than the level that was originally planned.