DAYTON, Ohio — As the U.S. Defense Department approaches a decision on whether to upgrade or replace the F-35 fighter jet′s engine, Air Force officials are concerned that opting against a full replacement could lead to the “collapse” of the advanced propulsion industrial base in the country.
In the next year, service officials expect to refine the fifth-generation fighter’s future propulsion profile and must make a choice between two engine modernization options.
The first is a full replacement of the current F135 with an advanced engine developed through a yearslong research and development effort called the Adaptive Engine Transition Program. Engine-makers General Electric Aviation and Pratt & Whitney each developed competing AETP prototypes that demonstrated a 25% gain in fuel efficiency, a 30% increase in range, and twice the power and thermal management capability than modern military propulsion systems.
The alternative is an upgrade to the Pratt & Whitney-made F135 that would likely build on technology developed through AETP but not require a full replacement.
The decision will involve cost and capability trade-offs, and the head of the Air Force’s Propulsion Directorate, John Sneden, recently told reporters it could have significant implications for the already “very thin” industrial base — particularly if the service chooses not to move forward with the AETP option.
“A portion of the industrial base would begin to collapse,” Sneden told reporters during an Aug. 11 briefing at the Air Force’s Life Cycle Industry Days conference in Dayton, Ohio. “If we end up with one vendor there, if we don’t move forward with AETP, that vendor can actually get us into a place where we have, essentially, a reduced advanced propulsion industrial base.”
Sneden’s directorate worked on AETP and its predecessor, the Adaptive Engine Technology Demonstrator, for the last decade. The team is leading development of the Next Generation Adaptive Propulsion program, which aims to field engine capabilities for the Air Force’s next fighter aircraft and which, like AETP, centers on designs from GE and Pratt & Whitney.
If the Pentagon decides to move forward with AETP as a new engine for the F-35, Sneden said the program could move into the development phase as soon as 2024 and to the field by 2030.
That timeline corresponds with the Next Generation Adaptive Propulsion program’s plan to choose a single company in fiscal 2024. If AETP ends without a customer, the department would be left with only one advanced propulsion provider.
“From an industrial base perspective, you start to get some atrophying if you don’t continue to push the marketplace forward to drive those outcomes,” Sneden said.
Along with his concerns about the industrial base, Sneden said AETP is the best option to support the Pentagon’s plan to upgrade the F-35 with advanced systems that require more power and cooling from its propulsion system. “We think the warfighter deserves the performance attributes that AETP can deliver,” he noted.
Air Force officials, including Secretary Frank Kendall and acquisition executive Andrew Hunter, said they’re impressed with AETP’s performance. Hunter told reporters in June the program is delivering the capability the service will need in a possible fight against China, where endurance and efficiency could offer an important advantage.
However, the cost to integrate a new engine into the F-35 could prove too high. Kendall told House lawmakers in April he expects that developing and transitioning AETP to production could cost $6 billion.
Pratt & Whitney, which is lobbying for the alternative modernization program, estimates the upgrade path would cost about one-third of AETP’s development price and may save up to $40 billion in life-cycle expenses.
The F-35 Joint Program Office — in partnership with the Air Force, Navy and Marine Corps — is leading a business case assessment that is analyzing the cost, schedule and potential performance of various engine replacement and upgrade options. That work is expected to wrap up this summer.
The Air Force is conducting a separate review, meant to complement the business case analysis, that considers how each upgrade option could impact a future combat situation. The study is slated for completion in September.