As F-35 engine decision nears, Pratt touts upgrade that execs say would be faster and cost less than AETP 

By Michael Marrow  / December 15, 2022

Boosted by a preliminary engine enhancement contract, Pratt & Whitney is touting cost savings and a speedier delivery through the company’s favored option for upgrading the F-35’s engine as executives ramp up their work on the modernized propulsion choice they say can be ready in 2028.

With the military nearing a decision for modernizing the existing Pratt F-35 powerplant, company executives say their Engine Core Upgrade option would more than double the current engine’s thermal management through a new partnership with Collins Aerospace, increase range and thrust each by 7% and offer at least twice as much in lifecycle cost savings compared to an adaptive engine.

Highlighted during an online media briefing this week with Pratt’s F135 Engine Program Vice President Jen Latka, the figures’ release comes in the weeks after the propulsion vendor was awarded a $115 million contract for the ECU -- renamed from what was previously known as the Enhanced Engine Packages -- that formally funds the program and provides preliminary development activities through 2023.

Those activities are occurring as officials and lawmakers are evaluating their options for modernizing the Joint Strike Fighter’s F135 engines given the need for greater power and cooling prompted by Block 4 upgrades and beyond.

The F-35 Joint Program Office is considering two courses for engine upgrades: Pratt’s ECU approach, a solution that would gradually upgrade the engines of all three variants of the jet; and an entirely new, adaptive engine.

The latter is currently in development through the Air Force’s Adaptive Engine Transition Program, in which both Pratt and General Electric are participating. GE, which favors the adaptive engine option, claims its AETP offering could be tri-variant compatible and offer superior capabilities.

“When we think about what our customer needs and what the warfighter needs, they need as many Block 4-enabled jets as we, industry, can provide for the future fight,” Latka said. “A new engine will take many more years to cut into production because it's an entirely new supply base and an entirely new design. And so, with a core upgrade, keeping that scope limited allows us to field much faster.”

Cheaper sustainment, faster timeline through ECU, Pratt says

On the front end, an adaptive engine is expected to cost at least twice as much -- ECU would require about $2.4 billion to develop compared to about $6.7 billion for an adaptive engine, according to Latka. That more costly development, Air Force Secretary Frank Kendall has previously said, may have to be financed by trimming the F-35A fleet size.

GE and Pratt have both indicated that an adaptive engine could be compatible with the C variant but disagree on whether a tri-variant solution is possible, with GE claiming it is. Officials such as Kendall, meanwhile, have suggested a tri-variant solution is likely off the table for now.

Pointing to that lack of commonality, Latka said the adaptive engine solution would result in far less savings, reiterating previous projections that the company’s preferred upgrade path would decrease lifecycle costs by $40 billion. “We believe that is twice as much, even a little bit more than twice as much, as a new engine,” she said.

Without a common engine solution for all F-35 variants, additional sustainment infrastructure would likely be necessary to support both an ECU and adaptive engine if at least one service decides to re-engine the fleet with an adaptive powerplant, according to a statement from Pratt.

“A second sustainment infrastructure would be required, as well as the associated logistics that go along with a second infrastructure, to service both an ECU as well as a brand-new AETP engine,” Pratt said in the statement.

“This will introduce substantially increased costs (~$20 billion) and additional sustainment challenges into the program,” the statement adds.

Latka said ECU will be ready to plug into the fighter in 2028.

ECU will further include an Emergency Power and Cooling System developed by fellow Raytheon Technologies subsidiary Collins Aerospace. Kim Kinsley, vice president of environmental and airframe control systems at Collins, said EPACS would reach DOD’s technology readiness level six next year and more than double the F-35 engines’ thermal management.

GE has said its offering for AETP, the XA100, will be ready in 2028. Inside Defense previously reported that JPO is targeting a five-to-seven-year timeline for engine modernization, with the expectation that a new engine would arrive in 2031.

Besides timeline and cost, pursuing an adaptive engine brings other potentially countervailing considerations such as the impact on a common engine supply chain currently shared by the aircraft’s international customer base, which primarily buys the A-variant.

An engine decision will also be shaped by customers’ mission requirements. For example, observers note the F-35C flown by the Navy is housed on carriers, which likely lack maintenance infrastructure space for more than one engine type.

Still, a common engine upgrade will have its own challenges, considering hundreds of the fighters have already been delivered.

‘A lot of it depends’

Experts told Inside Defense that a full accounting of costs and capabilities is likely difficult to determine at this stage.

“I would take it with a grain of salt,” a government analyst familiar with F-35 sustainment issues, who requested anonymity since they were not authorized to publicly discuss the matter, said of Pratt’s $40 billion figure in an interview with Inside Defense.

“Conceptually, it would make sense” for ECU to generate greater cost savings, the analyst said. “But there are a lot of ‘it depends,’” the analyst added, pointing to topics such as assumptions about flight hours, fuel consumption and a host of other considerations that factor into an aircraft’s lifecycle estimates.

The analyst also emphasized that maintainability of the engine is a primary place to find lower costs. “If it breaks down less often and you have to fix it less often, you’re going to be able to save a lot of money in the long run,” they said.

However, according to aviation analyst J.J. Gertler, some of Pratt’s cost savings estimates are “largely illusory.” About $30 billion in cost savings are already built in with either engine upgrade options to address known issues with the F135, Gertler, a senior analyst at the Teal Group consultancy, said in an email to Inside Defense.

Moreover, adaptive technology could offer promising improvements for the jet’s range, fuel efficiency and thrust. A range improvement of about 30% and more efficient fuel burn, which GE says is available through its XA100 engine, would significantly decrease the aircraft’s fuel consumption and reduce the need for tanker support to keep the fighter in the air.

“That range and efficiency improvement times the number of airplanes winds up being a very large number, even before you factor in the possible reduction in things like tanker infrastructure,” said Gertler, who previously advocated for the adaptive engine option in an Aviation Week op-ed.

“Yes, they would have to set up service depots for the new adaptive engine, but the core enhancement Pratt is proposing would require the existing depots to put in all new parts and procedures anyway,” he said. “It’s either a new engine or it isn’t. If it’s a new engine, they’re going to have to make new arrangements.”

Pratt added in the statement to Inside Defense that the $40 billion estimate encompasses all costs under the program.

“Because ECU is a core upgrade and not a new engine, it shares significant parts commonality with the current F135, providing an affordable, easy-to-install solution,” Pratt said.

“ECU also preserves and improves the existing global sustainment network, avoiding the duplicative cost of standing up a new network for a second engine. The potential cost savings yielded by fuel consumption does not compare to the cost savings ECU and EPACS can offer across the life of the program,” the statement added.

Even if it comes at a higher cost, officials may still be inclined to consider an adaptive engine option given its potential for greater capabilities. Pratt has claimed its own XA101, for example, would offer notable range and thrust improvements, though the EPACS addition for the ECU option may offer comparable thermal management.

“If you go with AETP, maybe you’re better positioned for the future, but it could end up costing more, possibly a lot more, and you move away from the common sustainment approach, which has been one of the hallmarks of the program,” the government analyst said.

“If there is a substantial cost difference between the two, I would think there would need to be a discernable performance advantage for AETP to carry the day,” the analyst added.

GE Aerospace said in a statement to Inside Defense that AETP represents “the only solution that provides the propulsion capability the F-35 needs in 2028 and beyond to continue to maintain a competitive edge over near-peer adversaries.

“Through AETP, GE Aerospace has developed an engine with 30% more range, 20% greater acceleration and double the thermal management capacity -- revolutionary new capabilities that can be delivered in quantity by the end of the decade,” the statement added.

A looming fight on the Hill

Analysis of all potential costs and benefits of the two paths for engine modernization are currently being assessed in two studies: one through a business case analysis conducted by JPO and a separate analysis from the Air Force.

JPO’s analysis will soon be briefed to lawmakers, who will have the ultimate say on the fate of the F-35 powerplant. If signed into law, an agreement on the fiscal year 2023 defense policy bill between House and Senate authorizers would also require the Government Accountability Office to audit the BCA and available engine modernization options.

Ahead of these developments, lawmakers have already started to dig in on their positions for modernization, circulating letters against a complete re-engine and in support of adaptive engine technology.

Support for Pratt and GE is largely led by lawmakers from the companies’ respective home states of Connecticut and Ohio, but a new majority in the House will see committee gavels to change hands.

Key power shifts will occur in the House Appropriations Committee, currently chaired by Rep. Rosa DeLauro (D-CT), and on the House Armed Services Committee, where incumbent chairman Adam Smith (D-WA) has been vocal about his support for an adaptive engine. Incoming Armed Services Chair Mike Rogers (R-AL) has yet to publicly state his position on an engine upgrade.

“There are calculated risks on either branch, and it’s going to be a tough call,” the government analyst said. “I think a lot of this is going to come down to whoever screams the loudest and has the most political clout.”