The “War on Cost” is a priority at Pratt & Whitney Military Engines, made more difficult as U.S. military budget constraints stretch out the delivery schedule for the F-35 Lightning II fighter and its PW F135 powerplant. “We face stronger headwinds,” says P&W Military Engines president Bennett Croswell. “But we continue to make progress.”

Pratt & Whitney’s goal is to bring the cost of the F135 down to that of the F119 from which it is derived, even though the new engine has more power and less weight. Production of the F119, which powers the F-22 fighter, ended last year.

Engines for the F-35 are contracted in batches, with cost reductions for each batch negotiated with the Pentagon’s F-35 Joint Program Office. The signing last month for the fifth batch of low-rate initial production (LRIP-5) engines came with a 6% price reduction from LRIP-4, representing a $3 million savings per engine in just the last two years. “And since 2009, we’ve taken out 40% of cost,” Croswell says.

The $1 billion contract for LRIP-5 includes 32 installed and three spare engines, sustainment, support and spare parts. In addition, P&W assumed 100% of the risk of any cost overruns. “We had to do that for LRIP-6 anyway, but we did it a year early,” Croswell notes.

With 98 F135 engines now delivered and with more than 25,000 hr. of ground testing or flight experience, Croswell is so confident of the track record that he is proposing to offer a fixed-price, performance-based logistics program four years earlier than planned, with the company assuming any cost overruns.

“We are demonstrating the future support contract today,” he says. A notable feature is the ability to test engines in an aircraft instead of in a test cell; the F135’s variable geometry and software allow it to run at full speeds and pressures without developing full thrust.

Croswell notes that technologies continue to be developed for advanced military programs, and these could be called upon to increase the performance or reduce fuel burn in future F135s.

Among the technologies are the U.S. Air Force Research Laboratory’s adaptive engine technology development (AETD) for an adaptive, three-stream fan. “We’ve just completed the initial design review and we’re about to run a fan rig at our compressor research center in Dayton, Ohio,” Croswell says.

Another is the U.S. Navy’s variable cycle advanced technology (VCAT) demonstrator program, which brings AETD technologies to carrier-based aircraft.

“So you can see, we are in development, in production, and in sustainment,” Crosswell says.

Engine problems that led to two groundings of the F-35 fleet earlier this year “are all behind us,” Croswell says. “The fleet is flying safely, and we’re seeing mission readiness of 98%.”

The first grounding was after a turbine blade cracked in an aircraft using extreme pressures and thrust in an unusually severe test flight environment; no other incidents were found in the rest of the fleet.

The second was a supplier issue involving an improperly cramped hose fitting that resulted in a fuel leak. “That’s been resolved with the supplier,” Croswell notes.

The future is looking bright for Pratt & Whitney’s military engines business despite cuts in the U.S. defense budget and slowdowns in the Joint Strike Fighter program.

“After 2015 we’ll ramp up production for the F-35 and KC-46A tanker, and by 2020 we’ll be delivering 200 engines a year,” Croswell says.

Deliveries this year will be in the mid-50s, dramatically less than the 150 shipped last year. That’s because of the ending of production last November of the F119 engine for the F-22 fighter, and delivery of the last F117 turbofans for the 224 four-engined C-17 transports ordered by the U.S. Air Force.

Pratt & Whitney this year will deliver the first PW4062s for the new KC-46A tanker as production gets under way at Boeing on 179 aircraft for the USAF. But output of F135s for the Joint Strike Fighter will remain at about 50 through 2015, rising to 80 a year from 2016.

“Military Engines has a bright future. We just have to work through the next few years,” says Croswell.