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Pratt & Whitney is proposing a Block 1 upgrade to its F135 engine, with hopes that the programme will be funded in a long-term budget plan starting after 2019, the company’s president of military engines says.

If funded in the 2019 programme objective memoranda, the upgrade could enter service by 2023, Bennett Croswell told FlightGlobal during a pre-Farnborough air show briefing in London on 10 July.

“It’s perfect timing, because that’s when engines start to come in for overhaul,” he says. “So an engine will come in for overhaul with the current capability, we’ll replace those parts that will improve the capability and it will leave the depot a better engine that [when it] came in.”

In April, P&W secured a $1 billion contract to fund the first 66 of the 167 F135 engines contained within the F-35 programme's next two lots of production. The proposed Block 1 upgrade would improve the baseline F135 engine, with 5-7% better fuel burn and up to 10% more thrust, Croswell says. That could increase the engine’s capability up to a thrust rating of 47,300lb (210kN).

But that increase could affect the lift system for the short take-off and vertical landing variant, Croswell notes. With an increased thrust on the back of the engine, P&W must keep the balance by increasing the thrust on the front, he says. While the company is in talks with Rolls-Royce and the US Navy, there is no technology programme for lift system components yet.

“The technology work to do it is about four or five years behind where we are on the engine,” Croswell says.