Pratt & Whitney believes it has solved the three problems with the lift-fan system on the STOVL variant of the Lockheed Martin F-35 Lightning II.
The issues were highlighted by US Secretary of Defense Robert Gates earlier this year and included the lift-fan driveshaft, roll-post nozzles and lift-fan clutch plates.
Both short- and long-term fixes are now in place, said P&W, whose F135 engine powers the fighter.
© Lockheed Martin
Bennett Croswell, president of military engines at P&W, said that in the case of the long-term change to the design of the driveshaft, it has actually cut production costs.
The engine manufacturer says it is still setting "aggressive goals" for cost reduction in line with an affordability plan agreed with the Department of Defense in 2009.
"When we look at that plan we are either in line with or the cost is lower than it," said Croswell.
However, he said that P&W is working with Rolls-Royce (chalet B89), which provides the lift-fan system, to "mitigate any kind of cost increase that will come from the substantial decrease in volume" due to a reduction in orders for the STOVL variant this year. Only three F-35Bs will be produced this year, down from a planned 17.
It cut the cost per engine by 15% between LRIP3 and LRIP4, said Croswell, and expects another fall for the LRIP5 contract,