Chairing the hearing, Sen. Dick Durbin lamented that the F-35 already has cost taxpayers billions more than what Congress signed up for more than a decade ago. The Democrat asked military leaders to justify costs that have soared more than 70 per cent and estimates that the entire programme could exceed USD 1 trillion over 50 years.
"The Joint Strike Fighter programme has had more than its share of problems over the last decade," Durbin said. "Frankly, its history reads like a textbook on how not to run a major acquisition effort."
Costs vary by the features in each model of the plane, but can reach USD 169 million per unit. An F/A-18 Super Hornet can cost half that much.
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Leaders of the US military's different branches stressed that costs were now decreasing.
Pentagon acquisitions chief Frank Kendall said that with the plane 90 per cent developed and testing almost half-done, officials were still focusing on creating a more stable design that would help bring production costs down.
"Indications are that this time these efforts are succeeding, but we still have a lot of work left to do," he told a Senate appropriations subcommittee. Kendall, who once criticized the decision to produce the F-35 ahead of its testing as "acquisition malpractice," said stopping production while all problems were worked through would have resulted in significant further costs and disruption.
Gen. Mark Welsh, Air Force chief of staff, said his service could not afford not to build the plane if the US is to maintain the air superiority it has enjoyed since World War II and prepare for emerging global threats.