“Other numbers cited, obviously have to do not just with the acquisition of the F-35 but operations of the F-35,” he said. “There’s more than one number, there’s more than one cost depending on what you’re counting. These things have all been well known for some time. But in terms of our numbers, I’ve been very clear.”
The PBO wrote in its report that a “rough” cost for the overhaul and upgrade for a single plane was “estimated at US$ 30.38 million +/- US$ 5 million per aircraft,” bringing the total overhaul costs over 30 years to that $3.9 billion. Going off the PBO’s analysis, calculating the costs of the program over 20 years rather than 30 would eliminate having to account for the second predicted overhaul of the fleet (which, according to the graph, would take a few years to complete).
With a 20-year projection, at least half the overhaul costs (those made at, or after, the 20-year mark) are discounted, along with whatever further costs incurred afterward up to (as the AG suggested) 36 years. So, the overall price comes down.