Because “the F35 JPO does not have an independent record of the global spares pool, and the values of the lost spare parts are not the fully burdened cost, the $85 million of identified losses by [the subcontractor] may not accurately represent the full quantity and value of lost spare parts,” the GAO found.

But worse than the unknown number of “lost, damaged or destroyed” taxpayer-funded equipment is fact that the F-35 Joint Program Office lacks the ability even to be aware of what spare parts are out in the world, thanks to how the supply chain for the fighter is set up.

https://breakingdefense.com/2023/05/over-85m-in-f-35-parts-are-unaccounted-for-gao-says-and-that-number-could-be-much-larger/

https://www.gao.gov/products/gao-23-106098