F-35 Joint Strike Fighter: Actions Needed to Address Late Deliveries and Improve Future Development (GAO-25-107632)

The F-35 program continues to experience late deliveries […] Lockheed Martin delivered all 110 aircraft late in 2024 due to TR-3 hardware and software delays and continuing parts shortages. Additionally, the average number of days each aircraft was late grew from 61 days in calendar year 2023 to 238 days in calendar year 2024

Lockheed Martin has delivered every lot of aircraft with major variance […] requests (MVR), which are contractor requests to deliver aircraft that do not fully meet the contract specifications. […] In June 2025, the F-35 program requested over $283 million to correct some aircraft defects and deficiencies associated with MVRs, among other things.

The F-35 program continues to experience late deliveries […] In 2024, Pratt & Whitney delivered all 123 engines late due to production and supply chain issues. […] Pratt & Whitney delivered engines an average of 68 days late in calendar year 2023 and 155 days late in calendar year 2024—a worsening trend over the last 3 years.

Pratt & Whitney identified seven MVRs on the engine in 2024. Although there are fewer engine MVRs than aircraft MVRs, the engine contractor is still not delivering engines to contract specifications after nearly 20 years of production.

The F-35 program negotiated an incentive fee structure for the engine […] Pratt & Whitney earned tens of millions of dollars in incentive fees because the value of the fees it earned for keeping total assembly time down more than offset the penalties levied on it for delivering engines late. This incentive structure and late delivery penalty was not effective at improving on-time deliveries