GAO finds risk of additional delays to F-35 programme

US Air Force F-35A Lightning II. F-35 deliveries are on hiatus until the Department of Defense certifies the TR-3 configuration for service. (US Air Force/Staff Sergeant Zade Vadnais)

The US Government Accountability Office (GAO) found that problems with F-35 hardware and software have led to delays and cost overruns, the agency said in a report released on 16 May.

In 2023 most Lockheed Martin F-35s and the Pratt & Whitney (P&W) F135 engines that power them were delivered late, with the risk of delays to future deliveries.

“The engine contractor – Pratt & Whitney – did not deliver any engines on time in 2023,” noted the GAO. “Furthermore, in 2023, engines were delivered more than 2 months late, on average, compared with 1 month late in 2022.”

Engine deliveries were suspended following a December 2022 crash of an F-35B during a Department of Defense (DoD) acceptance evaluation flight. The cause was traced to harmonic vibrations in an engine fuel delivery tube, which cracked under the strain. Deliveries resumed in February 2023 following the development of a fix to prevent such resonance.

P&W has delivered a majority of engines late since 2018, with delays worsening each year. The impacts have been limited, the GAO said, because the DoD took delivery of unused engines until they were needed for operational or newly manufactured jets.

The GAO credited P&W for implementing a self-funded USD100 million quality improvement programme, which cut reported quality defects on each engine from an average of 1,443 in 2021 to 647 in 2023.

Nor is Lockheed Martin delivering completed F-35s on time, which the GAO ascribed to a variety of causes, the engine delays following the December 2022 grounding being only one of them.