(Bloomberg) -- Lockheed Martin Corp.’s  F-35 may need $38 billion in extra engine overhauls in coming decades to meet increasing demands to help cool radar and other components of the fighter jet, according to government auditors.

“The cooling system is over-tasked, requiring the engine to operate beyond its design parameters,” the Government Accountability Office said Tuesday in its annual report on the $412 billion acquisition program for the F-35, the world’s costliest weapons system. “The extra heat is increasing the wear on the engine, reducing its life and adding $38 billion in maintenance costs.”

Barring an effective fix, engine overhauls that may come sooner than expected and will add another to-do item to the Pentagon’s $1.3 trillion estimate to operate and maintain the fleet of F-35s over 77 years of operation.

The engine issue concerns the aircraft’s “power and thermal management system,” which transfers pressure from the fighter’s single engine, directing the flow to cool other components. The more air pressure transferred, the hotter the engine runs.

The power system, based on specifications designed years ago by a Lockheed subcontractor, can’t keep up with the cooling demands of the jet’s increasingly complex avionics as well as new capabilities already installed or planned through 2035 during a current upgrade program called Block 4, the GAO said.

The GAO’s annual report also discloses that the cost of the Block 4 upgrade has grown by an additional $1 billion, to $16.5 billion, and that half of Lockheed’s 2022 aircraft deliveries were late. 

Global Interest

On the positive side for Lockheed, the F-35’s international profile has never been higher. Global interest has increased since Russia’s invasion of Ukraine and amid increased tensions with China. South Korea has indicated it wants more of the jets, and two US Air Force F-35 units have flown deterrence patrols over Europe. Twelve military services worldwide have declared the F-35 operational.

Asked about the cooling system issue before the release of the GAO report, Lockheed said in a statement that “capabilities have continued to mature based on customer needs” and it “has efforts underway to account for and support these requirements.” 

Lockheed said that the original design specifications for the power system were made by a team that included Lockheed, Pratt & Whitney, General Electric Co., Rolls Royce Plc and government representatives.

In separate comments before the GAO report was released, the Defense Department’s F-35 program office said the operational life of the F-35 engine is estimated to decrease by as much as 20%, including the Block 4 upgrades, because they are running hotter than originally designed. 

The crucial  “hot section” of the engine in the Air Force’s F-35A model is projected to need an overhaul every 1,600 flying hours rather than the specified 2,000 flying hours, it said. The Air Force is the largest F-35 customer.

The Pentagon’s F-35 program office said it’s “already very confident we can minimize” the potential $38 billion impact with a new “Engine Core Upgrade.” There are also multiple options under review to improve the cooling system that are in the early design phase, it said. Both improvements are expected to be deployed in the early 2030s, it said.

“Lockheed Martin developed and provided the engine performance and interface requirements” in 2001 “that the government put on contract to Pratt & Whitney,” the program office said.

Other GAO findings on the F-35:

  • The Pentagon is working to determine the root cause of a high-pressure fuel tube failure in December during a flight that temporarily led to a delivery halt.
  • The F-35 program is meeting about half its metrics for reliability and maintenance, including mean flight-hours between failures caused by contractor design issues.
  • The program has made progress in reducing the “Category 1” deficiencies that would jeopardize safety and security to five from 277 since 2006.
  • Pratt & Whitney, now a unit of Raytheon Technologies Corp., delivered only four of 127 F-35 engines on time in 2022 “even with multiyear efforts to address this long-standing issue.”
  • Parts shortages “have increased significantly in 2022 and Lockheed Martin is taking steps to address late parts that affect the production line.”

(Updates starting in 14th paragraph with additional GAO findings)

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