The Air Force’s version of the F-35 Joint Strike Fighter can fly in lightning and thunderstorms again after the service lifted a restriction that had been in place for four years.

The F-35 Joint Program Office confirmed in an email that the 2020 standoff restriction placed on the aircraft, officially called the Lightning II, was lifted on March 19. The news was first reported by Breaking Defense.

The military stopped F-35As from flying within 25 miles of lightning after a problem was discovered with its Onboard Inert Gas Generation System, or OBIGGS, which is meant to keep the jet safe from strikes. OBIGGS pumps nitrogen-enriched gas into the F-35′s fuel tank to render it inert, and keep the fuel tanks from exploding if struck by lightning.

In 2020, maintainers conducting depot maintenance on an F-35A at Hill Air Force Base in Utah found that one of the tubes that distributes the gas to the fuel tank was damaged. Subsequent inspections found problems with tubes in multiple other F-35s, and the military restricted it from flying near lightning until a fix could be developed.

F-35Bs and Cs were not affected by the lightning problem and did not have their flying restricted.

In a statement to Defense News, F-35 manufacturer Lockheed Martin said, “The F-35 remains the most capable aircraft in providing global 21st century security that protects the United States and our allies.” BAE Systems, which makes OBIGGS, was not immediately available to comment.

The JPO said the fix included “a more robust” design for the fighters’ OBIGGS hardware, as well as updates to its software. The modification was tested both in the lab and in flight. It credited government and industry engineers for finding a solution to the lightning restriction problem. The JPO declined to further detail how the system was fixed, or how many F-35As have been modified, due to operational security concerns.

“The fix restores operational capability, while providing additional safety for the pilots and aircraft,” the JPO said.

This story has been updated with a statement from Lockheed Martin.

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at He has traveled to the Middle East to cover U.S. Air Force operations.

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