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The Air Force has lifted a four-year ban that prevented its F-35 Joint Strike Fighter from flying in lightning and thunderstorms. This restriction, initially put in place due to safety concerns, was officially removed on March 19, marking a significant step forward for the aircraft known as the Lightning II.

The restriction occurred in 2020 after discovering a flaw in the F-35A’s Onboard Inert Gas Generation System (OBIGGS). The system, designed to prevent fuel tank explosions by filling them with nitrogen-enriched gas, was found to be compromised due to damaged distribution tubes. This defect was uncovered during maintenance at Hill Air Force Base in Utah, where it was observed that the tubes meant to safeguard the jet from lightning strikes were not functioning as intended. Further inspections revealed similar issues across multiple F-35A units, prompting a temporary flight ban near lightning-prone areas.

While the F-35A variant faced this limitation, its counterparts, the F-35B and F-35C, remained unaffected by the OBIGGS issue and continued their operations without restrictions. The resolution of this problem involved an exhaustive approach that resulted in new hardware for the OBIGGS and updating its software.

Lockheed Martin, the aircraft’s manufacturer, alongside BAE Systems responsible for the OBIGGS, focused on a more rugged design and rigorous testing to ensure the jet’s safety and operational capability. The government would not specify how many jets had to be modified, citing security reasons.

In a statement to Defense News, 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.