After completing inspections, more than 80% of operational Lockheed Martin F-35 Lightning II aircraft flown by US services and international partners have been cleared for flight operations.

The worldwide fleet of Lockheed Martin F-35 aircraft was grounded for inspections on 11 October after a problem with the aircraft’s engine fuel tube was discovered, which is believed to be related to the first crash of the stealth fighter a few weeks ago. The incident was the first ever crash of any variant of the F-35 since the aircraft began flying 12 years ago. The pilot safely ejected from the aircraft.

Operators of the stealth fighter are drawing upon current fuel tube inventory, while Pratt & Whitney, the manufacturer of the aircraft’s F135 turbofan, is rapidly procuring more parts to minimise the overall repair timeline for the remaining jets, says the F-35 Joint Program Office (JPO). Current inventory should restore about half of the impacted jets to flight operations, and the remaining aircraft are expected to be cleared for flight over the coming weeks.

“The action to perform the inspection resulted from the ongoing investigation of the F-35B that crashed in the vicinity of Beaufort, South Carolina on 28 September. The aircraft mishap board is continuing its work and the US Marine Corps will provide additional information when it becomes available,” says JPO. “The issue is not expected to impact F-35 deliveries and the program remains on track to meet its target of 91 aircraft for the year.”

Lockheed Martin has delivered more than 320 F-35s to the US military and international customers. The fuel tube issue impacted all three variants of the aircraft: The F-35A conventional takeoff and landing variant, the F-35B short take-off and vertical-landing variant, and the F-35C carrier-based variant.