The worldwide fleet of F-35 Lightning II aircraft was grounded for inspections 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 F-35 Joint Program Office (JPO) requested on 10 October that the US Air Force, Navy and Marine Corps inspect the aircraft’s Pratt & Whitney F135 turbofan before flying again. Some aircraft have already resumed flights after inspections.

“If suspect fuel tubes are installed, the part will be removed and replaced. If known good fuel tubes are already installed, then those aircraft will be returned to flight status,” the JPO says in a statement. “Inspections are expected to be completed within the next 24 to 48 hours.”

Lockheed Martin has delivered more than 320 F-35s to the US military and international customers.