WASHINGTON, Sept. 17 (UPI) -- The Air Force grounded more than a dozen of its controversial F-35 Joint Strike Fighter jets because of crumbling insulation in fuel tanks, officals announced Friday.
The Air Force said 15 jets have been temporarily removed from service because of crumbling insulation in fuel tank lines spokeswomanAnn Stefanek said. The jets were stationed in Arizona, Nevada and Utah bases. Two of the jets belonged to Norway.
Another 42 F-35 jets, which are still in the Lockheed Martin production line, were also affected.
Stefanek said engineers are "currently developing procedures to resolve or mitigate the issue."
The F-35s are the most expensive in Pentagon history and have come under fire for their $400 billion price tag.
The aircraft was deemed combat-ready several weeks ago, though officials warned problems could still occur.
Lockheed Martin said the insulation issue is not widespread and is due to faulty parts and not the aircraft's design.
"This is not a technical or design issue; it is a supply chain manufacturing quality issue," the company said.