The crack was found in an F-35A Lightning II aircraft at Edwards Air Force Base in California.
The stealth fighter aircraft has one engine and one seat and is designed for tactical bombing and aerial warfare. It's flown by air force, navy and marine corps divisions of the U.S. military.
The U.S. Department of Defence is working with Lockheed Martin and United Technologies Corp.’s Pratt & Whitney unit — the maker of the engines — to investigate the matter further.
All versions — a total of 51 planes — were grounded Friday pending a more in-depth evaluation of the problem discovered at Edwards. None of the planes have been fielded for combat operations; all are undergoing testing.
The F-35 is the Pentagon's most expensive weapons program at a total estimated cost of nearly $400 billion US. The Pentagon envisions buying more than 2,400 F-35s, but some members of Congress are balking at the price tag.
In a brief written statement, the Pentagon said it is too early to know the full impact of the newly discovered problem. The suspension of flight operations will remain in effect until an investigation of the problem's root cause is determined
Canada was planning to purchase 65 F-35s to replace the CF-18 Hornets. The purchase is currently on hold, following a report released in spring 2012 by the auditor general that said costs were understated by defence officials and the Canadian government did not run a fair bidding competition regarding the planes.
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