U.S. Military Grounds F-35 Joint Strike Fighter

WASHINGTON (CNN) — The U.S. military on Friday grounded the F-35 fighter jet due to a crack in an engine component that was discovered during a routine inspection in California.

The Pentagon said in a statement that it was too early to assess the impact on the fleet of jets designed for use by the Navy, Air Force and Marines.

The nearly $400 billion Joint Strike Fighter is the Pentagon’s most expensive weapons system. It is currently being tested.

The program has been beset by cost overruns and various technical problems during development.

Currently, there 51 planes in the F-35 fleet.