Pentagon grounds entire F-35 Joint Strike Fighter fleet

The U.S. Department of Defense has suspended airborne testing of its Joint Strike Fighter because of a crack in an engine turbine blade discovered during routine inspection, the Pentagon said this week.

The grounding covers every one of the three versions of the F-35 involved in the $396 billion program -- 51 fighter jets that had hitherto been active for testing and training and have been described by the Pentagon as "the most affordable, lethal, supportable, and survivable aircraft ever to be used."

Just 10 days ago, one of the three versions of the fighter, the F-35B, designed for the Marines, was cleared to resume tests after a monthlong suspension having to do with a fuel line defect.

To understand the specific cause of the current issue -- the cracked turbine blade discovered February 19 -- the engine is being returned to the manufacturer: United Technologies unit Pratt & Whitney. The Pentagon said it hopes to return the fleet to the air as soon as possible.

Eventually, there will be more than 2,400 of the next-generation fighter jets, which will come in three models: the Air Force's agile F-35A, the Marines' VTOL model F-35B, and the Navy's F-35C, which has a larger wing surface and reinforced landing gear to withstand catapult launches and deck landings on an aircraft carrier.

The Pentagon stressed yesterday that the grounding is precautionary and that it's not possible to know the impact of the crack on the low pressure turbine blade until the investigation is complete.

Additional delays aside, the warplane is currently expected to formally take to the skies and be battle-ready in 2018 or 2019.