Multi-Billion Dollar F-35 Fleet Grounded Tom Reynolds/Lockheed Martin The military has grounded its entire fleet of F-35 stealth fighters, the most expensive weapons program in history, after finding a crack in one of the multi-million-dollar plane's engines. The grounding comes just days after the Marine Corps gave its variation of the fighter the green light to fly again after its own month-long grounding for an unrelated problem. The F-35 Joint Strike Fighter program office released a statement today saying a routine engine inspection on Feb. 19 "revealed a crack on a low-pressure turbine blade of an F-35 engine" and the office took the "precautionary measure" of suspending all F-35 flight operations. The F-35 Joint Program Office is working closely with [engine maker] Pratt & Whitney and [primary plane manufacturer] Lockheed Martin at all F-35 locations to ensure the integrity of the engine, and to return the fleet safely to flight as soon as possible. The F-35 Joint Strike Fighter program, which has a baseline price tag of over a third of $1 trillion as of last March, represents America's costly foray into fifth-generation stealth fighters along with the troubled $79 billion F-22 Raptor. The plane comes in three variants: an Air Force version with standard takeoff and landing capabilities, a Navy version designed to take off and land from aircraft carriers and the Marine version, which is designed to land vertically like Britain's famous Harrier jet. The military currently has 58 planes total, but plans to purchase more than 2,400 more in order to replace the aging F-16 and F-18 legacy fighters. The F-35 program has suffered a long history of delays and cost overruns, which officials said is partially because it is one of the most complex weapons systems in history and because it was put into production far too early - before major issues could be found. This time last year Frank Kendall, then the Pentagon's Acting Undersecretary for Defense Acquisition, Technology and Logistics, said that the government's plan to field the plane was so reckless it amounted to "acquisition malpractice." The engine itself has not been without controversy as well. For months General Electric teamed up with Rolls Royce to provide the military with an engine to compete with Pratt & Whitney, even though the military repeatedly said a second engine was not necessary. The alternate engine was partially funded by the U.S. government to the tune of $3 billion before it was called off in December 2011. Despite its well-documented problems, the F-35 is seen by top military and government officials as the backbone of America's future air power. The F-35 Program Office said it is currently investigating the cause of the engine crack. READ: F-35 Stealth Fighter Cost Increases by Billions