Ground testing of the most complex version of Lockheed Martin Corp.’s F-35 jet has uncovered two small cracks the Pentagon describes as minor, according to a statement to congressional staff.
The cracks were discovered in late August during an inspection of the U.S. Marine Corps’ short-takeoff and vertical landing model that’s used in ground testing to evaluate an airframe’s long-term durability. The airframes are designed to last through 8,000 flight hours. They are tested on the ground to the equivalent of two lifetimes, or 16,000 hours.
The F-35B model is to be flown by the Marine Corps, the U.K. and Italy off amphibious warfare vessels and aircraft carriers. The $391.2 billion F-35 program is the Pentagon’s most expensive.
“Two minor cracks were identified” in one of the test aircraft’s four load-bearing “wing carry-through bulkheads,” according to a Pentagon statement provided to Bloomberg News.
The cracks were discovered after the aircraft accumulated more than 9,400 hours of ground testing -- or into its second 8,000-hour cycle.
“Because of the high hours accumulated on this test article, this discovery does not affect current F-35B flying operations, nor is it expected to impact” the Marine Corps’s plan for a 2015 declaration of initial combat operating capability, according to the statement.
“The costs and time frame associated with fixes to the current F-35B fleet are not known at this time,” according to the statement. “Depending on when the appropriate engineering solution is incorporated into the production line, about 50 F-35Bs will require bulkhead repairs.”
The initial estimates indicate any modification would add less than 2 pounds to the aircraft’s weight, according to the statement.
As of September, 37 F-35B models have been delivered, including models used by the Marines and the U.K. for pilot training.
“A combined effort by government and Lockheed Martin engineering teams is under way to address modifications to the bulkhead that will be incorporated into production and the fleet as part of the normal program,” Kyra Hawn, a spokeswoman for the Pentagon’s F-35 office, said in a statement.