The Pentagon has ordered that engines on its F-35 Joint Strike Fighters must be inspected before the planes can resume flying.
The order, issued June 13, came in response to “an in-flight emergency” on June 10, when a Marine Corps version of the plane had to return to base at Air Station Yuma, Arizona, after its engine lost oil. There were no injuries, according to a Defense Department statement.
Inspections of three other planes at the station revealed “suspect findings,” the Pentagon said in the statement. Engines inspected at other bases have turned up no defects so far, it said. Planes that pass inspection will be allowed to return to service, while those with defects will remain grounded until repairs are made, the Pentagon said in its statement.
The examinations are focused on a valve regulating oil flow in the engines, which are made only by United Technologies Corp.’s Pratt & Whitney unit.
The F-35 is the Pentagon’s most expensive weapons program. The projected cost to develop and produce the fighter jet, built by Lockheed Martin Corp., has risen 1.9 percent in the past year to $398.6 billion, for an eventual fleet of 2,443 planes, according to Pentagon estimates released in April.
Frank Kendall, the Pentagon’s top weapons buyer, said last week the plane has yet to demonstrate sufficient reliability.
There has been “some marginal evidence of improvement, but it’s not enough,” Kendall told reporters June 12.
The Pentagon in March withheld funds from Pratt & Whitney because of delays in delivering engines stemming from quality flaws and technical issues.