Pratt & Whitney is reportedly set to start testing a potential design change aimed at fixing the problem that led to the failure of the engine that powered the F-35 Lightning II joint strike fighter in June.

Two sources with knowledge of the matter were quoted by Reuters as saying that the testing would be undertaken at the company’s facility in West Palm Beach, Florida, following weeks of preliminary work.

One of the sources said the tests were initially supposed to start last week, but were postponed as engineers struggled with how to control the vibration of the engine during testing.

In June, one of the F-135 engines on a US Air Force F-35A conventional takeoff and landing variant broke apart and caught fire as the aircraft was taking off for a training flight from Eglin Air Force Base in Florida, US.

The incident prompted the US Department of Defense to ground the entire F-35 fleet for several weeks as a precautionary measure.

Although the F-35 flights resumed the following week, certain restrictions on speed and other manoeuvres still remain in place.

"The tests were postponed as engineers struggled with how to control the vibration of the engine during testing."

Pratt & Whitney spokesman Matthew Bates told the news agency that the company plans to conduct engine and rig testing this month to evaluate the suspected root cause of the engine failure and also test a proposed solution.

The company is working on a solution that would enable the F-35 test aircraft fleet to soon resume the full range of flight tests, Bates added, noting that work is also being undertaken on tests that would clarify the changes required for the operational aircraft fleet.

Bates also revealed that the company is expecting to complete talks soon for the seventh and eighth lot of engines with the Pentagon.

As of 2 September, the US military possesses a total 84 F-35 training jets and 19 test aircraft, according to the F-35 Program Office.

Image: An F-35A Lightning II fighter stationed at Eglin Air Force Base, Florida, US. Photo: courtesy of US Air Force photo/Samuel King Jr.

Defence Technology