March 7 (Reuters) - Pratt & Whitney is investigating a crack in the jet engine that powers the F-35 Joint Strike Fighter aircraft, causing damage but posing no immediate risk to jets now in use, the company confirmed on Friday.
The crack occurred in a bladed rotor at the front of the engine, damaging the rotor and the engine, known as the F135, said Pratt, a unit of United Technologies Corp.
The F-35 is the latest-generation fighter jet designed for use by three branches of the U.S. military and sold to foreign governments. At nearly $400 billion, it is the most expensive weapons program in Pentagon history and has been restructured three times, partly in an effort to cut costs.
Pratt said it had determined the incident, which occurred during ground testing in December, did not pose a flight safety risk and would have no immediate impact to the fleet in operation. The engine in question had about nine years worth of service as a test engine, more than 10 times the hours of any operational F135 engine, according to the company.
"We perform aggressive accelerated mission testing of our developmental engines at or near design limits on purpose," Pratt said in a statement. "The nature of development testing is to push the hardware at these boundaries so that we can find and fix any issues early and prior to occurrences in flight."
Aviation Week earlier reported that Pratt was investigating the engine issue.
The engine maker said it had already started redesigning the bladed rotor, even before the incident, as part of an effort to reduce overall engine costs.
The new design will include solid blades, rather than the current hollow blade design, and allow for simpler manufacturing techniques, according to a company spokesman.
It plans to offset the change in weight elsewhere in the engine to meet overall weight requirements for all F-35 variants.
Joe DellaVedova, spokesman for the Pentagon's F-35 program, said the redesign would add about six pounds of weight to the engine, but it would also make the part easier to manufacture, reducing costs.
He said the cost of the redesign, as well as which party would shoulder the cost, would be discussed with the company during contract negotiations.
"This is all part of learning about the durability of the F135 propulsion system," DellaVedova said. "Findings and discoveries are to be expected on test articles."