A worn-down component in the forward section of United Technologies Corp's F135 engine for the F-35 fighter jet may have caused the tip of a fan blade to break off during testing, the company said on Friday.

A spokesman for Pratt & Whitney, the United Technologies unit doing the work, said the modifications will be minor and would result in little to no disruption in cost or schedule.

The company said earlier this week that the engine, which it builds for the Lockheed Martin Corp F-35 fighter jet, was damaged during a qualification test last week.

The engine had been tested for five hours at supersonic conditions and endured the equivalent of 8 years of use, a Pratt program expert told reporters Friday.

The findings of the investigation are preliminary, said Matthew Perra, the Pratt spokesman.

The worn-down component, called a bushing, was located in front of the fan. All the bushings in the engine were severely degraded and two were missing, the program expert said.

While Pratt continues to verify the cause, it will clip the trailing-edge tip of the fan blade to prevent any loose parts from damaging the engine, a common industry practice, the expert said.

The expert also said this was not a design flaw issue, but a function of a periodic maintenance issue.

(Reporting by Deepa Seetharaman; Editing by Gary Hill)