Pentagon expands probe of troubled components on fighter jet-sources WASHINGTON (Reuters) - The Pentagon is inspecting other components of the F-35 fighter jet in addition to the faulty fuel lines blamed for the grounding of the Marine Corps version of the warplane, two sources familiar with the program said on Friday. Vice Admiral David Dunaway, head of Naval Air Systems Command, asked for the expanded "material audit" this week after being briefed on plans by the Pentagon's F-35 program to resume training and test flights of the F-35B, the sources said. "There's too much at stake here," said one of the sources, who was not authorized to speak publicly. The grounding of the F-35B has raised questions about the ability of the $396 billion Joint Strike Fighter program to keep up with an aggressive flight test schedule for this year. Dunaway wanted to be certain that other components made by Stratoflex, a unit of Parker Hannifin Corp, for the Lockheed Martin Corp F-35 fighter jet did not have the same problems as the fuel lines. "He wants to assess the company's quality assurance practices and make sure they are doing business the right way," said the source. Dunaway's office was not immediately available to comment. It was not immediately clear how long the additional inspections would take and when the B-model would be cleared to start flying again. Dunaway is responsible for approving flights of the F-35Bs used for training, while the Pentagon's F-35 program office is responsible for approving test flights. "This is a prudent step which will help to ensure that when we're ready to return to flight we do so with confidence," said a second source, who was not authorized to speak publicly. The Pentagon this week began shipping fuel lines made by Stratoflex for CT scanning by an independent company in Minnesota after it determined improper crimping had caused a fuel line to detach just before a training flight at a Florida Air Force base on January 18, resulting in a grounding of the entire fleet of 25 F-35 B-model planes. The Pentagon on Monday blamed the problem on faulty manufacturing, not the component's design or maintenance, and said both engine maker Pratt & Whitney, a unit of United Technologies Corp, and its subcontractor, Britain's Rolls-Royce, were taking steps to beef up their quality control procedures. Stratoflex is a subcontractor to Rolls Royce. U.S. military officials had already decided to have all the affected fuel lines produced by Stratoflex inspected using CT scans since problems could not be easily detected otherwise, but Dunaway decided to have other components made by the company inspected as well. No comment was immediately available from Parker Hannifin, the parent company of Stratoflex. Earlier this week, a Parker Hannifan spokeswoman said the company makes many other components for the aircraft and was working around the clock to support the Pentagon investigation. Lockheed is building three different models of the F-35 fighter jet for the U.S. military and eight countries that helped pay for its development: Britain, Canada, Italy, Turkey, Denmark, the Netherlands, Australia and Norway. The Pentagon plans to buy 2,443 of the warplanes in coming decades, although many analysts believe U.S. budget constraints and deficits will eventually reduce that overall number. Reporting by Andrea Shalal-Esa; Editing by Lisa Shumaker