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Mr. LaHood denied that Boeing had asked the government to lift the grounding order.

“Absolutely not,” he said. “Boeing is cooperating 100 percent with the review.”

The groundings have been a nightmare for Boeing, which competes with Airbus for the position as the world’s largest commercial aircraft maker. At the time of the groundings, Boeing had orders for more than 800 of the planes from airlines around the world attracted by the 787’s increased fuel efficiency. The aircraft maker has said it has stopped delivering new planes to customers, although it is continuing to manufacture them.

The 787 is the world’s first airliner with a structure made mostly from lightweight composite materials. It also uses electronic systems for most of its functions instead of hydraulic or mechanical systems. And it is the first airliner to make extensive use of lithium ion batteries, which are lighter, can hold more energy and are easier to fit into odd-sized spaces in airplanes than other types of batteries.

The FAA certified the 787 battery system even though lithium ion batteries are more susceptible to catching fire when they overheat or short-circuit than other types of batteries. Boeing built several safeguards into the design of the battery system.