* Airline suffers technical problems with both Dreamliners * Both aircraft now back in service OSLO, Sept 9 (Reuters) - Norwegian Air Shuttle said it grounded a second Boeing Dreamliner within a week for a technical problem and will seek compensation for its troubles with the high-tech aircraft. The airline operates two Dreamliners and lost use of both in the past week due to unrelated problems, forcing it to lease Airbus A340s on short notice, it said. The Dreamliner, which seats about 250 passengers, was expected to be a game-changer for the aviation industry as its use of lighter materials and new engines promised 20 percent savings in fuel consumption. But the program has been troubled by more than three years of delays in getting the planes into service and several incidents that have raised concerns about the plane's safety. Norwegian said one plane was stuck in Stockholm for five days because of a brake problem while the other was grounded in Oslo over the weekend because it would not receive power on the ground, requiring new parts. "We will talk to Boeing now and expect that Boeing will take their share of responsibility," said airline spokesman Lasse Sandaker-Nielsen. "Of course you expect some minor problems initially (with a new aircraft), but now we have experienced two incidents in a few days that have taken way too long a time to fix." Boeing said it had worked with Norwegian to fix the problems and that the aircraft were back in use. "We are committed to improving the 787's in-service dispatch reliability and are applying the resources required to achieve the results that we and our customers expect," said Boeing spokesman Marc Birtel. "We have a significant focus on component reliability improvements and working airline-by-airline to ensure we have the right support in place to help them through the entry into service process." He didn't say what had caused the planes to be grounded for so long. Boeing has a real-time customer support system and teams of technicians poised to respond quickly when an aircraft is on the ground for a mechanical problem. The Dreamliner suffered its biggest setback earlier this year when authorities grounded the entire fleet for more than three months after a faulty lithium-ion battery system caused two batteries to overheat, and in one case resulted in a fire. The system was redesigned, retrofitted on existing jets and added to new production. Despite the Dreamliner crisis, Boeing has a record order book and is expected to deliver more planes this year than at any time in its history. Investors, unperturbed by the plane's problems, have sent Boeing stock up more than 40 percent this year. Norwegian has three more Dreamliners on order and three it intends to lease three more to expand its transatlantic service. The eight-plane fleet is worth about $1.65 billion at list prices.