Boeing delivered the first of four KC-767A aerial refueling tankers to the Italian Air Force last week.
The plane left Wichita on Tuesday and flew to Italy's air force facilities at Pratica di Mare, near Rome, the company said Monday. It arrived on Wednesday.
Boeing Wichita workers are performing the modification work to turn the four 767 commercial airliners into aerial refuelers.
Work on the second tanker continues, Boeing officials say.
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The company is not providing specific dates on when the remaining three tankers will be delivered to the Italian Air Force, Boeing spokesman Felix Sanchez said.
Boeing, working with the Italian air force, is enhancing the capabilities of the final two tankers, Sanchez said. He declined to specify what those enhancements entail. But that will delay their delivery.
The first tanker delivery was originally slated for 2005, three years after Boeing received the contract.
Boeing officials have said previously that the company faced penalties for delays in the contract.
The tanker that arrived in Italy will now undergo a series of tests before entering service, Defense News said.
The second aircraft is undergoing testing at Boeing, the report said.
Italy's tanker is configured for troop and cargo transport.
The aerial refueling boom is designed for NATO interoperability, Boeing said. The tanker can refuel using a boom system with wing-tip air refueling pods, or a centerline hose and drogue system.
It also features a refueling receptacle that makes it capable of being refueled in flight, giving it increased range.
Also last week, Boeing Wichita on Friday delivered the 11th C-40A transport aircraft to the U.S. Navy. It began deliveries to the Navy in 2001.
The plane is a modified Boeing 737-700 airliner equipped with a main-deck cargo door.
Boeing is under contract to deliver the 12th C-40A to the Navy later this year.