THE first of Boeing Co's highly anticipated 787 jetliners is on track for a June "power on" milestone, and subsequent planes are arriving at the final assembly floor in better and better shape, according to the executive in charge of the 787 program.

Boeing invited reporters into its 40-hectare production area on Monday to show that the aircraft maker has overcome parts shortages and hiccups in its new, decentralized manufacturing model and is making steady progress toward the 787's much-delayed first flight.

Last month, Boeing postponed the jet's debut in commercial service until the third quarter of 2009. The latest delay was the third revision to its delivery schedule. The delays will likely cost the company billions of dollars in costs and penalties.

Inside the massive hangar, four planes were lined up nose-to-tail in varying states of completion. Patrick Shanahan, general manager for the 787 program, said the mood on the assembly floor had shifted from frustrated to "fired-up" in the last two months as the installation of critical systems on Plane No. 1 neared completion.

But despite seven-day work weeks, Shanahan said he expects some of the pieces of the first plane to come together at the last moment in a "photo finish," and joked someone tosses the equivalent of a grenade into his office every half hour or so.

Powering up the 787 for the first time - a major milestone, but one of many that remain before Boeing can deliver the first of its new planes - will show the company how successful its next-generation production model really is. The company relied almost entirely on outside companies to manufacture, test and put together major parts of the aircraft.

The 787, Boeing's first newly designed jet since airlines started flying the 777 in 1995, will be the world's first large commercial airplane made mostly of carbon-fiber composites, which are lighter and more durable than aluminum and don't corrode like metals.

Boeing says it will be cheaper to maintain and offer greater fuel efficiency than comparable planes flying today.