Mechanics at the Boeing Company began final assembly work on the first 777 Freighter at the company's Everett, Wash., facility this week.

Based on the 777-200LR Worldliner passenger model, the first cargo aircraft of its size will roll out of the factory in late April, the company said. Test flights will take place in the summer. The 777 Freighter is expected to fly farther and provide more capacity than any other twin-engine cargo airplane.

Boeing said it will deliver the first 777 Freighter to its launch customer Air France in the fourth quarter of 2008. Eleven customers around the world have ordered 78 of the aircraft.