(Reuters) - Boeing Co (BA.N) contractually delivered its first 787-9 to Air New Zealand (AIR.NZ) on Monday, allowing Boeing to book the delivery of the new, stretched Dreamliner in its second-quarter results.
 
Delivery of the 787-9, the latest of Boeing's carbon-composite aircraft, marks a major milestone for Boeing, showing the company's ability to move rapidly and on schedule through design, fabrication and testing.

Boeing has said for months that it would deliver the first 787-9 around mid-year, and it hit that date precisely on Monday.

"Boeing is proud to have contractually delivered the first 787-9 Dreamliner to Air New Zealand," spokesman Doug Alder said.

The Dreamliner uses lightweight plastic construction and a newly developed electrical system to replace heavier metal systems on older planes. Coupled with new engines produced by General Electric (GE.N) and Rolls-Royce Holdings PLC (RR.L) it offers 20 percent fuel reduction over existing, similar-sized aircraft.

Boeing struggled with early production of the smaller 787-8, and a number of those jets required extensive reworking and modification. The Dreamliner also has had problems with lithium-ion batteries that grounded the fleet for more than three months last year and required extensive modification of the battery system.

The 787-9 incorporates all of those changes along with a fuselage that is about 20 feet longer than the 787-8. The "dash nine" carries 38 more passengers than its predecessor, up to 280, in a typical three-class configuration, with a range of about 8,300 nautical miles, about 450 miles more than the 787-8.

The plane got Federal Aviation Administration approval in June, including the ability to operate extended operations (ETOPS) flights up to 5-1/2 hours away from a diversion airport, enabling it to fly certain long-range routes.

Boeing has said the 787-9 includes numerous refinements over the earlier model, including a laminar flow control system on the tail that helps reduce drag and improve fuel efficiency.

A longer Dreamliner, the 787-10, that seats up to 323 passengers, was launched last year and is due for first delivery in 2018.

Air New Zealand said it plans to take physical delivery of its new 787-9, painted with a striking black livery, on July 9 and fly it away from Seattle on July 10.

The plane is due to enter service with the airline on Oct. 15, likely after All Nippon Airways (9202.T) begins service with 787-9s that are due for delivery in July.

ANA already operates the smaller 787-8, and so requires less flight training to fly the bigger version.

Boeing has sold the 787-9 to 25 customers, including American Airlines (AAL.O), British Airways (ICAG.L), Japan Airlines (9201.T) Air France (AIRF.PA) and Air Canada (ACb.TO).(Reporting by Alwyn Scott)