NEW YORK - Boeing said on Monday that the first flight test of its reworked battery system for the 787 Dreamliner went "according to plan," enabling it to move on to formal testing.
The successful mission means Boeing can conduct a second flight test that will gather data for the Federal Aviation Administration, which must approve the new system before the 787 can be used for commercial service.
Regulators grounded the global fleet of 50 Dreamliners in January after a battery burned aboard a jet on the ground in Boston, and a second battery overheated on a flight in Japan.
"During the functional check flight (on Monday), crews cycled the landing gear and operated all the backup systems, in addition to performing electrical system checks from the flight profile," Boeing spokesman Marc Birtel said in a statement.
The flight carried six crew members: two Boeing pilots, two instrumentation engineers, a systems operator and a flight analyst, Boeing said.
"More than 600 of these functional check flights were completed in 2012 across Boeing commercial airplane programs."
Resuming flights would be a huge boost for Boeing, which is losing an estimated $50 million a week while the 787 is grounded, and for airlines, which are barred from flying the 787. Boeing also is prevented from delivering the planes to customers during the grounding, though it continues to build them.
Some Boeing officials have said the jet could be back in service by May 1. But some experts cautioned it could take longer.
Oliver McGee, an aerospace and mechanical engineer who was a deputy assistant secretary of transportation under President Bill Clinton, said he was skeptical that federal regulators would allow the 787 to resume flights as early as May 1.
"Take whatever date is agreed upon and add three to six months to it," McGee told Reuters. "I don't think that you're going to see any type of quick fix or compromising on the FAA side."
Once data from the flight has been analyzed, Boeing said it would prepare for a ground and flight demonstration aimed at certifying the company's proposed changes to the battery system, a key step toward getting permission from the FAA to resume flights of the grounded plane.
Birtel said it wasn't clear if the demonstration test for the FAA would conclude Boeing's testing of the new battery system, which was unveiled in Tokyo on March 15. The tests are being conducted in the laboratory, in planes on the ground, and in flight.
"Obviously, progress is being made on all three fronts," Birtel said.
The battery system is made by Thales SA of France, while the battery itself is made by Japan's GS Yuasa Corp.
Boeing plans to conduct one certification demonstration flight using the same LOT plane, Line number 86, to show that the new battery system performs as intended during flight conditions.
Separately, the U.S. National Transportation Safety Board on Monday said it would hold a two-day forum April 11-12 to examine the design and performance of lithium-ion batteries in transportation -- a comprehensive review sparked by the battery failures on the two Boeing 787 Dreamliners in January.
The public forum will examine the design and development of various lithium-ion batteries, how their use and manufacturing are regulated, and the use and safety of such batteries in various modes of transportation.
The FAA grounded all 50 Boeing 787s in use worldwide in January after failures of two batteries on two separate aircraft - one parked at the Boston airport, and the other forced to make an emergency landing in Japan.