MINNEAPOLIS (AP) — Boeing Co. said Wednesday that some kind of foreign debris probably caused the electrical fire aboard a test flight for one of its new 787s earlier this month.
The company said is making "minor design changes" to the plane's power-distribution panels and is working on a plan to resume test flights of the much-delayed plane.
Boeing doesn't know what the foreign object was, because whatever it was burned up in the fire, spokeswoman Lori Gunter said.
"It was small, it wasn't as big as a tool," she said. "A tool would leave evidence."
The Chicago-based company said its engineers believe the problem began as either a short circuit or an electrical arc in a power distribution panel, "most likely caused by the presence of foreign debris."
Boeing said it simulated key aspects of the Nov. 9 fire in a laboratory, and is fixing the design to shield the panel. It also plans software changes, the company said.
The panel is one of five major power distribution panels on the 787, receiving power from the left engine and distributing it to a variety of systems.
The fire broke out as the plane was approaching Laredo, Texas, forcing an emergency landing. It caused smoke in the cabin and some structural damage.
The plane will soon be returned to Seattle, the company said.
Boeing has been flight-testing the 787, which it calls the Dreamliner, aiming to deliver the first one to Japan's All Nippon Airways around February, which would be nearly three years later than originally hoped.
That seems increasingly unlikely, and an additional delay is widely expected. On Wednesday, Boeing said it would present a plan to resume flight testing to the Federal Aviation Administration as soon as it is complete. It didn't say when that would be. It said a revised 787 schedule would be finished in the next few weeks.
The 787 is made mostly of composite materials designed to make it lighter and more fuel-efficient than other planes of the same size.
Boeing shares on Wednesday rose $1.81, or 2.9 percent, to close at $65.41 on anticipation that any delay news wouldn't be as bad as some people had feared.