Boeing 787 catches fire at gate at Boston airport

Fire trucks surround a Japan Airlines Boeing 787 Dreamliner that caught fire at Logan International Airport in Boston, Massachusetts January 7, 2013.

BOSTON (Reuters) - A Boeing Co (BA.N) 787 Dreamliner aircraft with no passengers on board caught fire at Boston's Logan International Airport when a battery in its auxiliary electric system exploded, officials said.

A mechanic inspecting the Japan Airlines Co Ltd (9201.T) jet discovered smoke in the cockpit while performing a routine post-flight inspection and reported it to airport authorities at around 10:30 a.m. EST (1530 GMT), said Massport Fire Chief Bob Donahue.

A fire crew responded and determined that a battery used to power the plane's electric systems when the engines are not running had exploded, Donahue said. The mechanic was the only person on board the plane when the smoke was discovered and no one was hurt by the blaze, he added.

"Passengers were in no danger as this event had happened at least 15 minutes after they deplaned," Donahue said.

The fire is the latest reported mechanical failure in a string of incidents affecting the Dreamliner, which was also plagued by production problems that delayed initial delivery by 3-1/2 years.

The U.S. jet maker's shares fell more than 2 percent to $76.01 on the news.

Boeing spokesman Marc Birtel said, "We are aware of the event and are working with our customer."

Japan Airlines representatives did not immediately respond to a call for a comment.

Officials with the Federal Aviation Administration are now looking into what caused the fire, Donahue said. The National Transportation Safety Board also announced it was opening an investigation.

The 787 relies heavily on electrical power to drive onboard systems that in other jet models are run by air pressure generated by the engines. It also suffered electrical problems during testing that prompted a redesign.

The aircraft is Boeing's first to be made of carbon composites rather than aluminum, a change that lowers the plane's weight and allows it to burn less fuel.

The Dreamliner has suffered a string of mishaps with electrical systems in recent weeks. On December 4, a United Airlines (UAL.N) flight from Houston to Newark, New Jersey, made an emergency landing after it appeared that one of its power generators failed. On December 13, Qatar Airways said it had grounded one of its three 787 jets because of the same problem United had experienced. On December 17, United said that a second 787 in its fleet had developed electrical issues.

Boeing Chief Executive Jim McNerney last month argued that the 787 has not experienced an unusual number of problems for a new aircraft.

Boeing competes with European jetmaker Airbus (EAD.PA).

(Additional reporting by Alwyn Scott in New York; Editing by Leslie Gevirtz and M.D. Golan)