Dreamliner flies home

1,671.

That's how many miles one Boeing 787 Dreamliner is flying for the first time in three weeks, since U.S. civil aviation regulators grounded all Dreamliners due to several safety mishaps.

Thursday's flight is to ferry a plane from Fort Worth, Texas to Boeing's plant in Everett, just north of Seattle, Washington with only crew on board.

At an unrelated press conference, National Transportation Safety Board chairman Deborah Hersman says the NTSB has pinpointed the origin of a battery fire on a 787 in Boston last month to a single cell, but has not yet determined the cause of a short circuit in that battery.

SOUNDBITE: DEBORAH HERSMAN, CHAIRMAN, NATIONAL TRANSPORTATION SAFETY BOARD, (ENGLISH) SAYING:

"We have ruled out mechanical impact damage to the battery. All mechanical damage to the cells and the battery case occured after the initiating event, the short-circuiting in cell number 6."

And she plans to issue an interim report in 30 days.

SOUNDBITE: DEBORAH HERSMAN, CHAIRMAN, NATIONAL TRANSPORTATION SAFETY BOARD, (ENGLISH) SAYING:

"But, you know, we do have a long way ahead of us, and it really depends where the evidence leads us. One of the challenges in a fire, in any fire, is that the best evidence is often consumed by fire."

Hersman admits, because the Dreamliner is such an innovative plane, some of its new features were not addressed in the certification process.

SOUNDBITE: DEBORAH HERSMAN, CHAIRMAN, NATIONAL TRANSPORTATION SAFETY BOARD, (ENGLISH) SAYING:

"There are nine special conditions, there are nine factors that they need to take a look at in special conditions to the battery. And what we've seen that with respect to a number of those special conditions, and also the assumption that they would not have a smoke event less than once every ten million flight hours, that we have not seen that in the fleet performance. We have seen two events on two aircraft less than two weeks apart. So we know that some of the assumptions that were made to make sure that they didn't have a smoke event were not met, much less a fire event."

The 50 Dreamliners in service have been grounded since January 16th, while the NTSB, FAA and other aviation regulators around the world investigate battery troubles.