NTSB sees no anomalies in 787 battery cells; more tests

The cause of a Jan. 7 battery fire on a Boeing 787 remains unknown Friday as officials bring in more battery experts and continue their investigation.

The National Transportation Safety Board released a seventh update on its investigation into the fire last month aboard a Japan Airlines 787 parked at Logan International Airport in Boston. Boeing's 787 has been grounded since Jan. 16.

Here's a list of new information from the NTSB:

• The auxiliary power unit battery was the original battery delivered with the airplane on Dec. 20, 2012. All eight battery cells came from the same manufacturing lot; the battery was installed on the aircraft Oct. 15, 2012.
• Testing this week, which includes electrical and mass measurements and infrared thermal imaging, shows no anomalies in the individual battery cells.
• The cells are undergoing CT scanning to examine their internal condition.
• A battery expert from the Department of Energy joined the investigative team on Thursday to lend his expertise to the ongoing testing and validation work.
• Next week, the NTSB battery testing team will initiate a non-invasive "soft short" test of all battery cells to find high resistance or "soft" shorts within a cell.
• An NTSB investigator will travel to France with the battery contactor from the JAL event battery, for examination at the manufacturer. The battery contactor connects a wiring bundle from the airplane to the battery.

Meanwhile, Japan's Civil Aviation Bureau is sending investigators to Everett -- one of two sites where Boeing assembles its Dreamliner. Japan's aviation officials are investigating a Jan. 15 battery failure aboard an All Nippon Airways 787. That aircraft was forced to make an emergency landing in Japan.

ANA, the Dreamliner's launch customer, said yesterday that the jet's grounding has cost it about $15.4 million in lost revenue.