No Cause Yet Determined, Agency Says It Won't Rush The Airplane Back To Flight

In May of 1979, an American Airlines DC-10 went down departing Chicago's O'Hare International Airport following the separation of the number one engine from the wing. The accident resulted in the fatal injury of 273 people, including two on the ground.

In January of 2013, the battery of an ANA Dreamliner (pictured in NTSB photo) caught fire while sitting at the gate at Boston Logan International Airport. No one was injured, though other battery issues were soon discovered aboard other Dreamliners.

The Dreamliners have now been grounded longer than the DC-10 feet was following the Chicago accident.

The disparity may be partly due to the fact the the NTSB found that the Chicago accident was attributed to damage caused to the engine pylon during maintenance, and not a design flaw in the airplane. No definitive cause for the battery fire has yet been determined, but most say it will require a re-design of some or all of the components associated with the system. Boeing on Friday proposed a potential fix of the problem to the FAA, which those with knowledge of the proposal say includes modifications to the box which encloses the batteries, better venting of the case, monitoring of individual battery cells, and improved insulation between the cells to prevent thermal runaway.

But the Seattle Times reports that the FAA said following the Friday meeting that it will take Boeing's proposal and "analyze it closely," but the FAA said in a statement that the agency will not rush to get the Dreamliner fleet flying again. “The safety of the flying public is our top priority, and we won’t allow the 787 to return to commercial service until we’re confident that any proposed solution has addressed the battery failure risks,” the statement said.

A preliminary report on the battery incident is not expected from the NTSB until next month, and the FAA is likely to want extensive testing on what ever solution is implemented by the planemaker. Meanwhile, the FAA still says it plans to review the Dreamliner's certification process in an effort to determine how the potential battery issue was missed.

All Nippon Airways and Japan Airline, which operate 24 of the 50 Dreamliners already delivered, also have to contend with the Japan Transport Safety Board, which may be even more conservative than the NTSB.

FMI: www.faa.gov, www.ntsb.gov, www.boeing.com