March 18, 2013
Boeing and 787 operators around the world may be breathing easier following U.S. Federal Aviation Administration approval of the manufacturer's battery system redesign certification plan, but the hard work is only just beginning,
As the grounding of the 787 stretches into an unprecedented 10th week, Boeing has been told by the FAA the aircraft will only be cleared to return to service after the manufacturer conducts “extensive testing and analysis to demonstrate compliance with the applicable safety regulations and special conditions.”
The question now for operators and Boeing is how much “extensive testing” will be required, particularly since this time around the process will also involve testing to a far more stringent level than when the 787 was first certificated. In addition to the standard FAA Part 25 certification requirements, the augmented test plan for the improved battery system for the first time includes guidelines published by the RTCA, formerly known as the Radio Technical Commission on Aeronautics. RTCA is a regulatory advisory committee which most recently has been guiding ruling on advanced navigation practices.
Boeing says the RTCA guidelines were simply not available in the 2000s when the original 787 battery certification plan was developed. Although much of the relevant RTCA committee battery and electrical system expertise resides within Boeing itself, the FAA appears satisfied with the overall certification plan, which will involve a series of tests that show how the improved battery system will perform in normal and abnormal conditions.
Among the tougher tests to be conducted will be an evaluation of the containment system's ability to withstand a deliberately induced thermal runaway. This self-propagating phenomenon was cited by the National Transportation Safety Board (NTSB) in its March 7 interim report on the first battery failure on a Japan Airlines 787 in early January. Although not identifying a specific cause, the report described several shortcomings in both the baseline battery system design and the original means of testing and certification of the device.
The NTSB has announced plans to hold a forum and investigative hearing in April to review the battery's technology, safety and process used in its certification. The agency's investigation found—among other things—no record of the final production-standard charging system having been tested with the actual GS Yuasa-made battery. According to the NTSB report, Securiplane, the charging system developer, tested the unit with a simulated electric load instead of an actual battery. The company apparently took this precaution after having earlier suffered a fire at its facility during battery testing.
News of the approval on March 12 was greeted with huge relief by Boeing, which proposed its redesign package to the FAA on Feb. 22. Since the original issues forced the grounding of the worldwide fleet on Jan. 16, the company has been focused on an urgent redesign effort. Boeing Commercial Airplanes President Ray Conner and 787 Vice President and chief project engineer Mike Sinnett unveiled the first official details of the battery system improvements at a press conference in Tokyo on March 14. The chief changes included a revision of the internal battery components to minimize the chances of initiating a short circuit, as well as better insulation of the cells and the addition of a new containment and venting system (see graphic, p. 28).