IntellIgence No End in Sight for 787 Problems


The 787 lithium-ion battery problems have proved challenging for Boeing.


The Boeing 787’s lithium-ion battery problems— besides grounding the fleet worldwide—have left maintainers shaking their heads in puzzlement and frustration.


Initial hopes of a speedy resolution have fizzled, along with expectations of promptly published service bulletins on how to handle the problem. It may, in fact, turn out to be a something that lacks a simple fix. It may be a bigger issue, requiring a redesign and another round of tests and certification. The airlines and their maintenance personnel may be kept on hold for a protracted period. The battery test equipment interface is said to be extremely expensive. One MRO source says he knows of no airline maintenance shops that are able to do the testing. Given the current uncertainties, there would seem to be little incentive to invest in such equipment. Although Japanese investigators found no quality problems during their initial visit to the 787’s battery maker, GS Yuasa, U.S. National Transportation Safety Board (NTSB) Chairman Deborah Hersman said at a Feb. 7 press conference that the evidence suggests that short circuits within a single battery cell, which led to thermal runaway and cascaded to other cells, were the initiating events of the battery fire aboard a Japan Airlines Dreamliner parked at Boston’s Logan International Airport in early January. NTSB, however, indicated that the root cause of the Japan Airlines


787 fire remains to be found. In other words, what caused the short circuiting? Among the potential causes of the short circuiting which the agency is evaluating are battery charging, battery design and


6 Aviation Maintenance | avm-mag.com | February / March 2013


construction, and defects which might have been introduced in the manufacturing process.


The NTSB chief also cast doubt on the assumptions made in the Federal Aviation Administration (FAA) battery certification process. And Hersman called into question Boeing’s pre-certification assessments and tests and the company’s assertions that smoke emission events were extremely unlikely—less than one in every 10 million flight hours. On the contrary, she said, two critical battery events resulting in smoke happened less than two weeks apart on two aircraft in a fleet with less than 100,000 flight hours. Although the 787 model has experienced a string of engine and electrical problems, these were not deemed critical enough for regulators to take drastic action. But the recent battery problems— with their potential to cause in-flight emergencies or worse—were something else. Days after the Japan Airlines fire in Boston, another battery incident occurred aboard an All Nippon Airways jet, resulting in smoke and prompting an emergency landing. It also has come to light that All Nippon Airways maintenance personnel had had to replace 787 lithium-ion batteries 10 times before the event that triggered the worldwide grounding. The latest insight into the NTSB’s investigation is that the agency is considering whether dendrites, microscopic lithium “whiskers” that can build up inside lithium ion batteries, might be connected with the short circuits, according to a Wall Street Journal report. These structures can form if the battery is charged rapidly or unevenly, the report says. If dendrites prove to be part of the problem, the chances of a quick battery fix and return to service seem even less likely. Neither Boeing, United Airlines nor the FAA would comment for this story. United, which has experienced power panel problems, is currently the only U.S. operator of the 787. — By Charlotte Adams


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