(This first appeared as a Comment in Flight International 19 March 2013)
Should everything now go according to plan, the Boeing 787 will be flying passengers again before the Paris air show in June. The entire grounded fleet will be back in service within a few months. The battery crisis that erupted on 7 January may be a distant memory by year-end, barely even noticeable in Boeing’s results.
However, many questions about how the 787 got to this point and how Boeing has responded to this lithium-ion battery affair remain unanswered. Safety investigators in the USA and Japan still do not know why the 787′s lithium-ion batteries malfunctioned in two instances, but do understand why those malfunctions triggered a “thermal runaway” chain reaction. The explanation is simple enough to beggar belief that the overheating problem was not caught during certification. There is inadequate separation within and between each of the eight cells of the GS Yuasa-supplied batteries, and the overall enclosure and venting arrangement is insufficient for the power and temperatures produced by these 32V lithium-ion batteries.
Boeing’s plan, accepted by the US Federal Aviation Administration on 12 March, keeps the battery design and chemistry essentially unchanged, but improves the separation, containment and venting inside and around the cells. If the batteries ever malfunction again, these changes are aimed at preventing the first problem from causing a much larger second problem, such as a fire or the release of toxic smoke into the passenger cabin.
Boeing calls this plan a “permanent solution” for the 787′s battery problems; the FAA describes it as a “comprehensive” fix. Neither can know that for sure, however, until the safety investigations run their course.
More worrisome, potentially, is the lack of a back-up plan. Contrary to public messaging, Boeing has more than one option. Not all involve the drastic step of keeping the 787s grounded until the lithium-ion batteries are replaced with less powerful and proven nickel-cadmium batteries. A simpler path would be launching an alternate certification programme with nickel-cadmium, while continuing to pursue recertification of an improved installation of the lithium-ion batteries.
Lithium-ion batteries are a new and unproven aviation technology. The 787 is the only operational aircraft to use them as a primary back-up power source for the electrical system.
Boeing’s insistence on a lithium-ion-only recovery strategy may yet prove successful, but smacks of undeserved over-confidence. ■