19d • General discussion
Boeing 787: a More Electric Aircraft
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The development of the Boeing 787 Dreamliner represented a radical departure from traditional aerospace engineering, moving toward a "More Electric" architecture that replaced heavy pneumatic systems with electrical actuators. To power this leap in technology, Boeing selected Lithium-Ion (Li-ion) batteries due to their superior energy density and weight savings compared to traditional nickel-cadmium alternatives. However, the path to innovation was rocky; even before the 2013 grounding, the flight test program faced a setback in 2010 when a test aircraft (ZA002) suffered an onboard electrical fire in its power distribution bay. This early incident, attributed to foreign object debris (FOD) causing a short circuit, served as a precursor to the systemic electrical challenges that would later plague the fleet's entry into service.
The primary "fires" associated with the 787 occurred in January 2013, when two separate aircraft operated by Japan Airlines (JAL) and All Nippon Airways (ANA) suffered catastrophic battery failures. The JAL incident involved an auxiliary power unit (APU) battery catching fire while the plane was parked in Boston, while the ANA flight was forced to make an emergency landing in Japan after pilots detected smoke in the cockpit. These back-to-back events led to a historic decision by the FAA to ground the entire global 787 fleet—the first time an entire aircraft type had been pulled from service since the DC-10 in 1979. The grounding lasted four months as investigators and engineers scrambled to identify the root cause of the smoke and flames emanating from the aircraft's electronics bays.
Technically, the failures were identified as a phenomenon known as thermal runaway. Investigators discovered that an internal short circuit in a single cell, likely caused by manufacturing defects, microscopic "dendrites," or contamination, triggered a cascading chain reaction. As the first cell overheated and vented flammable electrolyte, the heat transferred to adjacent cells, causing the entire 8-cell battery pack to fail in a violent release of toxic smoke and high-temperature fire. The NTSB later criticized Boeing's original safety assessments, which had predicted such a failure would occur only once in every 10 million flight hours; in reality, two failures occurred in less than 52,000 hours, revealing a significant "blind spot" in the industry’s understanding of large-scale lithium-ion behavior in aviation.
To resolve the crisis and restore regulatory and public confidence, Boeing chose not to abandon lithium-ion technology but instead adopted a containment-based safety architecture. The redesign combined measures to reduce failure likelihood, such as improved cell insulation, tighter manufacturing controls, and revised charging logic to limit electrical and thermal stress, with a fundamental shift in system philosophy. The battery was housed within a sealed stainless-steel enclosure capable of withstanding internal fire, overpressure, and toxic gas release, and connected to a dedicated overboard vent that safely expels smoke and combustion byproducts outside the fuselage. This approach explicitly assumed that a worst-case battery failure could still occur and ensured that its consequences would remain fully isolated from the aircraft. The resulting design established a new benchmark in aerospace energy storage, marking a shift from failure prevention alone toward certified failure tolerance and containment.
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Boeing 787: a More Electric Aircraft
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