Boeing has received approval from the US Federal Aviation Administration to test improvements to the 787 Dreamliner’s battery system — the first step in winning FAA approval to resume commercial 787 flights.
The fuel-efficient Dreamliner has been grounded since January following a lithium-ion battery fire on a Japan Airlines plane in Boston and an emergency landing by an All Nippon Airways jet in Japan, prompting the FAA to issue a global alert. Governments in the US, Japan, India and Europe all grounded the planes.
Boeing says it has improved the battery design, adding thermal and electrical insulation materials and other changes, to prevent faults from occurring and to isolate any that do.
The company also says it has improved its battery system production and testing processes. These now include more stringent screening of battery cells prior to battery assembly. Operational improvements focus on tightening of the system’s voltage range. A key feature of the new enclosure is that it ensures that no fire can develop in the enclosure or in the battery.
Boeing says it will announce additional design details in the days ahead.
The FAA also granted Boeing permission to begin flight test activities on two airplanes: line number 86, which will conduct tests to demonstrate that the battery fixes work as intended in flight and on the ground; and ZA005, which is scheduled to conduct engine improvement tests unrelated to the battery issue.
Meanwhile, the National Transportation Safety Board continues to investigate the cause of the Jan. 7 battery fire, and is reviewing the design, testing, certification and manufacturing processes for the 787 lithium-ion battery system. NTSB has issued an Interim Factual Report, but hasn’t concluded what caused the battery failure, nor made any recommendations.
Last month, Boeing informed airlines that further deliveries of the Dreamliner — of which 50 have been delivered to date — could be delayed because of the ongoing investigation.
The Dreamliners are designed to use 20 percent less fuel than similarly sized planes.
An analysis released by Lux Research in January said Boeing should have chosen a safer type of lithium-ion battery for its 787 Dreamliner planes. Lux says the Dreamliner uses a high-energy battery inherently at risk of thermal runaway, and should switch to an alternate type of lithium-ion battery.