As Boeing begins modifying the defective battery design used on its 787 Dreamliner planes, it admits it may never know what caused the malfunctions which grounded the fleet in January. James Pozzi reports.
Leaders at aircraft manufacturer Boeing heaved sigh of relief in April as the US Federal Aviation Administration (FAA) approved design modifications and new safety measures for the lithium-ion batteries used on its mammoth 787 Dreamliners to power brakes and lights when the plane is on the ground.
Ten teams of 30 engineers began the refit process for the 50 Dreamliners in operation around the world as soon as approval was given on April 19. The first fixes were carried out for Japanese carrier Nippon Airways with carriers in America, Ethiopia and India next on the list.
It is not clear yet how production rates for the newly designed battery will impact delivery dates for customers awaiting delivery of 787 orders – British Airways, for example, was expecting delivery of the first of 24 Dreamliners this month but now has no set date.
Boeing’s lithium-ion batteries are manufactured in Japan by GS Yuasa. The new design includes increased thermal and electrical insulation and an enclosure to prevent overheating batteries from affecting other parts of the aircraft. New batteries will also be enclosed in stainless steel boxes with an added ventilation pipe going directly to the outside of the plane. This will take five days per plane to install.
The extra steel housing and other additions detailed above add around 150 lbs to the plane, cancelling out the weight savings which were originally a key motivator for the use of lithium-ion over nickel-cadmium batteries which are traditional in aerospace applications.
The redesign process for the Dreamliner’s lithium-ion batteries involved an intense three month investigation. Over 200,000 engineering man hours were worked around the clock by a team of international experts in order to ensure the batteries would no longer overheat and combust as they did in January on board two Japanese carrier planes – one in Boston, USA and the other at Takamatsu Airport on Shikoku Island, Japan.
Yet even with the focus of this combined expertise, and the approval of a new battery design, the suitability of lithium-ion batteries in aerospace applications remains in doubt for some.
Rival manufacturer Airbus has reverted to the use of traditional nickel-cadmium batteries for the upcoming A350, a direct competitor to the 787. Meanwhile, the National Transportation Safety Board (NTSB) and Japan National Safety Board (JTSB) are still conducting an investigation into the root cause of the battery fires on Boeing’s planes.
Larry Loftis, vice president and general manager of the 787 programme told press at a technology briefing in London on April 22 that “it is possible we will never know the specific root cause,” for the battery fires, but defended the suitability of lithium-ion batteries on the 787, and potentially other aircraft such as the projected 787-9, going forward. “We see this as the permanent fix and we have found no compelling reason for us to move away from the lithium-ion battery,” he said.
Boeing says it will continue ramping up production of the 787 which received strong orders on release. The current production rate is five planes per week and there are plans to increase this to seven and then 10 planes per week by the end of the year.