The transport ministry on April 26 permitted All Nippon Airways and Japan Airlines to resume flights of Boeing 787 Dreamliners, following the U.S. Federal Aviation Administration’s approval of Boeing’s modification of the jetliner’s battery system, which had developed “thermal runaway” problems. Boeing claims that the changes to the airliner’s battery system will ensure the aircraft’s safety. But the cause of the overheating problems has not been pinpointed. The aircraft maker and airlines cannot be too careful in ensuring that the Dreamliner’s battery system is operating without trouble.
On Jan. 7, a fire ignited in the battery pack for an auxiliary power unit of a JAL 787 at Boston’s Logan International Airport. On Jan. 16, an ANA 787 made an emergency landing at Takamatsu airport in Kagawa Prefecture after smoke from the battery system was detected in the cockpit.
The batteries involved in these accidents were lithium-ion batteries manufactured by Kyoto-based GS Yuasa Corp. Shortly after the Jan. 16 emergency landing incident, the FAA grounded all 787s, and the transport ministry told ANA and JAL to stop flying the jetliner. Since Japanese makers are responsible for 35 percent of the aircraft’s parts and components, the grounding had a significant effect on them. Eight airlines have introduced 50 Boeing 787s, with ANA owning 17 and JAL seven, expecting that Dreamliners will contribute to increasing their profitability.
The Boeing 787 uses five times more electricity than conventional jets because many of its systems are operated electronically rather than mechanically. This power is supplied independently of the engines by lithium-ion batteries — an approach that allows the engines’ output to be used solely for thrust. This, combined with the 787′s lightweight composite bodywork, gives it 20 percent better fuel economy than conventional jets — the primary reason why airlines worldwide have ordered roughly 800 787s. The better fuel efficiency enables them to use 787s for international flights.
Because of the grounding, ANA is expected to suffer an estimated decrease in sales of ¥12.5 billion and JAL, ¥6.5 billion, from mid-January to the end of May.
In modifying the battery system, Boeing covered each of the eight lithium-ion batteries with insulation tape and placed the batteries in an oxygen-free stainless steel container. ANA and JAL will take additional measures. Each of their Boeing 787s will undergo a test flight. Data on the voltage of the battery system will be transmitted to the ground throughout a flight. The two airlines will carry out a sampling test of the battery system once every few months and share data. Boeing should make further efforts to pinpoint the cause of the overheating accidents.
ANA and JAL should realize that if customers do not have trust in the safety of the battery system, they will not return. The airlines cannot be too careful in their daily check of the battery system and should sufficiently share related data with customers.