WASHINGTON (AP) — It’s likely that fires on two Boeing 787 Dreamliners were caused by overcharged lithium ion batteries, aviation safety and battery experts said Friday, pointing to developments in the investigation of the Boeing incidents as well as a battery fire in a business jet more than a year ago.
An investigator in Japan, where a 787 made an emergency landing earlier this week, said the charred insides of the plane’s lithium-ion battery show the battery received voltage in excess of its design limits.
The similarity of the burned battery from the All Nippon Airways flight to the burned battery in a Japan Airlines 787 that caught fire Jan. 7 while the jet was parked at Boston’s Logan International Airport suggests a common cause, Japan transport ministry investigator Hideyo Kosugi said.
In the case of the 787 in Boston, the battery in the plane’s auxiliary power unit had recently received a large demand on its power and was in the process of charging when the fire ignited, a person familiar with the investigation said. The plane had landed a short time earlier and was empty of passengers, although crews were working in the plane.
The Federal Aviation Administration issued an emergency order Wednesday temporarily grounding the six 787s belonging to United Airlines, the lone U.S. carrier operating Boeing’s newest and most technologically advanced airliner. The Japanese carriers already had grounded their 787s, and airlines and civil aviation authorities in other countries followed suit, shutting down all 50 Dreamliners that Boeing has delivered so far.
A battery fire in a Cessna Citation CJ4, a business jet, prompted the FAA in October 2011 to issue an emergency order requiring the lithium-ion batteries in all 42 of the jets in operation at that time to be replaced with a conventional nickel-cadmium or lead-acid battery. The fire occurred while the plane was hooked up to a ground charging station at Cessna’s aircraft completion center in Wichita, Kan.
The Citation was Cessna’s first business jet with a lithium-ion battery as its main battery.