NTSB Finds Significant Fire Damage to the APU Li-Ion Battery in Boeing 787 Incident in Boston

January 08, 2013 by Jeff Shepard

The National Transportation Safety Board (NTSB) today released an update on its formal investigation of Monday's fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston. The NTSB investigator on scene found that the auxiliary power unit battery had severe fire damage. Thermal damage to the surrounding structure and components is confined to the area immediately near the APU battery rack (within about 20 inches) in the aft electronics bay. The cause of the fire is still under investigation.

The Boeing "Dreamliner" electrical systems generate 1.45 megawatts of electricity, four times as much as a larger 777 jet. The 787 carries two large lithium-ion batteries, located in forward and rear electronics bays. The battery in the rear bay that caught fire is about 50% larger than a car battery. It's used to start a small turbine engine in the tail that serves as the auxiliary power unit (APU) and is used to provide electrical power while the plane is on the ground or as a backup power source during an in-flight emergency.

According to the NTSB report, rescue and fire personnel and equipment responded to the airplane and detected a fire in the electronics and equipment bay near the APU battery box. Initial reports indicate that the fire was extinguished about 40 minutes after arrival of the first rescue and fire personnel.

GS Yuasa is the supplier of the batteries in the electrical power conversion system of Boeing's 787 Dreamliner. According to the company, this is the first commercial aviation application of Li-ion technology anywhere in the world.

GS Yuasa's Li-ion technology was selected because it offers some key advantages over the existing nickel-cadmium solution used in commercial jetliners. With 100% greater energy storage capacity, lithium-ion offers two times of energy from the same dimension nickel-cadmium battery. The battery can charge from 0 to 90% in only 75 minutes and comes with battery management electronics which guarantees multiple levels of safety features. The rugged prismatic sealed battery design is capable of withstanding extreme operating conditions far greater than those normally seen in commercial aircraft operation and requires absolutely no maintenance.