Boeing and the US Federal Aviation Administration have concluded that a flying 787 was in no danger of a catastrophic fire in January despite an overheating main battery that prompted the flightcrew to perform an emergency landing.
FAA air transport certification manager Ali Bahrami and Boeing vice-president and 787 chief project engineer Michael Sinnett agreed at a 23 April fact-finding hearing that the All Nippon Airways flight was never at risk of greater damage following the battery malfunction.
"It appears that the aircraft was not put in any danger," Bahrami told the hearing hosted by the National Transportation Safety Board (NTSB). Sinnett was then asked by an NTSB official if that was his position as well. "Yes," he replied, "it is."
The statements revealed a continued division between the NTSB on one side and Boeing and the FAA on the other over the seriousness of the 787 battery incidents in January, even as the fleet has been cleared to return to service despite the absence of a root cause.
Sinnett was careful to say that an overheating battery caused by a short-circuit is an issue Boeing takes "very seriously".
Bahrami, meanwhile, concedes that the FAA was more concerned about the frequency of the two failures less than 10 days apart. That "surprised" the FAA staff who had approved Boeing's recommendation to certificate the aircraft as airworthy only 15 months before the battery incidents.
At the same time, both officials said there was no evidence to suggest the aircraft was at risk of catastrophic damage. In the case of the ANA incident, no flames or smoke were reported and thermal damage was limited to the immediate area around the battery box.
The FAA and Boeing also downplayed the incident on 7 January involving a parked Japan Airlines 787 in Boston. It was the only incident in which flames were detected, but the flames did not cause any damage to surrounding systems and primary structure and were themselves not the result of an exploding battery. Instead, the flames were generated by a short-circuit that formed in wires attached to the overheating battery box.
The NTSB members focused on why two such incidents occurred within 50,000 flight hours of the 787 fleet, when the FAA special conditions to certificate the aircraft's lithium-ion batteries required no more than one incident in 10 million flight hours.