Boeing Co said on Tuesday that it did not believe during design and testing that a fire could occur in the lithium-ion battery system that failed on its 787 Dreamliner.
Under questioning at an investigative hearing by the National Transportation Safety Board in Washington, Mike Sinnett, Boeing's chief 787 engineer, said: "Any form of internal short circuit could lead to venting of that cell and release of electrolyte, but nothing more than that."
He added: "The only time we were ever able to make a cell vent with fire was with significant overcharging."
Separately, Ali Bahrami, the transport airplane manager for the Federal Aviation Administration, said the special conditions the agency established for the battery addressed safety concerns for the aircraft "quite eloquently."
He added: "We did the best we could under the circumstances and the knowledge that existed" at the time to develop standards for the battery.
(Reporting by Alwyn Scott and Andrea Shalal-Esa; Editing by Gerald E. McCormick)