So far, 50 Dreamliners have been delivered to airlines by Boeing, but all are currently grounded due to concerns that one of the lithium-ion batteries on board could leak, potentially causing fires.

BBC: A Boeing 787 at Farnborough air show

Investigators in Washington have taken X-rays and CT scans of the lithium-ion battery that caught fire in Boston, the safety board said.

CNN: Quick fix for Dreamliner looks less likely, experts say

Additional details released by the safety board said all eight cells of the lithium-ion battery involved in the Boston 787 fire showed varying degrees of thermal damage.

CNN: What's wrong with the Dreamliner?

The National Transportation Safety Board is also asking how problems with the aircraft's lithium-ion battery system that led to a fire aboard one plane and smoke in another escaped the notice of regulators and company officials who certified the plane's safety.

NPR: NTSB Probes Safety Testing Of Boeing 787 Batteries

Analysis of a flight recorder from that plane showed that a lithium-ion battery experienced a sudden drop in voltage and was not overcharged, the Japan Transport Safety Board said Wednesday.

CNN: What's wrong with the Dreamliner?