Lawmakers briefed on FAA's Boeing 787 Dreamliner investigation

The Transportation Committee leaders promised to "continue to monitor the situation closely and to receive regular updates from the parties involved.

"We have also requested that the FAA share any lessons learned as a result of their review so that we can continue to ensure the U.S. civil aviation system remains the safest in the world,” the group added.

The FAA has not provided a time frame for returning the 787 to flight.

The National Transportation Safety Board (NTSB), which is conducting its own 787 investigation, has attributed the battery fires to short-circuiting and accelerated temperature increases known as "thermal runaway."

The NTSB has additionally raised questions about the FAA's original certification of the Dreamliner airplane.

Boeing has argued that the vet of the airplane was "rigorous," and the company has maintained the 787 will be ultimately be ruled safe to fly. 

The company has completed several test flights of the 787 after doing so was approved by the FAA.