Huerta explained that the second incident occurred during a flight.
"And that for us was an important consideration where we needed to identify what was causing these power- and battery-related incidents," he said.
The FAA order applied directly to the six Dreamliners operated by United Airlines, the only ones flown by U.S. carriers. But its directive was picked up aviation authorities globally and requires that the planes be deemed safe before they fly again.
Although there are only 50 wide body Dreamliners in service, there are several hundred on order. The world's largest aircraft manufacturer has made a big bet on the most technologically advanced airliner.
The 787 is highly touted because of its mostly lightweight carbon fiber construction, which airlines expect will help them save billions in fuel costs on long-haul routes. Its cockpit design and cabin appointments are state of the art.
The high level of attention and widespread concern about its problems and image now are partly due to the Dreamliner's difficult development. The 787 program at Boeing was plagued by cost overruns and production delays. The first one flew commercially last year.