(CNN) -- Boeing spent more than 60,000 hours testing changes to the lithium-ion battery system for the 787 Dreamliner, which has been grounded in the wake of incidents on two planes, the chief project engineer for the project said Friday.
At a news conference in Tokyo, Mike Sinnett said the company "may never get to the single root cause" of the battery issues, which included a small fire on the front of the battery box of a plane that was on the tarmac at Boston's Logan International Airport. He believes improvements to the system will prevent problems.ground the batteries, which Sinnett said will prevent fires. He said engineers also minimized potential combustion sources in the batteries, and if there were a release of gas from the batteries, the enclosure would keep it from the rest of the airplane and vent it.
There are 50 grounded Dreamliners worldwide, and Boeing has orders for several hundred more.
When the plane returns to the skies, "I plan to fly on the very first flight," Boeing President and CEO Ray Conner said.
The Federal Aviation Administration will evaluate the redesign and must approve it before the Dreamliner can fly again.