Boeing’s Dreamliner, which was touted to revolutionize commercial air travel with its 50 percent composite materials design and impressively low fuel burn, hasn’t taken off quite like CEO James McNerney expected, due to costly battery problems that have left the entire fleet grounded. 

According to USA Today, Boeing is currently in the middle of another round of tests of its lithium-ion battery, which McNerney says will wind down in “the next several days.” McNerney, who is confident in the company’s revamped battery, said the plane will hit the skies “sooner rather than later.”

Although the three-month grounding of the fleet has been “frustrating,” as McNerney put it, the problems haven’t had any affect on airlines’ appetite for the fuel efficient aircraft. 

“We have a high degree of confidence in the technical solution we are testing right now,” McNerney said.

After the Federal Aviation Administration grounded the plane in January because of overheating and smoking batteries, Boeing teamed up with the agency as well as Japan’s All Nippon Airways to develop a solution to the problem. 

Rival manufacturer Airbus, which is expected to release its competitor to the Dreamliner in the next few years, is learning from the Dreamliner’s mistakes and taking a different approach to testing its own lithium ion batteries. Early assessments show it could potentially scrap the battery type altogether to avoid Boeing’s current problems.