He said Metro was notified last week by New Flyer of America, based in Winnipeg, Manitoba, of the defect.
Stessel said Metro plans to keep operating the buses, which serve routes in Montgomery County and the District. He said Metro has received “certification” from New Flyer and BAE Systems, which supplies an electric propulsion system for the bus, that the vehicles are safe to use.
New Flyer and BAE Systems are working to fix the problem, Stessel said, with BAE Systems paying for the work. He did not know immediately how much it will cost.
Metro has an $89.3 million contract with New Flyer to buy 152 of the buses. So far, Metro has received 147. Only 47 of those buses have energy storage systems supplied by BAE Systems; the rest have systems supplied by Allison Transmission, New Flyer officials said.
Metro is expected to receive five more buses from New Flyer later this year, which are scheduled to have the battery problem fixed before the transit authority takes delivery, Stessel said.
There have been 10 incidents involving the parts in North America during the past 15 months, New Flyer and BAE officials said. Those electrical shorts occurred on Orion buses made by Daimler, they said.
Kristin Gossel, a spokeswoman for BAE, said the problem involves debris caught in the energy storage system, which sits on top of the bus.
“That debris and moisture causes a breech in the electrical isolation of the battery pack,” she said.
When that happens, she said, there is smoke and the battery pack melts, but no flames. She said the smoke does not penetrate the passenger area.
Paul Soubry, chief executive of New Flyer, said the problem was first noticed when Orion had troubles in the fall with an energy system made by BAE. At the time, he said New Flyer, which had the same components in its buses, “viewed it as not a problem” because the systems were installed differently. Soubry said a computer-generated alert notified bus drivers of the problem.
But Soubry said the company “deemed we should correct this” after a recent investigation. He said six other customers have 37 buses that are also affected. He would not name who had the other troubled buses.
On a tour of the new buses last year, Jack Requa, assistant general manager of Metrobus’s service department, called the New Flyer Xcelsior XDE40 the “Prius of buses.
Metro has replaced 401 of its older buses that ran on diesel with hybrids, and the new order will bring the hybrid fleet to 553. Metro has about 600 buses that run on diesel and a total bus fleet of 1,492.