NORCROSS - The engine of a Gwinnett County Transit bus on its way to Discover Mills Mall caught fire Thursday morning on northbound Interstate 85 with no passengers aboard.
According to the Gwinnett County Fire Department, firefighters found heavy smoke coming from the engine compartment upon arrival just north of Indian Trail Road, but were able to contain the small blaze to the engine compartment only.
The driver was uninjured and no service interruptions were experienced by transit riders.
Transit Director Phil Boyd said the cause - the failure of a turbocharger, - was the same that led to a bus nearly catching fire in March. A turbocharger is an engine component present in heavy duty engines that helps boost horsepower.
During the March incident, the engine smoked from a failed turbocharger but never caught fire.
Boyd said the turbocharger that caught fire Thursday had 37,000 miles on it and the March incident that caused one to smoke had logged 67,000. He also said a vast majority of turbochargers are able to operate without incident throughout their normal service life interval of 175,000 miles, whether on a compressed natural gas running bus like the bus that caught fire on Thursday or in a diesel one.
Considering Thursday's incident was the second of 2009 caused by a failed turbocharger, he said the latest incident has the organization "concerned."
"We've asked our contractor to look at and revisit our failure history," Boyd said. "We've also asked them to look at other properties they operate transit for and to review their history. We want to see if we can make a determination to see if we need to change our interval test rate."
The contractor for Gwinnett County Transit - Veloia Transportation - said it's not uncommon for a turbocharger to fail, but having one do so doesn't mean there will always be a fire.
"It's a manufacturer issue, not a maintenance issue," said Veloia spokeswoman Valerie Michael. "We're working with the manufacturer to resolve the issue but there is no way to predict when one will fail. We do have a regular maintenance program to replace turbos, but this isn't a maintenance issue."
Boyd said all of the nearly 100 buses in the transit fleet are inspected daily. He also said as a result of the most recent fire, the inspections on the turbochargers would be "re-upped."
"Safety is our number one priority and that's what we strive to do everyday," Boyd said. "We're just going to redouble our efforts along with the contractor to make sure everything is done and shared in training as well."
Boyd said the driver's efforts would especially be noted in training exercises because he did everything correctly. He pulled over safely, turned off the engine and then pulled the ring for the fire suppression unit. That system automatically triggered a foam that was sprayed on the engine components to assist in extinguishing the fire.
"We always want to make sure the drivers know what to do," Boyd said.