Nearly all of Metro’s hybrid buses have a flaw with their engines that is going to take a year to fix, according to Metro. Of the agency’s 401 hybrid buses, 351 of them need repairs in what the agency officials call a “fleet defect.”
And the problem with the Cummins Inc. engines is having a ripple effect throughout the Metrobus system, causing overall bus reliability to drop. The average distance between failures for Metro’s 1,492 buses fell below the agency’s target during April for the first time this year.
Metro is continuing to run the hybrid buses, bringing in about 15 buses at a time, said Jack Requa, an assistant general manager who oversees the bus division.
“The buses are all running,” he said. “It’s not like we’ve had to park the fleet.”
This is not the first problem with the hybrids — or their engines. In 2008, the agency had a problem with the first 50 hybrids it ordered. A microcomputer inside the Cummins engine was not properly sealed so moisture seeped in, causing the engine to cut off while the buses were running.
The agency has added 351 more to the fleet in the past four years. About 105 had defective roof-mounted cooling fans that have been fixed, Requa said.
Now all of the hybrids bought in the past four years need to have the engines fixed, this time to repair a problem with the fuel injection and calibration on the Cummins engine. Also, 329 of them have a problem with the exhaust system, requiring them to retrofit an air dam on the buses at the same time.
“This is routine. There’s always something that can be made better,” Requa said. “If we thought there was anything unsafe, we’d be taking all the buses off the streets.”
The repairs are covered by the agency’s warranty with the manufacturers. The company is updating hardware and software in the engines, working with Metro to schedule the fixes during the evenings to minimize any effect on the bus schedules, spokeswoman Christy Nycz wrote in an email.
Meanwhile, Metro has 152 more hybrid buses on order. About 14 of them have arrived but are not running routes.
Requa said he doesn’t know if the new model will have the same flaws. But he said the agency isn’t going to shy away from buying hybrids.
“Overall it’s the best fleet we have,” Requa said.
Metrobuses averaged a distance of 7,948 miles between failures for the first four months of the year. But the hybrids run far longer before breaking down than the clean diesel, compressed natural gas or other style buses in Metro’s fleet. At its peak, the hybrids traveled a mean of 14,198 miles in November before failing, though that number fell to 9,536 miles in April — still higher than any of the other bus types.
