Emissions system glitch forces D.C. ambulance carrying shooting victim to shut down

A malfunction in a fail-safe system designed to assure compliance with federally mandated diesel emissions standards forced a D.C. ambulance to shut down on Interstate 295 while its crew transported a gravely injured gunshot victim Wednesday.

D.C. fire department officials are still probing the glitch, but they said the issue seems to be specific to a sequence of warning lights that ultimately notify the ambulance crew the engine will shut off imminently. And while it’s the first time city officials said a department ambulance has failed while in transport as a result of the emissions system, widespread problems have been reported nationally.

“What I want to do is see what the computer says about this problem, and then we can re-evaluate if we need to do anything,” Deputy Chief John Donnelly said, assessing the extent of the issue. “We’re going to look at the series of warning lights and the indicators. They should lead us back to the problem.”

Medic 19 was dispatched at about 2:20 p.m. Wednesday after a man suspected in a Southeast carjacking initiated a shootout with police and was hit by gunfire. The ambulance carrying Nathaniel McRae, 34, to Howard University Hospital pulled over en route when it shut down. Emergency workers continued to perform CPR on the man and waited for about 10 minutes until another ambulance could respond. In all, it was about 45 minutes from the dispatch of the first ambulance until the second ambulance arrived at the hospital.

Mr. McRae was pronounced dead at the hospital, but fire officials said the delay “wouldn’t have had any impact” on his chances of survival.

Officials said the problem with Medic 19 stems from the need for the ambulance to “regenerate,” a process that heavy diesel engines are routinely required to undergo in order to cleanse particles, similar to soot, from their exhaust systems after it is captured in a filter. If the soot is not removed routinely, an engine can suffer a drop in power or fail in a manner similar to what would occur if an exhaust pipe was obstructed.

The problem has plagued fire departments across the country since manufacturers of rescue equipment added the devices to comply with stronger Environmental Protection Agency standards governing diesel emissions in 2007 and again in 2010.

Over a 20-month period, the San Diego fire department reported more than 500 regeneration-related issues, Firefighter Nation reported in 2011. And the Southeastern Association of Fire Chiefs in 2011 wrote to the EPA outlining the problem and lobbying for an exemption.

“Fire trucks across the country are breaking down at record rates because of this filter system that EPA forces them to use,” the association said.

Responding to the concerns, the EPA last year acknowledged that “power and speed reductions were occurring on some vehicles with soot filters.” Amendments to the federal regulations that took effect in August allow manufacturers to seek approval for devices that would temporarily moderate the allowed emissions output to avoid an emergency vehicle shutting down while in service.

Any changes to the District’s fleet probably would come with new equipment purchases, as retrofitting the ambulances would likely be impractical, Chief Donnelly said.

In many cases, engines running at high levels for long periods of time can generate enough heat to cleanse the filters and avoid a drop or failure in engine performance. But for urban departments, which often perform short runs, the vehicles are required to undergo what’s called “manual regeneration,” in which the vehicle must be parked and the engine run at a high level for an extended period of time in order to generate the heat necessary to burn the soot from the filter.

On the 32 District ambulances equipped with the regeneration devices, warning lights are supposed to signal to drivers that the vehicles need to be taken out of service so that the regeneration can be completed, Chief Donnelly said.

In Wednesday’s instance, the ambulance driver told investigators that the first two warning lights — which could have given the driver up to several hours’ notice — never came on.

“There was no one or two warning and it went right to stage three,” said D.C. Firefighters Association President Edward Smith. “It did not allow enough time to address it.”

Once the third warning light engaged, the ambulance almost immediately began to shut down, Chief Donnelly said.

The firefighters union reported that since August it has seen three reports of malfunctions involving the emissions system on Medic 19.

An overheating issue was reported as recently as May 22 and the ambulance was sent back to the dealer for work, Chief Donnelly confirmed. When the ambulance was returned it seemed to be working fine, so officials are waiting for the information from the unit’s computer system to be processed in order to determine what went wrong this time. On Thursday, officials were unable to provide details on the other reported instances.

“Obviously it’s unnerving that when seconds count that yesterday there was a five- to seven-minute delay,” Mr. Smith said. “If there is an exemption out there we should be first in line applying for it.”