- The Washington Times - Friday, June 19, 2009

A series of recalls has raised concerns about so-called “smart” airbags and occupant detection systems and whether the front passenger airbag can be fooled into not deploying when it should, or deploying when it should not.

Clarence Ditlow, executive director of the Ralph Nader-founded Center for Auto Safety, calls this erroneous airbag detection a serious safety defect. But a top official at the National Highway Traffic Safety Administration, Ron Medford, senior associate administrator for vehicle safety, says the occupant detection system is working fine and no changes are planned.

Still, passengers risk injury or death when these systems malfunction, say some safety advocates, engineers and lawyers. The occupant detection system of the front passenger seat is designed to signal the airbag whether to deploy, when to deploy, and in some systems with how much force to deploy based on the weight of the passenger.

Some systems use sensors on a mat in the seat bottom to determine weight; others use bladders filled with gel. In the simplest terms, the system tells the airbag controller not to deploy in a crash when the front-seat passenger weighs less than 105 pounds.

“Systems are being tricked and fooled,” said Sean Kane, president of Safety Research & Strategies Inc. The problems are long-standing with a number of different manufacturers having trouble getting it right, he said.

These occupant detection systems and “smart” or “advanced” airbags were first phased in with 2004 model-year vehicles and were installed in all passenger vehicles by the 2007 model year. They replaced the first-generation airbags, which were designed to protect an unbelted, 165-pound man and deployed at a single level with a force powerful enough to kill or injure small adults or children seated in the front passenger seat.

Chris Caruso, an engineer who spent 20 years designing automotive airbag systems, says the complex system faces challenges that include environmental extremes and wear-and-tear.

Temperature extremes can change the way gel flows; a leather seat can read weight differently when it’s hot than when it’s cold; and over time, foam in the seat can break down or shift. That means things can go wrong.

A 2008 BMW recall of 200,000 vehicles found that small cracks could develop in the mat containing the sensors that could keep the airbag from deploying. Hyundai recalled almost 394,000 Sonatas sold between 2006 and 2008 because the sensors might mistake a small adult for a child, stopping the airbag from deployment.

Mr. Caruso said the probability that a passenger could be killed or seriously injured because this system is being tricked is very low, but it isn’t zero. Since July 2007, he said, lawyers have hired him to investigate four cases in which the driver’s front airbag deployed but the passenger’s did not and the passenger was seriously injured or killed. He declined to identify the automakers.

Texas lawyer Stephen Van Gaasbeck said he handled one case in which the front airbag did not recognize a 128-pound woman seated in the passenger seat.

“Both the driver and passenger airbags were ordered to deploy at the highest level because it was that severe a wreck,” he said. “Unfortunately hers did not deploy and she sustained a brain injury. The event data recorder indicated that the airbag had been suppressed.” He said the suit against the automaker was resolved out of court and includes an agreement to not disclose the details.

But NHTSA’s Mr. Medford said the agency is not aware of any deaths or serious injuries related to problems with this system.

“It seems to us from all the data that we have … they have been extraordinarily effective,” he said.


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