Building The Gentle Air BagSuppliers refine technology to avoid minor injuries

Once upon a time motorists praised air bags for saving their lives in a crash. Now they expect air bags to save their lives, and if they suffer a minor burn or scrape during deployment, they sue. Although lawsuits involving relatively minor injuries from air bags are becoming common, a recent $64 million class-action judgment against DaimlerChrysler Corp. for an incident that caused minor burns on a woman's hand caught even jaded industry observers by surprise.

DaimlerChrysler spokesman Jay Cooney likens the suit to holding the manufacturer of bulletproof vests liable because its product saved someone's life, but resulted in a few bruised ribs. Others liken its impact to the well-publicized judgment against McDonald's Corp. where a woman was awarded a huge sum for spilling coffee in her lap. "I think this case will replace it. It's generated an awful lot of interest," says Mr. Cooney.

The air bags involved in the DC suit were supplied by Morton International, now part of air bag giant Autoliv Inc., headquartered in Sweden. Interestingly, engineers and executives at air bag suppliers - even those who don't supply DaimlerChrysler - seem more hurt than indignant about the judgment. They argue that consumers don't understand how difficult it is to counteract the potentially deadly forces involved in crashes at speeds as low as 10 mph, adding that they are spending millions not only to eliminate accidental deaths from air bag deployments - but minor injuries as well.

"It's been an evolving product and an evolving industry. Certainly everyone can sit back and Monday morning quarterback and say you should have done things different, you should have done things better, but all I can tell you is we did the best we could with the technology available," says Douglas P. Campbell, vice president of engineering for TRW Inflatable Restraint Systems.

Most worrisome to Mr. Campbell and other industry executives is the fact that by far most injuries and almost all air-bag related deaths are the result of children or adults not being properly restrained with seatbelts or child safety seats. Officials also are worried that the new generation of "smart" air bags that will soon be phased in on a growing number of vehicles will make consumers overconfident and cause them to use seatbelts - and common sense - even less.

"My concern is that occupant sensing will be promoted as THE FIX (for small children being killed by air bags), and people won't put their kids in the back seat anymore," says Mr. Campbell.

Here's what happened in the Crawley v. DaimlerChrysler Corp. case: In July 1992, Louise Crawley was traveling about 25 mph (40 km/h) when she had a head-on collision with another car in her 1989 Chrysler LeBaron. The air bag deployed. Ms. Crawley, who was pregnant at the time, suffered burns to her left hand from hot gas that escaped through vents in the bag when it inflated. (Vents control the cushioning effect of the bag as it is impacted by a person's head and body.)

Ms. Crawley - who was wearing her seatbelt - was otherwise uninjured, and her unborn child was not harmed in the accident. She was referred to a doctor for her burn, which reportedly healed in a few weeks.

The award is the largest ever in a suit involving air bags and is believed to be the first verdict in a class-action suit involving the safety devices. The jury awarded the plaintiffs $3.75 million in punitive damages plus $730 in compensatory damages to every registered owner of a 1988-90 model Chrysler car in Pennsylvania equipped with a driver-side air bag - about 82,000 owners. The $730 represents the cost of replacing the driver's side air bag, presumably with a newer design. Ms. Crawley's lawyers noware requesting damages awarded by the jury be tripled and that the class action suit be expanded to include the entire U.S.

Chrysler, on the other hand, is trying to have the verdict set aside. If it isn't, the automaker will appeal. The judge has until July to make a decision.

Engineers at air bag suppliers say facing litigation is an inevitable aspect of their business, at least in the U.S. (Canada currently has no ongoing air bag suits, DaimlerChrysler's Mr. Cooney says). Nevertheless they are chagrined at how minor some of the injuries involved in lawsuits are. Even so, they cite an impressive list of changes they've made in recent years to lessen the number and severity of minor burns, cuts and abrasions someone can suffer when being involved in a violent crash and then hitting an air bag face-first that is expanding at up to 200 mph (320 km/h).

"We haven't been sitting around doing nothing. We've made a lot of subtle changes, and a lot more dramatic improvements are coming in a couple of years," says TRW's Mr. Campbell.

In addition to new inflator designs that deploy air bags less aggressively in lower-speed impacts, most air bags now vent hot inflation gas through the back of the expanding bag, away from the driver or passenger, pretty much eliminating any concerns about burns from hot gas in the future.

Randy Clark, North America marketing manager for Autoliv's Inflator Div. says suppliers also are constantly striving to use cooler inflation gases because lower temperature gases sustain pressure in an inflating bag better than hot gases, providing a better cushioning effect. Very hot gases dissipate faster. Some inflators do not even generate gas by burning chemicals, he adds. Instead, they store gas in a pressurized container and then release it when necessary. Stored gas inflators can't always be used, though, because they are heavier and take up more space.

Suppliers also have made changes in air bag fabrics and the way the bag opens when it inflates. Much lighter-weight fabrics are now being used for the air bag themselves, and this can significantly reduce abrasions, says TRW's Mr. Campbell. He says that bags also now are designed so that rather than rushing out toward an occupant's face, they expand in more of a radial, sidewise manner, which also reduces abrasions.

Craig White, senior vice president-engineering and chief technical officer for Breed Siemens Restraint Systems, says even the way air bags are folded into their canisters can reduce minor injuries. It's becoming so important, in fact, he says suppliers are patenting their folding methods. BSRS, for instance has patented its "scrunch fold" process, which makes the bag fold up in a random fashion as it is packed into its case. The random folds create less turbulence inside the bag as it inflates; that translates into fewer abrasions.

"What you are trying to do is minimize the amount of turbulence in the bag as it opens," Mr. White says. "Because the turbulence is unpredictable, it's hard to model (on computer), and when you have an interaction with an out-of-position occupant, you don't know what kind of abrasions you're going to get. So no matter what kind of light fabric you have, if you have it unfolding in a funny way and you just happen to have your face there, it's going to swipe your face. So what you do is change the folding pattern so you don't get major shifts in the fabric," Mr. White says.

Will the proliferation of more and more gentle air bags translate into fewer lawsuits down the road? Air bag engineers are unsure, citing the unpredictability of the American legal system.

Nevertheless, BSRS's Mr. White believes logic eventually will prevail. "We as engineers can't afford to let litigation affect the products we deliver, he says. What we need to do is appraise the top injuries and continually work on them and bring them down. As a secondary event, the litigation will decrease. Most awards that are frivolous are thrown out by data," he says.