Japanese air-bag supplier Takata has vowed to stop using ammonium nitrate as a propellant in kits being produced to replace some of its air bags, which so far have been tied to six deaths and more than 100 injuries.
The change comes from testimony a Takata executive plans to give Tuesday before the U.S. House Committee on Energy and Commerce. The testimony was posted Monday on the committee’s website.
Kevin Kennedy, Takata North America executive vice president, also plans to tell the committee that so far, Takata has found 67 reported cases of air-bag inflators rupturing, but that figure represents 0.0087 percent of estimated deployments of Takata-made air bags, or nine failures out of every 100,000 activations.
The problem has led 11 automakers to recall nearly 34 million vehicles in the U.S. and to urge owners to get the driver’s- and passenger’s-side air bags and inflators replaced. It’s the largest recall for one issue in U.S. auto-safety history.
Some experts familiar with the chemical makeup of ammonium nitrate say the propellant can be volatile when exposed to high humidity and moisture. As it becomes destabilized, it can vaporize with so much pressure that the inflator canister bursts and hurls metal and plastic shards at drivers and passengers.
“In the past several months, Takata has conducted ballistic tests of more than 12,500 of these driver inflators, and nine of them have ruptured during testing,” according to Kennedy’s testimony. He added that a “disproportionate number of tested inflators were from older vehicles that were driven in areas of high humidity.”
“This is not meant in any way to minimize the issue,” Kennedy is expected to say. “Even one rupture is too many. And six of these reported field ruptures have involved fatalities. We deeply regret each instance in which a Takata air-bag inflator has ruptured.”
Of the 67 reported ruptures, 46 were driver’s-side air bags and 21 occurred on the passenger’s side.
Under the direction of the National Highway Traffic Safety Administration, Takata and some of its competing suppliers are cooperating to make enough replacement inflator kits to install in 33.8 million recalled vehicles. It will take years.
Takata will give priority to older models manufactured by Honda, BMW, Chrysler, Ford and Mazda that have what the company calls “batwing” driver inflators.
“We are working with our automaker partners to transition to newer versions of driver inflators in our replacement kits or inflators made by other suppliers that do not contain ammonium nitrate,” Kennedy will say.
Takata has increased its production of replacement kits from 350,000 per month last December to 700,000 in May. Kennedy said that is expected to increase to 1 million per month by September. But even with the help of other suppliers such as TRW and Autoliv, it could take years to make enough to repair all the recalled vehicles.