For nearly a year, federal regulators and researchers have pointed the finger at the volatile chemical ammonium nitrate found in Takata-produced airbags as the reason the safety devices can rupture with such violence that pieces of shrapnel are sent flying at drivers and passengers. Today, a consortium of 10 automakers are expected to announce that the chemical is just one factor in the deadly defect. 

Automotive News reports that the group, known as the Independent Testing Coalition, determined that three factors – the use of ammonium nitrate, inflator construction issues, and exposure to moisture – contributed to the defect, which has been linked to nine deaths in the U.S., 10 worldwide, and hundreds of injuries.

According to the group, which consists of reps for Toyota, Honda, Fiat Chrysler, BMW, Ford, General Motors, Mazda, Mitsubishi, Nissan and Subaru, the issues begin with the construction of inflators used in Takata’s airbags.

The inflators, which house the ammonium nitrate, fail to protect the component from moisture.

If the device is exposed to humidity and related temperature swings over a period of time the chemical can combust violently, rupturing the inflator when the airbag deploys in the event of a crash.

“You can’t have the energetic disassembly without all three factors,” David Kelly, leader of the group and former chief of the National Highway Traffic Safety Administration, told Automotive News of tests of more than 2,000 inflators conducted by Orbital ATK. “You have to have all three.”

The group’s findings validate long-held concerns from automakers, Takata, and NHTSA, which believed that exposure to high humidity climates contributed to these ruptures.

When recalls of vehicles containing Takata airbags began they were focused on areas of muggy, humid weather, including southern U.S. states.

Takata tells Automotive News in a statement that the group’s findings are consistent with its own tests conducted by a German scientific research organization.

“We fully cooperated with ITC to support their analysis, and we will continue to work closely with them, NHTSA and our customers to take aggressive actions that advance vehicle safety,” a Takata spokesman said in a statement.

While the group’s findings provide the first scientifically backed reason for the ruptures, Kelly cautions that the issue is far from over.

For one, the group only tested four Takata airbag designs that were deemed defective in May 2015. It didn’t include other inflators covered by subsequent recalls.

Additionally, the group didn’t test inflators that contained a chemical drying agent used in newer versions of Takata inflators that use ammonium nitrate.

ITC’s next step is to investigate replacement inflators, some of which were recalled by Takata last year.

Takata airbag ruptures caused by mix of 3 factors, investigators find [Automotive News]

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