Failed Seals Targeted in Takata Airbag Inflator Probes

Investigators say a metal cleaning fluid, damaged O-ring seals and failed tape adhesives each may help explain why some Takata Corp. airbag inflators explode when triggered in a crash, The Wall Street Journal reports.

The misfires have killed eight people and prompted 11 car and truck manufacturers to recall more than 40 million vehicles, including about 32 million in the U.S. But the exact cause of the failures remains unclear in spite of intense research by multiple teams.

Several experts say a contributing factor is Takata's use of ammonium nitrate as a propellant. The material is more likely than others to destabilize when exposed to moisture, thus causing it to burn too quickly when ignited.

But how can moisture seep in? The Journal says investigators are pointing to two possible routes, one for driver-side inflators and another for passenger-side devices.

In driver-side inflators, researchers have found damaged or distorted O-ring seals that could allow humid air inside. For passenger-side inflators, Takata points to evidence of deterioration of adhesive tape used to seal holes through which gas flows into the airbag.

Takata says adhesion failure appears to be a result of long-term exposure to high ambient temperature and humidity. But the Journal says one carmaker is trying to determine whether traces of cleaning fluid used during the production of steel propellant canisters might cause the tape's adhesive to weaken.

Meanwhile, investigators caution that other factors beyond sealing problems may play a role. None of the research teams has announced a definitive root cause to explain all failures.