GM Recalls a Million Vehicles Over Airbag Inflators

Years after the Takata recall, airbags are still an issue.

The U.S. National Highway Traffic Safety Administration (NHTSA) has ordered the recall of almost a million GM midsized SUVs due to defective airbag inflators. According to NHTSA, deployment of the airbags may propel metal shrapnel into the passenger compartment, causing possible injury or death. The manufacturer of the modules, ARC Automotive, has rejected the government allegations. The company argues that single-digit failures in parts manufactured in quantities of million or more represent a sample size statistically too small to justify wholesale replacement.

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Episode Transcript:

General Motors has announced that the company is recalling almost 1 million sport-utility vehicles in the U.S. as part of a NHTSA push to recall 67 million defective airbag inflators manufactured by Tier One supplier ARC Automotive. 

The federal agency claims that the inflators can project potentially lethal metal shrapnel into the passenger cabin when airbags deploy. ARC Automotive has rejected the government’s allegations, and has stated that airbag issues are random, one-off manufacturing anomalies that are better addressed with smaller, targeted recalls. According to ARC, the government’s conclusion is based upon seven incidents in the U.S., which the company claims is too small a sample size to justify a recall of 67 million inflators produced over 18 years. 
Nevertheless, GM is recalling 994,763 Buick Enclave, Chevrolet Traverse and GMC Acadia vehicles built between 2014 and 2017. Similar inflators are installed in some Stellantis, BMW, and Kia vehicles as well. 
Airbag engineering is deceptively simple: sodium azide is oxidized in an electrically-triggered exothermic reaction to produce sodium oxide and a large amount of nitrogen gas, which inflates the bag. To protect occupants in a crash, the reaction has to be rapid, and the bag can inflate in as little as 50 ms. 
While total bag peak pressures are not large, on the order of five psi, the bag itself deploys at speeds as fast as 200 mph, meaning that small metal fragments caught in the inflation process can be propelled with considerable, possibly lethal force. 
In 2014, over 3 million vehicles from BMW, Chrysler, Ford, Honda, Mazda, Nissan and Toyota were recalled due to similar safety concerns with Takata-made airbags, with that company identifying the cause as moisture seepage into the inflators which destabilized the propellant inside. That recall occurred after an NHTSA investigation following three injury complaints. 
While the Takata recalls involved over 40 million vehicles, the ARC issues are so far limited to just under 1 million GM-produced SUVs. The total cost is not yet known, but this recall poses a question important to auto manufacturers of safety critical assemblies throughout the industry: what is the acceptable failure rate for parts produced in volumes of hundreds of thousands or millions? 
Zero defects are always the goal, but in practice, it’s almost never achievable. Can these issues be fixed with conventional QC or SPC methods? We’ll know as this and similar recalls work through the system.

Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.