The U.S. government is turning up the pressure on ARC Automotive to recall 67 million potentially dangerous air bag inflators by ordering the company to answer questions under oath and threatening fines if it doesn鈥檛 respond.

The National Highway Traffic Safety Administration argues that the recall is justified because two people have been killed in the United States and Canada and at least seven others injured by ARC inflators, which can explode with too much force and expel shapnel. The explosions, which first occurred in 2009, have continued as recently as this year.

The special order from the ddministration asks multiple questions about whether ARC expects any of its inflators to blow apart in the future, and whether it has notified customers about the risk.

The agency wants ARC Automotive Inc., based in Knoxville, Tennessee, to recall the inflators, which can blow apart a metal canister. But ARC is refusing, setting up a possible court fight.

ARC maintains that no safety defect exists, that NHTSA鈥檚 demand is based on a hypothesis rather than technical conclusions and that the agency has no authority to order a parts manufacturer to carry out recalls.

NHTSA has tentatively concluded that the inflators are defective. The next steps are a final conclusion, public hearing and potential lawsuit asking a judge to order a recall.

Since ARC inflators can be in both driver and passenger front air bags, people who travel in at least 33 million U.S. vehicles could be at risk.

In the order, NHTSA asks ARC to explain if it expects inflators to rupture due to something more than 鈥渞andom 鈥榦ne-off鈥欌�� manufacturing problems. More than 1 million ARC inflators have been recalled already due to what the company describes as isolated trouble with manufacturing.

The order also instructs the company to estimate how many inflators will rupture while in use in the U.S. in the future, and it asks ARC why it changed its inflator manufacturing process in 2018 to install a scope that detects whether welding debris can block inflator vents.

NHTSA contends that byproducts from welding during manufacturing can clog a vent inside the inflator canister that鈥檚 designed to let gas escape to fill air bags quickly in a crash. Pressure can build to the point where the canister is blown apart.

Messages were left Thursday seeking comment from ARC. The company has to respond by June 14 or face a maximum fine of $131.6 million and potential criminal penalties.

Michael Brooks, executive director of the Center for Auto Safety, a nonprofit advocacy group, said NHTSA is going back and connecting dots to counter what ARC asserted in its response to the recall request.

The agency, he said, seems to be trying to get ARC to say that it鈥檚 possible other inflators can rupture in the future. 鈥淭hey are simply looking for an admission from ARC that this can happen again,鈥� Brooks said.

The company, he said, would have a hard time arguing that no more problems will occur. 鈥淚 don鈥檛 know that this is something that they can legitimately assert, that there鈥檚 never going to be another inflator rupture,鈥� Brooks said. 鈥淭here鈥檚 a high likelihood of another rupture of this type. There may not be a lot of them.鈥�

NHTSA also wants to know why ARC added the scope to its manufacturing process in 2018, and it鈥檚 demanding to know which ARC employee approved the decision. 鈥淚 think they鈥檙e trying to get at what was ARC basing that decision on and does it suggest that there鈥檚 a defect in the population of inflators that were produced before that date,鈥� Brooks said.

The agency said in its recall request letter sent to ARC in April that it鈥檚 not aware of any inflators rupturing that were manufactured after the scope was installed.

Owners of vehicles made by at least a dozen automakers 鈥� Chevrolet, Buick, GMC, Ford, Toyota, Stellantis, Volkswagen, Audi, BMW, Porsche, Hyundai and Kia 鈥� are left to wonder anxiously whether their vehicles contain driver or front passenger inflators made by ARC.

Because ARC supplies inflators that are included in other manufacturers鈥� airbags, there鈥檚 no easy way for vehicle owners to determine whether their inflators are made by ARC. Neither NHTSA nor ARC nor the automakers have released a full list of affected models.

One of the people who died after an inflator explosion was Marlene Beaudoin, a 40-year-old mother of 10 from Michigan鈥檚 Upper Peninsula who was struck by metal fragments when her 2015 Chevrolet Traverse SUV was involved in a minor crash in 2021. She and four of her sons had been on their way to get ice cream. The sons were not hurt.

In a response letter to NHTSA earlier this month, ARC said no automaker has found a defect common to all 67 million inflators, and no root cause has been identified in the inflator ruptures.

The standoff with ARC has sent automakers struggling to find out just how many of their vehicles contain the inflators. Many say they鈥檙e still gathering information from later model years to determine which vehicles contain the affected inflators.

From 2017 to 2022, the ARC problems triggered seven small recalls from automakers. Earlier this month, General Motors announced the recall of nearly 1 million more

Tom Krisher, The Associated Press