December 18, 2017
On July 10, 2017, Takata recalled PSDI-5 driver air bag inflators containing phase-stabilized ammonium nitrate (PSAN) as a generant and calcium sulfate as a desiccant, which were used in vehicles sold in the United States as original equipment in frontal driver airbag modules. Recall 17E034 affected 2.7 million Ford, Mazda and Nissan vehicles produced between 2005 and 2012.
Takata’s accompanying chronology in its Part 573 Notice of Defect and Noncompliance describes a field recovery program conducted with Nissan and Ford at NHTSA’s request between March 2016 and June 2017, to gather inflators and subject them to a variety of tests. These included live dissections, chemical and dimensional propellant analysis and ballistic testing. Takata reported to the agency that the field-returned inflators had zero ruptures in ballistic test deployments, but that “some within the population analyzed show a pattern of propellant density reduction over time that is understood to predict a future risk of inflator rupture.” It also allowed that “inflator design and vehicle environment differences between the Nissan and Ford inflators/vehicles may influence their aging characteristics.” (Emphasis added.)
Nonetheless, Takata determined, “out of an abundance of caution,” to recall its first-generation PSDI-5 PSAN driver air bag inflators containing calcium sulfate. In notifying NHTSA of a defect and announcing a recall, Takata acknowledged that these inflators represent an unacceptable risk.
Nissan responded by recovering 895 inflators from the field for testing, and acquiescing to the recall without complaint. Ford responded by collecting only 400 inflators from the field, and filing a petition asking NHTSA to declare the affected Takata inflators in its vehicles to be an inconsequential risk to safety. At the same time, Ford requested that NHTSA delay a decision on its petition until the automaker can conduct more testing. Got it? Ford asked NHTSA to declare the inflators in its vehicles safe, but not until Ford does more testing to prove it.
Ford argued that 360 live dissections of Ford vehicle inflators demonstrated “consistent inflator output performance — specifically, measurements of ignition tablet discoloration, generate density, and moisture content of certain inflator constituents did not indicate a reduction-in-density trend.” Ford also maintained that the inflators in its 2006-2007 Ford Rangers were in no danger of failing because it had taken unique steps to prevent “potential” exposure to moisture: “the inflators contain only two, foil-wrapped auto-ignition tablets (instead of three that are not foil-wrapped), contain divider disk foil tape, and utilize certain EPDM generate cushion material (instead of ceramic) that “reduces generate movement over time, maintains generate integrity, and leads to consistent and predictable burn rates.”
There are so many things wrong with this ask and Ford’s argument, it’s hard to know where to begin, so we’ll start here: First, It has already been established that, with or without drying agents, PSAN is too volatile of a generant – period. PSAN must be used with extraordinary precision and care, or it is likely to over-pressurize, especially when exposed to temperature cycling and moisture. And we know from everything that has been publicly revealed so far that Takata had pretty bad manufacturing processes and lax quality control.
PSAN is the underlying root cause of the ruptures. Takata has affirmed this in a variety of patents filed over two decades. A study, conducted at the behest of Takata and Honda by researchers at Pennsylvania State University’s High Pressure Combustion Laboratory also showed, over Takata’s protests, that PSAN is susceptible to dynamic burning. That means that when the propellant is exposed to sudden pressure increases, it may burn at a much faster rate and at higher temperatures than expected, leading to over-pressurization.
Second, calcium sulfate, used extensively as a commercial desiccant in laboratory use, does not provide any guarantees that the inflator won’t eventually rupture. Manufacturers like it because it’s cheap, stable non-toxic and non-corrosive, but it only adsorbs 10 percent of its weight in water vapor.
Third, we suppose that it’s fine and dandy to reduce the ingress of moisture that can create porosity in the wafers of generant. If that was the only mechanism of failure, Ford might have made a decent argument. Only, it seems that Ford is putting as much effort into keeping up with the science of inflator ruptures as it has been in recovering inflators from the field. Technical experts that served as consultants to NHTSA and Takata agreed moisture intrusion is of lesser importance in inflator ruptures than temperature cycling.
For example, the Exponent report, Investigation of Takata Inflator Ruptures, emphasizes the role of thermal cycling in failure scenarios: “However, even in hot and dry environments like Arizona, the large daily temperature cycles in the absence of significant moisture ingress can also cause propellant degradation over a prolonged period. High moisture content alone in the absence of temperature cycling will not increase degradation.”
NHTSA consultant Fraunhofer ICT and Takata also acknowledged that variances among vehicle types are determinants in whether or how significantly an airbag inflator will deteriorate due to temperature cycling, stating:
“One of the key observations in the analysis of the field return data is that there exists a strong dependence on outcome based on the vehicle in which the inflator was installed. Limited vehicles studies conducted by Takata show variation in inflator surface temperatures between different vehicle types and models, given identical environmental exposure conditions. This temperature variation appears to have some correlation with different field performance of those models, as shown in Figure 19 below. This is not to say that the vehicle is the cause of the issue- only that the vehicle type may influence the rate that the inflator degrades.”
Finally, the death of Joel Knight is a warning about the price of recall delays.
On December 22, 2015, Knight, 52, of Kershaw County South Carolina, was fatally injured in an otherwise survivable and moderate crash when a defective airbag ruptured in his 2006 Ford Ranger. Knight’s vehicle struck a cow that wandered into the road; the airbag inflator exploded during deployment, causing a piece of metal shrapnel to pierce his neck and spine.
Knight’s death was unwarranted and preventable – this defective Takata airbag inflator type, the Smokeless Driver Inflator or SDI, had already been recalled in 2014 in at least 61 other countries by Honda and Toyota. Those recalls were initiated following ruptures that took the life of at least one other driver – a pregnant woman in Malaysia.
From June 2014 to May 2015, however, Ford dithered – and never actually recalled the SDI inflators in all of its vehicles.
The automaker issued its first Takata-related campaign as a voluntary field service action for a select group of vehicles in certain model years, which included Ford Rangers. After July 2014, when a rupture caused by a failed SDI inflator (the very same used in Knight’s 2006 Ranger) killed a pregnant woman in Malaysia, NHTSA requested that Ford replace driver side airbag inflators in Ranger vehicles. Ford launched another regional field service campaign in November 2014 to replace driver side frontal air bag inflators in the 2004-2005 Ford Ranger vehicles. The action was still limited to Florida, Hawaii, Puerto Rico, and the U.S. Virgin Islands, despite other manufacturers expanding the affected regions, and still, inexplicably, did not include the 2006 Ranger.
In May 2015, Ford finally converted its regional recall for passenger inflators into a nationwide recall after Takata issued a recall requesting such an action, but never converted its recall of SDI inflators from the limited regional recall into a nationwide recall, nor did it recall the 2006 Ranger with the same SDI.
Knight’s death was partly the impetus for a Takata airbag inflator recall of about 5 million vehicles, which would have included the 2006 Ford Ranger. The family of Joel Knight has publicly stated his death would have been prevented if Ford had launched a timely recall.
As other manufacturers have acknowledged to their customers the dangers of defective Takata airbag inflators and have begun to move more actively to recall these components, Ford continues to demonstrate its apathy. It continues to install the same non-desiccated Takata inflators that are the subject of the massive recalls in what NHTSA has dubbed” like-for-like” inflators – which very few other manufacturers are using. In the three years since NHTSA first ordered manufacturers to treat this defect as an urgent public safety issue, almost all manufacturers have procured either desiccated inflators or inflators from other suppliers. Ford sought extensions, telling the Agency that three years was not enough for it to find a safe alternative in sufficient numbers to meet the demand. Owners of these vehicles will have to go into the shop again in early 2020 for another replacement, which could lead to reduced completion rates because owners are frustrated or feel the interim remedy is safe enough.
Astoundingly, Ford is still telling its customers that the inflators are safe, while Honda has (finally) mounted a full-court press to capture defective inflators – including a door-to-door effort to recovery a particularly dangerous subset of airbags. In contrast, Ford’s webpage entitled, “Frequently Asked Questions regarding Takata Airbag Inflator Recalls,” puts out this bull in response to a query about whether vehicles with recalled Takata airbags are safe to drive:
"Based on currently available technical data, Ford Motor Company understands that the vehicles involved in the recent Takata recall are safe to drive while you are waiting for replacement parts. You should have the repair completed as soon as possible after you are notified that parts are available.”
Ford’s got nerve – we’ll give them that. But one thing they shouldn’t be given is permission to forego the recall. NHTSA should not let Ford play Rupture Roulette with its customers.