HOT AIR BAG STORY JUST GOT HOTTER
Takata air bag recalls keep growing

Associated Press reports that eight automakers are recalling more than 12 million vehicles in the U.S. to replace potentially dangerous Takata air bag inflators. Documents detailing recalls by Honda, Fiat Chrysler, Toyota, Mazda, Nissan, Subaru, Ferrari and Mitsubishi were posted by the National Highway Traffic Safety Administration. Seventeen automakers are adding 35 million to 40 million inflators to what already was the largest auto recall in U.S. history. Editor Doug Stokes comments. Airbags, which are considered as secondary* restraint systems (after seatbelts) are devices which are asked to function at a reliability rate that is hundreds of times more critical than any aerospace operation after lying dormant for (in the case of my 2002 Ford Focus, for example) many (14!) years**. These devices, in order to be at all effective, must deploy precisely at the millisecond that the driver or passenger is being propelled forward, expanding to attenuate that abrupt motion and cushioning it by releasing the gas that expanded it in controlled fashion. If the propellant (and that is the proper term ... whatever the compound used, it is oxidized at a very high rate*** to generate the gas that expands the air bag) be it sodium azide or ammonium nitrate, or the canister that it is contained in, suffer any sort of deterioration over time, the system is compromised; and that extra layer of protection afforded by the air bag is gone. In the case of some of the older Takata air bags, not going off at the right time is the least of the problem, with shards of the canister becoming lethal projectiles, perfectly-aimed at a driver’s throat. Involuntary recalls are always after the fact and almost always based on some sort of casualty list. Airbag manufacturers need to set a standard of usefulness (like tire manufacturers and other comestible items in use on cars and trucks) and hold their dealers and customers to it. Five years, 10, whatever the number, they should have a check and replace date on every unit. Yeah, that would be expensive, but it would not be the deadly crap shoot that we have now with these devices (particularly the steering wheel units). - Doug Stokes *Please remember that air bags deflate almost as quickly as they inflate and that any sort of second hit in a violent accident that invokes air bag deployment will only be attenuated by the seat belt. The air bag is not a giant, happy marshmallow of protection; it’s gone, collapsed in less than a tenth of a second. That means it protected you when you crashed through the guard rail, but it is out of the picture for whatever is beyond. (By the way that’s precisely why airbags are not used in motor racing where most of the hard crashes are multiple affairs lasting for multiple seconds.) **It will take a better mathematician than me to figure out the fail/safe numbers here: one-thousandth of a second versus 14 years lying dormant is a big little number. *** In real world terms this is an explosion ... the only way that the bag can be filled as quickly as it needs to be to be effective.