The airbag's ability to function probably does not end on the expiration date. Almost 100% of the time a safety factor on life span is built in by the engineers that design the system, and that safety factor is usually enhanced by corporate attornies, in my experience.
If the chemists and engineers feel that the device is good for, say, 10 years, they may certify it for 10-25% shorter time. The lawyers, working from the standpoint of liability aversion, may subtract another 10-25% from the life span of the device, on the theory that the engineers could have been wrong about the expected life span.
It is really all about probability. A new airbag (or anything else, for that matter) has a very small but real probability of not working when needed, or going off at the wrong time. As it ages, the probability of failure increases, along some "average" curve. The fact that there is an average curve does not garantee that a particular airbag will respond like that curve! Some devices may last 25 years - 10 years longer than expected by the engineers. Others may have been 'dead' in our steering wheels since day one, and we will never know when it 'died'.
I am not one to bet my life on used or expired safety equipment. I plan on replacing the stock belts and tensioners in my car next year (air pollution and dust particles can degrade nylon belt material). I may also do the airbag, as my car is in top condition with low miles, but I do not regard the airbag as my primary safety feature.
To me, the primary safety devices are the condition of the car's tires, brakes, and suspension, and overall mechanical reliability (coupled with my ability to drive
) The secondary line of defense is the structure of the car and the seat belt system. My last line of defense is the airbag. I may choose to spend $1000 on a driving course that will enhance my 1st line of defense rather than enhancing my 3rd line of safety. Others may choose differently in their priorities.
Sorry to be so long winded, hope this helps. I know that your asking the question helped me clarify my thinking on this pending expense! Thanks for asking!
[Edited by JCE on 05-05-2001 at 01:31 PM]