Airbag expiration?
04-26-2004, 09:05 PM
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Airbag expiration?
I saw a warning sticker on the doorjam of a new A4 that said the airbags needed to be replaced after a certain number of years - 10 or 13 I think. Is the issue is that bag the material ages, and may not be able to take the force of an accident after sitting folded up in the your steering wheel that long?
Is this an issue for all airbag-equipped cars, including late-model 928s?
Is this an issue for all airbag-equipped cars, including late-model 928s?
04-27-2004, 04:36 AM
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Yup every car with the aero-wheel...
All airbags (theoretically) have a proscribed life span. Most are supposed to be replaced at 10 years (IIRC). Pretty sure that it's a NHTSA 'requires you to tell people' thing, but I'm sure the lawyers had a hand in it (liability limiter).
I believe the areas of concern are:
Electrical connections - not really a big deal since I think they all use gold plated contacts. Not sure if that's by mandate or common sense. If not mandated, I'm sure somebody's saving 10 cents a unit by using silver or something that won't last quite nearly forever like gold does. There's also a bunch of inputs that are required to trigger a bag - a with newer multi-stage bags, there's even more inputs. More inputs =higher potential failure rate. Even if the bag would fire fine, maybe one of the bumper sensors went partially bad, and it wouldn't send the signal it should.
The 'inflator' - IIRC they're all still 'deployed' (read: exploded to an inflated state) with a small charge of sodium azide (not sure about current stuff, haven't kept up). Anyway, concern about the reliablilty of this stuff going 'boom' when it should after that long - moisture, condensate, heat cycling and whatnot. Car interiors are really miserable places, esp. when they're parked. Multiply by 10 years.
The bag - probably will be floating around junkyards long after we have turned to fertilizer. Much like 2-liter bottles and half-eaten Twinkies. But all things safety have an engineer determined life span (like racing seatbelts) and as such, they might be fine, but they might not be 100% when you need them to be. So, they 'expire'.
Plastic covers - they bag resides under a carefully engineered piece of plastic. If it does not breakaway as it should during a deployment, the deployment may not be in time - causing more problems than it solves. Plastic on steering wheels and on dashboards tends to get a lot of UV degredation. Hell, it might rip the bag - with your car giving you a final 'raspberry' as your head accelerates toward the steering wheel.
Best I can recollect - never got too much into airbag tech. Any engineers from an appropriate Tier I out there?
Greg
All airbags (theoretically) have a proscribed life span. Most are supposed to be replaced at 10 years (IIRC). Pretty sure that it's a NHTSA 'requires you to tell people' thing, but I'm sure the lawyers had a hand in it (liability limiter).
I believe the areas of concern are:
Electrical connections - not really a big deal since I think they all use gold plated contacts. Not sure if that's by mandate or common sense. If not mandated, I'm sure somebody's saving 10 cents a unit by using silver or something that won't last quite nearly forever like gold does. There's also a bunch of inputs that are required to trigger a bag - a with newer multi-stage bags, there's even more inputs. More inputs =higher potential failure rate. Even if the bag would fire fine, maybe one of the bumper sensors went partially bad, and it wouldn't send the signal it should.
The 'inflator' - IIRC they're all still 'deployed' (read: exploded to an inflated state) with a small charge of sodium azide (not sure about current stuff, haven't kept up). Anyway, concern about the reliablilty of this stuff going 'boom' when it should after that long - moisture, condensate, heat cycling and whatnot. Car interiors are really miserable places, esp. when they're parked. Multiply by 10 years.
The bag - probably will be floating around junkyards long after we have turned to fertilizer. Much like 2-liter bottles and half-eaten Twinkies. But all things safety have an engineer determined life span (like racing seatbelts) and as such, they might be fine, but they might not be 100% when you need them to be. So, they 'expire'.
Plastic covers - they bag resides under a carefully engineered piece of plastic. If it does not breakaway as it should during a deployment, the deployment may not be in time - causing more problems than it solves. Plastic on steering wheels and on dashboards tends to get a lot of UV degredation. Hell, it might rip the bag - with your car giving you a final 'raspberry' as your head accelerates toward the steering wheel.
Best I can recollect - never got too much into airbag tech. Any engineers from an appropriate Tier I out there?
Greg
