Portugal993

I just wanted to ask how many people here have had their airbags deploy on impact? I just remembered my car's been in 2 accidents, and in one of them the car rear-ended a trailer at about 100 km/h and the airbags didn't deploy. The whole front end was wrecked, so shouldn't that have set off the airbag sensors?

TwinDaddy

I've been wondering that myself. With our cars being 10+ years old, are the original airbags as reliable as they once presumably were, despite not receiving an airbag warning light? For instance, perhaps the explosive chemicals or the bag itself could deteriorate without being sensed by the airbag warning system?

Portugal, I assume the speed difference between you and the trailer was not 100 km/hr, or else your car would have been history. If the speed difference was small enough, then it's possible the airbags rightfully might not have deployed.

Portugal993

hmmm I'm guessing the speed difference was about 40 kmh. My dad was driving and the road was wet. As he hit the brakes the car slid right int the back of the other one. And during the toher accident we were rear-ended, mostly on the rear left side and still nothing. I'm starting to think the airbags don't work.

TwinDaddy

Possibly. 40 km/h should be enough, I would think anything above about 35 km/h. But a rear-end collision generally is not supposed to deploy front airbags.

Portugal993

Hmm. I guess not, but it's the first one that makes me suspect they're not working.

Pickled Piper

Hi, I can answer some of your airbag questions. I am a degreed Engineer that worked for many years on the design and implementation of airbag systems.

In answer to question about deployment, it is important to understand that the airbag sensor that is mounted under the dash measures change in velocity at that point and not necessarily the speed of the vehicle. In very general terms the airbag is configured to deploy if the occupants head is likely to come into contact with the steering wheel as a result of the crash. If your vehicle experiences a frontal collision and you hit the steering wheel hard, then it is likely that the airbag should have deployed. In many frontal crashes that severely damage the front of the car, a large amount of energy is absorbed in the crush and hence the sensor and the occupant actually experience very little deceleration.

In answer to the question about the life of an airbag;:The pyrotechnic substances in the airbag can degrade over a period of time. However, due to the safety critical nature of the airbag, the chemicals and the airbag were severely overtested during development. If your vehicle is parked at -20degC at night and is in a temperature of +45degC during the day then there is a very small possibility that after ten years of this cycling your airbag may have degraded. In reality, vehicles never see these sort of temperatures on a regular basis and certainly not continually for ten years. I may consider changing the airbag on my 993 when it gets to 30 or 40 years old.

Finally, the diagnostic system built into the airbag module is very effective at flagging electrical faults. If you do not have a warning light then the system is fine and requires no maintenance.

Hope this helps.

pp

TwinDaddy

Thanks pp, that's good to know.

Robin 993DX

Also depending if you are wearing your seat belt or not, if you are not wearing your seat belt the air bag will deploy at a much lower impact speed.

zicoramone

Well as an airbag systems Engineer perspective your explanation was great, but in my perspective as a lawyer I certainly disapprove changing the airbag only after that huge period, specially if your car have a passenger airbag. In case of accident with a passenger fatality you can get yourself in serious problems. The Insurance Company will not cover the damages because Porsche states in their owners manuals that the life period of an airbag it's about 15 years. You will have to prove that there was no malfunction on it. And that in a trial can be a very hard task.

mhm993

Well, I'm neither an engineer nor an attorney, but I can assure the original poster that our airbags will, indeed, activate when hitting a stationary object. You know the next sentence...."Ask me how I know".....