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  • Airbags not deploying

    One incident I considered a fluke, two incidents must be a design flaw?

    In the last month we have had two vehicles strike the rear of semi trailers causing moderate damage to the front of the vehicle, but only above the level of the bumper. In both cases the car crumpled approx 12 to 18" into the engine. the speed at impact was >30 mph and pt's recieved minor to moderate injuries to their face and chest.

    In both incidents the airbags failed to deploy. batteries were cut and pt's removed without incident.

    Has anyone seen similar incidents. I was under the impression that any impact to the front of the vehicle that severe would cause the airbags to deploy. The vehicles were a late 90's honda accord and a late 90's chevy cavalier.

    Any insight would be appreciated.

    Stay Safe

  • #2
    A simular incident was posted here a while back. The theory at that time was that when the collision occurred, the vehicle was actually in a downward deceleration direction rather than a forward since it under road the trailer. Since the sensor system is designed to trigger on forward deceleration only, it was believed that the downward movement overroad the forward which did not allow the sensors to trigger.

    I too am interested in hearing other theories on this...



    ------------------
    Richard Nester
    Orrville (OH) Fire Dept.

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    • #3
      In general airbag systems are designed to deploy in a head on collision into a solid nondeformable object @ 12 to 15 mph or about 25 mph into a vehicle of similar size, weight, $ crush characteristics-at least this is the theory. As what happened to my wife, when rear ending a large vehicle with a smaller vehicle the smaller vehicle impacts not with the bumper but above it with the grill and hood. This cushions the vehicle and does not allow the sensors to trigger due to the fact the "blow" was not sharp enough. We see this quit abit at rush hour responses. People have trained to think that at the slightest bump the bags will deploy, but at least it keeps em buckled up.

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      • #4
        Interesting . We have had 2 MVA's both vehicles were Toyota's.
        1st T bones a full size Chevy pickup
        2nd rear ended a full size Buick.
        In both cases the front airbags did not deploy. At both MVA's 2 pt's were in the front seat of both vehicles.
        Interesting .

        Jim Greene

        [This message has been edited by Jim Greene (edited October 07, 2000).]

        Comment


        • #5
          I crashed my wifes 99 toyota rav 4, 2 months ago. I hit a car in the rear, with the only damage to the grill, hood, and the radators. It suprised me that the air bags didnt go off becouse we hit about 30 miles an hour. I just figured that the sensor was in the bumper and becouse the bumper was not hit it didnt go off.

          Have a good day and be safe.

          Joe

          Comment


          • #6
            From a class I took that GM put on, most cars are equipped with two sensors located in two different locations. As I recal, one is usually in the dahsboard or under the hood and the second is located under a front seat. Both sensors must activate at the same time in order to trigger the airbags. I would have to guess that as jducharme states where two vehicles going the same direction, and as I state where a vehicle under-rides, the sensors apparently are not both activating at the same time.



            ------------------
            Richard Nester
            Orrville (OH) Fire Dept.

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            • #7
              Its my understanding that there are infact three sensors in the front of most vehicles and that it takes two of them to trip to make the air bags deploy. It would only be a guess but as described most incidents describe a underride effect which may not have allowed for the sensors to recieve the information needed for deployment.
              just my two cents
              stay safe

              Comment


              • #8
                I will get with my engineers on this issue and provide an answer monday. Currently I work in the automotive industry, interiors and seating systems. I have dealt with the side airbags and front ones as well. I will get with my engineers on this issue and provide an answer monday. While the side airbags will deply on side impact...the front ones will not. and visa versa. There is more than one sensor in both cases...this is to prevent an airbag going off if you by chance run into something or something hits you...
                I believe now they have made the front airbags to go off if it is indeed a full head on collision hitting more than two sensors. But like I said I will double check.

                PS...disconnecting the battery will NOT prevent an airbag from deploying.

                ------------------
                Camaro SS: [email protected]
                EMT/Fire Rescue Training

                Lauralee's Playground

                [This message has been edited by Lauralee_HotSS (edited October 22, 2000).]

                Comment


                • #9
                  On the same note. I dont know how many of you have had training with SAB deployment. This is tricky...due to the sew pattern and design of the seat. We have had seats in out plant area that their airbags have gone off...TIP, if at all possible. If you are performing a rescue on a car with SAB....STAY AWAY from the outboard front seat back and cushion section of the seat. Attemp rescue from the top or inboard side (if possible)

                  Many Chrysler cars (Sebring, 300M, stratus) and Ford models (Lincoln) have side airbags.

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                  • #10
                    Lauralee,

                    It is good to have someone with an "inside" scoop on these contraptions. I have had two training session on SRS and I am still not comfortable with them. Will look forward to your engineers explainations.



                    ------------------
                    Richard Nester
                    Orrville (OH) Fire Dept.

                    Comment


                    • #11
                      An airbag does not need to have a "charge" to them (ie a battery) when we receive the devices from TRW or any safety manufacturer they come either inert or active. These devices have to be locked up in a cage. At anytime an active restraint can go off...extreme heat is one cause and exposed wires.

                      This is the same case with pretensioners (seat belt buckles) Most vehicles have these integrated into their seat belt. they can activate the same way an airbag can...in this instance it can cut off someones hand...or leave a severe laceration.

                      In regards to airbags deploying...It does take more than one sensor to activate deployment of the bags...Engineers are constantly working on preventing airbag deployment when its not usefull and providing safer disarming methods.

                      I work with devices on a daily basis (To be able to handle any safety restraint all emplyees have to go through two classses a year. )...I have held them bare, in my hands and could see the bag sticking out of the case...I have carried a box of 50 devices (all live) knowing that if whoever made these, made them incorrect...I could loose my life instantly! Not to mention anyone that is within 150 ft from me! These puppies FLY! If a cement wall is in the way ... it will go through it.

                      I have my airbags out of my car...when I race at the track I have my roll cage and my 5point safety belt. I felt unsafe having it in there (the passenger one is still there).

                      I know this was a novel...hopefully it is helpful. If there are any questions regarding this...shoot me an email and I can send you some airbag safety info. Also some MSDS, I have learned a lot from these papers that are not in any textbook.


                      ------------------
                      Camaro SS: [email protected]
                      EMT/Fire Rescue Training

                      Lauralee's Playground

                      [This message has been edited by Lauralee_HotSS (edited October 24, 2000).]

                      Comment


                      • #12
                        ADSN/WFLD -

                        It has been far and few between as far as bags not deploying on a complete frontal impacts in the cases I have seen. Even in off set collisions. The only time I have not seen a bag go off in a vehicle in a frontal collision is when 1. The vehicles impact was to light. 2. The PASSENGER side bag did not deploy due to A> Smartbag on passenger side B> That pass. bag was turned off. In some cases as we all know different manufacturers place there impact sensors in an array of locations. The only thing I can say is that the impact in both of your cases were not on the bumper; you stated they were just above. But even with that, as far as the GM product involved with one of your cases, it does not make sence. GM "usually" had sensors located in the loaded bumper in the front on some vehicles, thus it would only have to go in 4-6 inches to deploy. Although, depending on the exact year of these vehicles, it might have to do with if new generation safety cages were put in them. This would lessen the chance of the bags deploying due to the cage absorbing most of the impact before deployment. Therefor eliminating an unessasary deployment; both cases for you were around 30mph, it may have not been enough umph to bang>

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