A Posting From Forum Moderator Ron Moore
If I hadn't been there, I would not have believed that it even happened. My first thought was, "this must be what the Dayton firefighters were thinking." My partner thought he had been shot with a gun, he just couldn't find the entrance wound.
While working on a 2001 VW Passat automobile that had been struck broadside on the passenger's side, I had the passenger's front seatbelt pretensioner accidentally fire off. I was 12 inches away from it at the time.
I was operating a recip saw, working to cut through the case-hardened anchor bolt that secures the pretensioner to the inside of the base of the B-pillar. My partner was on the driver's front seat.
The side-imapct airbag in the passenger's front seat had deployed. The roof-mounted airbag system on that side also had deployed down across the window area.
Without warning, the pretensioner's pyrotechnic charge fired, with a sudden loud bang that sounded exactly like a 22-caliber gun shot.
My partner had disconnected the only battery on the car about 15 minutes prior to this activation. Fortunately, I had cut the seatbelt in half about five minutes before. When the unit fired, the stub of the seatbelt just spun around the take-up spool until it ran out of energy. There was no smoke, no smell, no dust like you typically get with frontal airbag deployment. Just that big bang.
I don't know why the unit activated. I think it had to do with the fact that the saw was vibrating the pretensioner unit somewhat. The blade could have transmitted some heat through the bolt as I cut it but that was at the bottom and the firing cap was at the very top. I was not cutting through any wires nor were there any wires nearby.
Lessons Learned?<br />#1: Even killing the electrical system isn't always a 100% guarantee that bad things won't happen.
#2: Unbuckling the seatbelt at an extrication scene might not be enough. Always cut the seatblet in half when you do any work at all near a seatbelt pretensioner, rocker channel, or B-pillar. That way, you'll live to see the spool spinning around rather than your head.
Be Safe!
If I hadn't been there, I would not have believed that it even happened. My first thought was, "this must be what the Dayton firefighters were thinking." My partner thought he had been shot with a gun, he just couldn't find the entrance wound.
While working on a 2001 VW Passat automobile that had been struck broadside on the passenger's side, I had the passenger's front seatbelt pretensioner accidentally fire off. I was 12 inches away from it at the time.
I was operating a recip saw, working to cut through the case-hardened anchor bolt that secures the pretensioner to the inside of the base of the B-pillar. My partner was on the driver's front seat.
The side-imapct airbag in the passenger's front seat had deployed. The roof-mounted airbag system on that side also had deployed down across the window area.
Without warning, the pretensioner's pyrotechnic charge fired, with a sudden loud bang that sounded exactly like a 22-caliber gun shot.
My partner had disconnected the only battery on the car about 15 minutes prior to this activation. Fortunately, I had cut the seatbelt in half about five minutes before. When the unit fired, the stub of the seatbelt just spun around the take-up spool until it ran out of energy. There was no smoke, no smell, no dust like you typically get with frontal airbag deployment. Just that big bang.
I don't know why the unit activated. I think it had to do with the fact that the saw was vibrating the pretensioner unit somewhat. The blade could have transmitted some heat through the bolt as I cut it but that was at the bottom and the firing cap was at the very top. I was not cutting through any wires nor were there any wires nearby.
Lessons Learned?<br />#1: Even killing the electrical system isn't always a 100% guarantee that bad things won't happen.
#2: Unbuckling the seatbelt at an extrication scene might not be enough. Always cut the seatblet in half when you do any work at all near a seatbelt pretensioner, rocker channel, or B-pillar. That way, you'll live to see the spool spinning around rather than your head.
Be Safe!
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