It Was Dayton All Over Again!

[rmoore]

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!

[fftrainer]

Ron -

I'm just going to be dumb for a minute here and ask this question.

If you cut the seatbelt, the pretensioner poses no threat (other than the scare of the sudden bang)? I currently cut seatbelts as a personal rule. Some of my colleagues will not cut the seatbelt until they make an attempt at unlatching it first. If the simple cutting of the seatbelt removes the threat posed by a pretensioner then I will work to have cutting the belt an extrication SOG for my dept.

Please clarify at your earliest convenience!

[rmoore]

The concern with the seatbelt pretensioner is that if it would accidentally deploy as it did in my case with the VW Passat, the belt would instantly be tugged on, removing as much as 6 inches of slack from the belt.

If you unbuckled the belt and it recoiled normally, it would be out of your way when the slack is pulled out. If however, the belt unbuckled and did not rewind properly or if you or you patient were anywhere near or on the belt, you could get caught by it as it rewinds.

I would not, as a rule, make it mandatory that seatbelts be cut. Here's some food for thought to help you create a department seatbelt guideline (technically called a "seatbelt Algorithm").

1) If the seatbelt unbuckles and rewinds normally, leave it alone.

2) If the belt unbuckles and does not rewind, cut it.

3) If sidewall removal work is being performed(door, B-pillar, 3-door, etc.) cut it.

4 If the seatbelt cannot be unbuckled, cut it.

5) If in doublt, cut it.

Ron Moore
Forum Moderator

[lutan1]

Assuming your construction rules,etc are similar to ours, we are being encouraged by some car manufacturers to cut seatbelts at accidents to ensure that they get replaced if the car goes in for smash repairs.

Seatbelts are like fall arrest harnesses- they are good for one shock load. After that, they should be replaced or inspected by trained/competent persons.

A car that has been involved in a significant accident that is repaired and put back on the road without replacing seatbelts, is what I beleive to be a lawsuit waiting to happen.

We also encourage seatbelts to be cut as soon as we arrive to ensure they are out of the way in case we need to remove the roof, or pillars, etc. (Not sure what some of your designs are like, but all of ours are anchored on the pillars.)

[LA7Mary3]

Ron,
Excellent (and humorous) story that demonstrates rescuer safety.
If I may weigh in on this subject from a law enforcement
accident investigation standpoint. If you do cut the seatbelts, or
deflate the tires, PLEASE, please, please mark these items or make
notes to give to the investigating officer/trooper. These things are
critical in determining the cause of the accident or death in fatal
accidents, and may mislead the accident investigator.
Thanks, and keep up the great work.

[joergheck]

Did anyone of you heard of other incidents with seatbelt pretensioners than this one in plano?

I read about an incident on www.airbaginstitute.com:

-- FIREFIGHTER experiences Seat Belt Pretensioner firing during driver side (total) removal, while cutting top of "B" post with reciprocating saw. The vehicle was a 1999 Toyota Corolla with front end damage and glancing damage to the driver side, with 1 1/2- 2" intrusion. The Firefighter heard the sensor go off, and saw the seat belt snap back.

I think seatbelt pretensioners are less dangerous than airbags if you follow some safety-rules. But it would be interesting if there had been other incidents.