Tips on Roof Cutting
Received a question from a Lt in a California fire department asking the following;
"What is the general rule of thumb for cutting the A,B,C-post on newer autos. Should we be cutting the tops or the bottom of the post? I know we should take the molding off to expose the airbag systems. Is this correct?"
Basic philosophy for cutting posts varies with who you talk to and what you want to accomplish. I can explain what I see happening most frequently as I visit with crews across the US and then you can take it from there.
For flipping or flapping a roof, most crews cut the A and B-posts low at dashboard level. This minimizes the 'stub' left behind when the roof is lifted rearward.
For total roof removal, low cuts are also most commonly used. Minimal stubs to cover.
Some will tell you that the bottom 6 or 9 inches of the A-pillars are where there can be stronger roof pillar material, primarily due to the claim that the pillar may be double thick. The statement is made that at the assembly plant, the metal from the dash structure comes up and the metal from the A-pillar comes down and may actually overlap in those lower few inches of the A-pillar. I haven't found a crew yet who were stopped dead in their tracks because they cut the A-pillars low. Personally, I don't worry about it.
Roof evolutions for a side-resting vehicle can change roof cut locations. For total removal, low cuts are good. This removes or minimizes the stubs as much as possible.
When dealing with a side-resting vehicle and you are cutting just the high-side pillars to lay a roof down, you may want to consider cutting those pillars close along the roofline edge. In this way, when the roof is peeled down, the upper posts remain up above your patient. The roof on the ground that you will be walking on as the patient is longboarded out of the vehicle doesn't have any significant stubs with the roof-edge cut.
Then the consideration as always, strip the trim before you cut...just for safety.
Stripping the interior trim could also be good to identify the reinforced areas especially of the b-pillar and its a real easy evolution. On the attached picture you could see a reinforcement bar built into the b-post of a mercedes-benz e-class.
When cutting posts avoid to cut into pretensioners and hybrid-gas generators and avoid to cut the area whre the seatbelts are mounted.