Case Study: 1994 Saturn SL2

Origin and Propagation

Passenger compartment burn damage down to seat cushions. Frame of driver’s seat visible on right. Arrow shows burned edge of fuel tank exposed through gap in torn sheet metal.

Origin and Propagation: Fire damage to the undercarriage was limited to a small area forward of and above the left rear wheel well. Consumable materials remained in that region and showed little heat damage. The upper corner of the fuel tank (in damaged, post-impact position) showed heat exposure but no breach. Fire damage was extensive in the passenger compartment with little in the trunk. In the passenger compartment, most consumables remained at the level of the seat cushions and below. Some foam seat material remained as well. Carpeting showed little burn damage anywhere. The instrument panel was burn damaged on the upper left, upper right and lower right. No burn damage was evident in the engine compartment.

With extensive crush, the surface of the gasoline tank adjacent to the floor pan could not be examined in its entirety. However, inspection from above revealed no openings in the floor pan in the region of the center of the tank. Passenger compartment integrity was breached by seam openings of the left and right rear fender wells and floor pans; neither of these areas was adjacent to any observable fuel leaks. The area of suspected leakage was approximately centered in the vehicle; likely propagation paths were located along the sides of the vehicle, through the torn fenderwell-to-body spot-welds. There was minimal observable burn damage between these two points under the vehicle. There was no breach of the trunk floor pan from the front of the spare tire rearward and no burn damage in this area. Since burn damage was predominantly to the passenger compartment with limited incursion to the undercarriage, a continuous tank leak was discounted. Most likely, gasoline was released during impact compression of the tank and was sprayed into the passenger compartment.

Propagation time was established from several witness statements. The police officers, parked on the shoulder to the right of the Saturn point of impact, reported seeing flames immediately. An off-duty emergency medical technician (EMT) was passed by the police vehicle, then came upon the scene even before the police officers exited their stopped vehicle. He stopped immediately, identified himself to the officers, and approached the Saturn. As he approached the Saturn he observed flames behind the driver’s seat but none under the vehicle. His estimates and estimates from the activities described were consistent with his approaching the vehicle within 1-3 minutes of impact. He attempted to open the driver’s door, the passenger’s door, and the driver’s door again before the flames prevented his further attempts. The EMT walked quickly to the Taurus to assist occupants there and found it empty. Looking back at the Saturn he observed the passenger compartment was fully involved. It was estimated that the fire was fully involved within 3-5 minutes of impact. Fire service logs indicated their arrival 7 minutes after impact.