An April crash of a 2019 Tesla Model S into a tree that killed two occupants resulted in damage to the front of the car’s high-voltage lithium-ion battery case where a fire started that destroyed the car, investigators said in a preliminary report.
In its preliminary findings issued Monday, the National Transportation Safety Board said the fire also destroyed the car’s onboard storage device inside the infotainment console. However, investigators were able to recover the car’s restraint control module, which can record data associated with vehicle speed, belt status, acceleration and airbag deployment, but the module sustained fire damage and has been taken to an NTSB lab for evaluation.
The two men killed in the crash on April 17 in Spring, Harris County, Texas, included the owner and a passenger and both were seen entering the vehicle on footage from the owner’s home security camera. The owner took the driver’s seat and the passenger took the front passenger seat. Shortly after the crash, first responders discovered the body of the driver in the rear seat with the driver’s seat empty, raising questions about whether the driver had been relying on a semi-autonomous feature called Autopilot to pilot the vehicle.
Tesla CEO Elon Musk has disputed that Autopilot could have caused the crash because it would not be activated without lane markings, which were absent on the residential street where the crash occurred. In fact, NTSB tested Autopilot on an exemplar 2019 Model S at the crash location and found that one component, Traffic Aware Cruise Control, could be engaged, but the other component, Autosteer, was not available on that part of the road.
NTSB said both car occupants were fatally injured as a result of both the crash and fire. The security camera footage also showed the car leaving the owner’s house and traveling 550 feet before departing the road on a curve, driving over the curb and hitting a drainage culvert, a raised manhole and a tree. * Some earlier reports said it took firefighters four hours to put out the Tesla fire, but Fire Chief Palmer Buck from Woodlands Township Fire Department later said flames were put out in about three minutes upon arriving at the scene, although firefighters used water to cool the battery due to a reaction in the battery pan that lasted while they were on the scene about four hours.
The NTSB has investigated previous EV crashes and issued a report in November on the safety risk to emergency responders from lithium-ion battery fires. The nonprofit Insurance Institute for Highway Safety said some lithium-ion batteries in crashed vehicles have been extinguished only to re-ignite weeks later.
IIHS has been crash-testing EV models for years, going back to 2011, to make sure that when a battery case is damaged in a crash that the electrical charge is automatically cut off to prevent fires and electrocution of occupants and first responders. Of the EV models it has test-crashed, including a Tesla Model S in 2016, none have failed to cut off power from the EV batteries, an IIHS official said in a recent YouTube presentation.
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The NTSB said it is continuing to collect information about the crash, as well as postmortem toxicology test results, seat belt use, occupant egress and electric vehicle fires. “All aspects of the crash remain under investigation as the NTSB determines the probable cause, with the intent of issuing safety recommendations to prevent similar crashes,” the preliminary report says. It could take 12 to 24 months to complete the probe, NTSB said.
*This story has been corrected. Initially it said it took four hours to put out the Tesla fire.