Exploding vehicle struts: A hidden hazard

Five Near-Miss reports highlight unique danger present during vehicle fires


By Brad Van Ert

Today’s vehicles present myriad challenges to first responders. When performing extrication, we must be aware of air bags, electrical components, seat belt pretensioners, vehicle stabilization and overall scene safety. When the same vehicle is involved in fire, we must also consider fuel, oils, hydraulic fluids, combustible metals, compressed flammable gases, toxic byproducts from burning plastics as well as any unknown cargo.

Over the last decade, the Firefighter Near Miss Reporting System has received numerous stories dealing with compressed gas struts where the gas and fluid inside the strut becomes overheated during a vehicle fire, resulting in an explosion of the strut assembly. This can launch a projectile that can cause serious injury to first responders.

When a vehicle is fully involved (total loss) and there are no lives to save, we can afford to take a more cautious approach. (Photo/NPS)
When a vehicle is fully involved (total loss) and there are no lives to save, we can afford to take a more cautious approach. (Photo/NPS)

Compressed gas struts: Basic uses

Modern vehicles use compressed gas struts for multiple purposes. They are found in hoods, rear lift gates, trunks, third-row seats, camper shell hatches, toolboxes and other similar applications. They are used to prevent a door or hood from slamming shut under its own weight and to assist in holding the door open.

Struts consist of a hollow cylinder with a smaller solid metal rod or piston that slides inside. They are filled with an inert gas (usually nitrogen) and a small amount of oil and sealed where the solid rod exits the cylinder. When the strut assembly is subjected to fire, the gas expands, and the seal fails. The rod can become a missile, being launched with explosive force, damaging anything in its path.

The following excerpts from some of the many similar reports underscore this danger.

Near misses involving exploding vehicle struts

“During a live vehicle fire training event at the county fire training grounds, two gas struts exploded, sending a projectile approximately 95 feet from the vehicles being used for the training. ... We found a piece of the strut that holds the rear hatch of a minivan located behind the engine approximately 95 feet from the training vehicle. … The potential for injury was extensive.”

Read the full Near-Miss Report: Two gas struts explode during vehicle fire training.

“Upon arrival, the engine compartment of the vehicle was found to be well involved. As the attack team advanced from the side of the vehicle and opened the nozzle, a noise was heard, followed by the sound of an object piercing the garage door. It was then that the attack team realized that a pressurized hood strut had exploded and pierced the garage door. Luckily, no firefighters were located at the front of the vehicle due to the training and protocols for vehicle fire attack that state that the vehicles should be approached from the sides.”

Read the full Near-Miss Report: Hood strut becomes a projectile during fire.

“We found a late-model vehicle with total engine compartment involvement and involvement into the passenger compartment. After an initial attack, I attempted to release the hood without success from the passenger dash. I then attempted to access the release from under the hood. While on one knee, directly in front of the bumper, I heard an explosion. An engine hood strut struck me in the forearm. Luckily, the forearm was up covering my face and neck at that time. The exiting strut hit my arm with great force, causing nerve damage to my arm that required an extended time off.”

Read the full Near-Miss Report: Vehicle hood strut explodes and injures a firefighter.

“As the engine crew arrived at a car fire, I stopped the engine about 75 feet from the fire that seemed to be consuming the entire engine compartment. I am unsure because the hood was still closed, but the smoke was dark and heavy. I assisted the crew with pulling a 1¾-inch preconnect, and as I was flaking the hose, facing away from the vehicle, I felt like someone punched me in the left shoulder. Just before this, there were a couple of pops that came from the vehicle. I looked and saw that there was a burn mark on my shirt. After supplying water and the fire was under control, a police officer said that he saw something fly from the vehicle and it traveled about 150-175 feet. The officer said that he saw it go by me but didn’t know that it hit me. After searching, one of the officers found a gas strut cylinder from the hood of the vehicle that was on fire. We are not sure of its path of travel out of the car, but that is what grazed my shoulder and then traveled another 100 feet or so and broke the windshield of a minivan.”

Read the full Near-Miss Report: Engine driver hit in shoulder with strut from auto fire.

“… The vehicle was now fully involved. Access to the involved vehicle was not optimal, causing minor apparatus placement issues. The driver/operator and I discussed where to set the safety zone and proceeded to do so. The driver/operator parked the apparatus in a protective position that closed off the street entirely, allowing us to work safe, free from oncoming traffic. As I was donning my PPE and preparing to go on air from my SCBA, there was an explosion toward the back of the vehicle. Shrapnel flew in my direction, propelling straight toward me. A gas-loaded piston from the back hatch of the car exploded, causing a fair amount of glass and metal to fly in multiple directions. The velocity of the explosion and debris made a whizzing noise as it flew by me. The point of impact of the piston was about 4 inches from my head, slamming against the fire apparatus, leaving a silver-dollar-sized dent. Some of the glass and shrapnel hit my integrated protective eye shields, which were in place, averting significant injury to my head. I did incur some small abrasions and cuts, but nothing life-threatening.”

Read the full Near-Miss Report: Gas Shock Fails Prior to Attacking a Car Fire.

These are just a few of many reports that can be accessed on the Firefighter Near Miss website. Search the word “strut” to access and read more reports like these. There have been numerous cases reported from other sources where firefighters have been injured or experienced close calls as a result of these overheated struts.

Ways to reduce risks from exploding vehicle struts

To reduce exposure to these hazards, it is important that we perform a quick risk analysis prior to attacking a vehicle fire. As firefighters we risk a lot to save a lot. If there are trapped occupants in a burning vehicle, we will take greater risks to save lives. However, when a vehicle is fully involved (total loss) and there are no lives to save, we can afford to take a more cautious approach.

Full turnouts and SCBAs are always a must. Approach upwind and uphill when possible. When appropriate, try to begin extinguishment from a distance to reduce the heat before you approach and access the vehicle. There is no way to tell which direction one of these struts may fly, but it is best to avoid standing directly in front of the vehicle. A 45-degree approach may offer greater protection.

Consider all potential hazards involved in attacking a vehicle fire. Take the time to examine the vehicle and try to eliminate hazards prior to conducting live-fire training in vehicles. Examine the cars and trucks in your station’s parking lot. Look for all the places struts or other hazardous components are used. Discuss these with your crews and identify the most obvious directions an exploding strut could fly when overheated.

Seek out safety-related resources

It is critical that we learn from the lessons of our peers. By reading articles in fire magazines, subscribing to fire service newsletters, attending training, and studying line-of-duty death and near-miss reports, we can minimize the risks we face on a daily basis.

The Firefighter Near Miss Reporting System is a good place to start. Search through thousands of reports submitted by your brothers and sisters in the fire service and learn from their experiences. Sign up for the Report of the Week and share it with your crew. We owe it to ourselves, our crews and our families to make every effort to return home safely after every shift.

About the Author:

Brad Van Ert has 37 years in the fire service. He served for 32 years with the City of Downey (California) Fire Department with over 20 years as a captain. He is now the EMS Division Chief with the Northern Lakes Fire Protection District in Hayden, Idaho. Van Ert earned a bachelor’s degree in occupational studies and a master’s degree in emergency services administration at California State University, Long Beach. He has been an advisor with the IAFC Near-Miss Reporting System since 2005.

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