U.S. Department of Agriculture, Forest Service, National Technology and Development Program (NTDP)
Helmet Report:
San Antonio Fire Tree Limb Strike
This report is based on interviews, site visits, and a visual examination of the helmet.
On June 19, 2018, two wildland firefighters (Joel and Memo) of the Zig Zag Interagency Hotshot Crew (IHC) were struck by a 9-foot long section of a falling tree limb while performing fire suppression operations on the San Antonio Fire, Valles Caldera National Preserve, in New Mexico.
Tree Limb Species—White Fir (Abies Concolor)
Condition—Living
The height the limb fell from—50 feet
Calculated limb weight—12.3 pounds
Energy delivered to helmet—834 joules
Wildland Firefighting Helmet Make—Bullard Wildfire Series Fire Helmet
Model—FH911C (Cap-style)
Date of Manufacture—June 2016
Date Put into Service—May 2017
Certifications—NFPA 1977 Standard on Protective Clothing and Equipment for Wildland Firefighting, 2016 Edition; ANSI/ISEA Z89.1-2014, Type I, Class E&G.
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Rear
Front
Figure 1 – Photo shows scuff marks and dirt on the outer shell surface of the helmet. The front and rear of the helmet are labeled.
Helmet Shell/Outer Surface Condition—Scuff marks and dirt are visible on the outer shell surface. (See Figure 1.)
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Rear
Figure 2 – Photo shows the repositioned retroreflective marking on the rear brim of the helmet.
Three of the retroreflective markings have been removed. One of the retroreflective markings has been relocated to the rear brim of the helmet. (See Figure 2.)
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Figure 3 – Photo shows the faded antiglare material under the front brim of the helmet.
Helmet Shell/Inner Surface Condition—The antiglare material, located under the front brim of the helmet, appears to be faded and worn. (See Figure 3.)
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Helmet Suspension Condition—The sweatband is missing from the helmet suspension. (See Figure 4).
Rear
Front
Figure 4 – Photo shows the inside view of the helmet suspension. The front and rear of the helmet are labeled. The area where the sweatband should be located is labeled with black arrows. The Limb Strike Both Joel and Memo heard the limb release from the tree canopy above them. A portion of the limb struck Joel on the left side of his helmet at an “angle smearing the hard hat [helmet] off his head.” The remaining section of the limb struck Memo on his back. Both firefighters were knocked to the ground.
Joel received a laceration requiring 15 stitches to the upper right side of his head, and a concussion. Memo received bruising to his back. Both firefighters were transported to the hospital and later released.
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Discussion Tree strikes and limb strikes are accidents that happen fast. The impact from these objects typically comes from above. These objects are hard to see, especially when you are trying to protect yourself or get out of the way.
It is difficult to determine the exact angle of the limb impact to Joel’s helmet. However, both Joel and Memo recall the limb impacting Joel’s helmet with a “glancing blow”. Joel recalls the limb impacting/“smearing” the helmet out of position, and off of his head.
The Interagency Standards for Fire and Fire Aviation Operations (Redbook) for head protection requires firefighters to wear helmets designed for what is described as a Type I impact. Type I helmets are designed and tested for a top impact only.
Helmets intended for wildland firefighting are certified to National Fire Protection Association (NFPA) 1977 “Standard on Protective Clothing and Equipment for Wildland Fire Fighting”. Helmets that are manufactured and certified to meet NFPA-1977 requirements include retroreflective markings to improve firefighter visibility in low light situations on the fireline.
Helmet Protection Limitations Type I helmets are required to pass the force transmission test. This test is designed to emulate the weight of a typical brick falling one story (10 feet) onto a person’s head. The falling brick generates 54 joules of energy on impact with the helmet. It is believed that additional energy will cause vertebral damage.
Helmet Analysis The limb fell 50 feet before impacting Joel’s helmet. The impact energy from the limb was 834 joules. The impact energy of this limb was 15 times the force transmission test.
Type I helmets are intended to reduce the force of impact from a blow to the top of the head. Although Joel did receive a concussion and 15 stitches in his head, it is clear that Joel’s helmet functioned as designed and reduced the impact energy from the limb.
From past accidents involving helmet strikes, it has been shown that a majority of the impacts are glancing impacts. These impacts typically knock the helmet out of position or knock it off the head completely. Helmet performance is maximized when the helmet remains on the head.
Additional Helmet Information It is important to understand the use, serviceability, and performance limitations of personal protective equipment.
Helmet components include an outer shell, suspension components, and chin strap. Helmets require periodic inspection and maintenance.
Helmet manufacturer replacement components and accessories can be found at this Bullard Helmet website: https://www.bullard.com/product/hard-hat-accessories-and-replacement-parts.
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For guidance on current helmet information and inspection criteria please go to the National Wildfire Coordinating Group (NWCG) Equipment Technology Committee (ETC) website: https://www.nwcg.gov/committees/equipment-technology-committee.
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