20 Dec New approach is a critical necessity
It is important that the fire service, engineers and designers along with aviation professionals collaborate to achieve creative solutions to allow for innovation and expansion within the aviation industry writes Aaron Johnson, Fire & Building Code Strategist.
In 2018, a report released by Aerospace Property Consultants1 listed the top causes of airport and aviation facility related fires. The top fire causes included, electrical, cooking related, hot work operations, other or miscellaneous, arson and aircraft originating.
The most common cause of aviation facility fires are those that have an origin that is electrical related. The majority of these are caused by short circuits, and arc faults. Most electrical fires are quickly detected and extinguished, however, the damage done includes time intensive, major, and costly delays or airport shutdowns.
The second most common cause of aviation facility fires were cooking related. These being largely connected to restaurants in the terminal areas. Often, poor maintenance of the cooking equipment, ventilation, and hood system result in grease fires being started inside the vents.
The third most common cause of aviation facility fires are those caused by the conduct of hot work operations. “Hot work” is defined in NFPA 51B as, “work involving burning, welding, or a similar operation that is capable of initiating fires or explosions”.
The fourth most common cause of aviation facility fires fall into the category of ‘other’ or miscellaneous. These included outside fires, minor explosions, and one-off or freak type of incidents. Some fires included in this category are hangars that were destroyed by brush fires in the nearby area, a bus fire parked at the terminal building which then extended to the structure, and a truck loaded with shredding machine contents, parked in a basement area, caught fire, then spread to the terminal building itself.
Arson and aircraft
The fifth most common causes of aviation facility fires are arson and aircraft originating fire. These are fires that were intentionally set, and those fires that originated on an aircraft and then spread. The origin and cause of these is most typically, work being done, items within the aircraft igniting, or battery charging issues.
The top listed cause was fires whose origin and cause is marked as “undetermined”. The majority of aviation facility related fire incidents are ruled as undetermined. These undetermined fire incidents, most often result in major structural damage, and high economic loss.
The standard for the protection of aircraft hangars is drawn from NFPA 409. The scope of NFPA 409, Standard on Aircraft Hangars was developed to “provide a reasonable degree of protection from fire for life and property in aircraft hangars, based on sound engineering principles, test data, and field experience.” This standard requires the primary fire suppression agent for aircraft hangars be foam, with specific requirements based on the hangar group. The original intent for the foam requirement was to protect the structure against the risk of fuel spills and pooled fuel fires. In the event of a fuel fire, water alone would not be sufficient for extinguishment. Foam is required to blanket and seal the fuel vapors.
There is a growing majority of fire protection engineers, fire code officials, fixed base operators (FBO) managers, airport owners, pilots, and aviation associations that are vocalising the fact that “test data, and field experience” stated in the purpose statement of this standard no longer support the need or requirement for foam fire protection systems2.
The top causes of fires in aviation facilities does not include fuel, or large fuel spill fires, which is the reason and justification for the use of foam fire suppression in aircraft hangars. The data shows that the more probable, and costly, the risk is that of an unnecessary or inadvertent system discharge.
The average claim for a foam discharge exceeds $1 million and includes damages associated with physical damage to the aircraft, lost time and business opportunities, environmental damage and clean-up, and fire suppression system repair and restoration. With the data that is presently available to us, we must ask the question, “Is it time for a new approach to hangar fire protection?”
The National Air Transportation Association (NATA) recently released a report3 that advocates for changes in the next edition of NFPA 409. These suggestions include:
- Create a new category of hangar called “Hazardous Operations.” This classification will apply to hangars that permit higher risk operations such as hot work, in hangar fuel transfers, and spray finishing. Typical FBO hangars that are not classified as “Hazardous Operations” would not require foam.
- Increase the maximum door height requirement for Group II hangars from 28ft. to 35ft.
- Reinstate the “Cluster Hangar” exemption that was mistakenly removed during the previous 2016 NFPA 409 revision cycle.
These code change proposals would allow increased protection for high-hazard areas, where we see that fires do occur, provide for taller aircraft storage, and still remain a Group II hangar, and brings back the “hangar building cluster” exemption, which can allow for a greater fire area, and permits the fire protection for Group III hangar requirements.
Additionally, the aviation industry has suggested a shift in the standard from a prescriptive-based approach to a performance-based, or risk-based, fire protection design approach. A performance-based option would allow a registered design professional, engineer, or other entity approved by the authority having jurisdiction (AHJ), to assess the hangar and its use, and design a fire suppression system based on the hazard presented and risk of fire or life loss.
Applicable codes and standards would provide precise guidance on items to be assessed, with clear indicators of types of fire protection systems to be installed. Such a risk-based approach to hangar fire protection may include an analysis of such items as:
- Services provided
- Risk exposure to surrounding properties, the general public, or first responders
- Importance or impact of business continuity
- Fuel types and quantities, or products used or stored
- Potential economic loss
- Total occupants and life safety
- Local fire department capabilities, resources, and response times
- Construction, compartmentation, infrastructure
- Size and value of the aircraft or the structure
Aviation terminals, hangars, and support facility fire incidents may be low-frequency, but they often come with high-consequences. A new approach to fire protection is not just a “convenience”, but a critical necessity. Considering new types of “fuel”, advances in unmanned aerial vehicles, innovative aircraft shapes, sizes, and configurations, current fire protection requirements, such as a foam system, may become impractical, counter-productive, or even dangerous.
As we look toward the future of aviation, it is important that the fire service, engineers and designers, and aviation professionals work together to create fire protection and life safety solutions that promote and allow for innovation and expansion.