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The Art of Survival Crashworthiness Study Highlights Need for Occupant Safety Features

--by Tom Hoffmann, FAA Safety Briefing

Anyone who has ever had the unfortunate experience of being in a car accident knows that their vehicle’s many built-in safety features, such as air bags, seat belt pre-tensioners, and head restraints, likely played an important role in increasing your chances of survival. Like most vehicle owners, you probably take for granted that these required safety features are there when you need them, without you having to purchase and install them on your own. For many aircraft owners, however, improving a cockpit’s crashworthiness is not as straightforward. While existing airworthiness standards do address occupant safety when aircraft are manufactured, even for older aircraft, the pathways for enhancing crash survival with new technology have traditionally been difficult and costly. But change is on its way.

The use of performance-based regulatory requirements introduced in the 2017 part 23 rewrite for aircraft certification standards allows for increased flexibility when it comes to safety equipment, especially with regard to accident survivability. In fact, last year the FAA approved a generic airbag installation using part 23 (Amendment 23-64) methods that could be installed in many types of airplanes. Using performance-based requirements and a more generic design allowed the manufacturer to reduce the cost to consumers and facilitate an increased number of installations.

This new policy philosophy is what led the General Aviation Joint Steering Committee (GAJSC) to form a working group and perform a deep-dive study into crashworthiness and survivability factors for GA aircraft. The group consisted of 16 subject matter experts from government, industry, and academia. Their goal was to develop intervention strategies that could lead to safety enhancing recommendations and ultimately form the basis for new consensus standards. If successful, these standards could provide a path to reduce serious injuries and save countless lives.

The study looked at 20 fatal, but survivable accidents (i.e., at least one person survived). The group categorized the accidents according to energy level of the crash (high or low) and descent angle (horizontal or vertical). Members carefully reviewed NTSB accident reports, wreckage diagrams, photographs, and autopsy reports when available. Their examination of the accident data also focused on what went wrong during the flight with an emphasis on how the whole airplane plays into crashworthiness (e.g., noting when shoulder harnesses did not hold, or when seats did not remain bolted to the floor.)

After reviewing each of the accidents, the group developed the following four categories of recommendations, which considered both forward fit and retrofit solution sets:

  • Pilot and Occupant Restraints
  • Maintain Survivable Volume
  • Impact Energy Management
  • Prevent Post-Crash Fire

The first of these categories, restraint systems, particularly upper torso restraints, showed the greatest potential for improved survivability, as well as being the most affordable solution for the retrofit market. In fact, a separate study in Alaska showed that adding 4- or 5-point seatbelts and helmets could save 60-percent of the lives involved in an aircraft accident in that region.

“Four- and five-point restraints more widely distribute the loads, tend to keep the occupant in the right place for the restraint to work, and limit side to side motion,” says aerospace engineer Robert Stegeman with the FAA’s Policy and Innovation Division and member of the crashworthiness working group. “These restraints, by far, offer the best bang for your buck in upgrading your odds in crashworthiness,” adds Stegeman. If your aircraft was built before 1987 and lacks this safety enhancement, Stegeman suggests checking with your original equipment manufacturer (OEM) or your local type club for ways to get shoulder harnesses in your airplane.

The working group also noted the existence of other restraint solutions that can lead to increased survivability: inflatables, pre-tensioners, load limiters, and more robust restraints overall. “Inflatable restraints take normal restraints to a new level, allowing an extreme forward impact to be more survivable,” says Stegeman. Since aviation inflatable solutions are almost always integrated into a restraint system, it’s possible to kill two birds with one stone.

When it comes to seeking out ideas for enhancing cockpit safety, Stegeman suggests checking with type clubs and the open market to see what others have used. “If you have an idea that requires more modification than AC 43-13-2B, Acceptable Methods, Techniques, and Practices — Aircraft Alterations, allows, talk to your FSDO inspector. If necessary, they can collaborate with the local Aircraft Certification Office. The FAA is open to reasonable ideas that don’t otherwise compromise the airplane structure and don’t make a crash situation worse — like having a poorly attached shoulder belt reel break loose in a crash.” Also, be sure your restraints are installed using the appropriate materials and data and are properly inspected and maintained. See the FAA’s Information for Operators (InFO) 17004 or this issue’s Nuts, Bolts, and Electrons department for more details.

When it comes to seeking out ideas for enhancing cockpit safety, check with type clubs and the open market to see what others have used.

In its final report, the working group also pointed to the need for pathways to connect aircraft owners with technologies used in other industries and, where possible, to accept non-aviation specifications to speed the adoption of life-saving equipment. This approach could prove particularly important down the road with regard to lateral safety requirements, an area not currently covered in aviation regulations but which, according to the study, holds great promise in reducing fatal injuries. The focus now, however, is on restraint systems and mitigating forward impact injuries with practical innovation.

ASTM International’s F44 General Aviation Committee is now considering the working group’s recommendations as possible candidates for new, globally accepted consensus standards. This outcome would be a game-changer for operators and manufacturers. Not only would it spur innovation and increase the flexibility for compliance to new crashworthiness solutions, but it would also play an important role in minimizing cost. That would be a lifesaver in more ways than one. Stay tuned for more!

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Tom Hoffmann is the managing editor of FAA Safety Briefing. He is a commercial pilot and holds an A&P certificate.

This article was originally published in the May/June 2019 issue of FAA Safety Briefing magazine.
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