Safety Issues Investigation Report SII A05-01

- Value of Statistical Life
- Design Standards for New Aircraft
- Existing Production Aircraft

Post-Impact Fires Resulting from Small-Aircraft Accidents

Link to TSB Safety Study Report SIIA05-01 (http://www.tsb.gc.ca/eng/rapports-reports/aviation/etudes-studies/siia0501/siia0501.asp)

Executive Summary

For aircraft with a maximum certified take-off weight of 5700 kilograms (12 566 pounds) or less, post-impact fire (PIF) contributes significantly to injuries and fatalities in accidents that are otherwise potentially survivable. A potentially survivable accident is one in which the impact forces are within the limits of occupant tolerance, the aircraft structure preserves the required survival space, and the occupant restraint is adequate.

This investigation examined Transportation Safety Board of Canada (TSB) data and the history of PIF safety action to become more informed and to provide discussion material with the intent of mitigating risks surrounding PIF in small aircraft, specifically regarding design certification. The historical incidence of PIF occurrences in aircraft weighing less that 5700 kilograms demonstrates a high probability of future similar occurrences, resulting in adverse human consequences, if current design standards are not addressed.

Recommendations

Transportation Safety Board of Canada Recommendation A06-08 regarding Value of Statistical Life

The Board recommends that, “Transport Canada, together with the Federal Aviation Administration and other foreign regulators, revise the cost-benefit analysis for Notice of Proposed Rule Making 85-7A using Canadian post-impact fire statistics and current value of statistical life rates, and with consideration to the newest advances in post-impact fire prevention technology."

Transportation Safety Board of Canada Recommendation A06-09 regarding Design Standards for New Aircraft

The Board recommends that, "Transport Canada, the Federal Aviation Administration, and other foreign regulators include in new aeroplane type design standards:

  • methods to reduce the risk of hot items becoming ignition sources;
  • technology designed to inert the battery and electrical systems at impact to eliminate high-temperature electrical arcing as a potential ignition source;
  • requirements for protective or sacrificial insulating materials in locations that are vulnerable to friction heating and sparking during accidents to eliminate friction sparking as a potential ignition source;
  • requirements for fuel system crashworthiness;
  • requirements for fuel tanks to be located as far as possible from the occupied areas of the aircraft and for fuel lines to be routed outside the occupied areas of the aircraft to increase the distance between the occupants and the fuel; and
  • improve standards for exits, restraint systems, and seats to enhance survivability and opportunities for occupant escape."

Transportation Safety Board of Canada Recommendation A06-10 regarding Existing Production Aircraft

The Board recommends, "To reduce the number of post-impact fires in impact-survivable accidents involving existing production aircraft weighing less than 5700 kg, Transport Canada, the Federal Aviation Administration, and other foreign regulators conduct risk assessments to determine the feasibility of retrofitting aircraft with the following:

  • selected technology to eliminate hot items as a potential ignition source;
  • technology designed to inert the battery and electrical systems at impact to eliminate high-temperature electrical arcing as a potential ignition source;
  • protective or sacrificial insulating materials in locations that are vulnerable to friction heating and sparking during accidents to eliminate friction sparking as a potential ignition source; and
  • selected fuel system crashworthiness components that retain fuel."

Transport Canada Response to Recommendations A06-08, A06-09 and A06-10

With reference to recommendation A06-09, over the years many amendments to Airworthiness Manual (AWM) 523/FAR 23 regulations have been adopted to achieve this objective and may address certain elements of this recommendation. Many aircraft identified in the TSB report were certified to design standards from 1960 or earlier. These aircraft would not have been subject to the revised standards and therefore the benefits of these changes will not necessarily be evident in the data used by the TSB due to the date when many of the affected airplanes were certificated.

With reference to recommendation A06-10, Transport Canada is not aware of industry application for the approval of such technology for retrofit in production aircraft. It is believed this type of technology for use in aviation is still largely in the research and development stage and will require further developing and testing before it can be certified for use in a wide variety of aircraft. Departmental officials cannot conduct a viable risk assessment or mandate post certification until it is established that pertinent technologies are available, viable and required. Prior to undertaking any of this, a study would be required to clearly identify the benefit of such an undertaking. The technology would have to be identified, certified and hundreds of aircraft designs would require evaluation.

The vast majority of small aircraft registered in Canada are of foreign design and the expertise for implementing modifications to those aircraft rests primarily with the responsible Civil Aviation airworthiness authorities. These recommendations have a significant international impact that would require Transport Canada to involve other airworthiness agencies, such as the European Aviation Safety Agency and the United States Federal Aviation Administration.

Transport Canada supports the TSB objective of reducing fatalities and serious injuries due to post-impact fires in general aviation aircraft however, implementation of these recommendations would require an immense resource effort. Unfortunately, the Department is not in a position to commit the necessary resources at this time.

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