TSB Recommendation A01-04

In its response of 08 November 2001, Transport Canada (TC) agrees that any system in the pressurized portion of an aircraft should be evaluated before being certified to ensure that the system cannot contribute to an ongoing in-flight fire. The Canadian Airworthiness Manual 525.869 specifies fire protection requirements for electrical, vacuum and oxygen systems and current certification practice requires evaluation of those systems where specific fire risks are likely to occur.

The United States FAR 25.1309 requires that a system safety analysis be conducted as part of the certification process to ensure that equipment failures will not have any adverse effect on the safety of the aircraft. The FAA has directed the Wire Systems Harmonization Working Group to recommend whether the methods of compliance with FAR 25.1309 should be mandated.

Extensive projects are under way by airworthiness authorities in conjunction with the industry to develop improved flammability standards to minimize the probability of materials propagating fire when subjected to realistic fire threats. The corrective actions being considered by the Federal Aviation Administration (FAA) for improved material standards, redesigned circuit breakers and more comprehensive wiring insulation tests all contribute to the intent of a systematic analysis called for in the recommendation.

TC will continue to cooperate with the FAA to clarify any additional amendments to the present certification standard that will promote a system that has been designed and installed using a fail-safe methodology. TC will review the applicable Canadian Aviation Regulations on system fire protection in conjunction with the results of the ongoing research projects and will harmonize any changes required with the other airworthiness authorities.

In its response, TC agrees with the intent of the recommendation. However, TC submits that it already requires that electrical, vacuum and oxygen systems be certified against “specific fire risks.” Not extending these measures would constitute the status quo, which the Board’s recommendation cites as the safety deficiency. TC continues by stating that “the FAA has directed the Wire Systems Harmonization Working Group to recommend whether methods of compliance with FAR 25.1309 should be mandated.” Both of these statements provide little clarity as to whether or not TC has recognized the intent of the recommendation and the underlying unsafe condition, or exactly what action is being taken to address the safety deficiency. The staff contacted TC in an attempt to clarify their position. TC advises that, while there is a firm commitment by them, the FAA, and the European Joint Aviation Authorities (JAA) to cooperate in realizing the objectives of this recommendation, details of the action plan are still evolving. Consequently, staff will monitor the emergence of the action plan as TC works with its regulatory partners to address this safety deficiency. Based on the information provided, this response is considered as Satisfactory Intent.

TSB staff will closely monitor the progress of the TC/FAA deliberations to determine if their action plan addresses the identified deficiencies.

As stated in the Minister’s reply to the recommendation, TC will continue to be involved in the relevant FAA Aviation Rulemaking Advisory Committee (ARAC) and authority harmonization activities with the intention of revising Canadian requirements to harmonize with the international standards.

TC’s activity update of 14 December 2005 provides no further information than what is contained in its original response received 09 November 2001. TC states that it will continue to liaise with the FAA with the intention of harmonizing the Canadian Aviation Regulations with international standards. The planned action or the action taken will reduce but not substantially reduce or eliminate the deficiency.

Therefore, the assessment is Satisfactory-in-Part.

In its activity update dated 07 February 2007, TC restates that it will continue to be involved in the relevant FAA, Aviation Rulemaking Advisory Committee and authority harmonization activities with the intention of revising Canadian requirements to harmonize with the international standards.

TC’s response indicates that its action plan consists of revising Canadian requirements to harmonize with the international standards. As in its previous updates, TC has provided little in the way of clarity as to whether or not these international standards are being amended to mitigate the risks identified in Recommendation A01-04. The planned action or the action taken will reduce but not substantially reduce or eliminate the deficiency.

Therefore, the assessment is Satisfactory-in-Part.

TSB staff will follow-up with TC in order to seek details as to how harmonizing Canadian requirements with the international standards will address the deficiency identified in Recommendation A01-04.

TC’s response restates its original position, in that the Canadian Airworthiness Manual 525.869 specifies fire protection requirements for electrical, vacuum, and oxygen systems; and, current certification practice requires evaluation of those systems where specific fire risks are likely to occur.

Additionally, TC states that it considers this recommendation closed because:

• There is no safety deficiency in Canada;
• No further action will or needs to take place; and
• Any further changes in this area will take place only as a result of international regulation harmonization.

TC’s response reiterates that the requirements of AWM 525.869 are sufficient and that changes dealing with fire protection requirements for aircraft systems will only happen as a result of international harmonization. Because there has been no action taken or proposed to address the fact that not all aircraft systems in the pressurized portion of the aircraft are evaluated to ensure that their failure does not exacerbate a fire in progress, as identified in Recommendation A01-04. Consequently, the assessment is changed to Unsatisfactory.

The TSB Air Branch staff will continue to monitor occurrences reflecting similar type deficiencies, and to communicate concerns to TC regarding the deficiency identified in Recommendation A01-04.

In its latest position statement with respect to the deficiency identified in Recommendation A01-04 TC states that as “existing design standards adequately satisfy safety risks with fire and unsafe temperatures” and “nothing in the design standards was identified as a safety deficiency” it considers this recommendation closed.

Therefore, the assessment remains at Satisfactory-in-Part.

The Board also concludes that, as no further action is planned by TC to address any residual risk, continued reassessment will not likely yield further results. 

TSB Air Branch staff will not actively monitor TC’s regulatory activities to ensure that those systems whose failure could exacerbate a fire in progress are designed to mitigate the risk of fire-induced failures.

The Board requested that A01-04 be reviewed to determine if the Deficiency File Status was appropriate. After an initial evaluation, it was determined that the safety deficiency addressed by Recommendation A01-04 needed to be reassessed.

A request for further information was sent to Transport Canada (TC) and a reassessment will be conducted upon receipt of TC's response.

Therefore, the assessment of the response to Recommendation A01-04 remains Satisfactory In Part.

Consequently, the status of Recommendation A01-04 is changed to Active.