AD/DHC-8/31 - Firewall Electrical Terminal Block

Overview

The Civil Aviation Regulations 1998, specifically within Part 39 - 105, were enacted by the Commonwealth of Australia to regulate civil aviation safety, including the establishment of airworthiness directives. This legislative instrument aims to address safety issues related to aircraft operation by setting forth mandatory requirements for maintaining aircraft airworthiness, thereby ensuring the safety of air travel. The Civil Aviation Safety Authority, under the authority of the Civil Aviation Act 1988, implements these regulations. The policy objective is to mitigate risks associated with aircraft operations through standardised safety directives. One such directive, AD/DHC-8/31, pertains to Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes, specifically focusing on the firewall electrical terminal block to prevent corrosion and associated electrical faults. This directive was introduced following investigations into potential safety hazards identified in the DC firewall terminal block and battery shunt cable assemblies of certain DHC-8 models, aiming to ensure that such issues are proactively addressed to maintain the highest safety standards in civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority’s (CASA) Schedule of Airworthiness Directives for Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, with the directive AD/DHC-8/31 concerning the firewall electrical terminal block. This regulation applies to DHC-8 aircraft models 102, 103, 106, 301, 311, and 314 with serial numbers ranging from 003 through 362 inclusive. The requirement is to incorporate de Havilland Modification 8/1984 as per Bombardier Regional Aircraft Division de Havilland Dash 8 Service Bulletin S.B.8-24-47 Revision A dated 29 November 1993. This directive is a response to findings from a de Havilland investigation which revealed that the use of aluminium washers in the DC firewall terminal block and battery shunt cable assemblies can cause corrosion at electrical connections, potentially leading to loose connections or high electrical resistance. Compliance with this directive is mandated to prevent such issues, with an initial compliance deadline set for 23 April 1994, though Transport Canada extended their compliance requirement by 30 days. This regulation operates within the Commonwealth of Australia, enforcing compliance with airworthiness directives to ensure the safety of the aircraft involved.

Key Provisions

The Civil Aviation Regulations 1998, particularly in Part 39, Section 105, includes specific provisions aimed at ensuring the safety of Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes. The directive AD/DHC-8/31, dated 4th April 1994, mandates that certain DHC-8 aircraft models, specifically those with serial numbers ranging from 003 to 362, must incorporate de Havilland Modification 8/1984. This modification is to be carried out in accordance with the Bombardier Regional Aircraft Division de Havilland Dash 8 Service Bulletin S.B.8-24-47 Revision A dated 29 November 1993. This requirement is directly related to an investigation by de Havilland which revealed that the use of aluminium washers in the DC firewall terminal block and battery shunt cable assemblies could cause corrosion at electrical connections, potentially leading to loose connections or high electrical resistance at connection points. The obligations under this directive are quite clear: operators and owners of the specified DHC-8 aircraft models must ensure that the required modification is implemented prior to 23 April 1994. This involves adhering to the detailed procedures outlined in the aforementioned service bulletin, ensuring that all aluminium washers in the specified areas are replaced or otherwise managed to prevent corrosion. It is crucial that these modifications are carried out by certified personnel to ensure compliance with aviation safety standards. Failure to comply with these directives could lead to serious safety issues, potentially resulting in operational failures or even catastrophic events during flight. While the specific consequences are not detailed in the text, it is implied that non-compliance could result in penalties under the Civil Aviation Act 1988, including fines and potential grounding of the aircraft. Additionally, there could be implications for airworthiness certificates, which could be suspended or revoked, thereby preventing the aircraft from being operated until the required modifications are satisfactorily completed.