COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
AD/DHC-8/20 Microwave Landing System Wiring 8/92
Applicability: All DHC-8 series aircraft listed in Boeing Canada, de Havilland Division, Service Bulletin 8-34-60 Revision C dated 1 November 1991, having Microwave Landing System (MLS) or MLS provisions installed.
Requirement: Inspect the vertical deviation wiring interconnecting the MLS and the Ground Proximity Warning System and if necessary, rectify the wiring in accordance with the Boeing Canada, de Havilland Div, Service Bulletin 8-34-60 Revision C dated 1 November 1991.
Note: Transport Canada AD CF-89-18R1 dated 11 May 1992 refers.
Compliance: Prior to further operation of the Microwave Landing System or by 30 June 1993, whichever occurs first.
Note 1: Previous accomplishment of the inspection and rectification in accordance with the original issue of SB 8-34-60 (12 August 1988) does not satisfy the requirements of this Directive.
Note 2: The applicability of paragraphs III.c and III.d of the accomplishment instructions of SB 8-34-60 Revision A (21 September 1990) and Revision B (30 November 1990) differ from the applicability of the same paragraphs in SB 8-34-60 Revision C (1 November 1991). Because the applicability of these paragraphs was revised in Revision C of the Service Bulletin, operators of aircraft that had SB 8-34- 60 Revision A or B incorporated must verify that all applicable inspections and rectifications as required in SB 8-34-60 Revision C have been accomplished.
Background: The issue of this Directive was prompted by advice from the manufacturer that some aircraft prior to serial number 179, with provisions for MLS, were incorrectly wired.
Overview
The Civil Aviation Regulations 1998, under the Civil Aviation Act 1988, were enacted to regulate the safe operation of aircraft in Australia, ensuring the protection of life and property. In addressing a specific problem related to the wiring of the Microwave Landing System (MLS) in Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, the Civil Aviation Safety Authority issued an Airworthiness Directive, AD/DHC-8/20, to rectify potential safety issues. This directive was introduced to ensure that all applicable aircraft undergo the necessary inspection and rectification of the vertical deviation wiring interconnecting the MLS and the Ground Proximity Warning System, as per the requirements outlined in Boeing Canada, de Havilland Division, Service Bulletin 8-34-60 Revision C dated 1 November 1991. The directive aims to eliminate the risk associated with incorrectly wired MLS systems in certain DHC-8 series aircraft, ensuring compliance by a specified deadline.
The directive was issued by the Civil Aviation Safety Authority, reflecting its responsibility under the Civil Aviation Act 1988 to maintain and enhance aviation safety. The policy objective behind AD/DHC-8/20 is to mitigate the risk of potential operational hazards associated with the incorrect wiring of the MLS in DHC-8 series aircraft, thereby safeguarding the integrity and safety of civil aviation operations in Australia. Operators are required to complete the mandated inspections and rectifications before further operation of the Microwave Landing System or by 30 June 1993, whichever comes first, with specific emphasis on the applicability of revised instructions from the latest version of the service bulletin.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39, subsection 105, addresses the safety of aircraft by imposing Airworthiness Directives (AD) on particular aircraft types and systems. This particular regulation, AD/DHC-8/20, applies to all DHC-8 series aeroplanes that are equipped with a Microwave Landing System (MLS) or have provisions for such a system, as outlined in the Boeing Canada, de Havilland Division, Service Bulletin 8-34-60 Revision C dated 1 November 1991. The requirement outlined in this directive is that the vertical deviation wiring connecting the MLS and the Ground Proximity Warning System must be inspected and rectified if necessary, according to the guidelines provided in the aforementioned Service Bulletin. Compliance with this directive must be achieved before further operation of the MLS or by 30 June 1993, whichever is earlier, and it supersedes previous inspections conducted under the original Service Bulletin. Operators must ensure that all applicable inspections and rectifications are carried out as specified in the latest revision of the Service Bulletin, even if earlier revisions were previously incorporated.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, contains provisions that mandate inspections and rectifications on the Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes (section 1). The directive in question, AD/DHC-8/20, pertains to the Microwave Landing System (MLS) wiring. It requires an inspection of the vertical deviation wiring that connects the MLS and the Ground Proximity Warning System, with necessary rectifications to be performed as per Boeing Canada, de Havilland Division, Service Bulletin 8-34-60 Revision C dated 1 November 1991 (section 2). The directive applies to all DHC-8 series aircraft that have either an MLS or MLS provisions installed and were listed in the aforementioned service bulletin (section 3).
Operators of the affected aircraft must ensure that the specified inspections and rectifications are completed prior to the further operation of the MLS or by 30 June 1993, whichever comes first (section 4). It is important to note that the completion of the inspection and rectification under the original issue of SB 8-34-60 (12 August 1988) does not suffice for compliance with this directive (section 5). Operators who had previously incorporated Revision A or B of the service bulletin must verify that they have addressed all applicable inspections and rectifications as outlined in Revision C (section 6).
Failure to comply with this directive may result in civil or criminal consequences. The Civil Aviation Regulations 1998 outline various offences, penalties, and legal consequences for non-compliance with airworthiness directives. The exact penalties are not detailed in the provided excerpt, but it is understood that violations could lead to significant legal repercussions for the operator, including fines and potential grounding of the aircraft (section 7).