AD/DHC-8/6 - MLG Uplock Actuator

Overview

The Civil Aviation Regulations 1998, as amended through F2006B09216, was enacted to ensure the safety of aircraft operations within Australian airspace. This particular legislative instrument pertains to Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes, focusing on the airworthiness directive concerning the MLG (main landing gear) uplock actuator. The directive addresses the issue of trapped MLG uplock actuators that can occur under certain adverse conditions, which could prevent the main landing gear from releasing. The policy objective is to mandate specific inspections and rectifications to maintain the airworthiness of these aircraft, ensuring they comply with safety standards set by the Civil Aviation Safety Authority (CASA). Compliance with these directives is mandatory, with specific timelines provided to ensure that affected aircraft are addressed promptly and safely.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the airworthiness directives for Bombardier (Boeing Canada/De Havilland) DHC-8 series aeroplanes, focusing on the MLG uplock actuator. This directive applies to Model DHC 8 serial number 3 and subsequent aeroplanes that are equipped with MLG uplock actuators bearing specific part numbers, excluding those that have incorporated modification 8/1098. The directive is applicable within the Commonwealth of Australia and is enforced by the Civil Aviation Safety Authority. It mandates inspections and rectifications to ensure the safe operation of the aircraft, with compliance required within specified timeframes. The directive extends its application through subordinate instruments, which may provide additional details or amendments to the initial requirements. Exclusions from this directive include DHC-8 aeroplanes that have already integrated modification 8/1098, which addresses the identified safety concerns. The directive also references Canadian AD CF-89-03 for additional context. Compliance necessitates a thorough inspection and rectification of the MLG uplock installation as per De Havilland SB No. 8-32-79 Revision A, with a requirement to rework and re-identify all uplock actuators. Successful completion of the rework constitutes compliance with the inspection requirement. The directive sets specific deadlines, including a primary compliance period ending on 28 February 1990, and requires repeat inspections and actions whenever the proximity sensor and/or proximity sensor mounting bracket on an uplock actuator has been reset or replaced.

Key Provisions

The Civil Aviation Regulations 1998, specifically within Part 39, include a Schedule of Airworthiness Directives that govern the maintenance and operation of various aircraft types, including the Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes. The relevant Airworthiness Directive (AD) in this context is AD/DHC-8/6, which pertains to the MLG (Main Landing Gear) uplock actuator of the DHC-8 series aeroplanes (section 1). The directive applies to models DHC 8 with certain serial numbers and specific MLG uplock actuator part numbers installed, excluding those that have already incorporated a particular modification (section 2). Under the directive, operators are required to inspect and rectify the MLG uplock installation in accordance with De Havilland Service Bulletin (SB) No. 8-32-79 Revision A (section 3). Additionally, all uplock actuators must be reworked and re-identified as per the same service bulletin. It is important to note that compliance with the re-identification requirement serves as the terminating action for the initial inspection and rectification requirement (section 4). The directive references a Canadian Airworthiness Directive, CF-89-03, indicating alignment or reference to similar safety concerns or corrective measures in other jurisdictions (section 5). The obligations imposed by this directive include timely compliance with the specified actions. Operators must inspect and rectify the MLG uplock installation within 50 hours of the aeroplane being in service after 10 August 1989, or before further flight if the proximity sensor or its mounting bracket has been reset or replaced (section 6). Furthermore, these actions must be completed before 28 February 1990 to ensure compliance with the directive (section 7). Failure to adhere to these requirements may result in non-compliance with safety standards, potentially leading to operational issues or safety risks. Failure to comply with the provisions of this Airworthiness Directive can result in significant consequences. Non-compliance may be viewed as a breach of aviation safety regulations, potentially leading to enforcement actions by the Civil Aviation Safety Authority (CASA). Such breaches can attract penalties under the Civil Aviation Act 1988, which may include fines or other administrative actions. In severe cases, non-compliance could also result in the grounding of the aircraft until the required actions are taken, impacting the operator's ability to conduct flights and potentially leading to financial losses or reputational damage (section 9).