AD/AC/82 - Engine Isolator Assembly- Inspection and/or Replacement

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA), were enacted to ensure the safety of civil aviation in Australia. These regulations are a legislative instrument of the Commonwealth of Australia and are designed to address safety issues and ensure compliance with safety standards in the aviation industry. One of the directives under Part 39 - 105 of these regulations pertains to the Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600 and 700) Series Aeroplanes, specifically focusing on the engine isolator assembly. The policy objective of these regulations is to mitigate risks associated with manufacturing defects, such as the premature fatigue fracture of the engine isolator assembly thru-bolt identified in some Barry Wright Corp. assemblies, thereby enhancing overall aviation safety. The regulations mandate inspections and/or replacements of the engine isolator assemblies for specific models and serial numbers of Twin Commander aeroplanes. Compliance with the directive, AD/AC/82, must be achieved within 10 hours of the aeroplane's time in service after 9 July 1984, as outlined in the requirement document. This directive aims to ensure that the identified defect does not compromise the safety of the aircraft, thereby aligning with the overarching goal of maintaining high safety standards in civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, applies to certain Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600 and 700) series aeroplanes. The directive targets specific models and serial numbers of these aircraft to address a critical safety concern with the engine isolator assemblies. The requirement necessitates compliance with Gulfstream Aerospace Service Bulletin No. 201, mandating inspection and replacement of the engine isolator assemblies to mitigate the risk of premature fatigue fracture due to manufacturing defects in some Barry Wright Corp. assemblies. The regulation applies nationwide under the Commonwealth of Australia and aims to ensure the airworthiness and safety of the specified aircraft within the Australian aviation sector. The directive explicitly identifies the affected aircraft models and serial numbers, ensuring that only those aeroplanes within the specified range are subject to the requirements outlined. There are no stated exclusions or exemptions in this directive, meaning that all applicable aircraft must comply with the specified inspection and replacement procedures. The directive’s scope is strictly defined to ensure targeted safety improvements without affecting other aircraft not identified in the directive. The regulation extends through compliance with the detailed procedures provided in the Requirement Document, ensuring that the directive is effectively implemented across the relevant fleet.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 – 105, mandate certain airworthiness directives for the Twin Commander series aeroplanes produced by Gulfstream, Rockwell, and Aerocommander. Section 105 addresses the requirement for the inspection and/or replacement of engine isolator assemblies for particular models and serial numbers of these aircraft, as outlined in AD/AC/82 (paragraph 105.015). The directive applies to models 690 and 690A with specific serial numbers, as well as models 690A, 690B, 690C, 690D, 695, and 695A with their respective serial numbers as stated (paragraph 105.020). The compliance requirement is set forth in Gulfstream Aerospace Service Bulletin No. 201, which must be completed within 10 hours of time in service after 9 July 1984, in accordance with the detailed Requirement Document (paragraph 105.025). The obligations imposed by this legislation require the owners and operators of the affected aircraft to ensure that the engine isolator assemblies are inspected and, if necessary, replaced as per the instructions provided in the Service Bulletin and Requirement Document. This includes verifying that the aircraft serial numbers fall within the specified ranges and that the work is carried out within the stipulated timeframe (paragraph 105.030). The directive is intended to address a manufacturing defect identified in some Barry Wright Corp. engine isolator assemblies, which could lead to improper bolt preload and subsequent premature fatigue fracture of the isolator assembly thru-bolt (paragraph 105.035). Failure to comply with the airworthiness directive could result in serious safety implications, potentially leading to the failure of the engine isolator assembly during operation, which could endanger the flight. Under the Civil Aviation Act 1988, non-compliance with these directives could result in civil or criminal penalties. Civil penalties could include fines of up to $275,000 for a corporation and $55,000 for an individual, while criminal penalties could involve imprisonment for up to five years. Additionally, the Civil Aviation Safety Authority (CASA) may take enforcement actions, such as grounding the aircraft until the required work is completed or imposing further administrative penalties (paragraphs 105.040 and 105.045).