AD/TFE 731/10 - No. 1 Bearing - Replacement

Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 106, was enacted to ensure the safety of civil aviation within Australia. This legislative instrument, F2006B07394, addresses the issue of defective components in aircraft engines, thereby mitigating the risk of in-flight failures. The problem it was introduced to address is the potential for engine failure due to defective bearings in the TFE731 Series of AlliedSignal (Garrett/AiResearch) Turbine Engines. The Civil Aviation Safety Authority, the enacting body, aims to safeguard the public and maintain the integrity of the aviation industry by mandating the replacement of these suspect bearings. The overarching policy objective is to ensure the continued airworthiness of affected aircraft, thereby enhancing the safety standards of civil aviation. This particular directive, AD/TFE731/10, applies to TFE 731-2, -3, -5 Series engines with specific serial numbers and requires the replacement of the No. 1 bearings within 25 hours of time in service after 23 November 1984. The directive follows a reported failure and identifies the bearings as having insufficient roller end clearance, leading to skidding and subsequent failure. Compliance with this directive is essential to address the identified safety concerns and prevent potential catastrophic outcomes.

Scope and Application

The AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series Airworthiness Directive, AD/TFE731/10, pertains to TFE 731-2, -3, -5 Series engines with specific serial numbers as detailed in the Requirement Document. The directive applies to these engines to ensure compliance with safety standards by replacing the suspect defective Number 1 bearings. This directive is issued under the authority of the Civil Aviation Safety Authority (CASA) as part of the Civil Aviation Regulations 1998, specifically targeting the safety of civil aviation through the removal of defective components that could compromise engine performance and safety. The directive is geographically applicable within the Commonwealth of Australia and extends to any aircraft operators who possess the affected engines. The directive mandates that the replacement of the bearings must be completed within 25 hours of time in service after 23 November 1984, unless it has already been performed. The directive aims to address the identified issue of insufficient roller end clearance in the bearings, which can lead to skidding and subsequent engine failure, as referenced in G.T.E.C. Alert S.B.TFE 731-A72-3296 and AD/AIR-T/51.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39 - 106, include a schedule of airworthiness directives that specifically address the AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series. The relevant directive is AD/TFE731/10 concerning the replacement of No. 1 bearings (section 106). This directive applies to TFE 731-2, -3, and -5 Series engines with specific serial numbers outlined in the Requirement Document. The requirement is straightforward: all affected engines must have their suspect defective No. 1 bearings replaced (section 106.1). This mandate is supported by G.T.E.C. Alert S.B. TFE 731-A72-3296 and AD/AIR-T/51 (section 106.2). Compliance with AD/TFE731/10 must be achieved within 25 hours of the engines being in service after 23 November 1984, unless the replacement has already been completed (section 106.3). This directive ensures that the identified engines are brought up to the required safety standards by addressing the specific issue of defective bearings, which have been found to have insufficient roller end clearance leading to skidding and subsequent failure (section 106.4). Failure to comply with this airworthiness directive may result in serious safety risks, including engine failure, which could compromise the safety of the aircraft and its occupants. The obligations imposed by AD/TFE731/10 include the responsibility of the aircraft operators and maintenance providers to identify the affected engines, source the required replacement bearings, and ensure the replacement is carried out within the specified timeframe (section 106.5). This requires careful coordination and adherence to the technical instructions provided in the Requirement Document. Failure to comply with these obligations can result in the engine being deemed unairworthy, potentially leading to grounding of the aircraft until the directive is complied with (section 106.6). The consequences for non-compliance with AD/TFE731/10 can be severe, both in terms of regulatory and operational repercussions. Regulatory breaches may result in enforcement actions by the Civil Aviation Safety Authority (CASA), including fines and other penalties (section 106.7). Operationally, non-compliance can lead to the grounding of the affected aircraft, which can have significant financial and logistical impacts on the operators. In extreme cases, failure to adhere to this directive could result in civil or even criminal liability if it is determined that non-compliance contributed to an aviation accident or incident (section 106.8). The specific penalties for breaches of these regulations are determined by CASA, but they can include substantial fines and other sanctions as outlined in the Civil Aviation Regulations 1998 (section 106.9).