AD/FJ44/1 - High Pressure Turbine Disc

Overview

The Civil Aviation Regulations 1998, specifically under PART 39 - 106, introduced Airworthiness Directives to address safety concerns in the aviation industry. This particular directive, AD/FJ44/1, pertains to the Williams-Rolls Turbine Engines of the FJ44 series, focusing on the high-pressure turbine disc. Enacted by the Commonwealth of Australia, this directive aims to mitigate the risk of high-pressure turbine disc blade retention post separation and the subsequent release of turbine blades, which was identified as a critical safety issue following two in-flight incidents involving the FJ44 engine. The directive mandates an initial and repetitive eddy current inspection of the high-pressure turbine disc, aligning with Williams-Rolls Service Bulletin (SB) Number FJ44-A72-30, to ensure compliance and enhance safety standards. Compliance with the directive is crucial, with adherence to the specified inspection protocols and timelines to effectively address the identified risk and maintain the safety and reliability of the aircraft.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 106, pertain to the authority and operations of the Civil Aviation Safety Authority (CASA). This legislative instrument concerns Airworthiness Directives for the Williams-Rolls Turbine Engines of the FJ44 Series, particularly focusing on the high pressure turbine disc. The directive applies to the FJ44-1A engines as identified by specific serial numbers detailed in Williams-Rolls Service Bulletin Number FJ44-A72-30, excluding those that incorporate a particular part number (P/N) 55291 high pressure turbine disc. The directive is designed to prevent incidents of high pressure turbine disc blade retention post separation and the subsequent release of turbine blades. To ensure safety, it mandates an initial and repetitive eddy current inspection of the P/N 48629 high pressure turbine disc in accordance with the specified Williams-Rolls Service Bulletin. Compliance with an alternative Williams-Rolls Service Bulletin (No. FJ44-A72-31) may terminate the requirements of this directive. The directive became effective on 24 April 1997, with the compliance date revised to the same effective date. This directive was prompted by two in-flight events where the high pressure turbine disc blade retention posts separated due to material creep/fatigue, leading to safety concerns and necessitating regulatory action.

Key Provisions

The main operative sections of the Civil Aviation Regulations 1998, PART 39 - 106, specifically concerning the Williams-Rolls Turbine Engines - FJ44 Series, require an eddy current inspection of the P/N 48629 high pressure turbine (HPT) disc in accordance with Williams-Rolls Service Bulletin (SB) No. FJ44-A72-30. This directive applies to FJ44-1A engines as identified by serial number in Williams-Rolls Service Bulletin No. FJ44-A72-30 and excludes those engines incorporating a part number (P/N) 55291 high pressure turbine disc. The requirement is to prevent potential high-pressure turbine disc blade retention post separation and the release of turbine blades during operation. The obligations imposed by this directive include conducting an initial and repetitive eddy current inspection of the specified HPT disc. The inspections must adhere to the detailed requirements outlined in Williams-Rolls Service Bulletin No. FJ44-A72-30. Compliance with Williams-Rolls Service Bulletin No. FJ44-A72-31 constitutes a terminating action for the requirements of this directive. The directive became effective on 24 April 1997, as noted in the requirement document with a revised effective date of the same. The directive is in response to two reported in-flight HPT disc blade post separation events involving the Williams-Rolls FJ44 engine. In one instance, the event was uncontained, highlighting the importance of the mandated inspections to prevent similar incidents. The background information reveals that the separation of the HPT blade retention posts was caused by material creep/fatigue, making the directive a critical safety measure. Failure to comply with the requirements set forth in this Airworthiness Directive may result in severe consequences. While the specific civil or criminal penalties are not detailed in the legislative instrument, non-compliance with airworthiness directives can lead to substantial civil or criminal penalties under broader aviation regulations. These may include fines, suspension or revocation of certificates of airworthiness, and potential criminal charges if the non-compliance results in accidents or significant safety breaches. The exact penalties would depend on the specific circumstances and the regulatory framework governing aviation safety in Australia.