AD/AL 250/54 Amdt 1 - Engine Turbine Assembly No. 8 Bearing U-Ring Installation

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, serve to maintain and enhance the safety standards within the aviation industry. Specifically, Part 39 - 106 addresses the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives, with AD/AL 250/54 Amendment 1 targeting the Allison 250 Series turbine engines. This directive was introduced to address a critical safety issue where air leaks into the No. 8 bearing sump led to oil being forced through the No. 8 bearing labyrinth seal onto the No. 1 turbine wheel, potentially causing oil fires and damaging the first stage turbine wheels. The policy objective of this directive is to ensure compliance with the specified requirement documents, thereby mitigating these safety risks and ensuring the continued airworthiness of affected engines. The directive mandates adherence to the Allison 250 C28B/C28C CEB-A-72-2082 Rev 1 document, which provides comprehensive instructions for the installation of the No. 8 bearing U-Ring. This revision replaces the original document to ensure all operators and maintenance personnel are working from the most current and effective safety guidelines. By referencing FAA AD Allison 83-01-04 Amendment 3, the directive aligns with international standards, further reinforcing the safety measures in place to protect both aircraft and personnel.

Scope and Application

The Civil Aviation Regulations 1998, specifically PART 39 - 106 Civil Aviation Safety Authority Schedule of Airworthiness Directives, pertains to the Allison Turbine Engines - 250 Series. This directive applies to all Allison 250-C28B/C28C engines, which are subject to mandatory compliance to ensure safety and operational integrity. The directive mandates adherence to the Allison 250 C28B/C28C CEB-A-72-2082 Rev 1 document, which was updated to address previously noted issues, particularly those related to air leaks in the No. 8 bearing sump that could lead to oil fires and damage to the first stage turbine wheels. The directive references FAA AD Allison 83-01-04 Amendment 39-4539, further contextualising its application within existing regulatory frameworks. This regulatory measure extends its jurisdictional reach across the Commonwealth of Australia, enforcing compliance nationwide to maintain the safety and reliability of the specified engines in civil aviation operations.

Key Provisions

The primary operative sections of the Civil Aviation Regulations 1998, specifically Part 39 - 106, mandate the installation of an updated U-ring in the No. 8 bearing of Allison 250-C28B/C28C engines (Section 39-106). This directive is applicable to all Allison 250-C28B/C28C engines and requires compliance with the Allison 250 C28B/C28C CEB-A-72-2082 Rev 1 document (Section 39-106). This revision is a complete update, superseding the original documentation, and is intended to address instances of air leaks into the No. 8 bearing sump that have led to oil fires and damage to first stage turbine wheels. The obligations imposed by this legislation on the parties or entities it governs are primarily concerned with ensuring that the Allison 250-C28B/C28C engines are maintained in a state of airworthiness. Specifically, operators and owners of these engines must adhere to the updated requirements set forth in Allison 250 C28B/C28C CEB-A-72-2082 Rev 1 (Section 39-106). This includes the proper installation of the revised U-ring in the No. 8 bearing assembly to prevent air leaks, oil fires, and subsequent damage. Compliance must be achieved in accordance with the specified Requirement Documents, ensuring that all modifications and maintenance activities are conducted in a manner that maintains or restores the engines to an airworthy condition. Failure to comply with the provisions of the Civil Aviation Regulations 1998, particularly in relation to the installation of the updated U-ring as mandated in Section 39-106, may result in significant legal and financial consequences. The Act does not explicitly detail specific offences, penalties, or civil/criminal consequences for non-compliance with this directive; however, non-compliance with airworthiness directives generally could lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Potential consequences may include fines, operational restrictions, or even grounding of non-compliant aircraft until the required modifications are completed. The severity of these consequences is contingent on the specific nature and impact of the non-compliance, as well as any resultant safety risks identified by CASA. In summary, the key provisions of the Civil Aviation Regulations 1998, Part 39 - 106, focus on ensuring the airworthiness of Allison 250-C28B/C28C engines through the mandatory installation of a revised U-ring in the No. 8 bearing. Operators and owners of these engines are required to comply with the updated documentation to prevent air leaks and associated hazards. Failure to adhere to these requirements may result in enforcement actions by CASA, including financial penalties and operational restrictions.