Overview

The Civil Aviation Regulations 1998, specifically Part 39, was enacted to regulate the airworthiness of civil aircraft and related products. This particular legislative instrument, F2006B02313, addresses a specific safety issue identified with the AlliedSignal (Lycoming) Turbine Engines, namely the ALF502 and LF507 series engines. The primary objective of this Airworthiness Directive (AD) is to mandate the replacement of the No. 4 and 5 duplex bearing assembly with an improved single No. 4 bearing assembly to prevent potential failures that could lead to severe consequences such as an uncontained engine failure and damage to the aircraft. Issued by the Civil Aviation Safety Authority (CASA) under subregulation 39.1 (1) of the Civil Aviation Regulations 1998, this AD aims to ensure the continued safety of aircraft fitted with these specific engine models by adhering to the compliance timelines provided.

Scope and Application

The Airworthiness Directive (AD) AD/ALF/17 No. 4 and 5 Duplex Bearing Assembly 8/2001 issued under the Civil Aviation Regulations 1998 (CAR 1998) applies to specific Honeywell (formerly AlliedSignal) ALF502L, ALF502R and LF507 series engines that are installed on Canadair CL-600, BAe 146, and AVRO RJ series aircraft. The AD mandates the replacement of the No. 4 and 5 duplex bearing assembly with an improved single No. 4 bearing assembly in accordance with specified Honeywell Service Bulletins, with compliance required within 6,000 hours or 6,000 cycles in service from the date of the directive. This AD is effective from 9 August 2001 and was issued to mitigate the risk of bearing failures leading to catastrophic engine and structural damage. The AD extends across the Commonwealth of Australia and is applicable to all relevant aircraft operating within the jurisdiction. The AD does not specify exclusions, exemptions, or thresholds but relies on subordinate instruments and service bulletins to detail the compliance requirements.

Key Provisions

The Airworthiness Directive AD/ALF/17, issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998, applies to the Honeywell ALF502L, ALF502R, and LF507 series engines installed on specific aircraft models such as the Canadair CL-600, BAe 146, and AVRO RJ series. The directive mandates that the No. 4 and 5 duplex bearing assembly in these engines must be replaced with an improved single No. 4 bearing assembly. This replacement must follow the instructions provided in Honeywell Service Bulletin (SB) ALF/LF 72-1030, Revision 3, dated 3 April 2001, or SB ALF/LF 72-1040, Revision 2, dated 3 April 2001, as applicable. The directive aims to prevent potential failures in the No. 4 and 5 duplex bearing, which could lead to a stage 4 low pressure turbine rotor failure, an uncontained engine failure, and damage to the aircraft. This directive imposes specific obligations on the entities governed by it. The primary requirement is the replacement of the specified bearing assemblies within a defined timeframe. Operators of the affected aircraft must ensure that the replacement is carried out according to the specified service bulletins and that the work is completed within 6,000 hours of time in service or 6,000 cycles in service from the date of the directive, whichever comes first. The directive also clarifies that incorporating earlier versions of the service bulletins meets the intent of the directive, offering some flexibility to operators in meeting the requirement. Failure to comply with the Airworthiness Directive can lead to serious consequences. Non-compliance may result in unsafe conditions that could lead to catastrophic failures during flight, potentially endangering lives and causing significant damage to the aircraft. Under the Civil Aviation Regulations 1998, failure to adhere to an Airworthiness Directive can lead to enforcement actions by the Civil Aviation Safety Authority (CASA). These actions may include fines, suspension or revocation of airworthiness certificates, and other regulatory penalties. While the specific maximum penalties are not detailed in the directive itself, they can be substantial, reflecting the critical nature of maintaining airworthiness standards.