Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, provide the legal framework governing civil aviation within Australia. In 2001, the Civil Aviation Safety Authority (CASA) introduced the Airworthiness Directive AD/TPE 331/56 to address a specific safety issue concerning the AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series. The problem identified was the occurrence of uncontained failures in the second stage turbine wheels, which resulted from fatigue damage to the second stage turbine stator inner seal support. This led to turbine wheel rub and uncontained rotor failure, posing significant risks to flight safety. The directive mandates the replacement of the affected stator assemblies to mitigate these risks, ensuring the continued airworthiness of the affected engines and protecting public safety in accordance with the policy objectives of the Civil Aviation Regulations 1998.

Scope and Application

The Airworthiness Directive (AD) issued under the Civil Aviation Regulations 1998, specifically PART 39 - 106, pertains to the maintenance and safety of AlliedSignal (Garrett/AiResearch) Turbine Engines of the TPE 331 Series. This directive applies to specific models of the TPE331 series, namely TPE331-1, -2, -3, -5 and -6, that incorporate second stage turbine stator assemblies identified by part numbers 894528-1, -2, -3, -5, -6, -10 and -11. It is important to note that stator assemblies identified as P/N 894528-10 and -11, which have undergone flow testing and reidentification according to Honeywell Service Bulletin TPE331-72-2085RWK, are no longer applicable to this directive. The AD mandates the replacement of the specified stator assemblies in compliance with Honeywell Service Bulletin TPE331-A72-2082 and requires this action to be taken at the next access to the second stage turbine stator assembly but no later than 3100 engine hours in service since the last turbine section inspection. This directive is effective as of 28 November 2001 and is applicable nationally, extending to all aircraft or aeronautical products within the Commonwealth of Australia that meet the specified criteria.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, includes an Airworthiness Directive (AD) concerning the AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series. This AD, AD/TPE 331/56, pertains to the second stage turbine stator and is aimed at addressing safety issues identified in the TPE331-1, -2, -3, -5, and -6 series engines. The AD mandates that specific actions be taken in relation to these engines to mitigate the risk of uncontained failures. The applicability section of the AD specifies that it applies to TPE331-1, -2, -3, -5, and -6 series engines that include a second stage turbine stator assembly part number (P/N) 894528-1, -2, -3, -5, -6, -10, and -11. It is important to note that stator assemblies P/N 894528-10 and -11, which have been flow tested and reidentified in accordance with Honeywell Service Bulletin TPE331-72-2085RWK, are no longer applicable. The requirement section stipulates that the second stage turbine stator assembly must be replaced in accordance with Honeywell Service Bulletin TPE331-A72-2082. The compliance section directs that this action must be taken at the next access to the second stage turbine stator assembly, but no later than 3100 engine hours in service since the last turbine section inspection. The AD imposes obligations on the operators and maintenance personnel of the affected aircraft. Operators must ensure that the required actions are completed within the specified timeframe. Maintenance personnel are required to follow the instructions detailed in the Honeywell Service Bulletin TPE331-A72-2082 for the replacement of the second stage turbine stator assembly. Failure to comply with the AD could result in serious safety risks, as the directive was issued in response to reports of uncontained failures of the second stage turbine wheels due to fatigue damage. Failure to comply with the AD could result in significant consequences. The AD does not explicitly state penalties for non-compliance, but it is understood that such non-compliance could lead to safety violations and potential aircraft grounding until the required actions are taken. This could result in substantial operational disruptions and financial losses for the operators. Furthermore, the AD is closely aligned with the Federal Aviation Administration's (FAA) efforts to issue a similar mandate, highlighting the seriousness with which this safety issue is being treated across international aviation authorities.