AD/TFE 731/26 - Low Pressure Turbine First and Second Stage Disc Suspect Material Properties

Overview

The Civil Aviation Regulations 1998, which were enacted by the Parliament of the Commonwealth of Australia, form the backbone of civil aviation safety regulations in Australia. Specifically, Part 39 - 106 of these regulations includes a schedule of airworthiness directives that ensure the safety of aircraft and their operations. One such directive, AD/TFE731/26, was introduced to address the problem of suspect material properties in the low-pressure turbine first and second stage discs of AlliedSignal (Garrett/AiResearch) TFE731 Series engines. This directive was enacted to mitigate safety risks associated with potential material defects, which could lead to in-flight shutdowns or disc containment failures. The objective of this specific directive is to mandate the replacement of certain turbine discs, as detailed in AlliedSignal Alert Service Bulletin No. TFE731-A72-3557, thereby ensuring the continued airworthiness and safety of the affected engines.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 106, mandates the implementation of Airworthiness Directives issued by the Civil Aviation Safety Authority (CASA). These directives are designed to ensure the safety and airworthiness of aircraft operating within Australia's airspace. In this context, AD/TFE731/26 pertains to the AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series, specifically addressing the issue of suspect material properties in the low pressure turbine first and second stage discs. The directive applies to all TFE731-3 series engines identified by the serial numbers specified in AlliedSignal Alert Service Bulletin No. TFE731-A72-3557. The requirement under this directive is the replacement of certain first and second stage low pressure turbine discs as listed in the aforementioned bulletin. Compliance with AD/TFE731/26 is mandatory and must be adhered to by the relevant operators of the specified engines, with the directive taking effect from 2 March 1995. This measure is crucial to address both in-flight shutdown and disc containment concerns related to the identified material issues.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, include an Airworthiness Directive (AD) concerning the AlliedSignal (Garrett/AiResearch) Turbine Engines, TFE731 Series (AD/TFE731/26). This directive addresses low pressure turbine first and second stage discs that are suspect of having material properties that could lead to unacceptable crack growth. The directive applies to all AlliedSignal TFE731-3 series engines, as detailed in AlliedSignal Alert Service Bulletin No. TFE731-A72-3557. The requirement under this directive is to replace certain first and second stage low pressure turbine discs as specified by serial number in the referenced bulletin. This action is necessary to ensure the safety of in-flight operations and to prevent potential engine failure that could lead to catastrophic consequences. The Act imposes specific obligations on aircraft operators and maintenance entities to ensure compliance with the Airworthiness Directive. Operators of the affected engines must identify the specific engines within their fleet that are covered by the directive and take appropriate action to replace the suspect discs. This includes following the detailed instructions and serial number listings provided in AlliedSignal Alert Service Bulletin No. TFE731-A72-3557. Maintenance personnel must be adequately trained to perform these replacements, and the replacement parts must be sourced from approved suppliers. Proper documentation of the replacement process must be maintained, and compliance must be verified through inspection by the Civil Aviation Safety Authority (CASA). Failure to comply with the requirements of this Airworthiness Directive can result in significant civil and criminal consequences. The Civil Aviation Safety Authority (CASA) has the authority to enforce compliance through inspections and investigations. Operators who do not adhere to the directive may face enforcement actions, which can include fines and sanctions against their air operator certificate. In severe cases, CASA may order the grounding of non-compliant aircraft, leading to potential operational disruptions and financial losses. Additionally, the directive's non-compliance can lead to criminal charges against individuals responsible for the oversight and maintenance of the aircraft, with penalties including substantial fines and imprisonment. The exact penalties depend on the severity of the non-compliance and the specific circumstances of the breach.