AD/TFE 731/9 - L.P. Turbine Blade - Review, Inspection and Replacement

Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 106, under the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, introduced the AD/TFE731/9 directive in 1986 to address issues related to the L.P. turbine blades of the AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series. This legislative instrument was enacted by the Commonwealth of Australia to ensure aviation safety by addressing a manufacturing defect that reduced the service life of certain turbine blades. The policy objective was to mandate the review, inspection, and replacement of these blades to prevent potential safety hazards arising from their premature failure. The directive applies to TFE 731-3 models with L.P. turbine rotor assemblies part number 3072352 installed, requiring operators to comply with specified timelines for reviewing engine life limited parts log cards and conducting inspections or replacements of suspect blades as outlined in the Service Bulletin accomplishment instructions. This directive was issued to ensure that affected engines are maintained to safe operational standards, thereby protecting public safety and maintaining the integrity of civil aviation operations.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 106, applies to aircraft engines such as the AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series, particularly the TFE 731-3 models with L.P. turbine rotor assemblies Part Number 3072352 installed. This regulation mandates the review, inspection, and replacement of L.P. turbine blades, addressing an issue where certain blades have been found to have an incorrect coating during manufacture, reducing their service life to 1100 cycles. Compliance with these airworthiness directives is required within specified timelines, such as within 100 hours time in service after 31 July 1984 for log card reviews, and either before exceeding 1100 cycles on suspect blades, at the next access to the L.P. rotor assembly, or at the next scheduled major periodic inspection, whichever is the sooner. These regulations apply across the Commonwealth of Australia and are enforced by the Civil Aviation Safety Authority. The regulation extends its reach through subordinate instruments and service bulletins, which provide detailed instructions on compliance and implementation.

Key Provisions

The Civil Aviation Regulations 1998, particularly in Part 39, include the Airworthiness Directives (ADs) concerning specific aircraft components, such as the AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series. Specifically, AD/TFE731/9 addresses the low-pressure (L.P.) turbine blades of TFE 731-3 models (section 1). The directive applies to engines with L.P. turbine rotor assemblies identified by the part number 3072352 (section 2). The primary requirement of this directive is to review engine life limited parts log cards to determine applicability as per the Service Bulletin (S.B.) accomplishment instructions (section 3). These obligations mandate that operators of the affected aircraft must ensure compliance with the directive by performing specific tasks. For instance, operators must review the engine's life limited parts log cards to ascertain if the L.P. turbine blades are subject to the directive's requirements (section 4). Additionally, operators must inspect and, if necessary, replace suspect L.P. turbine blades in accordance with the Service Bulletin instructions (section 5). The inspection and replacement must occur within specified timelines: within 100 hours of time in service after 31 July 1984, or before exceeding 1100 cycles on suspect blades, or at the next access to the L.P. rotor assembly, or at the next scheduled major periodic inspection, whichever comes sooner (section 6). Failure to comply with the requirements set out in AD/TFE731/9 may result in significant consequences. While the regulations do not explicitly detail specific penalties, non-compliance with Airworthiness Directives can lead to severe civil and criminal penalties. Under the Civil Aviation Act 1988, failure to adhere to airworthiness directives can result in substantial fines and, in severe cases, imprisonment. Additionally, operators risk having their aircraft deemed airworthy, potentially leading to grounding of the aircraft and disruption of operations. Therefore, strict adherence to the directive is essential to avoid these serious repercussions.