Overview

The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/AE 3007/3 on 30 September 2004 to address safety concerns related to the Rolls-Royce Corporation (formerly Allison Engine Company) AE 3007A and AE 3007C turbofan engines, specifically those with second-stage high-pressure turbine (HPT) wheels bearing serial numbers prior to MM183060. This directive was enacted in response to reports of cracks in the aft bore face of the second-stage HPT wheels, which could result in wheel failure, power loss, and potential damage to the aircraft. The primary policy objective of this directive is to ensure the airworthiness of affected aircraft by mandating specific inspection and maintenance actions to prevent the early development of such cracks due to low-cycle fatigue. This action is necessary to ensure continued compliance with safety standards and to mitigate potential hazards identified in the field.

Scope and Application

This Airworthiness Directive issued under the Civil Aviation Safety Authority (CASA) pertains specifically to Rolls-Royce Corporation (formerly Allison Engine Company) models AE3007A and AE 3007C turbofan engines, particularly those with 2nd stage High Pressure Turbine (HPT) wheels that have serial numbers prior to MM183060. The directive is designed to address a safety concern related to the potential development of cracks in the aft bore face of the 2nd stage HPT wheel, which could lead to catastrophic failure and compromise the safety of the aircraft in which the engine is installed. The directive applies to all instances of the specified engine models within the stated serial number range and mandates specific inspection and maintenance actions to mitigate this risk. Compliance with this directive is mandatory and its jurisdictional reach is national, as it is issued by the CASA delegate on behalf of the Commonwealth of Australia. The directive does not specify exclusions or exemptions but sets clear timelines for compliance based on the engine's service history and current operational status. The directive may be extended or modified through subsequent notifications or subordinate instruments as required to ensure ongoing airworthiness.

Key Provisions

The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations (CASR) 1998, applies specifically to Rolls-Royce Corporation (formerly Allison Engine Company) models AE3007A and AE 3007C turbofan engines equipped with 2nd stage High Pressure Turbine (HPT) wheels with serial numbers (SN) prior to MM183060. The directive mandates that a one-time acid etch inspection be performed on the 2nd stage HPT wheel unless it has already been completed (Requirement 1). This inspection must adhere to the instructions provided in Rolls-Royce service bulletins AE 3007A-A-72-179, Revision 2 or 3, and AE 3007C-A-72-153, Revision 2 or 3, as detailed in Table 1 of the AD. If any damage is discovered during the inspection, the turbine wheel must be replaced with a serviceable part (Requirement 2). Additionally, any 2nd-stage gas-generator turbine wheel listed in Table 2 of the directive must not be installed unless it has undergone the specified inspection (Requirement 3). The AD imposes several obligations on the parties it governs. Primarily, it mandates that all affected Rolls-Royce AE3007A and AE 3007C engines undergo the specified acid etch inspection, as detailed in Table 2 of the directive. This inspection must be completed at the next shop visit or before the engine reaches 12,800 cumulative service hours, whichever comes first. If damage is identified during the inspection, the turbine wheel must be replaced before further flight. The directive also prohibits the installation of any 2nd-stage gas-generator turbine wheel listed in Table 2 without first completing the required inspection. Compliance with these requirements is crucial to ensure the airworthiness of the aircraft and to prevent potential failures that could lead to power loss and damage. Failure to comply with the requirements of the AD may result in significant consequences. The AD is a legally binding directive issued by the Civil Aviation Safety Authority (CASA) and non-compliance can lead to enforcement actions. The maximum penalties for non-compliance with CASA directives can include substantial fines and, in severe cases, prosecution. Specifically, the AD states that it becomes effective on 30 September 2004, and any failure to adhere to the specified requirements may result in the aircraft being deemed unairworthy, which could lead to grounding and potentially severe operational disruptions. It is imperative for operators and maintenance personnel to strictly follow the directives to avoid these severe consequences.