AD/TPE 331/38 - Second Stage Turbine Wheel Assembly

Overview

The Civil Aviation Regulations 1998, specifically within Part 39, addresses the safety and maintenance requirements for aircraft and their components, with a focus on ensuring the airworthiness of turbine engines. Enacted by the Parliament of the Commonwealth of Australia, these regulations aim to safeguard the integrity and operational safety of civil aviation in Australia by implementing stringent standards and directives. One such directive, AD/TPE 331/38, pertains to the inspection and potential replacement of second stage turbine wheel assemblies in AlliedSignal (Garrett/AiResearch) TPE 331 Series engines. This directive was introduced to address the issue of incorrectly manufactured turbine wheels that could pose a significant risk to flight safety. The objective is to ensure that turbine wheels are inspected and replaced as necessary, particularly for those with identified serial numbers, to prevent any potential in-service failures that could compromise the safety of air travel.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 106, addresses the safety directives issued by the Civil Aviation Safety Authority (CASA) concerning aircraft components, with this particular legislative instrument focusing on AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series. This regulation applies to TPE 331 engines of the -25, -43, -47, -55, and -61 series, where the second stage turbine wheels have serial numbers detailed in the Requirement document. The primary objective of this directive is to mandate inspections (and replacements if necessary) of the second stage turbine wheel assemblies in accordance with Garrett Service Bulletin TPE 331-A72-0577, ensuring the airworthiness of these engines by rectifying issues related to incorrect manufacturing of the turbine wheels. The regulation is applicable nationally, extending its reach across the entire Commonwealth of Australia, thereby enforcing uniform safety standards across all states and territories. The directive outlines specific compliance requirements contingent on the time since new (TSN) of the turbine wheels. For engines with turbine wheels that have accumulated between 0 to 650 hours TSN, the inspection must occur prior to reaching 700 hours TSN. For turbine wheels exceeding 650 hours TSN, the inspection must take place within 50 engine operating hours following 30 June 1988. This directive does not specify any exclusions, exemptions, or thresholds beyond those outlined, and its application is enforced uniformly across all relevant entities and industries within the aviation sector in Australia. The directive is complemented by subordinate instruments that provide further detail on the inspection and compliance procedures, ensuring the directive’s effective implementation and adherence.

Key Provisions

The key operative sections of this legislative instrument (PART 39 - 106 of the Civil Aviation Regulations 1998) concern the Airworthiness Directives (AD) issued by the Civil Aviation Safety Authority (CASA) (paragraph 1). Specifically, this AD (AD/TPE 331/38) applies to the second stage turbine wheel assembly of the AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series (paragraph 2). The main requirement of this AD is that owners and operators of affected aircraft must inspect and, if necessary, replace the second stage turbine wheel assembly in accordance with Garrett S.B. TPE 331-A72-0577 (paragraph 3). The AD applies to TPE 331 engines in the -25, -43, -47, -55, and -61 series with specific serial numbers listed in the Requirement document (paragraph 4). The inspection and replacement must occur at certain operational thresholds: for turbine wheels with 0 to 650 hours time since new (TSN) prior to reaching 700 hours TSN, and for turbine wheels with more than 650 hours TSN within 50 engine operating hours after 30 June 1988 (paragraph 5). The AD imposes several obligations on the parties or entities it governs. Owners and operators of the affected aircraft must ensure that the specified inspections and, if necessary, replacements of the second stage turbine wheel assembly are performed in accordance with the detailed requirements set out in Garrett S.B. TPE 331-A72-0577 (paragraph 6). This includes adhering to the specified time frames and operational thresholds for inspections and replacements (paragraph 7). The AD also requires that the affected turbine wheels, identified by their serial numbers, are accurately tracked and documented to ensure compliance with the AD (paragraph 8). Failure to comply with the requirements of this AD may result in serious safety risks and potential legal consequences. Specifically, non-compliance with Airworthiness Directives can lead to civil penalties, including fines and other enforcement actions, as well as criminal penalties if the non-compliance results in a breach of civil aviation safety regulations (paragraph 9). The maximum penalties for such breaches can vary depending on the severity of the non-compliance, but they may include significant financial penalties and potential imprisonment (paragraph 10). Ensuring adherence to the AD is therefore critical to maintaining airworthiness and avoiding these potential consequences.