AD/TPE 331/27 - FCU Drive Check

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, serve to regulate civil aviation safety, ensuring compliance with national and international standards. Part 39 of these regulations addresses airworthiness directives, specifically focusing on maintaining the airworthiness of aircraft and their components. One such directive, AD/TPE 331/27, targets AlliedSignal (Garrett/AiResearch) Turbine Engines of the TPE 331 Series, aiming to address issues related to the FCU drive check. This directive was introduced to ensure the reliability and safety of these engines by mandating regular inspections and checks on components such as torque sensors. The policy objective behind this regulation is to mitigate potential safety risks associated with engine malfunctions, thereby protecting both passengers and crew on board. The AD/TPE 331/27 directive specifies the requirements for inspecting the FCU drive of TPE 331 series engines, particularly those fitted with specific torque sensors. It outlines three methods for compliance, including checking backlash or inspecting the security of the torque sensor arm and drive gear, and mandates these checks at specified intervals post a certain date. This directive aims to ensure that these engines remain in a safe and operational condition by providing clear, actionable steps for maintenance personnel.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 106, mandate the Airworthiness Directives issued by the Civil Aviation Safety Authority (CASA) to ensure the safety and airworthiness of aircraft. This particular directive, AD/TPE 331/27, applies to all TPE331 series engines that are fitted with a P/N 3101726-1 torque sensor. The directive requires operators to check the backlash in accordance with AiResearch Service Bulletin TPE331-72-0095, or inspect the security of the torque sensor arm and drive gear using an approved alternative inspection procedure, such as Stillwell Aviation Engineering Release No. 80093, or AD/AIR-T/36A. The directive is jurisdictional across the Commonwealth of Australia, impacting all entities and persons operating aircraft equipped with the specified engines. The directive delineates compliance requirements based on the engine series. For -3 Series Engines, compliance is necessary within 125 hours of time in service after 30 November 1980, and subsequently at intervals not exceeding 125 hours until the P/N 3101726-2 torquemeter body is fitted. For all other series engines, compliance must occur at each hot section inspection completed after 30 November 1980 until the P/N 3101726-2 torquemeter body is fitted. This directive was updated to reflect changes in the inspection method and inspection intervals, and it removes the rework requirement from AiResearch SB 72-0095 due to potential ineffectiveness of the torque on the retaining bolt.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, establish the Civil Aviation Safety Authority's (CASA) schedule of airworthiness directives (ADs) which mandate specific safety measures for various aircraft components and systems. In this context, AD/TPE 331/27 addresses the inspection of the fuel control unit (FCU) drive for AlliedSignal (Garrett/AiResearch) Turbine Engines, TPE 331 Series, particularly those fitted with a certain torque sensor part number (3101726-1). The directive outlines a requirement to ensure the engine's FCU drive is safe and functional, aiming to prevent potential issues that could compromise the engine's performance or safety. Section (a) of the compliance requirement specifies that for -3 Series Engines, the inspection must occur within 125 hours of time in service after 30 November 1980, and subsequently, at intervals not exceeding 125 hours until a specific torquemeter body (P/N 3101726-2) is fitted. Section (b) mandates that for all other series engines, the inspection must be conducted at each hot section inspection completed after 30 November 1980 until the aforementioned torquemeter body is fitted. The inspection can be performed either by checking the backlash according to AiResearch Service Bulletin TPE331-72-0095, paragraph 2C, or by inspecting the security of the torque sensor arm and drive gear using an alternative procedure approved by the Secretary, such as Stillwell Aviation Engineering Release No. 80093, or by following AD/AIR-T/36A. The obligations under this directive impose specific responsibilities on aircraft operators and maintenance personnel. They must ensure that the inspection of the FCU drive is conducted as per the outlined procedures within the stipulated time frames. This includes verifying the backlash, inspecting the torque sensor arm and drive gear, or adhering to an alternative approved inspection method. Failure to comply with these requirements could result in non-compliance with the Civil Aviation Regulations, potentially leading to the grounding of the aircraft until the necessary inspections and repairs are performed. Non-compliance with the AD/TPE 331/27 may have significant consequences. Under the Civil Aviation Act 1988, non-compliance with an airworthiness directive is an offence that could result in penalties. The specific penalties are not detailed in the AD itself but generally include fines and potential imprisonment under the Civil Aviation Regulations. Furthermore, continued operation of an aircraft without ensuring compliance with the AD could lead to civil and criminal consequences, including the possibility of severe accidents due to engine failure, thereby posing a risk to passengers, crew, and the public.