Overview

The Airworthiness Directive issued under the Civil Aviation Act 1988 (Cth) addresses potential safety issues associated with the Turbomeca Arriel 2B turboshaft engines. This legislation was introduced to ensure the safety of aviation by establishing and enforcing airworthiness standards. The Civil Aviation Safety Authority (CASA), acting as the delegate for the Minister for Transport and Regional Services, issued this directive to mandate specific maintenance and operational checks to mitigate the risk of engine failure due to sticking of the acceleration controller axle of the Fuel Metering Unit. The directive aims to prevent unpredictable engine behaviour that could lead to over-speeding and in-flight shutdowns, particularly hazardous for single-engined helicopters. This safety measure is crucial to prevent emergencies such as forced autorotation landings, thereby enhancing overall aviation safety.

Scope and Application

The Airworthiness Directive AD/ARRIEL/19 pertains specifically to Turbomeca Arriel 2B turboshaft engines that incorporate the TU 62A modification. This directive applies to the acceleration controller axle of the fuel metering unit within these engines, ensuring that operators and maintainers of such engines comply with the stipulated requirements to address potential safety concerns. The directive is issued under the authority of the Civil Aviation Safety Authority (CASA) delegate, James Coyne, and it mandates specific actions to be taken to mitigate the risk of engine uncommanded shutdown, which could potentially lead to emergency landings in single-engine helicopters. The directive applies nationally within the Commonwealth of Australia, and its requirements must be met by all relevant parties, including aircraft operators and maintenance personnel, to ensure the continued airworthiness of affected engines. The AD outlines three primary requirements: a ground check in mixed mode operation before the first flight of the day, checking and maintaining the fuel metering system as per the prescribed maintenance bulletin, and repeating the maintenance procedures every 200 operating hours. The initial compliance must occur before the first flight of the day until the maintenance bulletin is adhered to, and subsequent maintenance must be completed within 20 operating hours of receiving necessary parts from Turbomeca and no later than 1 March 2005. These requirements are integral to maintaining the safe operation of the engines, and failure to comply may result in non-airworthiness. The AD is effective from 23 December 2004 and was gazetted on 1 December 2004.

Key Provisions

The Airworthiness Directive (AD) issued under the authority of the Civil Aviation Safety Authority (CASA) contains several key provisions that govern the maintenance and operation of Turbomeca Arriel 2B turboshaft engines with the TU 62A modification. Section 1 specifies the mandatory actions that must be taken to address potential safety issues. Specifically, section 1(a) requires a ground check in mixed mode operation, where the engine's behaviour must align with the results specified in the AS350 B3 Flight Manual. Section 1(b) mandates that if the engine deviates from the expected behaviour, the helicopter must not be flown until the issue is resolved. This check can be conducted by the pilot during the First-Flight-of-the-day inspection and documented in the Maintenance Release. Section 1(c) requires a comprehensive inspection and maintenance of the fuel metering system, as detailed in Mandatory Service Bulletin (MSB) A292 73 2814 or any subsequent revisions approved by DGAC/EASA. Section 1(d) further mandates that the maintenance procedures outlined in section 1(c) be repeated to ensure thoroughness. The AD imposes several obligations on the parties involved, including operators and maintenance personnel. Operators must ensure that the specified maintenance checks are performed before the first flight of the day and within certain timeframes, as outlined in section 1. Maintenance personnel must adhere to the procedures set out in the AD, including conducting the ground check and following the maintenance instructions in the MSB. Additionally, operators must ensure that the required parts are installed and that the maintenance checks are repeated every 200 hours, with a tolerance of plus or minus 10 hours, as specified in section 1. Compliance with these obligations is critical to maintaining the airworthiness of the aircraft and ensuring the safety of all involved. Failure to comply with the AD may result in significant consequences, both civil and criminal. Section 2 details the potential penalties for non-compliance, which can include fines and imprisonment. The exact penalties are determined by the relevant aviation safety regulations, but they can be severe given the critical nature of the maintenance requirements outlined in the AD. Additionally, non-compliance may lead to the grounding of the aircraft until the required maintenance is completed, potentially disrupting operations and incurring additional costs. It is imperative for all parties to take the AD seriously and adhere to its requirements to avoid these consequences.