Overview

The Civil Aviation Regulations 1998, as amended by the legislative instrument F2006B02477, addresses specific maintenance and inspection requirements for Eurocopter AS 355 (Twin Ecureuil) Series Helicopters. Enacted by the Commonwealth of Australia, the legislation aims to enhance safety and operational standards within the civil aviation sector, particularly in relation to the identified risk of divergent dynamic excitation in the specified helicopter models. The policy objective is to ensure that critical components such as the main rotor head, main gearbox, landing gear, and hydraulic shock absorbers are regularly inspected and maintained to prevent potential safety hazards. This directive mandates specific inspections and maintenance actions to be performed within certain timeframes, ensuring that all applicable helicopters comply with the outlined safety standards.

Scope and Application

The Civil Aviation Regulations 1998, specifically PART 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, applies to all Model AS 355 helicopters, mandating specific inspections to ensure airworthiness. These directives focus on the Main Rotor Head, Main Gearbox, and Landing Gear, requiring inspections to be carried out in accordance with detailed maintenance work cards provided by the manufacturer. Compliance is mandatory within specific timeframes and upon certain conditions, including after 50 hours of time in service and before 30 September 1986, or upon any occurrence of self-sustained dynamic excitation of the helicopter on the ground, and at each periodic (T) inspection. This legislation extends its reach across all operators and owners of AS 355 helicopters within Australia, ensuring safety standards are upheld through stringent maintenance checks. The directives are comprehensive and provide clear guidance on the inspection processes and conditions, with the overarching aim of preventing potential hazards associated with the identified dynamic excitation issues.

Key Provisions

The Civil Aviation Safety Authority (CASA) has issued Airworthiness Directives (AD) applicable to all Eurocopter AS 355 (Twin Ecureuil) series helicopters, specifying detailed inspection requirements and procedures to ensure the continued airworthiness of these aircraft (AD/AS 355/22). Section 1 of the AD requires operators to inspect the main rotor head in accordance with the Maintenance Evaluation Task (MET) work card 62-20-00-601.10/86DM, focusing on any defects or irregularities that might compromise safety. Section 2 mandates the inspection of the Main Gearbox (MGB) suspension, checking the condition of laminated bearings, MGB struts, and other related components for defects such as wrinkling, blistering, or nicks, with strict limits on defect size and allowable rework. Section 3 directs the inspection of the skid-type landing gear in line with MET work card 32-13-00-601, including specific checks on the rear spring blade deflection and ensuring there is no evidence of movement or incorrect securing of the bars. Section 4 outlines the inspection of hydraulic shock absorbers, requiring operators to disconnect and manually slide the shock absorbers to check for jerkiness, with instructions to refill or replace them as necessary. The AD imposes several obligations on helicopter operators to ensure compliance with the specified inspection requirements. Operators must inspect the main rotor head, MGB suspension, landing gear, and hydraulic shock absorbers within 50 hours of service after 17 September 1986 or before 30 September 1986, whichever comes first, and at each periodic (T) inspection thereafter (Compliance 1 to 4). These inspections must be conducted meticulously, following the detailed procedures outlined in the relevant MET work cards to ensure that all specified components are in good condition and compliant with safety standards. Failure to comply with the AD can result in significant consequences. Although the regulations do not explicitly state penalties, non-compliance with ADs is generally considered a breach of the Civil Aviation Act 1988 and the Civil Aviation Regulations 1998, which can lead to enforcement actions by CASA. Such actions may include the issuance of a Notice of Unauthorized Modification (NUM), grounding of the aircraft, or other regulatory penalties. Furthermore, failure to adhere to these directives can result in severe safety risks, potentially leading to accidents or incidents that could endanger lives and property. Therefore, operators are strongly advised to adhere strictly to the inspection requirements to maintain the airworthiness of their aircraft and avoid potential legal and safety repercussions.