Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, establish safety standards for civil aviation operations within the country. Within this legislative framework, Part 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives addresses specific safety concerns and mandates corrective actions to ensure the airworthiness of aircraft. One such directive pertains to the GAF N22 and N24 series aeroplanes, specifically targeting issues with the horizontal stabiliser structure, as outlined in AD/GAF-N22/58 Amendment 5. This directive was introduced to address the problem of cracking in the stabiliser centre section, which had been reported in the field and was suspected of potentially leading to unsafe conditions if left unaddressed. The policy objective of this directive is to enhance the safety of civil aviation by mandating inspections, modifications, and, where necessary, the retirement of the horizontal stabiliser structure to prevent catastrophic failures. Compliance with these directives is essential for maintaining the airworthiness of affected aircraft and ensuring the safety of all persons on board.

Scope and Application

The Civil Aviation Safety Authority Schedule of Airworthiness Directives under the Civil Aviation Regulations 1998 applies to all GAF N22 and N24 series aeroplanes, encompassing all models within the specified fleet. This legislation mandates specific maintenance and modification requirements for the horizontal stabiliser to ensure the continued airworthiness and safety of these aircraft. The directive applies to both individual aircraft operators and entities involved in the maintenance and operation of these aeroplanes, and it pertains to the structural integrity of the horizontal stabiliser and associated components. Geographically, the directive applies across the Commonwealth of Australia, aligning with national aviation safety standards. The directive includes detailed steps for the removal of specific machined braces, reinforcement of certain structural elements, and the installation of modifications, alongside stringent inspection and retirement criteria based on flight hours and spar replacement history. Notably, the legislation also provides for the phased implementation of certain changes, allowing operators time to comply with new inspection and modification protocols. The regulations are designed to be flexible yet rigorous, ensuring that aircraft remain safe while accommodating practical operational considerations.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39, Section 105, include Airworthiness Directives (AD) for GAF N22 and N24 series aeroplanes. This directive, identified as AD/GAF-N22/58 Amendment 5, applies to all models within the series and concerns the horizontal stabiliser. The directive mandates several actions to ensure the continued safety of these aircraft, including the removal of specific machined braces, inspection of the horizontal stabiliser centre section, reinforcement of the dorsal fin and rear fuselage structure, and the installation of modifications N663 and N768. Importantly, the directive also specifies that the installation of these modifications does not reset the 'zero time' status of the tailplane. Additionally, the directive requires the retirement of the complete horizontal stabiliser structure, including trim tab assemblies, once certain flight hour thresholds are met. Compliance with this AD is mandatory for all affected aircraft. Operators must carry out the specified inspections and modifications before further flight, unless they have already been completed. For aircraft with original main spars or those resparred at less than 5000 hours of tailplane time in service, the horizontal stabiliser must be retired before exceeding 15,000 hours of spar time in service. For aircraft resparred after 5000 hours of tailplane time in service, the retirement must occur before reaching 20,000 hours of tailplane time in service. Additionally, changes introduced by Revision 8 of the relevant Service Bulletin, including new lockwire requirements, must be implemented no later than the next issue of a Maintenance Release after 18 July 1996. Failure to comply with the AD can result in serious safety risks, as the directive addresses known issues with cracking in the stabiliser centre section that could lead to catastrophic failure. The AD was issued in response to field reports and investigations into a fatal incident where undetected cracks propagated beyond safe limits. Non-compliance could potentially lead to severe consequences, including the risk of mid-flight structural failure. The penalties for non-compliance with such safety directives can include fines and potential criminal charges, depending on the severity of the breach and the impact on aviation safety. The specific penalties are outlined in other sections of the Civil Aviation Act 1988, which govern the enforcement of these regulations.