Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, form a comprehensive set of rules governing all aspects of civil aviation within the country. One specific instrument under this act, F2006B02213, pertains to the Ayres Thrush (Snow) Commander Series Aeroplanes and addresses a safety concern identified with the horizontal stabiliser front and rear spar and attach fittings. This directive, AD/AC-SNOW/22, was introduced to mitigate the risk of failure in these critical components, which had been reported to potentially lead to catastrophic in-flight incidents. The policy objective is to ensure the continued airworthiness of affected aircraft by mandating specific inspections and modifications, thus safeguarding the safety of all persons on board. Compliance with these directives is essential for operators of the affected models to maintain their aircraft in a safe and airworthy condition.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 concerning Airworthiness Directives, apply to all operators and owners of Ayres Thrush (Snow) Commander Series Aeroplanes that use the P/N 40087 Horizontal Stabiliser assembly, as detailed in Ayres Service Bulletin SB-AG-37.5/95. This regulation is mandated by the Civil Aviation Safety Authority and pertains to the maintenance and safety inspections of the horizontal stabiliser front and rear spar attach fittings on specified models of the S2R with Ayres metal tails. The requirement includes conducting a close detailed visual inspection in accordance with Ayres SB-AG-37 “Inspection Instructions” and modifying the stabiliser structure in accordance with Ayres SB-AG-37 “Accomplishment Instructions.” Operators must replace RTV silicone sealant with a polysulphide sealant such as PR1422, PR1440, or PR1436 where specified. Compliance mandates an initial inspection within 10 hours of service after 27 April 1995, with subsequent re-inspections not exceeding 25 hours of service. Modifications must be completed before 27 April 1996, at which point the inspection requirement is nullified. This directive is aimed at preventing potential failure of the horizontal stabiliser due to cracks found in the stabiliser front spar assembly, which, if left unaddressed, could compromise the safety of the aircraft.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39 - 105, establish specific Airworthiness Directives (AD) for various aircraft types, with AD/AC-SNOW/22 focusing on Ayres Thrush (Snow) Commander Series Aeroplanes. Specifically, this directive addresses the horizontal stabiliser front and rear spar and attach fittings. The directive applies to all models of the S2R with Ayres metal tail using the P/N 40087 Horizontal Stabiliser assembly, as detailed in Ayres Service Bulletin SB-AG-37.5/95. Sections of the AD/AC-SNOW/22 mandate that operators perform a close, detailed visual inspection of the front and rear stabiliser-to-fuselage attach fittings according to Ayres SB-AG-37 “Inspection Instructions.” The inspection must occur within 10 hours’ time in service following 27 April 1995, and subsequent inspections must not exceed 25 hours’ time in service. Additionally, operators must modify the horizontal stabiliser and its attachment structure as outlined in Ayres SB-AG-37 “Accomplishment Instructions.” Modifications must be completed before 27 April 1996, and once completed, the inspection requirement of the AD is negated. If the specified polysulphide sealants such as PR1422, PR1440, or PR1436 are used in place of RTV silicone sealant where indicated, compliance is ensured. Operators of the affected aircraft are obligated to adhere strictly to the inspection and modification schedules. Failure to comply with the initial inspection within the stipulated 10 hours’ time in service or subsequent inspections within 25 hours’ time in service, and to complete the modifications by 27 April 1996, constitutes non-compliance with the AD. Non-compliance could result in serious safety risks, including potential failure of the horizontal stabiliser, which has been reported in some instances due to discovered cracks in the stabiliser front spar assembly. The AD/AC-SNOW/22 does not explicitly state penalties or specific consequences for non-compliance, but failure to adhere to such directives could result in severe civil or criminal penalties under the broader Civil Aviation Act 1988. The Civil Aviation Safety Authority (CASA) has the authority to enforce compliance and could impose fines, suspension of airworthiness certificates, or other regulatory actions against operators who fail to comply with the AD. These actions are in addition to any liability that may arise from accidents or incidents caused by non-compliance.