Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, form a critical framework for ensuring the safety and efficiency of civil aviation within the country. This legislation was introduced to address the need for comprehensive regulations to govern the operation of aircraft, including safety standards and directives. Part 39 - 105, specifically addressing Airworthiness Directives, is one segment of this regulatory body, aimed at maintaining the airworthiness of aircraft through mandatory compliance with safety directives. The Civil Aviation Safety Authority oversees these regulations, ensuring they meet the overarching policy objective of maintaining the highest safety standards in civil aviation. One specific Airworthiness Directive, AD/AC-SNOW/15, pertains to the Ayres Thrush (Snow) Commander Series Aeroplanes, specifically addressing the inspection and modification of the forward fuselage upper longerons to prevent structural failure. This directive was introduced in response to instances of upper longeron failure leading to potential engine separation in flight. Compliance with this directive is mandatory, requiring inspections before further flight and within specified intervals to ensure continued airworthiness and safety of the aircraft.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, under the authority of the Civil Aviation Safety Authority, mandate safety directives concerning the Ayres Thrush (Snow) Commander Series Aeroplanes. This legislative instrument, AD/AC-SNOW/15, pertains to all models S2R-R1820 with serial numbers ranging from R1820-001 to R1820-031, issued on 6 August 1984. The directive requires a mandatory visual inspection of the forward fuselage upper longerons for cracks and subsequent modification to mitigate potential risks. This regulation applies to aircraft operators and maintenance personnel within the Commonwealth of Australia and ensures compliance with international safety standards, referencing the FAA Ayres Emergency AD dated 7 May 1984. The inspection must occur before further flight after 17 May 1984 and at intervals not exceeding 10 hours’ time in service until the modification is completed within 100 hours’ time in service. The pilot in command may perform the inspection, certifying it in the maintenance release.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandate the application of Airworthiness Directives (AD) to ensure aircraft safety. In this instance, AD/AC-SNOW/15 pertains to the Ayres Thrush (Snow) Commander Series Aeroplanes, specifically all models S2R-R1820 with serial numbers R1820-001 to R1820-031. This directive requires the inspection and modification of the forward fuselage upper longerons to prevent potential structural failures (Section 1). The main requirements include visually inspecting the upper longerons for cracks in specific areas and modifying them using a tubular split-sleeve modification as outlined in Ayres Corporation Service Bulletin No SB-AG-16 dated 1 April 1984. The directive imposes several obligations on the operators of the affected aircraft. Firstly, the operator must ensure that the specified inspection of the forward fuselage upper longerons is conducted before further flight after 17 May 1984 and at intervals not exceeding 10 hours' time in service, until the modification is completed. The inspection must be performed by removing the fuselage side skins between the wing upper surface and the hopper to access the upper longerons between the firewall and the cockpit. Secondly, the operator must incorporate the tubular split-sleeve modification P/N CK-AG-19 on both upper longerons within 100 hours’ time in service after 17 May 1984. If the pilot in command performs the inspection, they must enter and certify for this AD in column 2 part 3 of the maintenance release on each occasion. Failure to comply with the provisions of AD/AC-SNOW/15 may result in significant consequences. The Civil Aviation Safety Authority (CASA) may take enforcement actions against operators who do not adhere to the inspection and modification requirements. While the specific penalties are not outlined in the legislation, non-compliance with ADs can lead to enforcement actions such as fines, grounding of the aircraft, or other regulatory sanctions. The safety of the aircraft and its occupants is paramount, and adherence to these directives is critical to prevent potential catastrophic failures in service.