AD/SD3-60/21 - Landing Gear Warning Horn

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, were enacted to regulate the safety of civil aviation within Australia. A key legislative instrument under this regulation is the AD/SD3-60/21 Airworthiness Directive concerning the landing gear warning horn for Short SD3-60 Series aeroplanes. This directive was introduced in response to reports indicating that the Keystone P/No. AC155F landing gear warning horn was inaudible when installed between Station 3 and 13.45 on the aircraft's top centre line, thus posing a safety risk. The directive mandates the relocation of the horn according to specific guidelines to ensure the continued effectiveness of the warning system, thereby addressing the identified safety gap and aligning with the overarching policy objective of maintaining high safety standards in civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, applies to all entities involved in the operation and maintenance of SD3-60 series aeroplanes with serial numbers SH3601 through SH3689. This legislation mandates the relocation of the mounting of the landing gear warning horn when replacing or fitting a specific model of the horn, as outlined in the AD/SD3-60/21 directive. The requirement necessitates adherence to the specifications provided in Shorts SD3-60 Service Bulletin SD360-32-23. The compliance timelines differ slightly depending on the condition of the aeroplane; for those replacing the Lucas horn with the Keystone horn, compliance is required upon replacement, while those already equipped with the Keystone horn must comply within 30 hours of time in service after 31 January 1987. This directive is issued under the authority of the Civil Aviation Safety Authority and pertains to the Commonwealth of Australia, ensuring that all relevant operators and maintenance providers comply with the specified safety directives.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, which details the Civil Aviation Safety Authority Schedule of Airworthiness Directives, includes a directive pertinent to SD3-60 Series Aeroplanes, designated as AD/SD3-60/21, focusing on the Landing Gear Warning Horn. This directive applies to all SD3-60 aeroplanes with serial numbers ranging from SH3601 to SH3689 (Part 39 - 105). The primary requirement of this directive is the relocation of the mounting of the landing gear warning horn when replacing or retrofitting the Lucas horn P/No V.0603L with the Keystone horn P/No. AC155F, as stipulated in Shorts SD3-60 Service Bulletin SD360-32-23 (AD/SD3-60/21, Para 1). Additionally, for aeroplanes already equipped with the Keystone horn P/No. AC155F, the mounting must be relocated in accordance with the same service bulletin, but within 30 hours of time in service after 31 January 1987 (AD/SD3-60/21, Para 2). Under these regulations, operators and maintenance personnel are obligated to follow the specified procedures for horn relocation to ensure compliance with safety standards. For aeroplanes undergoing a horn replacement, the new Keystone horn must be installed according to the specified requirements immediately upon replacement (AD/SD3-60/21, Para 1). In the case of aeroplanes already equipped with the Keystone horn, the relocation must be completed within 30 hours of time in service after 31 January 1987 (AD/SD3-60/21, Para 2). Failure to adhere to these requirements may compromise the effectiveness of the landing gear warning horn, potentially leading to safety issues. The consequences of non-compliance with AD/SD3-60/21 are significant. The Civil Aviation Regulations 1998 enforce strict penalties for violations of airworthiness directives. Operators who fail to comply with the specified directives can face substantial civil penalties, as outlined in the relevant sections of the Civil Aviation Act 1988. Additionally, failure to adhere to these safety directives could result in the aircraft being grounded until compliance is achieved, thus impacting operational availability and potentially leading to criminal charges for those responsible for the oversight.