AD/GENERAL/43 - Power Supply Connections to Hourmeters

Overview

The Civil Aviation Regulations 1998, as part of the broader legislative framework governing aviation safety in Australia, was enacted to ensure the safety and efficiency of civil aviation within the country. This legislation, overseen by the Civil Aviation Safety Authority, aims to establish and maintain a high standard of safety for all civil aviation activities. One specific focus of these regulations is outlined in the Airworthiness Directive AD/GENERAL/43, which addresses the critical issue of power supply connections to hourmeters on aircraft. This directive was introduced to mitigate potential hazards associated with improper connections, ensuring that hourmeters are not linked to Class 1 circuits and require appropriate protective measures if such connections are identified. The directive mandates inspections and necessary modifications within a specific timeframe to ensure compliance and enhance the overall safety of aircraft operations. The Civil Aviation Regulations 1998 were enacted by the Parliament of Australia to establish comprehensive regulations governing civil aviation safety, with the Civil Aviation Safety Authority acting as the primary enforcing body. The policy objective of AD/GENERAL/43 is to prevent potential electrical faults and system failures by ensuring that hourmeters are correctly isolated from critical circuits, thereby reducing the risk of accidents and maintaining the integrity of aircraft systems. Compliance with this directive is mandatory for all aircraft fitted with hourmeters, highlighting the importance of regular inspections and adherence to specified safety standards within the stipulated timeframe to maintain airworthiness and ensure the safety of all personnel involved in civil aviation activities.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Airworthiness Directives issued by the Civil Aviation Safety Authority and applies to all aircraft fitted with hourmeters within the Commonwealth of Australia. The directive AD/GENERAL/43 dated 6/70 mandates that aircraft hourmeters should not be connected to a Class 1 circuit. In instances where an hourmeter is found connected to a Class 1 circuit, the requirement is either to fit separate graded protection or to remove the system from the Class 1 circuit and connect it through a separate protective device. A notable exception is for hourmeters powered through the landing gear up lock switch, such as those found in Beech Aircraft, which must have a fuse or circuit breaker installed at the up lock switch connection. This protective device should be of such a value that it will open the circuit before the landing gear control and indication circuit breaker trips. Compliance with these directives is required within 100 hours of time in service after 30 June 1970.

Key Provisions

The Civil Aviation Regulations 1998 (Part 39 - 105) contain several key sections, including AD/GENERAL/43, which specifically addresses the power supply connections to hourmeters for all aircraft. According to section 1 of this directive, it is mandatory to inspect the hourmeter installation to ensure that it is not connected to a Class 1 circuit. If the hourmeter is found to be connected to a Class 1 circuit, the regulation stipulates that separate graded protection must be fitted or the system must be removed from the Class 1 circuit and connected through a separate protective device (section 2). Notably, for hourmeters that use the power supply through the landing gear up lock switch, such as those in Beech Aircraft, it is required to have a fuse or circuit breaker at the up lock switch connection, ensuring it will open the circuit before the landing gear control and indication circuit breaker trips. The obligations imposed by these provisions are clear and directive. Aircraft operators and owners must ensure that the inspections and necessary modifications are carried out within 100 hours of the aircraft being in service after 30 June 1970. This timeframe is non-negotiable and compliance is mandatory for all aircraft that fall under this directive. The directive aims to enhance safety by preventing potential electrical failures that could lead to hazardous situations during flight operations. Failure to comply with these safety directives can lead to significant consequences. While the specific regulatory text does not explicitly state the penalties for non-compliance, breaches of Civil Aviation Regulations can typically result in severe sanctions. These may include enforcement actions by the Civil Aviation Safety Authority (CASA), fines, suspension or revocation of airworthiness certificates, and potential criminal charges in cases where negligence leads to accidents or endangers lives. The gravity of the penalties underscores the importance of adhering strictly to the stipulated requirements to ensure the highest standards of aviation safety are maintained.