AD/HS 125/93 - Electrical Power - DC Bus Tie System

Overview

The Civil Aviation Regulations 1998, amended by F2006B10536, is a legislative instrument introduced by the Australian Government to enhance the safety standards in civil aviation. This particular update, part of the Civil Aviation Safety Authority’s schedule of airworthiness directives, specifically addresses the BAe 125 Series Aeroplanes. The regulation was enacted to address a problem identified in the electrical power system of the BAe 125 aeroplanes, particularly the DC bus tie system, which had potential safety implications if not properly managed. The Civil Aviation Safety Authority, under the authority of the Australian Parliament, established this directive to ensure compliance with safety standards and to mitigate any risks associated with the identified issue. The policy objective is to ensure the safety of aircraft operations by enforcing necessary modifications and actions as outlined in BAe 125 Service Bulletin 24-264, particularly for aircraft modified post 251335, and ensuring compliance prior to a specified date.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39 - 105, specifically pertain to the Civil Aviation Safety Authority Schedule of Airworthiness Directives for the British Aerospace BAe 125 Series Aeroplanes, as outlined in AD/HS 125/93. This regulation applies to all BAe 125 aircraft that have undergone modification 251335 or later. The requirement mandates that the action specified in BAe 125 SB 24-264 must be undertaken, ensuring compliance prior to 6 October 1988. The directive addresses an issue where the PS1 and PS2 DC bus bars were found to remain electrically connected despite the bus-tie contactor being opened, which poses a safety risk. The scope of this legislation extends to all entities operating BAe 125 aircraft within the Commonwealth of Australia, ensuring that these safety measures are universally implemented across the national airspace. This regulation does not provide specific exclusions or exemptions but necessitates strict adherence to the stipulated modifications to maintain airworthiness standards.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, include a Schedule of Airworthiness Directives that address the safety and compliance requirements for various aircraft types, including the British Aerospace BAe 125 series aeroplanes. One such directive, AD/HS 125/93, pertains to the electrical power systems of these aircraft, more precisely the DC Bus Tie System (section 8/88). This directive is applicable to all BAe 125 aircraft that have undergone modification 251335 or later. The requirement outlined in this directive is that all such aircraft must be addressed in accordance with BAe 125 Service Bulletin 24-264. This directive applies to aircraft that were in compliance prior to 6 October 1988. The obligations imposed by this directive include ensuring that the electrical power systems, particularly the DC Bus Tie System, are maintained and operated in accordance with the specified service bulletin. This involves implementing any necessary modifications or checks to prevent the PS1 and PS2 DC bus bars from remaining electrically connected when the bus-tie contactor is opened, a scenario that British Aerospace has reported as having occurred. Compliance with this directive ensures that the specified aircraft meet the safety standards required by the Civil Aviation Safety Authority (CASA). Failure to adhere to the requirements set out in the directive may result in significant safety risks, including potential electrical failures that could compromise the operation of the aircraft. The consequences for non-compliance with this directive are severe and include both civil and potential criminal penalties. The Civil Aviation Safety Authority has the authority to take enforcement actions against any person or entity that fails to comply with the provisions of the Civil Aviation Regulations 1998. Offences related to non-compliance with airworthiness directives can result in fines, and in more serious cases, criminal charges. The maximum penalties can include substantial financial penalties and, in cases where the non-compliance has led to an accident or serious incident, imprisonment. It is critical for operators of BAe 125 aircraft to ensure strict adherence to these directives to avoid such severe consequences.