AD/HU 269/69 - Alternator Circuit Protection - Modification

Overview

The Civil Aviation Orders (CAO) 1998 were enacted to establish a regulatory framework for civil aviation safety in Australia. This legislative instrument was introduced to address the need for a comprehensive and cohesive set of rules and standards governing the operation of civil aircraft within Australia, ensuring the highest levels of safety for all persons involved in aviation activities. The enactment of the Civil Aviation Orders 1998 was authorised by the Australian Parliament, with the primary policy objective being to provide for the regulation of civil aviation in Australia in a manner that safeguards the interests of the public and promotes the efficient and orderly development of civil aviation. The Civil Aviation Orders 1998 establish a framework for the issuance of airworthiness directives, including the specific requirements for the Schweizer (Hughes) 269 Series Helicopters, as outlined in AD/HU 269/69. This airworthiness directive, issued by the Civil Aviation Safety Authority, addresses a known issue with the helicopter's electrical system that may lead to smoke in the cockpit and potential grounding of the field circuit within the alternator. By mandating specific modifications to the helicopter's electrical system, the directive aims to prevent these issues and ensure the continued safe operation of the affected aircraft.

Scope and Application

The Civil Aviation Orders, specifically Part 105 Schedule of Airworthiness Directives, apply to all Schweizer (Hughes) 269 Series Helicopters operating under Instrument Flight Rules (IFR) or flights at night in Visual Meteorological Conditions (VMC). This legislation mandates that all such helicopters must undergo modifications to the alternator circuit protection to mitigate the risk of smoke in the cockpit and potential grounding of the field circuit within the alternator, which could lead to the loss of all electrical power and pose a significant hazard. The requirement is to install a 5 ampere circuit protective device between specific cables and the alternator switch, as well as another protective device between the alternator positive-cable and the bus, identified as “Alternator Field” and “Alternator” respectively. Compliance with these directives must be achieved within 100 hours of time in service after 30 June 1980. The legislative instrument does not specify exclusions or exemptions but provides acceptable means of compliance through the use of inline fuses and devices that meet the requirements of the cable and circuit protector coordination chart outlined in ANO 108.32, Appendix 3, Table 6.

Key Provisions

The Civil Aviation Orders, specifically Part 105 Schedule of Airworthiness Directives, addresses safety requirements for Schweizer (Hughes) 269 Series Helicopters. Section AD/HU 269/69 pertains to an essential modification related to the alternator circuit protection, which is applicable to all 269 Series helicopters operating under Instrument Flight Rules (IFR) or flights at night in Visual Meteorological Conditions (VMC). The directive mandates two specific installations: first, a 5 ampere circuit protective device between the cable-coded P34A20 and the alternator switch (269A4613), clearly marked as “Alternator Field”; and second, a protective device between the alternator positive-cable and the bus, sized according to the cable installed and marked as “Alternator.” Acceptable methods of compliance include using an inline fuse and adhering to the cable and circuit protector coordination chart in ANO 108.32, Appendix 3, Table 6. The obligations imposed by this Act require aircraft operators to ensure that these modifications are completed within 100 hours of time in service after 30 June 1980. This timeframe is crucial to address safety concerns identified in recent defect reports, such as smoke in the cockpit due to grounding within the alternator's field circuit and potential earth on the alternator positive line, which could necessitate the removal of all electrical power from the aircraft. These modifications are considered highly important to maintain airworthiness and safety, particularly in NVMC and VFR conditions. Failure to comply with the directives outlined in AD/HU 269/69 may result in significant civil and criminal consequences. While specific penalties are not detailed in the provided text, non-compliance with Civil Aviation Orders generally carries potential penalties under the Civil Aviation Act 1988. This could include fines, enforcement actions, and potential grounding of the aircraft, which could lead to severe operational disruptions and safety risks. Ensuring adherence to these airworthiness directives is paramount to maintaining the safety standards required by the Civil Aviation Safety Authority (CASA).