AD/HU 369/72 - Horizontal Stabilizer

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, establish comprehensive regulations governing civil aviation in Australia, with a particular focus on maintaining the highest safety standards. A specific legislative instrument under this act, F2006B10737, addresses a critical safety concern identified with the McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters, particularly models 369E and 369F/FF. The problem this legislation aims to resolve is the cracking of the horizontal stabilizer skin and tabs at the outboard ends, which can result in dangerous flutter due to vibration. The policy objective behind this regulation is to ensure the airworthiness of these helicopters by mandating a preventive modification to enhance the structural integrity of the horizontal stabilizer, thereby averting potential safety hazards. Compliance with these directives is mandatory within 100 hours of time in service after 1 December 1987, or by 1 March 1988, whichever comes first.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses safety directives related to airworthiness, with a focus on the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters. The regulation mandates modifications to the horizontal stabilizer assembly for all model 369E and 369F/FF series helicopters, requiring the removal of existing tab weights and the installation of stiffeners on the outboard ends of the stabilizer in accordance with McDonnell Douglas Helicopter Company SIN No. EN-40/FN-29. This directive is preventive, aimed at addressing potential cracking due to vibration, which could lead to flutter. Importantly, any existing cracks detected during the modification process must be separately repaired. Compliance with this directive must be achieved within 100 hours of time in service after 1 December 1987, or by 1 March 1988, whichever comes first. The regulation applies to all operators of the specified helicopter models, ensuring a consistent standard of airworthiness across the industry within the Commonwealth of Australia. The scope of the directive is national, overseen by the Civil Aviation Safety Authority.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, contains provisions related to the modification of McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters. Section AD/HU 369/72, dated 2 August 1988, mandates the modification of the horizontal stabilizer assembly on all model 369E and 369F/FF series helicopters. This requirement is detailed in the directive, which stipulates that existing tab weights must be removed and stiffeners installed on the outboard ends of the stabilizer, in accordance with McDonnell Douglas Helicopter Company SIN No. EN-40/FN-29. It is important to note that this directive is intended as a preventive measure rather than a repair scheme for pre-existing cracks. Should any cracks be detected during the modification process, they must be repaired separately. The Act imposes specific obligations on the parties and entities it governs. Operators of model 369E and 369F/FF series helicopters must ensure that the required modifications to the horizontal stabilizer assembly are carried out. The modifications must be completed within 100 hours of time in service after 1 December 1988, or by 1 March 1988, whichever occurs first. This compliance timeframe ensures that the safety measures are implemented promptly to mitigate the risk of cracking and potential flutter. Failure to comply with the provisions outlined in Section AD/HU 369/72 can result in significant consequences. The Act does not specify explicit offences or penalties within the directive itself, but non-compliance with Civil Aviation Regulations can lead to enforcement actions by the Civil Aviation Safety Authority. Such actions may include fines, grounding of the aircraft, or other regulatory penalties. The severity of the consequences can depend on the specific circumstances of the non-compliance and the impact on aviation safety.