AD/AS 355/10 Amdt 4 - Main Rotor Mast

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, aim to provide comprehensive regulations for civil aviation safety. This legislation seeks to address potential safety hazards and ensure the highest standards of safety for all aviation activities within Australia. A specific amendment to these regulations, identified as AD/AS 355/10 Amendment 4, targets the issue of fatigue cracks in the main rotor masts of Eurocopter AS 355 (Twin Ecureuil) Series Helicopters. This amendment responds to an incident where a fatigue crack, originating from an undetected corrosion pit, propagated to a critical size within 170 hours of service. The policy objective is to mandate visual checks and necessary inspections of the main rotor masts to prevent such occurrences, thereby enhancing overall aviation safety. Compliance with these directives is crucial to averting potential catastrophic failures.

Scope and Application

The Civil Aviation Regulations 1998, under the Civil Aviation Act 1988, govern the safety standards for aviation in Australia, with Part 39 specifically addressing airworthiness directives. This legislation applies to all Eurocopter AS 355 (Twin Ecureuil) series helicopters equipped with specific main rotor masts, namely those with part numbers 350A37.1076.04,.05, or.06. The directive mandates that operators must perform a visual check and, if necessary, a dye penetrant inspection as per Aerospatiale Service Bulletin 05-08 Revision 2 paragraphs C(1) and C(2), and protect any reworked surfaces in accordance with paragraph C(3). Magnetic particle inspection is permitted as an alternative to dye penetrant inspection, which is considered the preferred technique. The directive references additional requirements from Bureau Veritas AD 85-94-25(b) and Bureau Veritas AD 83-174-20(b). Compliance with these directives is required within 10 hours of time in service after 30 November 1985, unless already completed, and further details are provided in Aerospatiale Service Bulletin 05-08 Revision 2 paragraph D. This legislative instrument ensures the safety and airworthiness of these helicopter models by addressing a historical issue where a fatigue crack led to critical failure due to undetected corrosion.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, detail the requirements for the airworthiness directives concerning Eurocopter AS 355 (Twin Ecureuil) Series Helicopters, as outlined in AD/AS 355/10 Amendment 4. This legislative instrument focuses on the inspection and maintenance of the main rotor masts, particularly those identified by part numbers 350A37.1076.04,.05, or.06. The primary requirement (1) mandates a visual inspection and, if necessary, a dye penetrant inspection as stipulated in Aerospatiale Service Bulletin (SB) 05-08 Revision 2 paragraphs C(1) and C(2), with magnetic particle inspection being an acceptable alternative (section 1(a)). Following any necessary rework, the surfaces must be protected according to paragraph C(3) of the same Service Bulletin (section 1(b)). The inspection must be performed within 10 hours of service time after 30 November 1985, or if the inspection has already been completed, as per the detailed instructions in Aerospatiale SB 05-08 Revision 2 paragraph D (section 2). The obligations under this directive include ensuring that the inspections are performed by qualified personnel who are familiar with the procedures outlined in the referenced Aerospatiale SB 05-08 Revision 2. The operators of these helicopters must ensure that the inspections are documented accurately, with any findings or rework actions being recorded. Furthermore, any rework performed must adhere to the specifications provided in the Service Bulletin to maintain the structural integrity of the main rotor mast. Additionally, the directive references Bureau Veritas AD 85-94-25(b) and Bureau Veritas AD 83-174-20(b), which provide supplementary requirements and guidance on the inspection procedures. Failure to comply with the provisions outlined in the AD/AS 355/10 Amendment 4 can lead to significant consequences. The regulations do not explicitly state the penalties for non-compliance, but any breach of the Civil Aviation Regulations 1998 can result in enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions may include fines, enforcement notices, or the grounding of the aircraft until the required inspections and any necessary repairs are completed. The potential for civil or criminal liability also exists if non-compliance leads to an aviation accident or incident, which could result in severe penalties under the applicable aviation and safety legislation.